M12+ GPS Receiver User’s Guide
DOCUMENT PREPARED BY SYNERGY SYSTEMS, LLC. Information in this document is subject to change without notice and does not represent a commitment on the part of Motorola, Inc. The software described in this document is furnished under a license agreement. The software may be used or copied only in accordance with the terms of the agreement. Motorola, Inc.
Table of Contents CHAPTER 1 – INTRODUCTION 1 OVERVIEW M12+ Positioning Receiver M12+ Timing Receiver 2 2 2 PRODUCT HIGHLIGHTS 3 APPLICATIONS 4 LIMITED WARRANTY ON MOTOROLA GPS PRODUCTS How to Get Warranty Service 5 6 CHAPTER 2 - NAVSTAR GPS OVERVIEW 7 ABOUT THE GPS NAVIGATION MESSAGE Space Segment Ground Control Segment User Segment Additional Information Sources 8 8 8 8 10 CHAPTER 3 - RECEIVER DESCRIPTIONS 11 OVERVIEW Memory Backup Operating With a Backup Source Operating Without a Backup S
Automatic Site Survey (M12+ Timing Receiver Only) 100PPS Output (M12+ Timing Receiver Only) Mean Time Between Failure (MTBF) 24 24 25 Receiver Module Installation Electrostatic Precautions Electromagnetic Considerations RF Shielding Thermal Considerations Grounding Considerations PCB Mounting Hardware 25 25 26 26 26 26 27 System Integration Interface Protocols Serial Input/Output Motorola Binary Format Exclusive-Or (XOR) Checksum creation Millisecond to Degree Conversion NMEA Protocol Support NMEA Comma
CHAPTER 4 – ANTENNA DESCRIPTIONS Motorola HAWK Antenna Antenna Description Hawk Antenna Gain Pattern 51 52 52 54 Motorola Part Numbers RF Connectors/Cables Information Antenna Placement Antenna System RF Parameter Considerations Antenna Cable RF Connectors 57 58 59 60 61 Motorola Timing2000 Antenna Antenna Description Timing2000 Antenna Gain Pattern Timing2000 Installation Precautions Timing2000 Antenna Mounting Timing 2000 Antenna in Extreme Weather and Environmental Conditions Timing2000 Antenna Cable
1PPS TIME OFFSET COMMAND (@@Ay) 100 1PPS CABLE DELAY CORRECTION COMMAND (@@Az) 102 VISIBLE SATELLITE DATA MESSAGE (@@Bb) 104 ALMANAC DATA REQUEST (@@Be) 108 EPHEMERIS DATA INPUT (@@Bf) 110 PSEUDO-RANGE CORRECTION OUTPUT REQUEST (@@Bh) 112 LEAP SECOND STATUS MESSAGE (@@Bj) 114 UTC OFFSET OUTPUT MESSAGE (@@Bo) 116 REQUEST UTC/IONOSPHERIC DATA (@@Bp) 118 ALMANAC DATA INPUT (@@Cb) 120 PSEUDO-RANGE CORRECTION DATA INPUT (@@Ce) 122 SET TO DEFAULTS COMMAND (@@Cf) 124 NMEA PROTOCOL SELECT (@
12 CHANNEL TIME RAIM STATUS MESSAGE (@@Hn) 166 INVERSE DIFFERENTIAL WITH PSEUDORANGE OUTPUT (@@Hr) 12 CHANNEL SELF-TEST MESSAGE (@@Ia) 168 175 SYSTEM POWER-ON FAILURE (@@Sz) 176 NMEA GPGGA MESSAGE 178 GPGLL (NMEA GEOGRAPHIC LATITUDE AND LONGITUDE) 182 GPGSA (GPS DOP AND ACTIVE SATELLITES) 184 GPGSV (NMEA GPS SATELLITES IN VIEW) 186 GPRMC (NMEA RECOMMENDED MINIMUM SPECIFIC GPS/TRANSIT DATA) 188 GPVTG (NMEA TRACK MADE GOOD AND GROUND SPEED)0 190 GPZDA (NMEA TIME AND DATE) 192 SWITCH I/O FO
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Chapter 1 - Introduction Chapter 1 – INTRODUCTION CHAPTER SUMMARY Refer to this chapter for the following: • An introduction to GPS and the Motorola M12+ Oncore receivers • A limited warranty for the receivers Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 1 - Introduction OVERVIEW Nearly a decade of Global Positioning System (GPS) experience, combined with world-class expertise in semiconductor products and communications development, has led Motorola to the production of the M12+ GPS receiver modules, more compact and lightweight than ever before. Each channel independently tracks both code and carrier for the superior performance required in today's GPS user environment.
Chapter 1 - Introduction PRODUCT HIGHLIGHTS Features present on all M12+ receivers include the following: • 12-channel parallel receiver design • Code plus carrier tracking (carrier-aided tracking) • Position filtering • Antenna current sense circuitry • Operation from +2.85 to +3.
Chapter 1 - Introduction APPLICATIONS Considering that 24-hour, all weather, worldwide coverage is fundamental to GPS positioning and navigation, it is easy to envision a broad range of applications and a large community of GPS users.
Chapter 1 - Introduction LIMITED WARRANTY ON MOTOROLA GPS PRODUCTS What This Warranty Covers And For How Long MOTOROLA, INC. ("MOTOROLA") warrants its Global Positioning System (GPS) Products ("Product") against defects on material and workmanship under normal use and service for a period of twelve (12) months from Product's in-service date, but in no event longer than eighteen (18) months from initial shipment of the Product.
Chapter 1 - Introduction (e) Product disassembled or repaired in such a manner as to adversely affect performance or prevent adequate inspection and testing to verify any warranty claim. (f) Product which has had the serial number removed or made illegible. (g) Freight costs to the repair depot. How to Get Warranty Service To receive warranty service, contact your Oncore reseller. General Provisions This warranty sets forth the full extent of MOTOROLA's responsibility regarding the Product.
Chapter 2 - NAVSTAR GPS Overview Chapter 2 - NAVSTAR GPS OVERVIEW CHAPTER SUMMARY Refer to this chapter for the following: • A description of the NAVSTAR GPS segments • An explanation of the GPS navigation message • A list of available public GPS information services Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 2 - NAVSTAR GPS Overview ABOUT THE GPS NAVIGATION MESSAGE The NAVigation Satellite Timing and Ranging (NAVSTAR) Global Positioning System is an all weather, radio based, satellite navigation system that enables users to accurately determine 3dimensional position, velocity, and time worldwide. The overall system consists of three major segments: the space segment, the ground control segment, and the user segment.
Chapter 2 - NAVSTAR GPS Overview Figure 2.1 NAVSTAR GPS Segments The GPS navigation message is the data supplied to the user from a satellite. Signals are transmitted at two L-band frequencies, L1 and L2, to permit corrections to be made for ionospheric delays in signal propagation time in dual frequency receivers. The L1 carrier is modulated with a 10.23 MHz precise (P-code) ranging signal and a 1.023 MHz coarse acquisition (C/A code) ranging signal.
Chapter 2 - NAVSTAR GPS Overview The navigation message consists of a 50 bit per second data stream containing information enabling the receiver to perform the computations required for successful navigation. Each satellite has its own unique C/A code that provides satellite identification for acquisition and tracking by the user. There are several GPS related sites on the World Wide Web that are excellent sources of information about GPS and the current status of the satellites.
Chapter 3 - Receiver Descriptions CHAPTER 3 - RECEIVER DESCRIPTIONS CHAPTER SUMMARY Refer to this chapter for the following: • A simplified functional description of the operation of the M12+ Oncore receiver • Antenna power and gain requirements • Physical size and electrical connections of the M12+ Oncore receiver • M12+ Oncore receiver technical characteristics and operating features • M12+ installation precautions and mounting considerations • Binary and NMEA interface protocol descriptions
Chapter 3 - Receiver Descriptions OVERVIEW The M12+ Oncore receiver provides position, velocity, time, and satellite tracking status information via a serial port. A simplified functional block diagram of the M12+ receiver is shown below in Figure 3.1. Figure 3.1: M12+ Oncore Receiver Functional Block Diagram 12 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 3 - Receiver Descriptions The M12+ Oncore receiver is capable of tracking twelve satellites simultaneously. The module receives the L1 GPS signal (1575.42 MHz) from the antenna and operates off the coarse/acquisition (C/A) code tracking. The code tracking is carrier aided. Time recovery capability is inherent in the architecture. The L1 band signals transmitted from GPS satellites are typically collected, filtered, and amplified by microstrip patch antennas such as the Motorola Hawk or Timing 2000.
Chapter 3 - Receiver Descriptions Operating Without a Backup Source Without any backup power none of the setup information mentioned above is available to the receiver upon restart. The receiver must now perform a “Cold Start”, where position, time, and almanac information are not available. Note that this is not a serious problem, but Time To First Fix (TTFF) will be somewhat longer than if the information had been available.
Chapter 3 - Receiver Descriptions Antenna Drive and Protection Circuitry The M12+ is capable of detecting the presence of an antenna. The receiver utilizes an antenna sense circuit that can detect under current (open condition), over current (shorted or exceeding maximum receiver limits), or a valid antenna connection. The M12+ is designed to provide up to 80 mA of current via the antenna power supply circuit.
Chapter 3 - Receiver Descriptions The antenna status information is output in the following I/O messages: • • • @@Ha(12 Channel Position/Status/Data Message) @@Hb (12 Channel Short Position Message) @@Ia (12 Channel Self-Test Message). NOTE: Detection of an under current situation will not prevent the M12+ from operating. The M12+ will continue to operate normally, but will raise the error flag in the three messages, indicating a possible antenna problem. A chart of the typical output voltage vs.
Chapter 3 - Receiver Descriptions Active Antenna Configuration The recommended external gain (antenna gain minus cable and connector losses) for the M12+ is 18 to 36 dB. A typical antenna system might have an active antenna such as the Motorola Hawk with 29 dB of gain and five meters of cable with 5 dB of loss. The net external gain would then be 24 dB, which is well within the acceptable range.
Chapter 3 - Receiver Descriptions The following table lists the assigned signal connections of the M12+ receiver's power/data connector. Table 3.
Chapter 3 - Receiver Descriptions M12+ ONCORE RECEIVER PRINTED CIRCUIT BOARD MECHANICAL DRAWINGS 4 PLCS Ø0.125 [Ø3.2] 2.362 [60.0] OPTIONAL BATTERY M*CORE MICROPROCESSOR 1.347 [34.2] 0,0 - ORIGIN 0.662 [16.8] 1.575 [40.0] MMCX CONNECTOR PIN 10 RFIC PIN 2 PIN 9 XTAL PIN 1 1.570 [39.9] 0.114 [2.9] 0.100 [2.5] 2.134 [54.2] 0.043 [1.1] Figure 3.4: 0.299 [7.6] 0.125 [3.2] 0.225 [5.7] 0.063 [1.6] M12+ Oncore Printed Circuit Board Layout with Straight, 0.050" [1.
Chapter 3 - Receiver Descriptions M12+ ONCORE RECEIVER TECHNICAL CHARACTERISTICS Table 3.2: M12+ Positioning Receiver Characteristics GENERAL CHARACTERISTICS PERFORMANCE CHARACTERISTICS Receiver Architecture 12 Channel L1 (1575.42 MHz) operation C/A code (1.
Chapter 3 - Receiver Descriptions M12+ TIMING RECEIVER TECHNICAL CHARACTERISTICS Table 3.3: M12+ Timing Receiver Characteristics GENERAL CHARACTERISTICS PERFORMANCE CHARACTERISTICS Receiver Architecture 12 Channel L1 (1575.42 MHz) operation C/A code (1.
Chapter 3 - Receiver Descriptions RF Jamming Immunity (M12+ Timing Receiver Only) Many precise timing GPS installations require locating the GPS antenna at close range to other systems. Some of these transmitters may randomly cause the GPS receiver to lose lock on tracked satellites. This can be very disconcerting to the timing user since the system must rely on clock coasting until the satellite signals are reacquired.
Chapter 3 - Receiver Descriptions In most surveying systems and instruments, there are more measurements taken than are required to compute the solution. The excess measurements are redundant. A system can use redundant measurements in an averaging scheme to compute a blended solution that is more robust and accurate than using only the minimum number of measurements required. Once a solution is computed, the measurements can be inspected for blunders. This is the essence of TRAIM.
Chapter 3 - Receiver Descriptions Automatic Site Survey (M12+ Timing Receiver Only) The Automatic Site Survey mode simplifies system installation for static timing applications. This automatic position determination algorithm is user initiated and can be deactivated at any time. The Automatic Site Survey averages a total of 10,000 (slightly over 2 1/2 hours) valid 2D and 3D position fixes. If the averaging process is interrupted, the averaging resumes where it left off when tracking resumes.
Chapter 3 - Receiver Descriptions Figure 3.6 100PPS Output Waveform The 1PPS Offset and 1PPS Cable Delay features work the same in 100PPS mode as they do in 1PPS mode. In 100PPS mode, these commands are used to accurately control the placement of the pulse after the long pulse. Mean Time Between Failure (MTBF) The MTBF for the M12+ Oncore family of GPS receivers has been computed using the methods, formulas, and database of MIL-HDBK-217 to be approximately 750,000 hours (>85 years) at 40ºC.
Chapter 3 - Receiver Descriptions Electromagnetic Considerations The Oncore receiver PC boards contain a very sensitive RF receiver; therefore you must observe certain precautions to prevent possible interference from the host system. Because the electromagnetic environment will vary for each OEM application, it is not possible to define exact guidelines to assure electromagnetic compatibility. The frequency of GPS is 1.575 GHz.
Chapter 3 - Receiver Descriptions PCB Mounting Hardware The M12+ Oncore PCB is normally mounted on round or hex female threaded metal standoffs and retained with metal English or metric screws. Mounting standoffs are available in a wide variety of materials with English or metric threads. Several sources are listed in Table 3.5.
Chapter 3 - Receiver Descriptions Table 3.5: List of Threaded Standoff Suppliers Company Name Keystone Electronic Corp. Tel: 718.956.8900 Fax: 718.956.9040 www.keyelco.com RAF Electronics Hardware Tel: 203.888.2133 Fax: 203.888.9860 www.rafhdwe.com PEM Engineering and Manufacturing Corp. Tel: 215.766.8533 Fax: 215.766.0143 Part Description Plain female or 4-40 threaded standoffs, available in lengths of 0.125" to 1.0" Plain female or M2.5 and M3.
Chapter 3 - Receiver Descriptions System Integration The M12+ receiver is an intelligent GPS sensor intended to be used as a component in a precision positioning, navigation, or timing system. The M12+ is capable of providing autonomous position, velocity, and time information over a standard serial port. The minimum usable system combines the M12+ receiver, antenna, and an intelligent system controller device.
Chapter 3 - Receiver Descriptions inversion process in it. Most RS-232 driver/receiver integrated circuits (Maxim's MAX3232, for example) will provide all these functions with only a +3V power supply.
Chapter 3 - Receiver Descriptions Binary Data Sequence: A variable number of bytes of binary data dependent on the command type. Checksum: The Exclusive-Or of all bytes after the '@@', and prior to the checksum. Message Terminator: '0x0D 0x0A' - Carriage Return/Line Feed pair denoting the end of the binary message. Almost all receiver input commands have a corresponding response message so that you can determine whether the input command(s) have been accepted or rejected by the receiver.
Chapter 3 - Receiver Descriptions may be of the type that changes configuration parameters of the receiver. Examples of these input command types include commands to change the initial position, receiver internal time and date, satellite almanac, etc. These input commands, when received and validated by the receiver, change the indicated parameter and result in a response message to show the new value of the parameter that was changed.
Chapter 3 - Receiver Descriptions next message to be sent fits around the 800 byte length goal, then the message will be output. For example, if messages totaling 758 bytes are scheduled to be sent, and the user requests another 58 byte message, then 816 bytes will actually be sent. If the user requests yet another 86 byte message, then its output will be left pending and will be scheduled when the total number of output bytes allows.
Chapter 3 - Receiver Descriptions Exclusive-Or (XOR) Checksum creation In Motorola binary mode a checksum must be included with every command to the receiver. Conversely, all messages from the receiver include a checksum that may be used to verify the contents of the message. An example message is used to illustrate the procedure.
Chapter 3 - Receiver Descriptions Millisecond to Degree Conversion The primary output message of M12+ receiver in Motorola binary mode is the 12 Channel Position/Status/Data Message (@@Ha). In this message, the latitude and longitude are reported in milliarcseconds, (or mas). An example of converting mas to degrees is illustrated below. One degree of latitude or longitude has 60 arcminutes, or 3600 arcseconds, or 3,600,000 milliarcseconds.
Chapter 3 - Receiver Descriptions NMEA Protocol Support The M12+ Positioning Receiver firmware supports the NMEA 0183 format for GPS data output. Output of data in the NMEA-0183 standard format allows a direct interface via the serial port to electronic navigation instruments that support the specific output messages. NMEA formatted messages may also be used with most commercially available mapping and tracking programs.
Chapter 3 - Receiver Descriptions NMEA Command Examples 1. Assume the user desires a single (polled) RMC message. The required command string (without the optional checksum) is: $PMOTG,RMC,0000, 2. Assuming that the user now desires the RMC message to be sent once each second, the command string would change to: $PMOTG,RMC,0001, NMEA Response Examples The response to the command in Example 1 above would be: $GPRMC,hhmmss.ss,a,ddmm.mmmm,n,ddmm.mmmm,w,z.z,y.y,d.
Chapter 3 - Receiver Descriptions example, if messages totaling 334 bytes are scheduled to be sent, and the user requests another 80 byte message, then 414 bytes will actually be sent. If the user requests yet another 70 byte message, then its output will not be generated. The order for priority of transmitting messages is simply alphabetical. The NMEA messages are input and output on the primary serial port just as in binary mode. For further details on the command formats see Chapter 5 of this document.
Chapter 3 - Receiver Descriptions Input/Output Processing Time User commands sent to the M12+ are placed in an input buffer that is serviced once per second. When powered on and available satellites are tracked, the current receiver position is available. If insufficient satellite signals are received to develop a current fix, the last known position is output.
Chapter 3 - Receiver Descriptions DATA LATENCY The receiver can output position, velocity, and time data on the serial port at a maximum rate of once each second. The start of the output data is timed to closely correspond with the receiver measurement epoch. The measurement epoch is the point in time at which the receiver makes satellite range measurements for the purpose of computing position.
Chapter 3 - Receiver Descriptions To compensate for the one second computational pipeline delay, a one second propagated position is computed that corresponds to Tk based on the position and velocity data computed from measurements taken at time Tk -1. In this way, the position data output on epoch Tk will most closely correspond with the receiver true position when the data is output on the serial port.
Chapter 3 - Receiver Descriptions about one second later than the previous measurement epoch, where any difference from 1.000000000 seconds is the result of the receiver local oscillator intentional offset (about +60 µs/s) and the oscillator's inherent instability (+/-30 ppm over specified temperature range). When the M12+ processor computes receiver local time, this time corresponds to the time of the last receiver measurement epoch.
Chapter 3 - Receiver Descriptions between 0 to 50 ms after a measurement epoch. For the Position/Status/Data Message, the time output in the message reflects the best estimate of the most recent measurement epoch. A simple timing diagram is shown in figure 3.8. 1PPS Cable Delay Correction and 1PPS Offset (M12+ Timing Receiver Only) Users can compensate for antenna cable length with the 1PPS Cable Delay Command (@@Az).
Chapter 3 - Receiver Descriptions Time to First Fix (TTFF) TTFF is a function of position uncertainty, time uncertainty, almanac age, and ephemeris age as shown in the table below. The information shown below in Table 3.8 assumes that the antenna has full view of the sky when turned on. Table 3.
Chapter 3 - Receiver Descriptions If backup power is available, the M12+ retrieves its last known position coordinates from RAM when main power is reapplied, and uses this information in the satellite acquisition algorithm. In addition, the receiver retains the almanac and last used satellite ephemeris as long as the backup power is applied.
Chapter 3 - Receiver Descriptions Received Carrier to Noise Density Ratio (C/No) The Position/Status/Data Message output C/No for each receiver channel, which can be used to determine the relative signal levels of received satellite signals (refer to Figure 3.9 below). C/No is the received carrier to noise density ratio. The units are dB-Hz, where No is the noise density ratio received in a 1 Hz bandwidth. The C/No may be converted into received signal strength using the plot in Figure 3.9.
Chapter 3 - Receiver Descriptions SETTING UP RECEIVERS FOR SPECIFIC APPLICATIONS M12+ as a Standard Autonomous Positioning Receiver As supplied, the M12+ positioning receiver will work quite well without any operator intervention except for enabling the desired output messages and a couple of setup steps. These are: • • • Enabling the desired message strings (typically @@Ha or @@Hb, @@Bb, etc.) Setting the antenna Mask Angle using the @@Ag command.
Chapter 3 - Receiver Descriptions Note that a receiver operating in differential mode will discard corrections once they have aged more than 90 seconds. This is normally not a problem as corrections are typically applied every 5-20 seconds, but if you have a poor RF link between the Base Station and the rover, this condition may occur. The receiver will automatically switch between differential and autonomous modes as corrections are received or time out.
Chapter 3 - Receiver Descriptions @@Ge – This message is used to turn the T-RAIM function on and off. The receiver must be in Position-Hold mode in order to get full functionality from the T-RAIM algorithm. If the receiver is left in positioning mode the T-RAIM can only detect a bad satellite, it cannot remove it from the time solution.
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Chapter 4 - Antenna Descriptions Chapter 4 – Antenna Descriptions CHAPTER SUMMARY Refer to this chapter for the following: • Product descriptions for the Motorola Hawk and Timing2000 antennas • Installation precautions and setup • Electrical Parameters • Mechanical Dimensions Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 4 - Antenna Descriptions Motorola HAWK Antenna Figure 4.1: Hawk Antenna Antenna Description The Motorola active HAWK antenna is designed to operate with Motorola's successful family of Oncore GPS receivers, as well as many GPS receivers from other manufacturers. The 3V version of the HAWK GPS Antenna is specifically designed to operate with Motorola’s M12 and M12+ Oncore receivers.
Chapter 4 - Antenna Descriptions Table 4.1 Active Hawk Antenna Technical Characteristics GENERAL CHARACTERISTICS PERFORMANCE CHARACTERISTICS Antenna Description Passive dielectric patch antenna Top and bottom radome plastic housing assembly Active low noise amplifier/filter –PWB assembly RF cable with connector assembly Operating Frequency Input Impedance VSWR Bandwidth Polarization Azimuth Coverage Elevation Coverage Gain Characteristics of Antenna Element Filtering L1 (1575.42 MHz, +/- 1.
Chapter 4 - Antenna Descriptions Hawk Antenna Gain Pattern The sensitivity of an antenna as a function of elevation angle is represented by the gain pattern. Some directions are much more appropriate for signal reception than others, so the gain characteristics of an antenna play a significant role in the antenna's overall performance. A crosssectional view of the antenna gain pattern along a fixed azimuth (in a vertical cut) is displayed in the following figure.
Chapter 4 - Antenna Descriptions Mechanical Dimensions All dimensions are in mm and are for reference purposes only. Figure 4.3: Magnet/Direct Mount Configuration Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 4 - Antenna Descriptions Mechanical Dimensions (Continued) All dimensions are in mm and are for reference purposes only. Figure 4.4: HAWK Antenna Substrate Configuration 56 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 4 - Antenna Descriptions Motorola Part Numbers The Tables below show the various mounting styles and types of connectors that are offered with the Hawk antenna, along with the Motorola model numbers. Table 4.2 3V Active Hawk Antennas Motorola Model No.
Chapter 4 - Antenna Descriptions RF Connectors/Cables Information Shikoku 1.5DS-QEHV coaxial cable is used in the Hawk antenna assemblies. This cable is very similar to RG-316. Figure 4.5 shows simplified views of the cable construction while Table 4.8 details the electrical and mechanical characteristics. Figure 4.5: Antenna Cable Construction Table 4.
Chapter 4 - Antenna Descriptions Antenna Placement When mounting the Hawk antenna module, it is important to remember that GPS positioning performance will be optimal when the antenna patch plane is level with the local geographic horizon, and the antenna has full view of the sky ensuring direct line-of-sight to all visible satellites over head. Figure 4.6: Proper Antenna Placement Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 4 - Antenna Descriptions Antenna System RF Parameter Considerations Both the gain and the noise of the overall system affect the performance of the A/D converter in the Oncore GPS receiver. The illustration below illustrates typical values for the M12+ receiver when used with the Hawk antenna and the standard length of 5 meters of cable. The thresholds and ranges listed should be considered to have a tolerance of 2 to 3 dB. Figure 4.7 below details a typical configuration.
Chapter 4 - Antenna Descriptions Antenna Cable RF Connectors The following RF Connectors are used to terminate cables of various Antenna models. Table 4.5 – 3V HAWK Antennas Antenna Model Connector Type/Cable Length GC3LP272CA* Straight BNC Plug – Amphenol BNC-LP-1.5DQEHV GC3LP275CA* Right angle SMB Plug - Amphenol SMB-LP-1.5DQEHV GC3LP273CA* Straight SMA Plug - Amphenol SMA-SP-1.5DQEHV GC3LP279CA Right angle MMCX Plug - Amphenol MMCX-LP-1.5DV-CR GC3SU2790A* Right angle MMCX Plug - Amphenol MMCX-LP-1.
Chapter 4 - Antenna Descriptions Motorola Timing2000 Antenna Figure 4.8: Timing2000 Antenna Antenna Description The Motorola Timing2000 antenna is intended for use in GPS timing applications and is designed for use with Motorola’s Oncore receivers as well as many GPS receivers from other manufacturers. GPS signals are received by the antenna, amplified within the antenna assembly, and then relayed via cable to the M12+ receiver module for processing.
Chapter 4 - Antenna Descriptions Table 4.
Chapter 4 - Antenna Descriptions Timing2000 Antenna Gain Pattern The sensitivity of an antenna as a function of elevation angle is represented by the gain pattern. Some directions are much more appropriate for signal reception than others, so the gain characteristics of an antenna play a significant role in the antenna's overall performance. A cross-sectional view of the antenna gain pattern for the Timing2000 along a fixed azimuth (in a vertical cut) is displayed in the following figure.
Chapter 4 - Antenna Descriptions Timing2000 Installation Precautions The following precautions should be taken into consideration to avoid the introduction of hazards and adversely affecting performance when installing the Timing2000 GPS Antenna. • Mounting bracket must be grounded in accordance with the National Electrical Code Section 810-21. • Avoid contact with power lines; serious injury could result. • Avoid making the antenna the highest point on the roof.
Chapter 4 - Antenna Descriptions driven rain from directly impinging on the connector mating area. This tubing should be secured to the mounting nut of the antenna assembly and should extend several inches past the mating N connectors. A product similar to Armstrong’s Armaflex Pipe Insulation Tubing products is recommended. More information on this product can be found at www.armaflex.com. Use a weather resistant cable tie or clamp to secure the tubing material to the mounting nut.
Chapter 4 - Antenna Descriptions Environmental Tests Provided below is an outline of the product durability and environmental specifications to which the Timing2000 antenna was qualified. Durability Validation Tests Type of Test Test Description Thermal cycling Cycle Test: Temperature Range 600 hours -40 to +85 ºC Thermal Shock Cycle Test: Temperature range 200 hours -40 to +85ºC Humidity Cycle Test: Cycling temperature 240 hours -30 to +60ºC at 85% R.H. High Temperature Storage Test: +85ºC.
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Chapter 5 - I/O Commands Chapter 5 - I/O COMMANDS CHAPTER SUMMARY Refer to this chapter for the following: • The I/O commands supported by the M12+ Oncore receiver • Detailed command descriptions Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands OVERVIEW Motorola binary commands can be used to initialize, configure, control and monitor the M12+ receivers. The binary commands are supported on the primary communications port at 9600 baud. Immediately following this page are listings of the input commands in alphabetical order. Command and response structures are detailed on subsequent pages.
Chapter 5 - I/O Commands I/O COMMAND LIST INDEX BY BINARY COMMAND Table 5.
Chapter 5 - I/O Commands Table 5.
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Chapter 5 - I/O Commands SATELLITE MASK ANGLE COMMAND (@@Ag) Applicability: M12+ Positioning and Timing receivers The receiver will attempt to track satellites for which the elevation angle is greater than the satellite mask angle. This parameter allows the user to control the elevation angle that was used for this decision. Typical values are between 5 and 10 degrees.
Chapter 5 - I/O Commands SATELLITE MASK ANGLE (@@Ag) Motorola Binary Format Query current Satellite Mask Angle: @@AgxC where: x = 1 ‘0xFF’ hex byte 0xD9= checksum Message length: 8 bytes Complete hex string to query the current Satellite Mask Angle: 0x40 40 41 67 FF D9 0D 0A Change current Satellite Mask Angle: @@AgdC where: d = degrees C = checksum Message length: 8 bytes 0..
Chapter 5 - I/O Commands SATELLITE IGNORE LIST MESSAGE (@@Am) Applicability: M12+ Positioning and M12+ Timing receivers The receiver includes, in its list of satellites to track, all satellites that are healthy and in the almanac. The user can elect to ignore particular satellites in the almanac by using the Satellite Ignore Command. In addition, the user can restore any previously ignored satellite IDs by issuing a Satellite Ignore Command with the satellite IDs added back to the active list.
Chapter 5 - I/O Commands SV IGNORE LIST MESSAGE (@@Am) Motorola Binary Format Query current SV Ignore List: @@AmxxxxxC where: xxxxx = 0xFF 00 00 00 00 – fixed hex constant 0xD3 = checksum Message length: 12 bytes Complete hex string to query current SV Ignore List: 0x40 40 41 6D 00 00 00 00 00 D3 0D 0A Change current SV Ignore List: @@AmkssssC where: k = ssss = 0x00 - fixed hex constant 32 bit binary field, each bit representing one SVID.
Chapter 5 - I/O Commands POSITION LOCK PARAMETERS MESSAGE (@@AM) Applicability: M12+ Positioning receivers This message allows the user to modify the default speed and distance thresholds for the Position Lock function. The position reported by the receiver will be locked if the current speed and distance traveled are both less than their respective thresholds, and the Position Lock function has been enabled using the @@AS command.
Chapter 5 - I/O Commands POSITION LOCK PARAMETERS MESSAGE (@@AM) Motorola Binary Format Query current Position Lock Parameters: @@AMxxxxC where: xxxx = 4 out of range bytes, all 0xFF C = 0x0C Message length: 11 bytes Complete hex string to query current Position Lock Parameters: 0x40 40 41 4D FF FF FF FF 0C 0D 0A Change current Position Lock Parameters: @@AMifddC where: i = integer part of speed threshold f = fractional part of speed threshold dd = distance threshold C = checksum Message
Chapter 5 - I/O Commands MARINE FILTER SELECT COMMAND (@@AN) Applicability: M12+ positioning receivers The Marine Filter command controls the velocity filtering feature. The velocity filter is useful in marine applications to filter out some of the wave motion in the reported velocity. The filter is a single order alpha filter, where alpha is the value entered by the user ranging from 10 to 100 in increments of one.
Chapter 5 - I/O Commands MARINE FILTER SELECT COMMAND (@@AN) Motorola Binary Format Query current Marine Filter status: @@ANxC where: x = 1 out of range hex byte: 0xFF Checksum = 0xF0 Message length: 8 bytes Complete hex string to query current Marine Filter status: 0x40 40 41 4E FF F0 0D 0A Change current Marine Filter parameter: @@ANfC where: f = filter parameter C = checksum Message length: 8 bytes 10..100 (0x0A ..
Chapter 5 - I/O Commands DATUM SELECT COMMAND (@@Ao) Applicability: M12+ and M12+ Timing receivers The M12+ has one predefined datum (WGS-84) stored in non-volatile memory, and one user definable datum. Datums are referenced by an ID number. The predefined datum is number 49, and the user definable datum is number 50. The user instructs the receiver which datum to use by sending the Datum Select command.
Chapter 5 - I/O Commands DATUM SELECT COMMAND (@@Ao) Motorola Binary Format Query currently used Datum ID: @@AoxC where: x =1 out of range byte: Checksum = 0xD1 Message length: 8 bytes 0xFF Complete hex string to query current Datum ID: 0x40 40 41 6F FF D1 0D 0A Change currently used Datum ID: @@AodC where: d = datum ID 49 or 50 C = checksum Message length: 8 bytes (0x31 or 0x32) Response to either command: @@AodsssffiiffffxxyyzzC where: d = current datum ID: 49 or 50 sssff =
Chapter 5 - I/O Commands RTCM PORT BAUD RATE SELECT COMMAND (@@AO) Applicability: M12+ Positioning receivers This command allows the user to select the baud rate of the RTCM serial input port (pin 8 on the 10 pin power/data header). The allowable baud rates are 2400, 4800 and 9600. The baud rate of this secondary port is independent of the status of the primary serial port.
Chapter 5 - I/O Commands RTCM PORT BAUD RATE SELECT COMMAND (@@AO) Motorola Binary Format: Query current RTCM Port Baud Rate: @@AObC where: b = 1 out of range byte: C = 0xF1 Message length: 8 bytes 0xFF Complete hex string to query current RTCM Port Baud Rate: 0x40 40 41 4F FF F1 0D 0A Change current RTCM Port Baud Rate: @@AObC where: b = RTCM port baud rate 0x00 = 9600 0x01 = 4800 0x02 = 2400 C = checksum Message length: 8 bytes Response to either command: @@AObC where: b
Chapter 5 - I/O Commands DEFINE USER DATUM MESSAGE (@@Ap) Applicability: M12+ and M12+ Timing receivers The M12+ can accommodate one user defined datum stored as ID number 50. The Define User Datum command allows the user to define the constants used for this datum. A datum is defined by a semi-major axis, an inverse flattening constant, and an offset from the center of mass of the earth, given as delta-X, delta-Y, and delta-Z parameters.
Chapter 5 - I/O Commands DEFINE USER DATUM MESSAGE (@@Ap) Motorola Binary Format Query current User Defined Datum Parameters: @@ApdxxxxxxxxxxxxxxxxxC where: d = user datum ID: xxxxxxxxxxxxxxxxx = C = 0x31 Message length: 25 bytes 50 17 bytes, all 0x00 Complete hex string to query current User Defined Datum Parameters: 0x40 40 41 70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 31 0D 0A Change current User Defined Datum Parameters: @@ApdsssffiiffffxxyyzzC where: d = datum ID sssff =
Chapter 5 - I/O Commands PULSE MODE SELECT COMMAND (@@AP) Applicability: M12+ Timing receivers The M12+ Timing receiver can output either a 1PPS or 100PPS pulse train. The user selects the pulse output signal using the Pulse Mode Select command. More information on the characteristics of the 100PPS signal can be found on page 3.13 Default mode: 1PPS Legacy Code Compatibility: The @@AP command structure detailed here is identical to that used on Motorola UT+ timing receivers.
Chapter 5 - I/O Commands PULSE MODE SELECT COMMAND (@@AP) Motorola Binary Format Query Current Pulse Mode: @@APxC where: x = 1 out of range hex byte: C = 0xEE Message length: 8 bytes 0xFF Complete hex string to query current Pulse Mode: 0x40 40 41 50 FF EE 0D 0A Change current Pulse Mode: @@APmC where: m = mode 0x00 = 1PPS output 0x01 = 100PPS output C = checksum Message length: 8 bytes Response to either command: @@APmC where: m = mode 0x00 = 1PPS output 0x01 = 100PPS outp
Chapter 5 - I/O Commands IONOSPHERIC CORRECTION SELECT COMMAND (@@Aq) Applicability: M12+ Positioning and Timing receivers The user has the flexibility of turning the GPS ionospheric and/or tropospheric correction models on or off. The models do a reasonable job of taking out the range error induced by the earth’s ionosphere and troposphere by using algorithms and parameters transmitted to the users by the satellites.
Chapter 5 - I/O Commands IONOSPHERIC CORRECTION SELECT COMMAND (@@Aq) Motorola Binary Format Query current Ionospheric Correction Selection: @@AqxC where: x = 1 out of range byte: 0xFF C = CF Message length: 8 bytes Complete hex string to query current Ionospheric Correction Selection: 0x40 40 41 71 FF CF 0D 0A Change current Ionospheric Correction Selections: @@AqsC where: s = selection 0x00 = both models disabled 0x01 = ionospheric model enabled 0x02 = tropospheric model enabled 0x03 =
Chapter 5 - I/O Commands POSITION FILTER SELECT COMMAND (@@AQ) Applicability: M12+ Positioning and Timing receivers This message enables or disables the position filter. Default mode: Enabled 92 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands POSITION FILTER SELECT COMMAND (@@AQ) Motorola Binary Format Query current Position Filter Status: @@AQxC where: x = 1 out of range byte C = 0xEF Message length: 8 bytes 0xFF Complete hex string to query current Position Filter Status: 0x40 40 41 51 FF EF 0D 0A Change current Position Filter Status: @@AQsC where: s = selection 0x00 = disabled 0x01 = enabled C = checksum Message length: 8 bytes Response to either command: @@AQsC where: s = selection 0
Chapter 5 - I/O Commands POSITION HOLD PARAMETERS MESSAGE (@@As) Applicability: M12+ Positioning and Timing receivers The user can specify Position Hold coordinates both for timing applications to increase the timing accuracy and when the receiver is used as a source of differential correction data. This command is used to enter the position to be held.
Chapter 5 - I/O Commands POSITION HOLD PARAMETERS (@@As) Motorola Binary Format Query current Position Hold Parameters: @@AsxxxxxxxxxxxxxC where: xxxxxxxxxxxxx = 13 out of range hex bytes: 0xFF C = 0xCD Message length: 20 bytes Complete hex string to query current Position Hold Parameters: 0x40 40 41 73 FF FF FF FF FF FF FF FF FF FF FF FF FF CD 0D 0A Change current Position Hold Parameters: @@AslllloooohhhhtC where: llll = latitude in mas oooo = longitude in mas hhhh = height in cm t = h
Chapter 5 - I/O Commands POSITION LOCK SELECT MESSAGE (@@AS) Applicability: M12+ Positioning receivers This message enables or disables the Position Lock function. For further details on the Position Lock function, refer to the @@AM command. Default mode: Disabled Legacy Code Compatibility: The @@AS command was implemented in a similar fashion on the Motorola M12 Oncore receiver. 96 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands POSITION LOCK SELECT MESSAGE (@@AS) Motorola Binary Format Query current Position Lock Select Status: @@ASxC where: x = 1 out of range hex byte: C = 0xED Message length: 8 bytes 0xFF Complete hex string to query current Position Lock Select Status: 0x40 40 41 53 FF ED 0D 0A Change current Position Lock Select Status: @@ASeC where: e = selection 0x00 = Disabled 0x01 = Enabled C = checksum Message length: 8 bytes Response to either command: @@ASeC wher
Chapter 5 - I/O Commands TIME CORRECTION SELECT (@@Aw) Applicability: M12+ Positioning and Timing receivers This command selects the time reference (either GPS or UTC) used in the @@Ha 12 Channel Position/Status/Data and @@Hb Short Position Messages. This Time command is also used to determine the synchronization point for the 1PPS timing pulse.
Chapter 5 - I/O Commands TIME CORRECTION SELECT (@@Aw) Motorola Binary Format Query current UTC Time Correction Option: @@AwxC where: x = 1 out of range hex byte: C = 0xC9 0xFF Message length: 8 bytes Complete hex string to query current Time Correction Option: 0x40 40 41 77 FF C9 0D 0A Change current UTC Time Correction Option: @@AwmC where: m = time mode: 0x00 = GPS 0x01 = UTC C = checksum Message length: 8 bytes Response to either command: @@AwmC where: m = time mode 0x
Chapter 5 - I/O Commands 1PPS TIME OFFSET COMMAND (@@Ay) Applicability: M12+ Timing Receivers The M12+ outputs a one pulse-per second (1PPS) signal with the rising edge placed on top of the UTC or GPS one second tic mark, depending on which time reference has been selected by the user. The 1PPS Time Offset command allows the user of M12+ Timing Receivers to offset the 1PPS time mark in one nanosecond increments. This offset can be used to place the 1PPS signal anywhere within the one second epoch.
Chapter 5 - I/O Commands 1PPS TIME OFFSET COMMAND (@@Ay) Motorola Binary Format Query current 1PPS Time Offset: @@AyxxxxC where: xxxx = 4 out of range hex bytes: C = 0x38 Message length: 11 bytes 0xFF Complete hex string to query current user specified 1PPS Time Offset: 0x40 40 41 79 FF FF FF FF 38 0D 0A Change current 1PPS Time Offset: @@AyttttC where: tttt = time offset in ns 0..999,999,999 (0.0 to 0.
Chapter 5 - I/O Commands 1PPS CABLE DELAY CORRECTION COMMAND (@@Az) Applicability: M12+ Timing Receivers The M12+ timing receiver outputs a 1PPS signal, the rising edge of which is placed at the top of the GPS or UTC one second time mark epoch as specified by the Time Mode command. The 1PPS Cable Delay Correction command allows the user to offset the 1PPS time mark in one nanosecond increments relative to the measurement epoch.
Chapter 5 - I/O Commands 1PPS CABLE DELAY CORRECTION (@@Az) Motorola Binary Format Query current 1PPS Cable Delay Correction: @@AzxxxxC where: xxxx = 4 out of range hex bytes: Checksum = 0x3B Message length: 11 bytes 0xFF Complete hex string to query current user specified 1PPS Cable Delay Correction: 0x40 40 41 7A FF FF FF FF 3B 0D 0A Change current 1PPS Cable Delay Correction: @@AzttttC where: tttt = time offset in ns C = checksum Message length: 11 bytes 0..999,999 ns (0.0 to 0.
Chapter 5 - I/O Commands VISIBLE SATELLITE DATA MESSAGE (@@Bb) Applicability: M12+ Timing and Positioning Receivers This command requests the results of the most current satellite visibility computation. The response message gives a summary of the satellite visibility status showing the number of visible satellites, the Doppler frequency and the location of the currently visible satellites. The reference position for the most recent satellite alert is the current position coordinates.
Chapter 5 - I/O Commands VISIBLE SATELLITE DATA MESSAGE (@@Bb) Motorola Binary Format Query Current Visible Satellite Data: @@BbmC where: m = mode 0x00 = output response message once (polled) 0x01 = output response message data when visibility data changes (approximately once every 5-7 seconds) C = checksum Message length: 8 bytes Response to above command: @@Bbn iddeaas iddeaas iddeas iddeaas iddeaas iddeaas iddeaas iddeaas iddeaas iddeaas iddeaas iddeaas C where: n = number of visibl
Chapter 5 - I/O Commands ALMANAC STATUS MESSAGE (@@Bd) Applicability: M12+ Timing and Positioning Receivers This command requests almanac status information corresponding to the satellite almanac data currently stored in RAM. The GPS receiver continually captures a complete new almanac to internal RAM while tracking satellites. If an existing almanac is stored in RAM on power-up, satellite visibility information will be available immediately.
Chapter 5 - I/O Commands ALMANAC STATUS MESSAGE (@@Bd) Motorola Binary Format Query Current Almanac Status: @@BdmC where: m = mode 0x00 = Output status once (polled) 0x01 = Output status when RAM almanac data changes (continuous) C = checksum Message length: 8 bytes Response to above command: @@BdvwtassssrrrrrrrrC where: v = almanac valid flag 0x00 = no almanac in receiver 0x01 = valid almanac in receiver w = almanac week number (raw) 0x00..
Chapter 5 - I/O Commands ALMANAC DATA REQUEST (@@Be) Applicability: M12+ Timing and Positioning Receivers This command is used to command the M12+ to output its current almanac data. The user has the option of requesting the almanac data output one time (polled), or each time the almanac data changes (continuously).
Chapter 5 - I/O Commands ALMANAC DATA REQUEST (@@Be) (RESPONSE IS Cb) Motorola Binary Format Query Current Almanac Data: @@BemC where: m = response mode 0x00 = Output response message once (polled) 0x01 = Output response message when almanac data changes (continuous) C = checksum Message length: 8 bytes Response to above command: @@Cbsp xxx xxx xxx xxx xxx xxx xxx xxx C where: sp = subframe/page xxx = data words subframe 5 / pages 1-25, or subframe 4 / pages 2-5, 7-10, 25 words 3-10, e
Chapter 5 - I/O Commands EPHEMERIS DATA INPUT (@@Bf) Applicability: M12+ positioning and timing receivers This command will cause the receiver to accept satellite ephemeris data input via communications port 1 (pin 2). The receiver keeps the ephemerides decoded from all satellites in RAM, as long as backup voltage is applied to the receiver and the ephemerides are still valid (t-toe < 4 hours).
Chapter 5 - I/O Commands EPHEMERIS DATA INPUT (@@Bf) Motorola Binary Format Input Ephemeris Data: @@Bfi[24x{eee}]C where: i = SVID eee...eee = ephemeris subframe 0x01 .. 0x25 sf 1–3, words 3-10 (72 bytes per sat; format per ICD-GPS-200) C = checksum Message length: 80 bytes Response to above command: @@Cci[24x{eee}]C where: i - SVID eee...eee = ephemeris subframe 0x01 ..
Chapter 5 - I/O Commands PSEUDO-RANGE CORRECTION OUTPUT REQUEST (@@Bh) Applicability: M12+ Positioning Receiver This parameter sets the rate at which pseudo-range corrections are output from the M12+ receiver when being used as a master site receiver in a real-time differential system. The messages return pseudo-range and pseudo-range corrections for up to 12 receiver channels, and identify the satellite IDs that corresponds to each channel.
Chapter 5 - I/O Commands PSEUDO-RANGE CORRECTION OUTPUT REQUEST (@@Bh) Motorola Binary Format Request Pseudo-Range Corrections: @@BhmC where: m = mode 0 – output response message (once polled) 1..255 – response message output at indicated rate (continuous) 1 – once per second 2 – once every two seconds 255 – once every 255 seconds C = checksum Message Length: 8 bytes Response to above command: @@Cettt ippprrd ippprrd ippprrd ippprrd ippprrd ippprrd C where: ttt - GPS time ref 0..
Chapter 5 - I/O Commands LEAP SECOND STATUS MESSAGE (@@Bj) Applicability: M12+ Timing and Positioning Receivers This message polls the receiver for current leap second status information that has been decoded from the Navigation Data message received from the GPS satellites. The data sent back by the receiver provides specific date and time information pertaining to any future leap second addition or subtraction.
Chapter 5 - I/O Commands LEAP SECOND STATUS MESSAGE (@@Bj) Motorola Binary Format Query current Leap Second Pending information: @@BjmC where: m = mode C = 0x28 Message length: 8 bytes 0x00 Complete hex string to query current user specified Leap Second Status: 0x40 40 42 6A 00 28 0D 0A Response to above command: @@BjmC where: m = leap second status 0x00 - no leap second pending 0x01 - addition of one second pending 0x02 - subtraction of one second pending C = checksum Message length
Chapter 5 - I/O Commands UTC OFFSET OUTPUT MESSAGE (@@Bo) Applicability: M12+ Timing and Positioning Receivers This message allows the user to request the UTC offset that is currently being used in the time solution. The value reported is the integer number of seconds between UTC and GPS time. If the offset reported by the receiver is zero and UTC is the selected time reference, the receiver does not currently have the portion of the almanac that contains the UTC parameters.
Chapter 5 - I/O Commands UTC OFFSET OUTPUT MESSAGE (@@Bo) Motorola Binary Format Request Current UTC Offset: @@BomC where: m = mode 0 = output UTC offset once (polled) 1 = output UTC offset every time it is updated C = checksum Message length: 8 bytes Response to above command: @@BouC where: u = UTC offset in seconds C = checksum Message length: 8 bytes -128..+127 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands REQUEST UTC/IONOSPHERIC DATA (@@Bp) Applicability: M12+ Timing and Positioning Receivers This message allows the user to request UTC and ionospheric data decoded from the Navigation Data Message. Default mode: Polled Legacy Compatibility: The @@Bp message was used in an identical manner in the Motorola M12 receiver. 118 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands REQUEST UTC/IONOSPHERIC DATA (@@Bp) Motorola Binary Format Request Current UTC/Ionospheric Data: @@BpmC where: m = mode 0 = output response once (polled) 1 = output response when either UTC or ionospheric data changes C = checksum Message length: 8 bytes Response to above command: @@CoabcdefghAAAAaaaadtwWnDC where: a, b, c, d, e, f, g, and h = Ionospheric Data (see ICD-GPS-200, Table 20-X for scale factors) a = α0 b = α1 c = α2 d = α3 e = β0 f = β1 g = β2 h = β3
Chapter 5 - I/O Commands ALMANAC DATA INPUT (@@Cb) Applicability: M12+ Timing and Positioning Receivers This command allows the user to load a previously recorded almanac into the M12+'s RAM via the serial port. The entire almanac data message consists of 34 unique formatted messages that correspond to the subframe and page number of the almanac data (see GPS-ICD-200 for format description). It is not necessary to input an almanac at power up.
Chapter 5 - I/O Commands ALMANAC DATA INPUT (@@Cb) [RESPONSE TO Be] Motorola Binary Format Input One Almanac Data page: @@Cbspxxx…xxxC where: sp = subframe/page subframe 5 / pages 1-25, or subframe 4 / pages 2-5, 7-10, xxx…xxx = data words words 3-10, each word is 3 bytes long (format per ICD-GPS-200) C = checksum Message length: 33 bytes Response to above command: @@ChspC where: sp = subframe/page subframe 5 / pages 1-25, or subframe 4 / pages 2-5, 7-10, 25 C = checksum Message leng
Chapter 5 - I/O Commands PSEUDO-RANGE CORRECTION DATA INPUT (@@Ce) Applicability: M12+ Positioning Receivers The input message is structured to accept pseudo-range and pseudo-range-rate corrections for up to six satellites on serial port 1. The slave receiver uses the corrections in the input message by associating the satellite ID with the corresponding satellite (channel) that the slave is tracking. The user can specify up to 12 satellite corrections through the use of two back-to-back input commands.
Chapter 5 - I/O Commands PSEUDO-RANGE CORRECTION DATA INPUT (@@Ce) Motorola Binary Format Pseudo-Range Correction Data Input (for up to six satellites): @@Cettt ippprrd ippprrd ippprrd ippprrd ippprrd ippprrdC where: ttt = GPS time ref i = SVID ppp = pseudo-range corr 0.01 meter resolution rr = pseudorange-rate corr 0.001 m/s resolution d = issue of data ephemeris C = checksum Message length: 52 bytes 0..6047999 (0.0..604799.0) 0..37 0 = not used 1-37 = SVID -1,048,576..+1,048,576cm (-10485.76..
Chapter 5 - I/O Commands SET TO DEFAULTS COMMAND (@@Cf) Applicability: M12+ Timing and Positioning Receivers This command sets all of the GPS receiver parameters to their default values. Performance of this utility results in all continuous messages being reset to polled only output, and clears the almanac, ephemeris, time, and date data. Legacy Code Compatibility: The @@Cf command has been implemented in an identical fashion on virtually all Motorola Oncore receivers.
Chapter 5 - I/O Commands SET-TO-DEFAULTS (@@Cf) Motorola Binary Format Set the GPS receiver to Default values: @@CfC where: C = 0x25 Message length: 7 bytes Complete hex string to Set to Defaults: 0x40 40 43 66 25 0D 0A Response to above command: @@CfC where: C = checksum Message length: 7 bytes Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands NMEA PROTOCOL SELECT (@@Ci) Applicability: M12+ Positioning Receivers This command causes the M12+ positioning receiver to change the serial data format on the primary port from Motorola binary to NMEA 0183. The baud rate of the port is switched from 9600 to 4800 and input commands are recognized in NMEA format only. Note that the default mode of all of the NMEA output messages is off.
Chapter 5 - I/O Commands SWITCH I/O FORMAT (@@Ci) Motorola Binary Format Switch to NMEA Format command: @@CimC where: m = format C = 0x2B Message length: 8 bytes 0x01 = NMEA Complete hex string to Switch to NMEA Format: 0x40 40 43 69 01 2B 0D 0A There is no response message to this command. Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands RECEIVER ID (@@Cj) Applicability: M12+ Timing and Positioning Receivers The M12+ outputs an ID message upon request. The information contained in the ID string is self-explanatory. The model number can be used to determine the type of receiver installed. Legacy Code Compatibility: The @@Cj command has been implemented in an identical fashion on virtually all Motorola Oncore receivers. 128 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands RECEIVER ID (@@Cj) Motorola Binary Format Query Receiver ID: @@CjC where: C = checksum Message length: 7 bytes Complete hex string to query Receiver ID: 0x40 40 43 6A 29 0D 0A Response to above command: The response is output as a 25 column by 12 row array. General format is as shown below: 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 @ @ C j cr lf C O P Y R I G H T M O T O R O L A I N C .
Chapter 5 - I/O Commands UTC/IONOSPHERIC DATA INPUT [Response to @@Bp or @@Co] Applicability: M12+ Timing and Positioning Receivers As well as being the response to the @@Bp message, this message allows the user to input UTC and ionospheric data into the receiver which is then echoed in the response. 130 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands UTC/IONOSPHERIC DATA INPUT [Response to @@Bp or @@Co] Motorola Binary Format Change UTC/Ionospheric Data: @@CoabcdefghAAAAaaaadtwWnDC where: Ionospheric Data (see ICD-GPS-200, Table 20-X for scale factors) a = α0 b = α1 c = α2 d = α3 e = β0 f = β1 g = β2 h = β3 -128…+127 seconds -128…+127 seconds/semi-circle -128…+127 seconds/(semi-circle)2 -128…+127 seconds/(semi-circle)3 -128…+127 seconds -128…+127 seconds/(semi-circle) -128…+127 seconds/(semi-circle)2 -128…+127 seconds
Chapter 5 - I/O Commands UTC Data (see ICD-GPS-200, Table 20-IX for scale factors) AAAA = A0 aaaa = A1 d = ∆tLS t = tot w = WNt W = WNLSF n = DN D = ∆tLSF C = checksum Message length: 29 bytes 132 -2,147,483,648…+2,147,483,647 seconds -8,388,608…+8,388,607 seconds/second -128…+127 seconds 0…602,112 seconds 0…255 weeks 0…255 weeks 1…7 days -128…+127 seconds Motorola GPS Products - M12+ User's Guide Revision 6.
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Chapter 5 - I/O Commands ASCII POSITION MESSAGE (@@Eq) Applicability: M12+ Positioning and Timing Receivers The ASCII position output message contains position, time and receiver status Information similar in scope to the @@Hb binary Short Position message. The ASCII message may be a more convenient interface for certain applications where the ASCII output of NMEA is desired, but operation at 4800 baud is not desirable. The units and style of the data is similar to NMEA output.
Chapter 5 - I/O Commands ASCII POSITION MESSAGE (@@Eq) Motorola Binary Format Request ASCII Position Message: @@EqmC where: m = output mode 0x00 = output response message once (polled) 0x00 .. 0xFF = response message output at indicated rate (continuous) 1 (0x01)= once per second 2 (0x02)= once every two seconds 255 (0xFF) = once every 255 seconds C = checksum Message length: 8 bytes Response to above command: @@Eq,mm,dd,yy,hh,mm,ss,dd,mm.mmmm,n,ddd,mm.mmmm,w,shhhh.h, sss.s,h,m,t,dd.
Chapter 5 - I/O Commands ASCII POSITION MESSAGE (@@Eq) Motorola Binary Format Response Message Continued Height: s = sign of height hhhh.h = height in meters Velocity: sss.s = speed in knots hhh.h = heading in degrees Receiver status: m = fix mode t = fix type dd.d = dilution of precision nn = number of satellites in use rrrr = reference station ID aa = age of differential data in s CCC = checksum Message length: 96 bytes + or -1000.0..18,000.0 000.0..999.9 000.0..359.
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Chapter 5 - I/O Commands COMBINED POSITION MESSAGE (@@Ga) Applicability: M12+ Positioning and Timing Receivers This message allows the user to enter an initial position estimate. If the receiver is computing a 2D fix, the receiver will ignore any attempts to change the latitude and/or longitude using this command. If the receiver is computing a 3D fix, it will also ignore any attempts to change height with this command.
Chapter 5 - I/O Commands COMBINED POSITION MESSAGE (@@Ga) Motorola Binary Format Query Current Position Command: @@GaxxxxxxxxxxxxxC where: xxxxxxxxxxxxx = 13 hex bytes: C = 0xD9 Message length: 20 bytes 0xFF Complete hex string to query current Combined Position: 0x40 40 47 61 FF FF FF FF FF FF FF FF FF FF FF FF FF D9 0D 0A Change Current Position Command: @@GaaaaaoooohhhhtCLF> where: aaaa = latitude in mas oooo = longitude in mas hhhh = height t = height type -324,000,000..
Chapter 5 - I/O Commands COMBINED TIME MESSAGE (@@Gb) Applicability: M12+ Positioning and Timing Receivers This message allows the user to give the receiver an initial estimate of the current time and date. If the receiver is tracking at least one satellite, the receiver will ignore any attempts to change the time and date parameters using this command. Rather, the receiver will respond with currently calculated time and date.
Chapter 5 - I/O Commands COMBINED TIME MESSAGE (@@Gb) Motorola Binary Format Query Current Time Message: @@GbxxxxxxxxxxC where: xxxxxxxxxx = 10 hex bytes: C = 0x25 Message length: 17 bytes 0xFF Complete hex string to query current date, time, and GMT offset: 0x40 40 47 62 FF FF FF FF FF FF FF FF FF FF 25 0D 0A Change Current Time Message: @@GbmdyyhmsshmCLF> where: Date: m = month d = day yy = year 1…12 1…31 1982…2100 h = hours m = minutes s = seconds s = signed byte of GMT offset 0…23 0…
Chapter 5 - I/O Commands Response to above command: @@GbmdyyhmsshmCLF> where: Date: m = month d = day yy = year 1…12 1…31 1982…2100 h = hours m = minutes s = seconds s = signed byte of GMT offset 0…23 0…59 0…59 00 = positive 255 = negative 0…+23 0…59 Time: h = hour of GMT offset m = minutes of GMT offset C = checksum Message Length: 17 bytes 142 Motorola GPS Products - M12+ User's Guide Revision 6.
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Chapter 5 - I/O Commands 1PPS CONTROL MESSAGE (@@Gc) Applicability: M12+ Positioning and Timing Receivers This message allows the user to choose how the 1PPS output from the receiver will behave. Note that the allowable options are different depending upon whether the user is working with an M12+ timing or positioning receiver. Default mode: Continuous Legacy Code Compatibility: The @@Gc command was implemented in a similar fashion on the Motorola M12 Oncore receivers.
Chapter 5 - I/O Commands 1PPS CONTROL MESSAGE (@@Gc) Motorola Binary Format Query current 1PPS Mode: @@GcxC where: x = 1 hex byte: Checksum = 0x24 Message length: 8 bytes 0xFF Complete hex string to query current 1PPS Mode: 0x40 40 47 63 24 0D 0A Change 1PPS Control Command: @@GcpCLF> where: p = 1PPS control 0x00 = 1PPS disabled 0x01 = 1PPS on continuously 0x02 = 1PPS active only when tracking at least one satellite 0x03 = 1PPS on when T-RAIM conditions are met (timing receiver only) C =
Chapter 5 - I/O Commands POSITION CONTROL MESSAGE (@@Gd) Applicability: M12+ Positioning and Timing Receivers This message allows the user to choose in which positioning mode the receiver will operate. Note that the allowable options are different depending upon whether the user is working with an M12+ timing or positioning receiver. Default mode: Continuous Legacy Code Compatibility: The @@Gd command was implemented in a similar fashion on the Motorola M12 Oncore receivers.
Chapter 5 - I/O Commands POSITION CONTROL MESSAGE (@@Gd) Motorola Binary Format Query Current Position Control Mode: @@GdxC where: x = 1 hex byte: C = 0xDC Message length: 8 bytes 0xFF Complete hex string to query current Position Control Mode: 0x40 40 47 64 FF DC 0D 0A Change Current Position Control Mode Message: @@GdcCLF> where: c = control type 0x00 = enable normal 3D positioning 0x01 = enable position hold 0x02 = enable 2D positioning (positioning receivers only) 0x03 = enable auto-su
Chapter 5 - I/O Commands TIME RAIM SELECT MESSAGE (@@Ge) Applicability: M12+ timing receivers This message allows the user to enable or disable the Time RAIM algorithm. Default: T-RAIM off. This command was part of the @@En message used on 8 channel UT+ and VP timing receivers. 148 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands TIME RAIM SELECT MESSAGE (@@Ge) Motorola Binary Format Query Current Time RAIM Mode @@GexC where: x = one hex byte: C = 0xDD Message Length: 8 bytes 0xFF Complete hex string to query current Time RAIM Mode: 0x40 40 47 65 FF DD 0D 0A Change Current Time RAIM Mode @@GetC where: t = mode 0x00 = disable 0x01 = enable C = checksum Message Length: 8 bytes Response to either command: @@GetC where: t = mode 0x00 = disable 0x01 = enable C = checksum Messag
Chapter 5 - I/O Commands TIME RAIM ALARM MESSAGE (@@Gf) Applicability: M12+ timing receivers This message allows the user to enter the Time RAIM alarm limit in multiples of 100 ns, or to query the receiver for the current setting. The default alarm limit is 1000 ns. Default value: 1000 ns This command was part of the @@En message used on 8 channel UT+ and VP timing receivers. 150 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands TIME RAIM ALARM MESSAGE (@@Gf) Motorola Binary Format Query current T-RAIM Alarm Setting: @@GfxxC where: xx = two hex bytes: C = 0x21 Message Length: 9 bytes 0xFF 0xFF Complete hex string to query current T-RAIM Alarm Setting: 0x40 40 47 66 FF FF21 0D 0A Change T-RAIM Alarm Message: @@GfaaC where: aa = T-RAIM alarm limit C = checksum Message Length: 9 bytes (3 – 10,000 in 100s of nanoseconds) Response to either command: @@GfaaC where: aa = T-RAIM ala
Chapter 5 - I/O Commands LEAP SECOND PENDING MESSAGE (@@Gj) This command polls the receiver for leap second status information decoded from the Navigation Data message. The output response provides specific date and time information pertaining to any future leap second addition or subtraction. Present and future leap second values are also output rounded to the nearest integer value. This command only operates in a polled manner, thus it must be requested each time leap second information is desired.
Chapter 5 - I/O Commands LEAP SECOND PENDING (@@Gj) Motorola Binary Format Query Current Leap Second Pending Status: @@GjC where: C = 0x2D Message length: 7 bytes Complete hex string to query current Leap Second Pending Status: 0x40 40 47 6A 2D 0D 0A Response to above command: @@GjpfyymdiffffhmsCLF> where: p = present leap second value f = future leap second value yy = year of the future leap second application m = month of the future leap second application d = day of the future leap second
Chapter 5 - I/O Commands VEHICLE ID (@@Gk) Applicability: M12+ positioning and timing receivers This message sets or defaults the ID tag. By default, the ID Tag is the 6 character serial number of the receiver. The user may change the ID tag to any combination of six ASCII characters between 0x20 (space) to 0x7E (tilde) that may aid in identification of a number of remote sites or vehicles.Note that space characters (0x20) may only be used as fillers at the end of the ID tag.
Chapter 5 - I/O Commands VEHICLE ID (@@Gk) Motorola Binary Format Query Current Vehicle ID Tag: @@GkvvvvvvC where: vvvvvv = 6 ASCII ‘*’ characters: C = 0x06 Message length: 13 bytes ‘0x2A’ in hex Complete hex string to query Current Vehicle ID Tag: 0x40 40 47 6B 2A 2A 2A 2A 2A 2A 06 0D 0A Change Current Vehicle ID: @@GkvvvvvvC where: vvvvvv = 6 ASCII ‘+’ characters: or vvvvvv = 6 ASCII characters: C = checksum Message length: 13 bytes ’0x2B’ = revert to receiver serial number ‘0x20’ to
Chapter 5 - I/O Commands 12 CHANNEL POSITION/STATUS/DATA MESSAGE (@@Ha) This message is the ‘standard’ M12+ binary position/status message. The @@Ha message provides position and channel related data to the user at a specified update rate.
Chapter 5 - I/O Commands 12 CHANNEL POSITION/STATUS/DATA MESSAGE (@@Ha) Motorola Binary Format Request 12 Channel Position/Status/Data Message: @@HarC where: r = Output Rate 0x00 = output response message once (polled) 0x01 .. 0xFF = response message output at indicated rate: 0x01 = once per second 0x02 = once every two seconds 0xFF = once every 255 seconds C = checksum Message length: 8 bytes Response to above command.
Chapter 5 - I/O Commands Speed/Heading VV = 3D speed in cm/s vv = 2D speed in cm/s hh = 2D heading Geometry dd = current DOP 0…51400 (0.0 to 514 m/s) 0…51400 (0.0 to 514 m/s) 0….3599 tenths of degrees (0.0 to 359.9º) 0 .. 999 (0.0 to 99.9 DOP) (PDOP for 3D fix, HDOP for 2D fix, ) Satellite Data n = number of visible satellites 0 ..12 t = number of tracked satellites 0 ..
Chapter 5 - I/O Commands (URA continued) 1100 (12) 768.00m
Chapter 5 - I/O Commands GMT Offset: s = signed byte of GMT offset h = hour of GMT offset m = minute of GMT offset vvvvvv = ID tag 6 characters C = checksum Message Length: 154 bytes 0x00 = positive 0xFF = negative 0…23 0…59 (0x20 to 0x7e) *Represents UTC time offset from GPS time. Offset is rounded to the nearest integer value. 160 Motorola GPS Products - M12+ User's Guide Revision 6.
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Chapter 5 - I/O Commands 12 CHANNEL SHORT POSITION MESSAGE (@@Hb) Applicability: M12+ positioning and timing receivers This is a shortened version of the @@Ha position message provided to the user at a specified update rate. Default mode: Polled Note: 162 United States export laws prohibit commercial GPS receivers from outputting valid data if the calculated GPS height is greater than 18,000 meters (11 miles) and the calculated 3D velocity is greater than 514 meters/second (1135 miles/hour).
Chapter 5 - I/O Commands SHORT POSITION MESSAGE (@@Hb) Motorola Binary Format Request Short Position Message: @@HbrC where: r = output rate 0 = output response message once (polled) 1..255 = response message output at indicated rate (continuous): 0x01= once per second 0x02= once every two seconds 0xFF = once every 255 seconds C = checksum Message length: 8 bytes Response to above command. @@HbmdyyhmsffffaaaaoooohhhhmmmmVVvvhhddntssrr vvvvvvC Date m = month d = day yy = year 1..12 1..
Chapter 5 - I/O Commands Geometry dd =current DOP 0..999 (0.0 to 99.9 DOP) (PDOP for 3D fix, HDOP for 2D fix, 00.0 otherwise) Satellite Data n = number of visible satellites 0…12 t = number of tracked satellites 0…12 ss receiver status (msb) Bits 15-13: Bits 12-11: Bit 10: Bit 9: Bit 8: Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bits 2-1: Bit 0: rr vvvvvv = ID tag C = checksum Message Length: 54 bytes .
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Chapter 5 - I/O Commands 12 CHANNEL TIME RAIM STATUS MESSAGE (@@Hn) Applicability: M12+ timing receivers This message allows the user to request output of T-RAIM status information. Legacy Compatibility: The information in the @@Hn message constitutes a portion of the data in the @@En message utilized by the UT+ and VP timing receivers. 166 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands TIME RAIM STATUS MESSAGE (@@Hn) Motorola Binary Format Request Current Time RAIM Status: @@HnrC where: r = output rate 0 =polled once 1 ..
Chapter 5 - I/O Commands INVERSE DIFFERENTIAL WITH PSEUDORANGE OUTPUT (@@Hr) Applicability: M12+ positioning receivers This message contains information that allows the user to perform inverse differential positioning. The default value for the vehicle ID will be the receiver's serial number contained in the block of memory containing manufacturing data. 168 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands INVERSE DIFFERENTIAL WITH PSEUDORANGE OUTPUT (@@Hr) Motorola Binary Format Request Current Inverse Differential with Pseudorange Output @@HrmvvvvvvC where: m = mode vvvvvv vehicle ID 0 = response message output once (polled) 1 – 255 = response message output at indicated rate (continuous) 1 = once per second 2 = once every 2 seconds 3 = once every 3 seconds, etc. six ASCII encoded characters (range 20 to 7E inclusive) 1.
Chapter 5 - I/O Commands Unfiltered Position aaaa latitude -324,000,000 to +324,000,000 milliseconds (-90 to +90 degrees) oooo longitude -648,000,000 to +648,000,000 milliseconds (-180 to +180 degrees) hhhh height -100,000 to 1,800,000 cm (-1000 to +18,000 m) Velocity ss speed 0-51,400 cm/sec (0-514 m/sec) hh heading 0.0 – 359.9 degrees (0.
Chapter 5 - I/O Commands INVERSE DIFFERENTIAL WITH PSEUDORANGE OUTPUT (@@Hr) Motorola Binary Format Geometry dd = DOP 0-999 (0.1 resolution) (0.0-99.
Chapter 5 - I/O Commands For each of twelve channels [12x {iepppprrrr} ]: i = satellite ID 0-37 e = ephemeris IODE 0-255 pppp = pseudo-range 0 .. 4,294,967,295 cm rrrr = pseudo-range rate 0 .. 4,294,967,295 mm/sec Vehicle ID vvvvvv = six ASCII character vehicle ID: response depends on input command (default value is receiver SN) C = checksum Message length: 170 bytes 172 Motorola GPS Products - M12+ User's Guide Revision 6.
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Chapter 5 - I/O Commands 12 CHANNEL SELF-TEST MESSAGE (@@Ia) The M12+ receiver user has the ability to perform an extensive self-test. The tests that are accomplished during the Self-Test are as follows: • • • • • • Antenna connection RTC communication and time Temperature sensor RAM FLASH ROM Correlator IC The output of the self-test command is a 24-bit field, where each bit of the field represents the Pass/Fail condition for each parameter tested.
Chapter 5 - I/O Commands 12 CHANNEL SELF-TEST MESSAGE (@@Ia) Motorola Binary Format Request Self-Test Message (12 Channel): @@IaC where: C = 0x28 Message length: 7 bytes Complete hex string to request a Self Test: 0x40 40 49 61 28 0D 0A Response to above command: @@IasssCLF> where: sss = self test results (msb) Bits 23-22: Bit 21: Bit 20: Bit 19: Bit 18: Bit 17: Bit 16: Bit 15: Bit 14: Bit 13: Bit 12: Bit 11: Bit 10: Bit 9: Bit 8: Bit 7: Bit 6: Bit 5: Bit 4: Bit 3: Bit 2: Bit 1: Bit 0: Ant
Chapter 5 - I/O Commands SYSTEM POWER-ON FAILURE Applicability: M12+ Positioning and Timing Receivers Immediately after power-up, the M12+'s ROM is tested. If this test does not pass, the firmware will not execute its positioning algorithms. Rather, it will continuously output this message once every 10 seconds. Receipt of this message indicates that the receiver will need to be repaired and/or reprogrammed.
Chapter 5 - I/O Commands SYSTEM POWER-ON FAILURE (@@Sz) Motorola Binary Format @@SzcC where: c = constant equal to 0 C = checksum Message length: 8 bytes Complete hex string indicating a Power-On Failure: 0x40 40 53 7A 29 0D 0A Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands NMEA GPGGA MESSAGE This command enables the NMEA GPGGA GPS Fix Data message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously). Once the receiver is set to continuous output, the continuous flow can be stopped by sending a one-time (polled) output request.
Chapter 5 - I/O Commands GPGGA (NMEAGPS FIX DATA) NMEA-0183 Format Set GPGGA message rate: $PMOTG, GGA, yyyy*CC where: yyyy = update rate CC = optional checksum 0..9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPGGA, hhmmss.ss, ddmm.mmmm, n, dddmm.mmmm, e, q, ss, y.y, a.a, z, g.g, z, t.t, iiii*CC where: hhmmss.ss = UTC of position fix hh = hours mm = minutes ss.ss = seconds ddmm.
Chapter 5 - I/O Commands y.y = HDOP a.a, z = antenna height a.a = height z = units M = meters g.g, z geoidal separation g.g height z units M = meters t.t age of differential data iiii differential reference station ID 0000..1023 CC = checksum 180 Motorola GPS Products - M12+ User's Guide Revision 6.
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Chapter 5 - I/O Commands GPGLL (NMEA GEOGRAPHIC LATITUDE AND LONGITUDE) This command enables the GPGLL Geographic Position-Latitude/Longitude message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously).
Chapter 5 - I/O Commands GPGLL (NMEA GEOGRAPHIC LATITUDE/LONGITUDE) NMEA-0183 Format Set response message rate: $PMOTG, GLL, yyyy*CC where: yyyy = update rate CC = optional checksum 0..9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPGLL, ddmm.mmmm, n, dddmm.mmmm, e, hhmmss.ss,a*CC where: ddmm.mmmm, n = latitude dd = degrees mm.mmmm = minutes n = direction dddmm.mmmm, e = longitude dd = degrees mm.
Chapter 5 - I/O Commands GPGSA (GPS DOP AND ACTIVE SATELLITES) This command enables the GPGSA DOP and Active Satellites message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously). Once the receiver is set to continuous output, the continuous flow can be stopped by sending a one-time (polled) output request.
Chapter 5 - I/O Commands GPGSA (GPS DOP AND ACTIVE SATELLITES) NMEA-0183 Format Set response message rate: $PMOTG, GSA, yyyy*CC where: yyyy = update rate CC = optional checksum 0..9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPGSA, a, b, cc, dd, ee, ff, gg, hh, ii, jj, kk, mm, nn, oo, p.p, q.q, r.
Chapter 5 - I/O Commands GPGSV (NMEA GPS SATELLITES IN VIEW) This command enables the GPGSV GPS Satellites in View message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously). Once the receiver is set to continuous output, the continuous flow can be stopped by sending a one-time (polled) output request.
Chapter 5 - I/O Commands GPGSV (NMEA GPS SATELLITES IN VIEW) NMEA-0183 Format Set response message rate: $PMOTG, GSV, yyyy*CC where: yyyy = update rate CC = optional checksum 0..9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPGSV,t,m,n,ii,ee,aaa,ss,ii,ee,aaa,ss,ii,aaa,ss,ii,aaa, ss*CC where: t = number of messages m = message number n = number of satellites in message 1..4 1..4 1..
Chapter 5 - I/O Commands GPRMC (NMEA RECOMMENDED MINIMUM SPECIFIC GPS/TRANSIT DATA) This command enables the GPRMC Recommended Minimum Specific GPS/Transit Data message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously).
Chapter 5 - I/O Commands GPRMC (NMEA RECOMMENDED MINIMUM SPECIFIC GPS/TRANSIT DATA) NMEA-0183 Format Set message output rate: $PMOTG, RMC, yyyy*CC where: yyyy = update rate CC = optional checksum 0000 .. 9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPRMC, hhmmss.ss, a, ddmm.mmmm, n, dddmm.mmmm, w, z.z,y.y, ddmmyy,d.d, v*CC where: hhmmss.ss = hh = hours mm = minutes ss.
Chapter 5 - I/O Commands GPVTG (NMEA TRACK MADE GOOD AND GROUND SPEED) Applicability: M12+ positioning receivers This command enables the GPVTG Track Made Good and Ground Speed message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously).
Chapter 5 - I/O Commands GPVTG (TRACK MADE GOOD AND GROUND SPEED) NMEA-0183 Format Set message output rate: $PMOTG, VTG, yyyy*CC where: yyyy = update rate CC = optional checksum 0000 .. 9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPVTG, a.a, b, c.c, d, e.e, f, g.g, h*CC where: a.a = Track (degrees true) b = T (message formatting constant) c.
Chapter 5 - I/O Commands GPZDA (NMEA TIME AND DATE) This command enables the GPZDA Time and Date message and determines the rate at which the information is transmitted. The periodic rate field (yyyy) instructs the receiver either to output this message once (polled), or to output this message at the indicated update rate (continuously). Once the receiver is set to continuous output, the continuous flow can be stopped by sending a one-time (polled) output request.
Chapter 5 - I/O Commands GPZDA (NMEA TIME AND DATE) NMEA-0183 Format Set response message rate: $PMOTG, ZDA, yyyy*CC where: yyyy = update rate CC = optional checksum Once every 0..9999 seconds Note - the asterisk (*) is not present unless the optional checksum is present Response to above command: $GPZDA, hhmmss.ss, dd,mm, yyyy, xx, yy*CC where: hhmmss.ss = UTC time hh = hours mm = minutes ss.
Chapter 5 - I/O Commands SWITCH I/O FORMAT TO MOTOROLA BINARY This utility command switches the serial data format on the primary port from NMEA 0183 to Motorola binary. The baud rate of the port is switched from 4800 to 9600 and input commands are recognized in Motorola binary format only. 194 Motorola GPS Products - M12+ User's Guide Revision 6.
Chapter 5 - I/O Commands SWITCH TO BINARY NMEA-0183 Format Switch to Binary format: $PMOTG, FOR, x*CC where: x = format CC = optional checksum 0 = Motorola binary Note - the asterisk (*) is not present unless the optional checksum is present There is no response message to this input command. Motorola GPS Products - M12+ User's Guide Revision 6.
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Appendix APPENDIX 1 – GPS Terminology This section provides definition of terms used in the M12+ GPS Receiver User’s Guide Motorola GPS Products - M12+ User's Guide Revision 6.
Appendix Almanac Data transmitted by a GPS satellite which includes orbital information on all the satellites, clock correction, and atmospheric delay parameters. These data are used to facilitate rapid satellite acquisition. The orbital information in the almanac is less accurate than the ephemeris, but valid for a longer time (one to two years).
Appendix Binary Pulse Code Modulation Pulse modulation using a string of binary numbers (codes). This coding is usually represented by ones and zeros with definite meanings assigned to them, such as changes in phase or direction of a wave. Bluebook A slang term derived from a blue NGS reference book. The book contains information and formats required by NGS for survey data that is submitted to be considered for use in the national network.
Appendix Code Division Multiple Access (CDMA) A method of frequency reuse whereby many radios use the same frequency but with each one having a separate and unique code. GPS uses CDMA techniques with Gold codes for their unique cross-correlation properties. Cold Start Typical time a GPS receiver requires to develop a fix after application of power given that the receiver has no stored data.
Appendix A triple-difference measurement is the difference between a double difference at one epoch of time and the same double difference at the previous epoch of time. Differential GPS solutions can be computed using either code phase or carrier phase measurements. In differential carrier phase solutions, the integer ambiguities must be resolved. Differential (Relative) Positioning Determination of relative coordinates of two or more receivers that are simultaneously tracking the same satellites.
Appendix Dynamic Positioning Determination of a timed series of sets of coordinates for a moving receiver, each set of coordinates being determined from a single data sample, and usually computed in real time. Earth-Centered Earth-Fixed (ECEF) Usually refers to a coordinate system centered at the center of the earth that rotates with the earth. Cartesian coordinate system where the X direction is the intersection of the prime meridian (Greenwich) with the equator. The X and Y vectors rotate with the earth.
Appendix Flattening A parameter used to define the shape of an ellipsoid. f = (a - b)/a = 1 - (1 - e2)1/2, where a = semi-major axis b = semi-minor axis e = eccentricity Frequency Band A range of frequencies in a particular region of the electromagnetic spectrum. Frequency Spectrum The distribution of amplitudes as a function of frequency of the constituent waves in a signal. Fundamental Frequency The fundamental frequency used in GPS is 10.23 MHz.
Appendix GPS ICD-200 The GPS Interface Control Document is a government document that contains the full technical description of the interface between the satellites and the user. GPS receivers must comply with this specification if they are to receive and process GPS signals properly. Gravitational Constant The proportionality constant in Newton's Law of Gravitation. G = 6.672 x 1011Nm2/Kg2. Greenwich Mean Time (GMT) See Universal Time. HDOP Horizontal dilution of precision. See Dilution of Precision.
Appendix JPO Joint Program Office for GPS located at the USAF Space Division at El Segundo, California. The JPO consists of the USAF Program Manager and Deputy Program Managers representing the Army, Navy, Marine Corps, Coast Guard, Defense Mapping Agency, and NATO. Kalman Filter A numerical method used to track a time-varying signal in the presence of noise.
Appendix Mean Anomaly M = n(t - T), where n is the mean motion, t is the time, and T is the instant of perigee passage. Mean Motion n = 2/P, where P is the period of revolution. Microstrip Antenna A two-dimensional, flat, precisely-cut piece of metal foil glued to a substrate. Monitor Station Any of a worldwide group of stations used in the GPS control segment to monitor satellite clock and orbital parameters.
Appendix NAVSTAR The acronym given to GPS satellites, which stands for NAVigation Satellite Timing And Ranging. Observation Session The period of time over which simultaneous GPS data is collected by two or more receivers. Outage A point in time and space that the GPS receiver is unable to compute a position fix. This may be due to satellite signal blockage, unhealthy satellites, or a dilution of precision (DOP) value that exceeds a specified limit.
Appendix Phase Observable See Reconstructed Carrier Phase. Point Positioning Geographic positions produced from one receiver in stand-alone mode. At best, position accuracy obtained from a standalone receiver is 15 to 25 meters (without SA), depending on the geometry of the satellites. Polar Motion Motion of the instantaneous axis of the rotation of the earth with respect to the solid body of the earth.
Appendix RDOP Relative dilution of precision. See Dilution of Precision. Reconstructed Carrier Phase The difference between the phase of the incoming Doppler shifted GPS carrier and the phase of a nominally constant reference frequency generated in the receiver. For static positioning, the reconstructed carrier phase is sampled at epochs determined by a clock in the receiver.
Appendix SEP Spherical Error Probable, a statistical measure of precision defined as the 50th percentile value of the three-dimensional position error statistics. Thus, half of the results are within the 3D SEP value. Sidereal Day Time between two successive upper transits of the vernal equinox. One sidereal day is just under four minutes shorter than one solar day.
Appendix SPS Standard Positioning Service, uses the C/A code to provide a minimum level of dynamic or static positioning capability. The accuracy of this service is set at a level consistent with national security. See Selective Availability. Squaring-Type Channel A GPS receiver that multiplies the received signal by itself to obtain a second harmonic of the carrier that does not contain the code modulation. Used in codeless receiver designs to obtain dual frequency measurements.
Appendix Tropospheric correction The correction applied to the measurement to account for tropospheric delay. This value is normally obtained from the modified Hopfield model, the parameters of which are broadcast by the satellites. True Anomaly The angular distance, measured in the orbital plane from the earth's center (occupied focus) from the perigee to the current location of the satellite (orbital body). Universal Time Local solar mean time at Greenwich Meridian.
