CRESCENT VECTOR OEM INTEGRATOR ’S M ANUAL Part Number: Date: 875-0161-000 December 2005 i
COPYRIGHT NOTICE Copyright 2005 CSI Wireless Inc. All rights reserved. No part of this manual may be stored in a retrieval system, transmitted, or reproduced by any means, including, but not limited to photocopy, photograph, digitizing, or otherwise, without the prior written permission from CSI Wireless Inc. TRADEMARKS The CSI Wireless logo, COAST™, and e -Dif™ are trademarks of CSI Wireless Inc. All other trademarks are the property of their respective owners.
Products are not intended for primary navigation or for use in safety of life applications. The potential accuracy of Products as stated in CSI Wireless literature and/or Product specifications serves to provide only an estimate of achievable accuracy based on: 1. Specifications provided by the US Department of Defense for GPS Positioning, 2. GPS OEM Receiver specifications of the appropriate manufacturer (if applicable), and 3. DGPS service provider performance specifications.
T ABLE OF C ONTENTS Chapter 1: Quick Start .................................................................................. 7 Receiving Your Shipment ............................................................................ 7 Unpacking Your Crescent Vector................................................................... 7 Configuring the Crescent Vector Module ........................................................ 7 NMEA 0183 Message Interface.....................................................
Configuring the Data Message Output ..........................................................28 This Port and the Other Port ....................................................................28 Saving the Crescent Vector Configuration .....................................................29 Using Port D for RTCM Input .......................................................................29 Chapter 5: PocketMAX & PocketMAX PC ..........................................................
L IST Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table 6 OF T ABLES 1-1 Default Applications ........................................................................ 8 1-2 Default Port Settings....................................................................... 9 1-3 Default GPS NMEA Message Output ................................................... 9 1-4 Default Parameters .............................................
C HAPTER 1: Q UICK S TART RECEIVING YOUR S HIPMENT If you find that any of the items are damaged due to shipment, please contact the freight carrier immediately for assistance. UNPACKING YOUR CRESCENT VECTOR When you unpack your Crescent Vector system, please ensure that it is complete by comparing the parts received against the packing slip.
Where appropriate, relevant commands for making the configuration changes are discussed in the following chapters. Chapter 6, however, is devoted to describing the NMEA interface in detail. BINARY MESSAGE INTERFACE In addition to the NMEA interface, the Crescent Vector module also supports a selection of binary messages. There is a wider array of information available through the binary messages, plus binary messages are inherently more efficient with data.
Table 1 -2. Default Port Settings Port Baud Rate Data Bits Parity Stop Bit Interface Level A, B and C 19200 8 None 1 3.3 V CMOS D 9600 8 None 1 3.3 V CMOS Note: The data bits, parity, and stop bit are not adjustable. They are fixed with an 8-N-1 configuration. Table 1 -3. Default GPS NMEA Message Output. Port GPS NMEA Messages Update Rate A, B and C GGA, GSV, VTG, ZDA, HDT, ROT 1 Hz D NONE N/A Table 1 -4. Default Parameters.
C HAPTER 2: I NTRODUCTION OVERVIEW This chapter provides a brief introduction to the Crescent Vector mo dule and some of its high-level features. The remaining chapters provide more detailed information on the workings of the product and the integration requirements. For your convenience, both the GPS and SBAS operation of the Crescent Vector module features automatic operational algorithms.
POSITIONING ACCURACY The Crescent Vector is a sub-meter 95% accurate product under ideal conditions horizontally (minimum error). To determine the positioning performance of the Crescent Vector, Hemisphere GPS gathers a 24-hour data set of positions in order to log the diurnal environmental effects and also to log full GPS constellation changes. Shorter data sets than 24 hours tend to provide more optimistic results.
The SBAS demodulator features two-channel tracking that provides an enhanced ability to maintain acquisition on a SBAS satellite in regions where more than one satellite is in view. This redundant tracking approach will result in more consistent acquisition of a signal when in an area where signal blockage of either satellite is possible. SBAS PERFORMANCE The performance of the SBAS receiver is described in terms of a bit error rate (BER).
shorter period of time. COAST technology provides more consistent positioning during periods when signal loss occurs, thus bridging the gap to when the signal is reacquired. This means that the Crescent module is more tolerant than competing products to loss of SBAS or externally input RTCM SC-104 corrections. LOCAL DIFFERENTIAL OPTION Local differential is a specialized message type that can only be sent between two Crescent-based receivers.
We make a DOS-based RINEX translator available, however, RINEX has no facility to store station information. Our translator is available by contacting technical support at Hemisphere GPS. Note: To assist you in your integration of the Crescent, we can equip you with some code snippets to help you incorporate support for the Bin 95 and 96 messages within your software. If this is a need for your application, please contact your representative at Hemisphere and we will assist you further.
Product B’s specification of sub-meter rms, you can see the first Product A would offer better performance. To properly evaluate one receiver against another statically, they should be using identical correction input (from an external source) and also share the same antenna using a power splitter (equipped with appropriate DC-blocking of the receivers and a bias-T to externally power the antenna). With this type of setup, the errors in the system are identical with the exception of receiver noise.
C HAPTER 3: C RESCENT V ECTOR M ODULE UNDERSTANDING THE CRESCENT VECTOR OEM The purpose of the Crescent Vector OEM board is to provide accurate, reliable heading and position information at high update rates. To accomplish this task, the Crescent Vector OEM uses a high performance GPS engine for GPS signal processing. The one receiver processes information from both the primary GPS antenna and secondary GPS antenna.
Height Weight 20 mm (0.8”) 55 g (1.
TECHNICAL DRAWING Figure 3-1 below is a technical drawing for the Crescent Vector OEM board. Figure 3 -1. Technical Drawing.
CONNECTORS The following table details the connectors used by the Crescent Vector module. We have also provided information on the mating connectors. Since your requirements may be different, you are free to choose a different, compatible connector. The antenna input impedance is 50 Ω. Table 3 -2. Crescent Vector Connectors.
CRESCENT VECTOR OEM PIN OUT The Crescent Vector OEM module uses a 34-pin (17 pins by 2 rows) header connector for interfacing to power, communications, and other signals. You can identify the first pin of this connector by a small triangular corner on the silk-screen of the header connector footprint. There is also a small diamond symbol next to pin1 and also printed beside the pin is ‘P900’. Pin numbering is the conventional row-byrow approach.
SIGNALS This section provides more detail on the signals available via the 34-pin header connector. RF INPUT The Crescent Vector module is designed to work with active GPS antennas with an LNA gain of 10 to 40 dB. The purpose of this LNA gain above the minimum requirement of 10 dB is to accommodate for losses in the cable system. Essentially, there is a maximum cable loss budget of 30 dB for a 40 dB gain antenna.
If used, Port D will free up the task of Port A, B or C from being used for external correction input. If you wish to support external correction input when the product is in the field, we recommend that you offer the facility to the user to input corrections on Port A, B or C, and that Port D remain within the integration only. Note: DGPS corrections are not required for heading accuracies as specified. External corrections will only affect positioning performance.
The Event Marker input is active low 3.3 V HCMOS with falling edge synchronization. The input impedance and capacitance is higher than 10 kΩ and 10 pF respectively, with a threshold of lower than 0.7 V required to recognize the input. GROUNDS When connecting the four ground pins of the Crescent Vector module, all four grounds may be connected together (these are not separate analog and digital grounds that require separate attention). MISC.
C HAPTER 4: C RESCENT V ECTOR O PERATION This chapter introduces the general operational features of the Crescent Vector system, operating modes, and receiver default operating parameters. POWERING THE CRESCENT VECTOR SYSTEM As described in Chapter 2: Introduction, the Crescent Vector is powered by a 3.3 VDC power source. Once appropriate power is connected, the Crescent Vector will be immediately powered.
• • • • • • • • • • • • • • Install the Antenna Array in a horizon (as best as can be accomplished - this will provide a foundation for performance success when the internal tilt sensor is used to supplement Crescent Vector operation). Connect the primary antenna to the port marked J1000 on the Crescent Vector OEM board, and the secondary to the port identified as J2000. You may choose to increase the antenna separation of the Crescent Vector to increase the level of heading accuracy.
COMMUNICATING WITH THE CRESCENT VECTOR MODULE The Crescent Vector features three primary serial ports that may be configured independently from each other (Ports A, B and C). The ports may be configured for any mixture of NMEA 0183, binary, and RTCM SC-104 data. The usual data output is limited to NMEA data messages since these are industry standard.
BINARY INTERFACE Binary messages may be output from the Crescent Vector simultaneously as NMEA 0183 data. Binary messages have a proprietary definition and would likely require custom software support if you wish to use them. Binary messages are inherently more efficient than NMEA 0183 and would be used when you require maximum communication efficiency.
reference station and the remote unit – typically an additional 1 m error per 100 miles. This error is often seen as a bias in positioning, resulting in a position offset. The scatter of the receiver is likely to remain close to constant. The RTCM SC-104 data output by the Crescent Vector is converted from the RTCA SC-159 data broadcast by SBAS networks. Appendix B - Resources contains the contact information should you wish to purchase a copy of the RTCM SC-104 specification.
For example, if you are communicating with the Crescent Vector Port B, and wish to turn the GPGGA message on at an update rate of 5 Hz on Port A, the following command would be used. $JASC,GPGGA,5,OTHER If you wish to turn the GPGGA message on at 5 Hz on Port B, you would issue the following command. $JASC,GPGGA,5 When turning a message on or off on ‘This’ port, you do not need to indicate ‘This’ at the end of the message.
• • • • Type Type Type Type 1 2 3 5 • • • • Type 6 Type 7 Type 9 Type 16 To return to using SBAS as the correction source, send the following command to the Crescent Vector: $JDIFF,WAAS You will find detailed information on NMEA commands and messages supported by the Crescent Vector in the Programming Manual, available for download from the CSI Wireless website.
C HAPTER 5: P OCKET MAX & P OCKET MAX PC Hemisphere GPS offers configuration utilities designed for use with Hemisphere’s SLX, SX-1 and Crescent based products, including the Crescent Vector OEM. As these utilities were not designed specifically for any one product alone, they support features not offered by every product, such as tracking of the OmniSTAR differential service and display of our Vector product’s true heading, however, the interface may be used for all I/O operations.
may have specified, and can output a mixture of binary and NMEA data.
C HAPTER 6: C RESCENT V ECTOR C OMMANDS This section details the various settings that relate to the GPS heading aspect of the Crescent Vector OEM heading system. For a comprehensive list of all commands that can be used with the Crescent Vector, please refer to the CSI Programming Manual, available for download from our website at: http://www.csi-wireless.com/products/documents/ProgrammingManual_011.pdf The following table summarizes the commands detailed in this section.
To query the Crescent Vector for the current status of this feature, issue the following command. $JATT,TILTAID Note: If you choose to increase the antenna separation of your Crescent Vector OEM beyond the default 0.5 m length, use of tilt aiding is required. $JATT,TILTCAL The tilt sensor of the Crescent Vector can be calibrated in the field; however the Crescent Vector enclosure must be horizontal when performing the calibration.
below. You may wish to follow this procedure if you need the gyro fully calibrated at a certain time. When your Crescent Vector unit is installed, apply power and wait several minutes until it has acquired a GPS signal and it is computing heading. Ensure that the gyroaiding feature is on by issuing a $JATT,GYROAID command. Then, slowly spin the unit for one minute at a rate of no more than 15 degrees per second. Then, let it sit stationary for four minutes.
To show the current antenna separation, issue the following command. $JATT,MSEP $JATT,HTAU The heading time constant allows you to adjust the level of responsiveness of the true heading measurement provided in the $HEHDT message. The default value of this constant is 2.0 seconds of smoothing when the gyro is enabled. The gyro by default is enabled, but can be turned off. By turning the gyro off, the equivalent default value of the heading time constant would be 0.5 seconds of smoothing.
constant is 0.5 seconds of smoothing. Increasing the time constant will increase the level of pitch smoothing. The following command is used to adjust the pitch time constant. $JATT,PTAU,ptau Where ‘ptau’ is the new time constant that falls within the range of 0.0 to 3600.0 seconds. Depending on the expected dynamics of the vessel, you may wish to adjust this parameter. For instance, if the vessel is very large and is not able to pitch quickly, increasing this time is reasonable.
You may query the Crescent Vector for the current heading rate time constant by issuing the same command without an argument. $JATT,HRTAU Note: If you are unsure of the best value for this setting, it’s best to be conservative and leave it at the default setting of 2.0 seconds. $JTAU,COG The course over ground (COG) time constant allows you to adjust the level of responsiveness of the COG measurement provided in the $GPVTG message. The default value of this constant is 0.0 seconds of smoothing.
Where ‘tau’ is the new time constant that falls within the range of 0.0 to 200.0 seconds. The setting of this value depends upon the expected dynamics of the receiver. If the Crescent will be in a highly dynamic environment, this value should be set to a lower value since the filtering window would be shorter, resulting in a more responsive measurement. However, if the receiver will be in a largely static environment, this value can be increased to reduce measurement noise.
To determine what the current pitch compensation angle is, send the following message to the Crescent Vector. $JATT,PBIAS Note: The pitch / roll bias is added after the negation of the pitch / roll measurement (if so invoked with the $JATT,NEGTILT command). $JATT,NEGTILT When the secondary GPS antenna is below the primary GPS antenna, the angle from the horizon at the primary GPS antenna to the secondary GPS antenna is considered negative.
$JATT,SEARCH You may force the Crescent Vector to reject the current RTK heading solution, and have it begin a new search with the following command. $JATT,SEARCH Note: The SEARCH function will not work if the GYROAID feature has been enabled. In this case power must be cycled to the receiver to have a new RTK solution computed. $JATT,FLIPBRD This new command was added to allow for the Crescent Vector OEM board to be installed upside down.
Field htau hrtau ptau cogtau spdtau hbias pbias hexflag Description This data field provides the current heading time constant in seconds This data field provides the current heading rate time constant in seconds This data field provides the current pitch time constant in seconds.
RMTL Value Roll Tilt Aiding Level 0 1 2 3 8 9 A B Off Off Off Off On On On On Off Off On On Off Off On On Off On Off On Off On Off On $JATT,HELP The Crescent Vector supports a command that you can use to get a short list of the supported commands if you find yourself in the field without documentation. This command has the following format. $JATT,HELP The response to this command will be the following.
C HAPTER 7: C RESCENT V ECTOR E VALUATION S YSTEM This chapter describes the Crescent Vector Evaluation system as a complete integrated product. The Crescent Vector Evaluation system is composed primary of the following subassemblies: • • • • • An Evaluation Enclosure An Evaluation Motherboard A Crescent Vector OEM module Antennas Associated cables This chapter provides detailed information that describes the interface of the Evaluation system, its specifications, and its requirements.
• • • • • Do not run the extension cable through door or window jams Keep the cable away from rotating machinery Do not bend excessively or crimp the extension cable Be careful not to apply tension to the cable Remove unwanted slack from the cable at the opposite end to the antenna • Secure the cable route using plastic tie wraps WARNING! Improperly installed cables near machinery can be dangerous.
POWERING THE CRESCENT VECTOR EVALUATION SYSTEM The first step to powering the Crescent Vector Evaluation system is to terminate the power leads of the power cable, connect the IDC connector or connect the USB. There are a variety of power connectors and terminals on the market from which to choose if you are terminating the power cable yourself, depending on your specific requirements.
Table 7 -2 Port A Pin-out, RS-232C Interface Level Pin Signal Description 2 TXD NMEA 0183, binary, and RTCM output 3 RXD NMEA 0183, binary, and RTCM input 5 Sig. Ground Signal return Table 7 -3 Port B Port Pin -out, RS-232C Interface Level Pin Signal Description 2 TXD NMEA 0183, binary, and RTCM output 3 RXD NMEA 0183, binary, and RTCM Input 5 Sig.
Figure 7-2 displays the numbering scheme for extension cable’s DB9 socket connectors (female). The associated numbering for the plug connector (male) is a mirror reflection of scheme showed in this figure. 54321 987 6 Figure 7-2 DB9 Socket Numbering Note: For successful communications, the baud rate of the Crescent Vector serial ports must be set to match that of the devices to which they are connected. Please refer to the Programming Manual for the command to change the baud rate.
Table 7 -8 Default GPS NMEA Message Output Port GPS NMEA Messages Update Rate A,B,C GGA, GSV, VTG, ZDA, HDT, ROT 1 Hz Table 7 -9 Default Parameters Max DGPS Age Elevation Mask 1800 seconds 5° Note: Any changes you make to the Crescent Vector configuration need to be saved with the $JSAVE NMEA command in order to be present for a subsequent power-cycle. LED INDICATORS The Crescent Vector motherboard features surface-mounted diagnostic LEDs that provide a quick indication of module status.
Table 7 -10 LED Indicator Definition 50 LED Color Function POWER Red RESET Green Reset indicator – when the reset button is pressed, this LED will illuminate. The LED should also flash upon powerup. Note: the button to initiate reset is inside the enclosure and we highly recommend using ESD protection when opening the evaluation enclosure.
C HAPTER 8: T ROUBLESHOOTING Use the following checklist to troubleshoot anomalous Crescent Vector receiver operation. Table 8-1 provides a problem symptom, followed by a list of possible solutions.
• • Non-differential GPS output • • • • No heading or incorrect heading values • • • • • • • • • • • • • 52 grounds must be connected) There is only differential positioning enabled for the Primary receiver and RTCM corrections should be input to the Primary receiver (either Port A or B) Ensure corrections are being transmitted to the correct port.
