Space Flight Technology, German Space Operations Center (GSOC) Deutsches Zentrum für Luft- und Raumfahrt (DLR) e.V. User’s Manual for the GPS Orion-S/-HD Receiver O. Montenbruck, M. Markgraf Doc. No. : GTN-MAN-0110 Version : 1.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver ii Document Change Record Issue 1.0 Date Pages June 22, 2003 all Description of Change First release Disclaimer Information in this manual has been compiled with adequate care and represents the best knowledge of the authors. Any errors remaining after its release will be fixed upon notification. In no way shall DLR or the authors be held liable for direct or indirect damage resulting from missing or erroneous information.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver iii Table of Contents Document Change Record...................................................................................................... ii Table of Contents.................................................................................................................... iii Scope and Applicability ..........................................................................................................
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.4.3 4.3.4.4 4.3.4.5 4.3.4.6 4.3.4.7 4.3.4.8 iv LO – Load Orbit...............................................................................................................................30 TO – Transmit Orbit........................................................................................................................30 LE – Load Epoch..............................................................................................
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 1 Scope and Applicability This manual provides a user’s guide for the DLR’s GPS Orion receivers for space and high dynamics applications. It describes the hard and software interfaces required for operating the receiver in standalone and embedded applications. Information in this document supplements and supercedes related sections of the GPS Orion Product Brief [1] and the GP2000 Series Demonstrator Board User’s Guide [2].
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 2 Acronyms and Abbreviations A AGC ASCII C/N0 COM dB DC DLR EPROM FLL GPS GSOC I/F IIP IQ L1 LEO LNA MITEL NMEA NVM ORION PC PLL PPS PRN R/F RAM RX SAW SMA SNR SV TC TCXO TM TTL TX UART V W Document No.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 3 1. Introduction 1.1 GPS Orion Receiver The GPS Orion receiver represents a prototype design of a terrestrial GPS receiver for 12 channel single frequency tracking built around the Mitel (now Zarlink) GP2000 chipset ([3], [4]). The receiver main board comprises a GP2015 frontend and DW9255 saw filter, a GP2021 correlator as well as an ARM60B 32-bit microprocessor.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver • • • • • • • 4 Small form factor (50 x 95 mm) and weight (50 g) Sufficient radiation tolerance LEO usage Battery buffered non-volatile memory and real-time clock Two serial ports Discrete input pin 5V supply for active antenna (16-28dB) OrionMonitor control software for Windows PCs A hardware description of the Orion-S/HD receiver is provided in Chap. 2 of this manual. Chap.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 5 2. Receiver Hardware 2.1 Main Board A block diagram of the GPS Orion receiver main board is shown in Fig. 2.1 ([4]). The receiver is designed to work with an active antenna and +5 V power supply for the preamplifier is provided on the central antenna feed. Fig 2.1 Block diagram of the GPS Orion receiver main board (from [4]) After passing an R/F ceramic filter, the L1 signal (1575.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 6 RAM memory. The EPROM is arranged into two 16 bit wide chips (256 kB total), while RAM is partitioned into four 8 bit wide memory chips with a total size 512 kB. The RAM memory contents can be maintained by a dedicated backup power supply line with a current of approximately 0.1 mA. The main board offers an SMA (or MCX) connector for the GPS antenna.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 2.2 7 Interface Board The interface board provides auxiliary devices that are required for standalone operation of the Orion receivers. It comprises • • • a switching regulator allowing operation from unregulated power supplies, a rechargeable battery to maintain the non-volatile memory and real-time clock during power down times and two RS232 serial line drivers for communication with standard peripheral devices.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 8 3. Operations Guide 3.1 Basic Receiver Handling 3.1.1 Hardware Setup For operating the GPS Orion receiver in a ground based test environment, the following hardware items are typically required: • • • • • • Orion main board Orion interface board with power cable Power supply or battery (typically +12 V, 250 mA) Active GPS antenna (ca.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 9 For proper communication, these values must match the settings of the PC communication port. While the Orion receiver is most conveniently used via a dedicated monitoring and control program (e.g. OrionMonitor), elementary operations may likewise be carried out via a standard terminal program.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver • • • 10 If the above steps have taken more than two minutes, the receiver may have started to scan through the permitted range of frequency bins. Reset or reboot the receiver to start the signal search in the central frequency bin. Select the desired aiding mode (using the AM command). Set other operations parameters (e.g. output rates, elevation mask, etc.) as desired.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 3.1.6 11 Pulse-per-Second Signal Supporting receiver versions provide a one-pulse-per-second signal (CMOS TTL level) at pin 10 of the interface connector. The PPS signal is available in case of valid navigation. It has a one millisecond duration and its starting edge is aligned to the occurrence of an integer GPS second with an accuracy of better than 1 µs. The typical error amounts t ca. 0.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 3.2 12 Special Applications 3.2.1 Aiding for Ballistic Trajectories To allow a rapid acquisition and an optimal channel allocation in case of high vehicle dynamics the Orion-HD receiver can be aided by a priori trajectory information. For sounding rockets or other ballistic missions the nominal flight path is represented by a piecewise, low order polynomial approximation stored within the receiver (Fig. 3.1, [12]).
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 13 nals and ensures near-continuous tracking throughout the boost and free-flight phase of the ballistic trajectory. The command interface of the Orion-HD receiver supports a total of six different instructions to support the handling of ballistic trajectory information: • • • • • • The LT (Load Trajectory) command initiates the upload of a set of trajectory polynomials.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 14 play of the IIP allows the range safety officer to discern whether the rocket would eventually land outside the permissible range area and thus necessitate an abort of the boosted flight or even a destruction of the malfunctioning vehicle. For an optimal support of sounding rockets, the Orion-HD receiver is able to predict the instantaneous impact point (IIP) from its navigations solution.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 3.2.4 15 Aiding for LEO Satellites The Orion-S receiver provides a dedicated aiding mode to support the GPS signal acquisition onboard a low Earth orbiting (LEO) satellite. Similar to the HD receiver, it uses a coarse approximations of the nominal trajectory to forecast the visible GPS satellites and the expected line-of-sight Doppler shift. This information is the used to allocate and initialize new tracking channels.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 16 Aided operation of the Orion-S receiver is supported by a variety of dedicated commands: • • • For configuring the orbital elements of the user satellite, the LO (Load Orbit) command is used. The first and second line of the elements set are each embedded into a separate LO command and consecutively transmitted to the receiver.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 3.2.6 17 External LNA Power Supply The antenna line of the Orion GPS receiver provides a +5V DC power level to feed a low noise amplifier with a maximum current consumption of about 50 mA. In some cases this specification may not be appropriate and an external power supply be required. Possible applications include e.g. the use of multiple parallel antennas or the use of miniature antennas with 3.3V LNA.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 18 4. Command and Output Message Reference 4.1 Overview A summary of the available commands and output messages for the Orion-HD and –S receivers is provided in the subsequent table: Table 4.1 GPS Orion commands and output messages MsgID AC AM CH CS DR DS DW EM ET IP LA LE LO LT MC OE PM PV RH RM (obsolete) RP RS SA SD SM SS ST TA TE TM TO TT UR F00 F03 F04 F05 F08 F13 F14 F15 F40 F41 F42 F43 F44 F45 F46 F47 F48 Document No.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver F50 F51 F52 F99 $GPGGA $PASHR,POS $PDLRM,IIP $PDLRM,XSD $PDLRM,RAW Document No.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.2 20 Protocol Description The Orion-S and –HD receivers employ the Mitel proprietary WinMon format for commands and output messages. In addition, selected NMEA type output messages are supported. Other than in the standard GPS Orion firmware (cf. [2]), the choice of WinMon and/or NMEA messages is not controlled by the discrete input pin (slide switch) but configured by command.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.2.2 21 NMEA Format For compatibility reasons, a limited set of NMEA output messages is available in the Orion-S and –HD receivers. Even though the NMEA format could likewise be applied for commanding, this option is not presently supported. According to the NMEA-0183 standard, each message is initiated by a dollar (‘$’) character and terminated by a carriage-return (CR, ASCII 0x13) and line-feed (LF, ASCII 0x10) record delimiter (Fig. 4.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3 22 Commands The GPS Orion receiver scans the primary communication port for WinMon sentences embedded in the / frame and starts the command processing, if the checksum test is passed. Commands that are syntactically correct but do not match a supported command identifier are ignored.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.1 4.3.1.1 23 Basic Receiver Configuration UR – Update Rate The navigation solution update rate can be selected using the UR command within the limits specified for a given receiver. Upon execution, the revised settings are acknowledged by one of the following command responses: I-UR-Update rate set to 1Hz I-UR-Update rate set to 2Hz I-UR-Update rate set to 5Hz E-UR-Ignored (invalid argument) CmdID Chars.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.1.2 24 DR – Data Rate The DR command provides the means for an individual configuration of receiver output messages. Sentences can be deactivated completely, polled once or issued at selected intervals. CmdID Chars. Format DR 11 1x 2 xx 2 xx 3 x(xx) 2 xx 1x Description Data Rate Command Id (=DR) Message number Output interval (-1..
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.1.4 25 MC – Media Correction The MC command controls the application of media corrections to the raw measurements prior to computing the navigation solution.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.2 4.3.2.1 26 Status Queries TA – Transmit Almanac The TA command initiates the output of 32 messages (F13) containing the current GPS almanac data. CmdID Chars. Format TA 6 1x 2 xx 2 xx 1x Description Transmit Almanacs Command Id (=TA) Checksum Example: TA15 4.3.2.2 Dump current almanac TE – Transmit Ephemeris The TE allows polling of GPS ephemeris data (F14 message) for one or all GPS satellites.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.3 4.3.3.1 27 Initialization PV – Position-Velocity The PV command sets the Cartesian position and velocity vector. It should be used instead of the Initial Position (IP) command to initialise the receiver in unaided mode whenever its velocity is larger than 50 m/s. Execution of the command is acknowledged by an F98 command reply giving the message I-PV-Updated current position and velocity CmdID Chars. Format PV 72 1x 2 xx 11 sxxxxxxxx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.3.2 28 DW – Doppler Window If code lock for an allocated GPS satellite is not acquired within a given time, the search is extended in neighbouring frequency bins at steps of ±500 Hz. The maximum Doppler offset considered in this search can be specified by the DW command. Its value should account for the expected reference frequency error (±1575 Hz at 1 ppm) and the uncertainty of the predicted Doppler shift.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.4 29 Reference Trajectory Aiding The Orion-S and –HD software versions support a software based aiding of the signal acquisition using reference trajectory information in the form of trajectory polynomials (for ballistic flights) or twoline elements (for satellites in low Earth orbit). Aiding can be controlled by the AM command and various other commands are available to store and retrieve the parameters of the reference trajectory.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.4.3 30 LO – Load Orbit Twoline orbital elements for aiding the Orion receiver onboard a LEO satellite are loaded using the LO command. One command each is required to upload the first and second line of orbital parameters. Upon successful reception of the first command, an information message I-LO-Twoline elements line 1 received is issued.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.3.4.5 LE – Load Epoch CmdID Chars. Format LE 25 1x 2 xx 4 xxxx 2 xx 2 xx 2 xx 2 xx 4 xx.x 3 xxx 2 xx 1x 4.3.4.6 Description Load Epoch Command Id (=LE) Year Month Day Hours Minutes Seconds Time system (UTC, GPS) Checksum LT – Load Trajectory CmdID Chars. Format LT 6 1x 1x 2 xx 2 xx 1x 4.3.4.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4 32 Output Messages (WinMon Format) 4.4.1 4.4.1.1 Periodic Receiver Data F00 – Geographic Navigation Data (Mitel) See [2] for a complete message description. 4.4.1.2 F03 – Channel Status Data (Mitel) See [2] for a complete message description. 4.4.1.3 F04 – Satellite Summary (Mitel) See [2] for a complete message description. 4.4.1.4 F05 – Processing Status (Mitel) See [2] for a complete message description. 4.4.1.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.1.6 33 F40 – Cartesian Navigation Data The F40 message provides the Cartesian state vector (position and velocity) of the host vehicle in the Earth-fixed WGS84 system. It is aligned to the instance of an integer GPS second once the receiver has a achieved continuous 3D navigation fix. MsgID Chars. F40 104 1 3 4 12 2 12 12 12 12 12 12 1 2 4 2 1 Format x xxx xxxx xxxxxx.xxxxx xx sxxxxxxxx.xx sxxxxxxxx.xx sxxxxxxxx.xx sxxxxx.xxxxx sxxxxx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.1.7 34 F41 – Pseudorange and Range Rate (Smoothed) Carrier phase smoothed pseudoranges and carrier phase based range rate measurements for each of the twelve channels are provided in the F41 message. The data are identical to those employed by the receiver in the computation of the navigation solution for the same epoch. MsgID Chars. F41 337 1 3 4 12 2 12 2 13 9 1 Format x xxx xxxx xxxxxx.xxxxx xx xxxxxx.xxxxx xx xxxxxxxxxx.xx sxxxxx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.1.8 35 F42 – Pseudorange, Carrier Phase and Range Rate (Raw) Complementary to the smoothed measurements given in the F41 message, the F42 message provide the unprocessed, raw pseudorange, carrier phase and range rate (Doppler) measurements for the 12 tracking channels. All measurements are given in metric units (i.e. [m], [m/s]). MsgID Chars. F42 505 1 3 4 12 2 12 2 13 14 9 1 Format x xxx xxxx xxxxxx.xxxxx xx xx.xxxxxxxxx xx xxxxxxxxxx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.1.9 36 F43 – Channel Status The F43 message indicates the current tracking status of each channel. It provides information on the predicted and measured Doppler shift, the signal-to-noise ratio and the currently achieved lock status. The time tag of the channel status message refers to the instance of message generation and is typically 0.2 s late with respect to the navigation and raw data time tag. MsgID Chars.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 37 and narrowband (20 ms) IQ-vector powers during 1 s intervals. Both values are empirically related by the expression C/N0 [db-Hz] = 41.5 + 1.1· (SNR [db] – 13.0) which is also used to compute C/N0 values prior to frame lock. SNR values obtained with representative antenna systems range from a minimum of 5 dB to a maximum of 20 dB. This corresponds to C/N0 values between 33 dB-Hz and 49 dB-Hz, respectively. Example: F431139172840.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 38 4.4.1.10 F44 – Clock Data This message provides information related to the receiver internal clock model. MsgID Chars. F44 71 1 3 4 12 2 8 8 4 12 6 8 2 1 Format x xxx xxxx xxxxxx.xxxxx xx xxxxxxxx xxxxxxxx xxxx xxxxxx.xxxxx sx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 39 4.4.1.11 F45– Relative Navigation Data (WGS-84 System) MsgID Chars. F45 104 1 3 4 12 2 12 12 12 12 12 12 1 2 4 2 1 Format x xxx xxxx xxxxxx.xxxxx xx sxxxxxxxx.xx sxxxxxxxx.xx sxxxxxxxx.xx sxxxxx.xxxxx sxxxxx.xxxxx sxxxxx.xxxxx x xx xx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 40 4.4.1.13 F47 – IIP Prediction MsgID Chars. F47 52 1 3 4 12 2 1 9 1 8 1 6 1 2 1 Format x xxx xxxx xxxxxx.xxxxx xx x sxxx.xxxx x sxx.xxxx x xxxx.x x xx x Description IIP prediction Message Id (=F48) GPS week GPS seconds of week [s] (at output) GPS-UTC [s] Blank Longitude [deg] Blank Latitude [deg] Blank Time to impact [s]] Validity flag (0= no IIP pred. available, 1=valid IIP pred.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.2 4.4.2.1 41 Working Parameters F50 – Reference Epoch for Trajectory Polynomials MsgID Chars. F50 24 1 3 4 2 2 2 2 4 3 1 Format x xxx xxxx xx xx xx xx xx.x xxx x Description Reference epoch for trajectory polynomials Message Id (=F50) Year Month Day Hours Minutes Seconds Time system indicator (GPS or UTC) Example: F502003 4 1 52813.2UTC04 4.4.2.2 F51 – Trajectory Polynomials MsgID Chars.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.2.3 42 F52 – User Spacecraft Mean Elements MsgID Chars. F52 95 1 3 4 11 11 11 9 10 10 10 12 2 1 Format x xxx xxxx xxxxxxx.xxx xxxxxx.xxxx xx.xxxxxxxx xxxxx.xxxx xxxxx.xxxx xxxxx.xxxx xxxxx.xxxx xxx.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.4.3 4.4.3.1 43 Diagnosis Messages F98 – Command Response MsgID Chars. F98 var 1 3 4 8 1 1 1 2 1 var 2 1 Format x xxx xxxx xxxxxx.x x x x xx x xx x Description Command Response Message Id (=F98) GPS week GPS seconds of week [s] (at output) Dash (“-“) Message type (I=Info, W=Warning, E=Error) Dash (“-“) Command ID Dash (“-“) Text Checksum Examples: F981139172809.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.5 44 Output Messages (NMEA Format) 4.5.1 $PASHR,POS Navigation Data The $PASHR,POS sentence provides the position and velocity fix as well as the satellite tracking status. The following specification describes only those fields supported by the Orion GPS receiver implementation of the $PASHR,POS message.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 45 Example: $PASHR,POS,0,08,120210.00,6801.29229,N,02103.64356,E,+313516.69,,351.76,193.33,+ 2595.47,02.2,,,,D06E*26 If no navigation fix is available (e.g.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.5.2 46 $PDLRM,IIP Instantaneous Impact Point Data The $PDLRM,IIP sentence provides the predicted instantaneous impact point and time to impact.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 47 If no valid navigation fix is available for an IIP prediction a reduced sentence is transmitted: Quantity Format Sentence identifier single comma Secondary identifier single comma Current receiver time CCCCC C CCC C hhmmss.ss single comma IIP validity flag Commas C C CCCCCC Units h = hours (int) m = minutes (int) s = seconds (float) (see note 1) # of Chars Range 5 1 3 1 9 'PDLRM' ',' 'IIP' ',' 000000.00 to 235959.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.5.3 48 $PDLRM,XSD Extended Status Data The $PDLRR,XSD sentence contains channel and receiver status information. Quantity Sentence identifier Format CCCCC single comma Secondary identifier single comma UTC (time) C CCC C hhmmss.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 4.5.4 49 $PDLRM,RAW Raw Measurement Data The $PDLRR,RAW sentence contains carrier phase smoothed pseudorange and range rate data. Quantity Sentence identifier single comma Secondary identifier single comma UTC (time) Format CCCCC C CCC C hhmmss.ss single comma GPS week C XXXX single comma GPS seconds in week C FFFFFF.FFFFF single comma GPS to UTC time difference single comma Receiver clock offset C XX C ±F.
Document Title: User’s Manual for the GPS Orion-S/-HD Receiver 50 References [1] GPS Orion 12 Channel GPS Receiver Design; DS4808; Mitel Semiconductor; Issue 1.3, August 1997. [2] GPS Orion - GP2000 Series Demonstrator Board User’s Guide; DM4922; Mitel Semiconductor; Issue 4, March 1998. [3] GP2000 GPS Chipset - Designer’s Guide; MS4395; Mitel Semiconductor; Issue 2.3, April 1998. [4] GP2000 GPS Receiver Hardware Design; AN4855; Mitel Semiconductor; Issue 1.4, February 1999.
