Mitel GPS Orion-S/-HD Receiver User manual

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 :1.0
Date :June 22, 2003

Document Title: ii
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
Document Change Record
Issue Date Pages Description of Change
1.0 June 22, 2003 all First release
Disclaimer
Infor
mation 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 notific
a-
tion. In no way shall DLR or the authors be held liable for direct or indirect damage resul
t-
ing from miss
ing or erroneous information. Furthermore, DLR reserves the right to change
interfaces and system specifications in future releases.

Document Title: iii
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
Table of Contents
Document Change Record...................................................................................................... ii
Table of Contents.................................................................................................................... iii
Scope and Applicability .......................................................................................................... 1
Acronyms and Abbreviations................................................................................................. 2
1.Introduction......................................................................................................................... 3
1.1 GPS Orion Receiver....................................................................................................3
1.2 Functional Overview ....................................................................................................3
1.3 Receiver Versions........................................................................................................4
2. Receiver Hardware............................................................................................................. 5
2.1 Main Board...................................................................................................................5
2.2 Interface Board.............................................................................................................7
2.3 Antenna........................................................................................................................7
3. Operations Guide ............................................................................................................... 8
3.1 Basic Receiver Handling..............................................................................................8
3.1.1 Hardware Setup ...............................................................................................8
3.1.2 Precautions.......................................................................................................8
3.1.3 Serial Communication......................................................................................8
3.1.4 Start-Up and Initialization.................................................................................9
3.1.5 Output Selection.............................................................................................10
3.1.6 Pulse-per-Second Signal...............................................................................11
3.1.7 Troubleshooting..............................................................................................11
3.2 Special Applications...................................................................................................12
3.2.1 Aiding for Ballistic Trajectories.......................................................................12
3.2.2 Lift-off Signal..................................................................................................13
3.2.3 IIP Prediction..................................................................................................13
3.2.4 Aiding for LEO Satellites................................................................................15
3.2.5 Relative Navigation ........................................................................................16
3.2.6 External LNA Power Supply...........................................................................17
4. Command and Output Message Reference .................................................................. 18
4.1 Overview ....................................................................................................................18
4.2 Protocol Description...................................................................................................20
4.2.1 WinMon Format..............................................................................................20
4.2.2 NMEA Format.................................................................................................21
4.3 Commands.................................................................................................................22
4.3.1 Basic Receiver Configuration.........................................................................23
4.3.1.1 UR –Update Rate..........................................................................................................................23
4.3.1.2 DR –Data Rate...............................................................................................................................24
4.3.1.3 SM –Sentence Mode.....................................................................................................................24
4.3.1.4 MC –Media Correction..................................................................................................................25
4.3.2 Status Queries................................................................................................26
4.3.2.1 TA –Transmit Almanac.................................................................................................................26
4.3.2.2 TE –Transmit Ephemeris..............................................................................................................26
4.3.3 Initialization.....................................................................................................27
4.3.3.1 PV –Position-Velocity....................................................................................................................27
4.3.3.2 DW –Doppler Window...................................................................................................................28
4.3.4 Reference Trajectory Aiding ..........................................................................29
4.3.4.1 AM –Aiding Mode..........................................................................................................................29
4.3.4.2 RM –Run Mode..............................................................................................................................29

Document Title: iv
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
4.3.4.3 LO –Load Orbit...............................................................................................................................30
4.3.4.4 TO –Transmit Orbit........................................................................................................................30
4.3.4.5 LE –Load Epoch............................................................................................................................31
4.3.4.6 LT –Load Trajectory......................................................................................................................31
4.3.4.7 ET –End Trajectory.......................................................................................................................31
4.3.4.8 TT –Transmit Trajectory...............................................................................................................31
4.4 Output Messages (WinMon Format).........................................................................32
4.4.1 Periodic Receiver Data..................................................................................32
4.4.1.1 F00 –Geographic Navigation Data (Mitel).................................................................................32
4.4.1.2 F03 –Channel Status Data (Mitel)..............................................................................................32
4.4.1.3 F04 –Satellite Summary (Mitel)...................................................................................................32
4.4.1.4 F05 –Processing Status (Mitel)...................................................................................................32
4.4.1.5 F08 –Operating Parameters (Mitel)............................................................................................32
4.4.1.6 F40 –Cartesian Navigation Data.................................................................................................33
4.4.1.7 F41 –Pseudorange and Range Rate (Smoothed)....................................................................34
4.4.1.8 F42 –Pseudorange, Carrier Phase and Range Rate (Raw)...................................................35
4.4.1.9 F43 –Channel Status ....................................................................................................................36
4.4.1.10 F44 –Clock Data............................................................................................................................38
4.4.1.11 F45–Relative Navigation Data (WGS-84 System)...................................................................39
4.4.1.12 F46 –Relative Navigation Data (RTN Frame)...........................................................................39
4.4.1.13 F47 –IIP Prediction........................................................................................................................40
4.4.1.14 F48 –Configuration and Status Parameters..............................................................................40
4.4.2 Working Parameters......................................................................................41
4.4.2.1 F50 –Reference Epoch for Trajectory Polynomials .................................................................41
4.4.2.2 F51 –Trajectory Polynomials .......................................................................................................41
4.4.2.3 F52 –User Spacecraft Mean Elements......................................................................................42
4.4.3 Diagnosis Messages......................................................................................43
4.4.3.1 F98 –Command Response..........................................................................................................43
4.5 Output Messages (NMEA Format)............................................................................44
4.5.1 $PASHR,POS Navigation Data .....................................................................44
4.5.2 $PDLRM,IIP Instantaneous Impact Point Data.............................................46
4.5.3 $PDLRM,XSD Extended Status Data............................................................48
4.5.4 $PDLRM,RAW Raw Measurement Data.......................................................49
References.............................................................................................................................. 50

Document Title: 1
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
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 supple-
ments and supercedes related sections of the GPS Orion Product Brief [1] and the GP2000
Series Demonstrator Board User’s Guide [2]. It is applicable for s/w versions D06H (Orion-
HD) and D07N (Orion-S).

Document Title: 2
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
Acronyms and Abbreviations
AAmpere
AGC Automatic Gain Control
ASCII American Standard Code for Information Interchange
C/N0Carrier-to-Noise Ratio
COM Communication
dB Decibel
DC Direct current
DLR Deutsches Zentrum für Luft-und Raumfahrt
EPROM Erasable Programmable Read Only Memory
FLL Frequency-Locked Loop
GPS Global Positioning System
GSOC German Space Operations Center
I/F Intermediate Frequency
IIP Instantaneous Impact Point
IQ In-phase and Quadrature (correlator output)
L1 GPS frequency (1575.42MHz)
LEO Low Earth Orbit
LNA Low noise amplifier
MITEL Company name
NMEA Nautical Marine Electronics Association
NVM Non-Volatile Memory
ORION Product name
PC Personal Computer
PLL Phase-Locked Loop
PPS Pulse-per-second
PRN Pseudorandom Noise
R/F Radio Frequency
RAM Random Access Memory
RX Receiver
SAW Surface Acoustic Wave
SMA Sub Miniature Assembly
SNR Signal-to-Noise Ratio
SV Space Vehicle
TC Telecommand
TCXO Temperature Controlled Oscillator
TM Telemetry
TTL Transistor-Transistor-Logic
TX Transmitter
UART Universal Asynchronous Receive and Transmit
VVolt
WWatt

Document Title: 3
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
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. It can be supplemented by
an optional interface board featuring a switching regulator, serial line drivers (RS 232) and a
backup battery.
Fig. 1.1 GPS Orion main board
A basic software for the GPS Orion receiver has earlier been made available by Mitel Semi-
conductor as part of the GPS Architect Development Kit. It is restricted to purely terrestrial
applications and has received numerous extensions and modifications to provide accurate
navigation under the rapidly varying signal conditions encountered in typical space missions.
Key upgrades include enhanced tracking loops, a synchronization of measurements to inte-
ger GPS seconds, the provision of precise carrier phase measurements, a revised navigation
algorithm, as well as a software based aiding of the signal acquisition using reference trajec-
tory data. In addition to the above software changes, the original hardware design has been
amended by a supplementary pin for output of the pulse-per-second signal.
1.2 Functional Overview
DLR’s family of GPS Orion receivers comprises various firmware versions for space and high
dynamics applications. Available software configurations are:
•Orion-S for low Earth satellites and formation flying
•Orion-HD for high dynamics platform like sounding rockets and reentry vehicles
Features common to all receiver models are summarized below.
•12 fully independent tracking channels
•2-bit sampling
•3rd order PLL with FLL assist
•Low noise code, carrier and Doppler measurements
•Acquisition aiding using reference trajectory information
•Navigation update rate of up to 2 Hz
•Configurable ASCII output messages in WinMon and NMEA format
•Pulse-per-second signal
•Low power consumption (2 W at 5 Volts)

Document Title: 4
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
•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.3 addresses the receiver operation and the command and log functionality is described
in full detail in Chap. 4.
1.3 Receiver Versions
The Orion receiver is available in various versions, which basically differ by the employed
receiver software. Aside from the standard receiver (Mitel reference design [3], [4]), which is
restricted to terrestrial applications, a space (-S) version and a high dynamics (-HD) version
are available. These employ specific trajectory models to enable a safe and rapid signal ac-
quisition under rapid motion of the host vehicle. For satellites in low Earth orbit, aiding is pro-
vided by an analytical orbit model using twoline elements, whereas a set of piecewise poly-
nomials is employed to approximate the trajectory of ballistic vehicles (sounding rockets, re-
entry capsules) in the HD version. Various commands specific to each of these versions are
provided to load, dump and use the respective aiding information.
The two versions also differ by their choice of FLL/PLL loop settings that are adapted to the
specific application needs. A narrow bandwidth of the carrier tracking loop is chosen in the
Orion-S receivers to achieve the most accurate carrier phase measurements under typical
line-of-sight accelerations of 1G. Wide bandwidth settings, in contrast are chosen for in the
HD receivers to accommodate the extreme dynamics of a powered flight and the re-entry
shock.
Finally, a relative navigation mode is offered by the Orion-S receiver to support its use in
basic formation flying and rendezvous & docking applications.
A detailed account of the prototype software for the GPS Orion receiver is given in the GPS
Architect Software Design Manual [5]. Subsequent modifications for the S and HD version
are described in [6].

Document Title: 5
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
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 +5V power supply for the preamplifier is pro-
vided 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 (1575.42 MHz) is down-converted and digi-
tized in the GP2015 front-end chip [7]. An external discrete filter and a DW9255 SAW filter [8]
are used to filter the first (175.42 MHz) and second (35.42 MHz) intermediate frequencies,
while an on-chip filter is used for the third analog IF (4.31 MHz). Finally, the signal is digitized
and sampled to create a digital IF of 1.405 MHz with 2-bit quantization. The fundamental
reference frequency for the mixing process is provided by a 10.0 MHz TCXO with a specified
stability of 2.5 ppm. It also used to derive a 40 MHz clock frequency for the correlator.
The subsequent signal processing is performed in the GP2021 correlator chip [9], which pro-
vides 12 fully independent C/A code correlator channels. It also offers two UART ports for
external I/O as well basic memory management capabilities that can be used when working
with the ARM micro-processor. The GP2021 chip furthermore maintains a low accuracy real-
time clock fed by a 32.568 kHz crystal. It also derives a 20 MHz clock frequency for the ARM
processor.
All software tasks operate in the 32-bit P60ARM-B micro-processor [10] that provides a peak
performance of 20 MIPS and has a typical spare capacity of 35% at 1 Hz navigation rate and
25% at 2Hz. Upon start-up (or a reset) of the receiver, a boot loader (stored in EPROM) is
activated that copies the executable code and initialisation data from the EPROM into the

Document Title: 6
User’s Manual for the GPS Orion-S/-HD Receiver
Document No. Issue 1.0
GTN-MAN-0110 June 22, 2003
DLR/GSOCNo part of this document shall be reproduced in any form or disclosed to third parties without prior authorization.
RAM memory. The EPROM is arranged into two 16 bit wide chips (256 kB total), while RAM
is partitioned into four 8bit 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 ap-
proximately 0.1 mA.
The main board offers an SMA (or MCX) connector for the GPS antenna. It is connected to
the interface board via a 9-pin header that provides two bi-directional serial lines, the main
and backup power supply, an input discrete and a reset line. Optionally, a tenth pin is made
available for the pulse-per-second signal. A summary of the pin assignment is provided in
Table 2.1.
Table 2.1 Pin assignment for GPS Orion interface connector
Pin Function
1Ground
2Vdr (memory backup positive supply)
3RX B serial input
4RX A serial input
5TX B serial output
6TX A serial output
7Discrete input line (used as a “lift-off” signal)
8Vdd level sense circuit output (used as a “reset” if connected to GND)
9Vdd (+5V prime power supply input)
10 PPS output (optional)
General physical and electrical parameters of the Orion main board are summarized in Table
2.2. The GPS Orion receiver and its components have not been validated for space applica-
tions. Nevertheless, limited information on the radiation hardness of the core chipset sug-
gests it’s suitability up to a total dose of about 15 krad [11]. However, no latch-up protection
is presently provided to safeguard against destruction of CMOS circuits under the action of
heavy ions. Other than the standard Orion receiver, the main boards of the Orion-S and -HD
receivers are not equipped with a “supercap” capacitor, since this is not considered vacuum-
proof. This means that the non-volatile memory and real-time clock is lost whenever the main
board is disconnected from the backup power supply (pin 2).
Table 2.2 Physical and electrical parameters of GPS Orion main board
Parameter Value
Dimension 95mm x 50mm x ~10mm
Weight ca. 50g
Operations Temperature -40°C to +85°C (as per [1])
Storage Temperature -50°C to +110°C (as per[1])
Main power supply +5V DC (+/-10%), 400 mA (2W)
Backup power supply >+2.2V DC, ca. 100µA
Data I/O levels CMOS TTL (0V, +5V)
RF input
Connector SMA (or MCX)
Active antenna power supply +5V DC, 50 mA
Impedance 50Ω