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Document Title: 29
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 Reference Trajectory Aiding
The Orion-S and –HD software versions support a software based aiding of the signal acqui-
sition 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 parame-
ters of the reference trajectory. All relevant data are stored in non-volatile memory during
deactivation of the receiver.
4.3.4.1 AM – Aiding Mode
The Aiding Mode command is used to control the application of a priori trajectory information
in the Doppler and visibility computation for new tracking channels.
Upon execution of the command an F98 command response with either of the following in-
formation or errors messages is issued:
I-AM-Aiding disabled
I-AM-Aiding for ballistic trajectories enabled
I-AM-Aiding for low Earth orbits enabled
E-AM-Ignored unsupported aiding mode selection
CmdID Chars. Format Description
RM 7 Run Mode
1x <STX>
2xx Command Id (=AM)
1x Aiding mode (0=unaided,1=ballistic, 2=orbit)
2xx Checksum
1x <ETX>
Notes:
• The Aiding Mode command replaces the obsolete RM (Run Mode) command
• Aiding mode 1 is only available in the Orion-HD receiver, aiding mode 2 is only avail-
able in the Orion-S receiver
Examples:
<STX>AM03C<ETX> Select unaided operation
<STX>AM13D<ETX> Select aiding for ballistic vehicles using trajectory polynomials
<STX>AM23E<ETX> Select aiding for LEO satellites using twoline elements
4.3.4.2 RM – Run Mode
The run mode command is a syntactically identical but obsolete command for selecting the
aiding mode. It has been superseded by the AM (Aiding Mode) command in software ver-
sions D07L (Orion-S) and higher.
Examples:
<STX>RM02F<ETX> Select unaided operation
<STX>RM12E<ETX> Select aiding for ballistic vehicles using trajectory polynomials
<STX>RM22D<ETX> Select aiding for LEO satellites using twoline elements