[IGSMAIL-348] Rogue Firmware Upgrade V7.5

[U.]

IGS Electronic Mail       29-SEP-1993 08:25:45       Message Number 348
***********************************************************************
 

>From: U. Lindqwister
Subj: Rogue Firmware Upgrade V7.5
---------------------------------

A new Rogue GPS receiver firmware version (7.5) is available. The new version
will feature automatic switch-back to P-code tracking as soon as the the GPS
signal becomes non-encrypted and also it will have a satellite-independent
bias between the C/A pseudorange and the P-code pseudorange (with the
exception of satellite 19). Note that there is no bias between C/A and
P-code pseudoranges on the TurboRogue, hence this software upgrade will
only affect the Rogues (SNR-8, SNR-800, SNR-8C).

The C/A pseudorange is used when the GPS signal is encrypted (when AS is on)
and, unfortunately, in the currently software version (7.3), there are biases
between the P-code pseudorange and the C/A pseudorange and this bias is
different for different satellites. For this software release we attempted to
remove the biases altogether, however, after running into several technical
difficulties, we settled for insuring that the bias would be the same for all
satellites (with the exception of satellite 19 - the reasons for this is rather
obscure and will not be discussed here). After all the Rogues have been
upgraded we intend to obtain calibration values of each receivers bias in the
GPS Global Network. The description on how to obtain the calibration values have
been included in the firmware upgrade package sent to each organization 
which will perform the upgrade. It is our goal to generate a table of biases
for each station and satellite and then broadcast it to the IGS community.

Earlier versions of the Rogue software (up to and including version 7.4)
had the feature of continuing tracking a satellite in
P-codeless mode even after the satellite signal was not encrypted anymore. This
sometimes resulted in the collection of several hours of lower quality
P-codeless data, while the satellite actually was transmitting non-encrypted
signals and could have tracked in P-code mode. The receivers with the new
software (version 7.5) will stop tracking a satellite in P-codeless mode as soon
as the navigation message indicates that the encryption has been turned off and
then switch back to tracking in P-code mode.

A near simultaneous upgrade will reduce problems with combining data from
several stations when AS is turned on. We propose that the new firmware be
installed in the Rogues between Oct 14-15, 1993. Please indicate to us the date
of the upgrade by FAX (818-393 4965) or by email (ujl at logos.jpl.nasa.gov). If
you are having problems with the new firmware, then feel free to contact Steve
Dinardo by FAX or email (sjd at logos.jpl.nasa.gov) or myself.


- Ulf

=======================================================================
Ulf J. Lindqwister                 Telephone:   (818) 354 1734
GPS Networks & Operations Group    FAX:         (818) 393 4965
Jet Propulsion Laboratory          Email:       ujl at logos.jpl.nasa.gov
4800 Oak Grove Dr.
Pasadena, CA 91109
=======================================================================