[IGSMAIL-0553] GPS Global Network Advisory

[Ulf]

IGS Electronic Mail      Fri Apr  1 13:07:45 PST 1994      Message Number 0553
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Author: Ulf J. Lindqwister/JPL
Subject: GPS Global Network Advisory: Rogue Firmware Upgrade Status

Subject:	GPS Global Network Advisory: Rogue Firmware Upgrade Status

Dear Colleagues,

The Rogue receiver firmware version 7.5 definitivly has one or more
software bugs in it. An analysis of the data volume collected from
Rogue receivers running versions 7.3 and 7.5 and from TurboRogues
before and after AS came on (January 31, 94) shows the following:

Receiver   Software  # Stations    Before AS   After AS  Loss
-----------------------------------------------------------------
Rogue
           V7.3          7           95%         93%       2%
           V7.5         18           94%         81%      13%

TurboRogue
           V2.8         15           94%         90%       4%
-----------------------------------------------------------------

The Rogue V7.3 and TurboRogue data losses are essentially equivalent
(within the error bars) and are due to data acquisition and loss of
lock for satellites at generally higher elevation angels when AS is
on (AS data has lower SNR). The 13% data loss for receivers with the
latest Rogue software (V7.5) can only be a software bug. The data loss
is not uniform, were 75% data loss in all receivers (with V7.5) for a few
days are followed by 2-3 weeks of 95% data and then the receivers drop to
75% again, in a 2-3 week repeating pattern.

Version 7.5 had several bugs fixed and some added featurers (one of
which we believe is causing the data loss). We have decided to remove
the feature causing the data loss are currently testing Version 7.7.
The new version (7.7) is expected to be released 1 month from now.

For now we suggest the following solutions:
1. Switch the Rogue to a TurboRogue (if possible). For those of
you who have TurboRogues you will get more data at higher quality
compared the Rogues. Also, the Rogues owned by NASA are being faced
out and eventually the software in the Rogue will not be supported.
(the faceout period has been decied yet).
2. Switch back to Version 7.3. If you don't care about the pseudorange
data, then you are better off with 7.3 right now.



- Ulf

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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
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