[IGSMAIL-4358]: MCM4 (possible interference effect since 26nov2002)

[Dave Stowers]

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IGS Electronic Mail      29 Apr 09:12:55 PDT 2003      Message Number 4358
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Author: Seth White/Dave Stowers

Dear Colleagues,

On 11/26/02, an Iridium telephone testing system was installed near the IGS
station MCM4. A separate GPS receiver, operated from the same antenna as MCM4,
has shown L1/CA phase breaks that correlate in time with transmissions from
the Iridium system.

Although the MCM4 receiver and data has not outwardly appeared to have 
experienced similar problems, it is possible that MCM4 data may have experienced
some level of corruption due to the Iridium signal since 11/26/02. The Iridium
system operates intermittently throughout the day, but since it is transmitting
a large majority of the time, any interference would be essentially continuous. 

The Iridium system continues to operate, however measures are being taken to
modify this system to solve the known interference problem with the other
GPS receiver. Once the interference has been eliminated, another
notification will be sent and the sitelog updated, noting the period of
likely interference.

Seth White
Science Technician
McMurdo Station, Antarctica
scitech at mcmurdo.gov