Subject: [IGSMAIL-3374]: distortion testing of PRN19 (fwd)
From: Jim Ray (USNO 202-762-1444) <[email-masked]>
To: [email-masked]
Date: Mon, 11 Jun 2001 8:40:57 EDT

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IGS Electronic Mail      11 Jun 05:41:01 PDT 2001      Message Number 3374
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Author: Jim Ray (forwarding FGCS/GIAC message)

[Since geodetic receivers usually ignore the health bit, this could have
 some impact for the IGS.  --Jim]

June 08, 2001

FGCS/GIAC NEWS FLASH

There are tentative plans to perform a Digital Distortion Anomaly test on 
PRN19.  The tentative plan is that the test will begin on June 18, 2001, 
and to last for 5.5 days (132 hours).  The health bit for PRN19 will be 
set to "UNHEALTHY" for the duration of this test.  This test is not 
expected to be noticed with standard GPS receivers, since such equipment 
should not process data from unhealthy satellites.

One purpose of this test is to attempt to replicate a signal distortion 
observed in 1993 on PRN19.  When the distortion first occurred, it was 
corrected by switching to an alternative hardware path within the 
satellite.  If the distorted signal is successfully generated, it will 
be used to assess the performance of specialized GPS test equipment known 
as signal quality monitors.  These monitors are important components in 
aviation augmentation systems.

We will provide a follow-up message when we learn of the finalized
dates of the test.  We are also updating the GIAC web page
[http://www.ngs.noaa.gov/FGCS/] to provide this information.