NOAA-17, AMSU-A1, Beacon TIP Switching Test, 28 August 2003- Issued: 26 August 2003; 1220 UTC

8:20 AM
Subject: NOAA-17, AMSU-A1, Beacon TIP Switching Test, 28 August 2003- Issued: 26 August 2003; 1220 UTC

NOAA-17 beacon TIP switching to investigate AMSU-A1 channel-7 noise

Date/Time(UTC) Message Issued:
26 August 2003/ 1220 UTC

Satellite(s) Involved:

Instrument(s) Involved:
AMSU-A1 (could affect others)

Product(s) Involved/Affected:
Soundings, Level 1B, channel-7 data

Date/Time(UTC) of Initial Implementation:
28 August 2003, 1920 - 1935 UTC

Details/Specifics of Change:
NASA/GSFC has requested a special test as part of the investigation into the
NOAA-17 AMSU-A1 noise spikes on channel-7. They have requested that IPD
specifically observe the AMSU data (the Space View and Internal Warm Target
counts) during the test period to identify any coincident changes or science
data contamination on channel 7. Their request indicates the following:
"The instrument vendor performed a Root Cause Analysis which concluded that
radio frequency (RF) interference in the frequency range of 10 - 200 MHz
could be a possible cause of a problem. A joint connecting the channel 7
mixer to its intermediate frequency (IF) amplifier is known to have low
margin for rejection of this signal. ... the on-orbit interference could be
due to the proximity of NOAA-17 to other satellites broadcasting at a
frequency around 137.5 MHz."

NOAAs SOCC reports that the requested test will be performed on August 28.
During the time period from 1920 UTC to 1935 UTC, the following procedure
will be performed:
"Turn off the N17 beacon transmitter 2 for 5 minutes. Then, turn on beacon
transmitter #1 for 5 minutes, turn it off for 5 minutes, and finally turn
beacon transmitter 2 back on (it is the normal operations beacon

Users are asked observe their data carefully during this time period and
please contact us with problems or concerns. Thank you for your patience
and support.

Contact Person(s) Name/Email/Phone Number for Questions: ext. 117 or ext. 130

Web site(s) that contain other relevant information (where applicable): - History of level 1B
notices - All user notices - SOCC polar satellites status - SOCC morning reports