[IGSMAIL-3758]: TurboRogue L2 tracking
Angelyn W. Moore
Angelyn.W.Moore at jpl.nasa.gov
Fri Feb 22 15:05:16 PST 2002
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IGS Electronic Mail 22 Feb 15:05:18 PST 2002 Message Number 3758
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Author: Angelyn Moore
Dear Colleagues,
Recalling IGSMail #2071, TurboRogue receivers have been
known to experience significant degradation of L2 tracking
during times of high ionosphere.
(http://igscb.jpl.nasa.gov/mail/igsmail/1998/msg00298.html)
This effect continues to be seen today in all TurboRogue
stations not operating in a one-second sampling mode, and
negatively impacts the IGS network effectiveness.
A firmware upgrade for such receivers appears to
correct this difficulty. Several IGS stations have
utilized this firmware version and the L2 tracking
is seen to be restored at the time of the firmware
installation.
I've prepared two graphs to demonstrate.
http://igscb.jpl.nasa.gov/images/aoa1_p2c1.gif shows
that tracking when P2-C1 exceeds 12m was restored
at the time of the upgrade. (Although not too obvious
on this scale, the quantization effect for 8m<P2-C1<12m
is also removed).
http://igscb.jpl.nasa.gov/images/aoa1_l1l2.gif shows
over a few preceding days that the number of channels
tracking dual-frequency declined to about 2 near 00:00UT
every day (this is, predictably, near local noon).
After the firmware upgrade, no such decrease is seen.
Similar studies for the few other stations using this
firmware corroborate.
All agencies operating TurboRogue stations are requested to
test and install 3.2.32.11 as soon as possible, to restore these
sites to reliable dual-frequency operation (as is required by
the IGS station guidelines!).
Jim Holston (j_holston at aoa_gps.com; +1 805 495 8420) can be
contacted at AOA to arrange to receive the firmware.
Analysts wanting to examine the effect can check data
quality for sites that have had 3.2.32.11 installed
before and after the firmware changes:
AOA1 y2002 d052
AOML y2000 before d207 vs. after d229 *
DUBO y2001 d023
HNPT y2000 d222
SOL1 y2000 d242
USNA y2000 d242
BRMU y2001 before d093 vs. after d110
* AOML was in operation between these days, but had
an interim release of firmware during this time.
I ask that you please let us know at the CB of any relevant
experiences in operating stations or using 3.2.32.11 data.
Please note that this firmware, while apparently restoring
such stations to dual-frequency tracking, does not offer all
the improvements of upgrading to a modern codeless receiver,
and agencies operating stations with cross-correlation
receivers should continue to plan to upgrade to codeless
receivers wherever possible. Stations of high
importance to the IGS (for instance, ITRF sites or
particularly remote sites with few nearby IGS stations)
Please note that this firmware, while apparently restoring
such stations to dual-frequency tracking, does not offer all
the improvements of upgrading to a modern codeless receiver,
and agencies operating stations with cross-correlation
receivers should continue to plan to upgrade to codeless
receivers wherever possible. Stations of high
importance to the IGS (for instance, ITRF sites or
particularly remote sites with few nearby IGS stations)
should take precedent in such planning.
Many thanks to Dave Stowers and Jim Holston for arranging
the AOA1 test and demonstration on short notice, and to all
site operators for maintaining accurate information in
the site logs!!
With best regards,
Angie
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Angelyn W. Moore, Ph.D. Deputy Director, IGS Central Bureau
JPL/Caltech Angelyn.W.Moore at jpl.nasa.gov
4800 Oak Grove Dr. MS 238-540 voice: +1 818 354 5434
Pasadena CA 91109 USA http://igscb.jpl.nasa.gov fax: +1 818 393 6686
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