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From: "Luck, John"
To: "'Claudine'" , "'Jim Ray'"
Cc: "Manning, John" ,
"Govind, Ramesh"
,
"Woodger, John"
Subject: Response to CfP for IGS/BIPM Pilot Project
Date: Fri, 13 Mar 1998 10:43:22 +1100
X-Priority: 1
Return-Receipt-To: "Luck, John"
X-Mailer: Internet Mail Service (5.0.1458.49)
Status: RO
Dear Jim and Claudine,
Below is AUSLIG's response to your Call for Participation in the
IGS/BIPM Pilot Project.
Also included at the end of this message is a Word 6 Attachment
containing the same response.
I wish you great success in this exciting and important project.
With best regards,
Yours sincerely,
John
Dr John Luck
Director, Orroral Geodetic Observatory
AUSLIG
PO Box 2
Belconnen ACT 2616
Australia
Phone: +61 (2) 6201-4349 (occasionally +61 (2) 6235-7111)
Fax: +61 (2) 6201-4366
Email: johnluck@auslig.gov.au
Response to CALL FOR PARTICIPATION in an
IGS/BIPM PILOT PROJECT TO STUDY ACCURATE TIME AND FREQUENCY
COMPARISONS USING GPS PHASE AND CODE MEASUREMENTS
Agency or group: Australian Surveying and Land Information Group
(AUSLIG)
Contact person(s): Dr John McK. LUCK
Dr Ramesh GOVIND
E-mail address(es): johnluck@auslig.gov.au
Rameshgovind@auslig.gov.au
Areas of participation:
1) Deployment of GPS receivers: Yes
Ashtech Z-12 at Orroral, 5 MHz input from HP5071A cesium, 1 pps output
monitored at 1-minute intervals against HP5071A designated
UTC(AUS)linked
by GPS Common-View to UTC/TAI. Likely to cease at end of July 1998.
Ashtech Z-12 or Z-18 at Mount Stromlo, Canberra, similarly configured,
is
a possibility after July 1998.
2) GPS data analysis: Yes
Routine daily orbit solutions, as IGS Associate Analysis Centre,
including
receiver clock estimates.
Comparison of estimated clocks against 1 pps results on suitably
configured receivers as above.
Extension of strategies to characterize satellite clocks similarly.
3) Analysis of instrumental delays: Maybe
A limited opportunity exists to study correlations with environmental
Parameters while receiver is at Orroral.
Agreement-in-principle has been reached to measure inter-channel delays
and variations, once a GPS Simulator is installed in South Australia.
4) Time transfer comparisons: Yes
Existing time transfers by GPS Common-View, Multichannel, and MCCV at
Orroral.
The potential exists to tie in with existing TWSTFT between NML-CRL and
NML-NIST but there are many difficulties unlikely to be resolved within
six months.
6) Other: (please list)
Coordination between areas of participation, and between cooperating
institutions within Australia.
Limitations on participation: (please list any restrictions)
1. The Australian National Time Scale Service is being rearranged
administratively and financially at the moment, so it may be six months
or
more before increased participation is possible.
2. Geographical separation is at present a barrier to meaningful
comparisons
against other techniques such as TWSTFT and SLR.
Comments or suggestions:
1. VLBI "Time Syncs" between Tidbinbilla (equipped with IGS TurboRogue
driven
from hydrogen maser) and Goldstone,CA have been discontinued. It may be
possible to persuade JPL to resurrect them (and correct some anomalies)
for
this Pilot Project.
2. There may be sufficient other sites combining IGS station, VLBI
station and
timing laboratory to warrant establishment of a Topical Sub-Group to
study
comparisons of GPS Carrier Phase against VLBI. For example, within
Europe,
and the KeyStone system with CRL in Japan.
3. LASSO/T2L2 could be considered between e.g. Graz, Grasse, Wettzell
and Matera
(new SLR system) if any on-board packages can be deployed or
reactivated. It
is also conceivable that SLR time transfer will occur between Canberra
and
CRL, Tokyo - but not yet. Although it is probably premature to consider
SLR
as a serious candidate for time transfer comparisons, developments
should be
monitored.
4. It would be of value for the Pilot Project Working Group to produce a
paper
explaining exactly how the receiver clocks are set in each geodetic
receiver
- Ashtech, TurboRogue, 3S R-100, Trimble, etc. - when running from
internal
oscillator, from external frequency standard; what is the (hardware)
relationship between internal clock (the one estimated in geodetic
processing) and 1 pps out; time constants and mechanisms for driving
receiver
clocks against GPS time; extent of carrier phase smoothing of code
signals;
and similar matters.
5. IGEX'98 would appear to be a great opportunity to justify inclusion
of
GLONASS in this Pilot Project - unless it would complicate it unduly.
Please return to jimr@maia.usno.navy.mil and cthomas@bipm.fr,
preferably by 15 March 1998
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