Subject: [IGSMAIL-2039] Radio noise suppressed at Petropavlovsk
From: Grigory Steblov and Mikhail Kogan
Date: Tue, 13 Oct 1998 2:13:45 PDT

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IGS Electronic Mail      Tue Oct 13  2:13:45 PDT 1998      Message Number 2039
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Author: Grigory Steblov and Mikhail Kogan
Subject: Radio noise suppressed at Petropavlovsk

PS TRACKER ID:  PETR
DOMES No.:      12355M001
LOCATION:       Petropavlovsk-Kamchatka, Kamchatka Peninsula, Russia
                NEDA: Northern Eurasia Deformation Array created and run by
                RUSEG: Russia/US Experiment on Geodynamics by GPS Technology. 
                NEDA operational control is provided by RDAAC: 
                Regional GPS Data Acquistion/Analysis Center, Moscow, Russia 
                (contact Grigory Steblov: [email-masked])
****************************************************************************
We are glad to report that there are NO MORE problems 
with the intense radio noise at IGS station in Petropavlovsk-Kamchatka.
The noise was suppressed completely although it took 3 months to overcome
the problem.
****************************************************************************

IGS station PETR worked without any problems for 8 months, since October '97.

- In our igsmail of 28-Jul-98, we stated the following:

"We recommend TO DISREGARD ANY DATA collected at PETR since 27-JUL-98 (DOY 208)
until further notice.

REASON: Continued problem with locking enough satellites at local (Kamchatka)
        daily hours (See our IGSMail of: 
        Mon Jul 27 9:01:03 PDT 1998 / Message Number 1964)."

- The problem started 9-Jul-98 and it was caused by the new antenna of RosTelecom
about 7 km away from our GPS antenna. 2-3-4 satellites only were locked sometimes 
for 2-3 hours degrading the data for purposes of IGS. We discussed the situation 
with experts at UNAVCO, JPL, and MIT. UNAVCO provided to us replacement antennas
and cables. Yet the problem persisted. We also replaced the TurboRogue receiver 
with the Ashtech Z12, because of its better SNR, but it helped insignificantly.

- A combination of three actions solved the problem last week:

1) Setting up of the grounded, flat, steel shield vertically, at a distance 
of 0.96 m from the antenna axis. 
Dimension of the shield: 0.63 x 0.32 m. 
Its upper edge is almost flush with choke rings so that we do not expect 
any significant multipathing.

2) Shifting of the antenna to a new location at a distance of 8.25 m from
the old mark (PETR).

3) Setting the antenna lower by 0.53 m.

As a result, we now have mostly 7-8 satellites locked with the 8-channel 
TurboRogue all 24 hrs, and never less than 6. 
**********************************************************
- We labelled the new mark: PET1.
The same receiver and antenna are used at PET1 as was used at PETR.
PETR does not function since DOY 283.
Instead, PET1 does function smoothly since DOY 281.
**********************************************************
The GPS mark PET1 exists since 1996.
Both marks, PETR and PET1 were tied with synchronous GPS observations in 1997 and
again last week. We give below the differences in X/Y/Z (GAMIT solution from 
two 24-hrs sessions in each year):

Year                              PETR minus PET1
----                  -----------------------------------------------
                      DX (m)                DY (m)             DZ (m)
                      ------                ------             ------

1997                  +3.8297               +7.1705             +1.3853
1998                  +3.8300               +7.1719             +1.3857
=======================================================================
MEAN:                 +3.8298               +7.1712             +1.3855

We also processed one 24-hrs session (DOY 284: 11-Oct-98) at PET1 by GAMIT, 
including five additional IGS stations: FAIR, USUD, IRKT, MAG0, YAKZ.
Results are VERY GOOD:

  Postfit nrms: 0.19243E+00

ONE-WAY POSTFIT RESIDUAL STATISTICS: Pass  22
---------------------------------------------
RMS by site and satellite (mm): Pass  22
RMS  IT Site   All  01  02  03  04  05  06  07  08  09  10  13  14  15  16  17  18  19  21  22  23  24  25  26  27  29  30  31
RMS  22 PET1   6.2   6   7   6   7   6   7   6   6   5   5   5   5   6   5   7   6   7   5   5   6   9   7   6   6   6   5   5
RMS  22 ALL    7.1   6   7   7   8   7   8   7   7   6   7   7   6   7   7   7   7   7   7   7   6  10   9   8   7   7   6   6

 DATA AMOUNTS (Good: # good data; Gap: # deleted in gaps; BF: # bias flags  < 2*max separation)
PET1 PN01  654   26   0 PN02  717   34   1 PN03  665    1   0 PN04  590    1   0
      PN05  647   21   0 PN06  612   24   0 PN07  622   15   3 PN08  685    8   0
      PN09  686    4   1 PN10  631    6   0 PN13  596   22   0 PN14  565   12   2
      PN15  572   32   2 PN16  617   17   2 PN17  703   15   1 PN18  736   39   0
      PN19  733   26   0 PN21  593   18   1 PN22  626    3   0 PN23  828   26   0
      PN24  732   13   1 PN25  659   27   0 PN26  665    4   0 PN27  579   26   2
      PN29  709   58   0 PN30  676   18   0 PN31  671    0   0

                               *       *       *

- The 24-hrs rinex files from PET1 since DOY 284 are made available as earlier
for PETR by arrangements of RDAAC with world data centers. 

- We will apply for IERS Domes Number of PET1 immediately.

Finally, we thank Dmitry Frolov and Sergei Egorov, electronics engineers of RDAAC,
who made most of the job on saving the IGS station at Petropavlovsk together
with Vasiliy Levin and Vilory Bakhtiyarov, geodesists operating the Kamchatka
GPS Center. Advice kindly provided by workers of UNAVCO, JPL, Scripps, and MIT, 
and by Ted Koczynski at Lamont, is appreciated. 

Regards,

-- Grigory Steblov ([email-masked])

-- Mikhail Kogan   ([email-masked])

[Mailed From: Mikhail Kogan <[email-masked]>]