[IGSMAIL-2133] ONSA receiver and radome change

Jan Jan
Fri Jan 22 08:55:25 PST 1999


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IGS Electronic Mail      Fri Jan 22  8:55:25 PST 1999      Message Number 2133
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Author: Jan Johansson and Bo Jonsson
Subject: ONSA receiver and radome change


Dear Colleagues,

February 1, 1999 the IGS station Onsala (ONSA) will undergo some important
changes:

1) The TurboRogue SNR-8000 receiver will be replaced by an Ashtech Z12
   as the primary receiver called ONSA in the IGS.
2) A hemispheric radome will replace the old conical-shaped radome.
3) Both daily and hourly data will be available from ONSA.
4) The National Land Survey of Sweden (NLS) will be responsible for the
   data retrieval and distribution to the BKG data center.
5) The Onsala station will be continuously monitored (in real time)  by
   the operational center of the Swedish Permanent GPS Network (SWEPOS) at
   the NLS using computer networks (TCP/IP).

Due to the change of radome and to avoid confusion, no ONSA data will be
available for February 1, 1999 (Day 032). We anticipate that the change of
radome may influence the results (e.g. jumps in the coordinate and
atmospheric time series) for those using Onsala data. The change of radome
will also influence the IGEX-station (OS0G) since it is using the same
pillar/antenna/radome system.

The TurboRogue will remain operational for a long time to come(years). The
TurboRogue  data will be available only on special request and with a
different abbreviation  (ONST).
 
Updated station log-file for ONSA and OS0G (IGS and IGEX stations) will be
available on day 032.

Below we have included a brief summary of the present status at the ONSA
station.

At present, 3 GPS receivers (2 Ashtech Z12 and 1 TurboRogue) and 1
GPS/GLONASS receiver (Ashtech Z18) are continuously operating at Onsala.
All receivers are connected to the same antenna/monument. Up to January
31, 1999  the TurboRogue SNR-8000 will remain as the primary receiver
delivering data to the IGS. The main receiver thereafter will be one of
the Ashtech Z12 receivers. The main reasons for this change are listed
below.

1) The ONSA TurboRogue is of the first TurboRogue version. It can only
   track up to 8 satellites simultaneously (The Ashtech Z12 can track up to
   12 satellites)

2) The Ashtech Z12 deliver real time 1 sec. data over TCP/IP to the SWEPOS
   operational center at the National Land Survey of Sweden. This has several
   advantages. 
   a) We can submit hourly data from Onsala to the IGS and EUREF.
   b) High data availability and redundancy since the Ashtech Z12 is
      continuously monitored.
   c) We can easily switch to any other sample rate in our deliverables.

We would like to stress the fact that we still use the same antenna (DM-B)
and the same monument. The Ashtech Z12 is hooked up to external 5 MHz
frequency standard (H2-maser) just like the TurboRogue. 

As stated above we will take the opportunity to change radome. A recently
developed hemispherical radome have been installed at the other stations
in the Swedish permanent GPS network. We will now replace also the
conical-shaped radome at Onsala with the new type of radome. The change of
radome will most likely be visible e.g. in coordinate- and atmospheric
time series for users of Onsala IGS/IGEX data. 

The National Land Survey will, from now on, be the primary contact for the
Onsala IGS station. However, the Onsala staff is available and happy to
assist. (See station log-file). 
The National Land Survey will also be responsible for data distribution
both regarding the daily files as well as the hourly data submission to
BKG/IFAG.

It is important to note that the TurboRogue will remain operational for
several years to come and data is available on request. Such a request for
data could be put forward to either the Onsala Space Observatory or to the
National Land Survey of Sweden.

We hope that these changes will not cause too much problems but instead
lead to improvements to the benefit of the IGS community!

Sincerely,
Jan Johansson				Bo Jonsson
Onsala Space Observatoy           	National Land Survey of Sweden
email: jmj at oso.chalmers.se		email: bo.jonsson at lm.se
Tel:   +46 31 772 55 58		        Tel: +46 26 633738


[Mailed From: Jan Johansson <jmj at oso.chalmers.se>]



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