[IGSMAIL-0752] Wellington antenna height

[John]

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IGS Electronic Mail      Thu Oct 20  1:08:56 PDT 1994      Message Number 0752
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Author: John Beavan
Subject: Wellington antenna height

The antenna heights of the CIGNET station that ran in Wellington, New
Zealand from Feb 1990 to Dec 1992 are not easily accessible in any
of the international GPS data bases.  Since a TurboRogue has recently 
been installed on the same monument by AUSLIG and DOSLI this is a good 
time to review the Wellington antenna heights.

The CIGNET site "WELLINGTON" was established on a galvanized iron mast,
approx 3" diam, whose base is set in a mass of concrete on the roof of 
a building, and which is well guyed.  There is a cap screwed on the top
of the mast.  The top surface of this screw cap is reasonably flat, and 
this defines the top of the mast, from which all antenna height 
measurements have been taken.  All heights reported here are vertical 
measurements from this surface.

The following antenna height information for the 1990-92 Trimble
4000 SST occupation of WELLINGTON was obtained by John Beavan 
direct from Glen Rowe of DOSLI on October 12, 1994.  Glen supervised 
the operation of the CIGNET 4000 SST while it was in Wellington.

>From installation until 12 June 1990 the vertical height from the 
top of the mast to the bottom of the SST ground plane was 0.120 m.  
On 12 June 1990 the equipment was exchanged for a different set, 
but was still a 4000 SST receiver and antenna.  The height was 
0.122 m after the exchange, presumably due to readjustment of the 
tribrach.  This height was maintained until 12 November 1990 when 
a storm blew the antenna off the mast.  The tribrach adaptor that 
had come loose was replaced by a different type and the height from 
13 November 1990 to 16 December 1992 was 0.132 m to the bottom of 
ground plane.

The station was occupied by an Ashtec XII from approximately 18 Jan 
- 15 Mar 1994, though data collection was not continuous during this
interval.  The antenna height was 0.134 m to the bottom of the ground 
plane, or 0.138 m to the top of the ground plane (= L1/L2 phase centre), 
or 0.074 m to the bottom of the pre-amp housing.

For the TurboRogue occupation that began on 10 October 1994, the
antenna height is 0.084 m to the bottom of the pre-amp.

The antenna eccentricities in the following table are from the top of
the mast to the standard antenna reference point (ARP), which is the
bottom of the pre-amp for all three antenna types used at this site.

    Date of occupation     north    east      up   antenna
    ------------------    ------   ------   ------ ------------------
    15-feb-1990 00:00     0.0000   0.0000   0.0600 trim-sst
    12-jun-1990 00:00     0.0000   0.0000   0.0620 trim-sst
    13-nov-1990 00:00     0.0000   0.0000   0.0720 trim-sst
    17-dec-1992 00:00                              instrument removed
    18-jan-1994 00:00     0.0000   0.0000   0.0740 ashtech
    16-mar-1994 00:00                              instrument removed
    10-oct-1994 00:00     0.0000   0.0000   0.0840 turborog

John Beavan


[Mailed From: beavan at gamma.gns.cri.nz (John Beavan)]