From jimr@maia.usno.navy.mil Mon Jul 27 15:58:59 EDT 1998
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From: Jim Ray (USNO 202-762-1444)
Message-Id: <199807271945.PAA12813@maia.usno.navy.mil>
Subject: changes planned at USNO
To: gpst@maia.usno.navy.mil
Date: Mon, 27 Jul 1998 15:45:37 EDT
X-Mailer: Elm [revision: 212.4]
Status: RO
In order to make the following configuration changes, data from the USNO
receiver will be interrupted on Wednesday, 12 August:
* The AOA TurboRogue SNR12 receiver will be moved to an environmentally
controlled chamber within the USNO clock vault. (The receiver will
not otherwise be changed). Within the chamber, the temperature is
controlled to +/- 0.15 C and relative humidity to +/- 1%.
* A new antenna cable will be installed:
Antenna cable 24-APR-1997 to 12-AUG-1998:
Belden RG-214/U -- 200 feet (60.96 m) length (mostly exposed to full
sun running along rooftop of Bldg 52)
specifications:
Velocity factor 0.66
Capacitance 30.8 pf/foot
Loss at 1200 MHz 9.0 db/100 foot
Loss at 1500 MHz 10.1 db/100 foot
Electrical Length Change versus Temperature:
3000 PPM over (-10 to 42 C range) or 58 PPM/C
=> 0.2 ps/m/C or 12 ps/C for 200 feet
Antenna cable 12-AUG-1998 to present:
Andrew FSJ1-50A (35422-33 phase stabilized) 1/4 inch Superflexible
Foam Dielectric Heliax -- electrical length will be measured at
the time of installation (mostly run in the ceiling of the 3rd
floor of Bldg 52)
specifications:
Velocity factor 0.84
DC resistance 2 to 3 ohms per 1000 foot
Capacitance 24.2 pF/foot
Inductance .061 uH/foot
Loss at 1250 MHz 6.77 db/100 foot
Loss at 1500 MHz 7.47 db/100 foot
Electrical Length Change versus Temperature:
400 PPM over (-40 to 30 C range) or 5.7 PPM/C
=> 0.02 ps/m/C or 1.2 ps/C for 200 feet
* A new PC controller will be installed.
An updated station log will be sent to the IGS Central Bureau.
We apologize for the service disruption but are hopeful that the changes will
improve the USNO clock stability and performance by greatly reducing the
sensitivity to temperature changes.
=========================================================================
Jim Ray e-mail: jimr@maia.usno.navy.mil
U.S. Naval Observatory, EO Dept. phone : 202-762-1444
3450 Massachusetts Avenue, NW fax : 202-762-1563
Washington, DC 20392-5420
=========================================================================
From igscb@igscb.jpl.nasa.gov Fri Aug 28 13:44:58 EDT 1998
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Date: Fri, 28 Aug 1998 09:51:26 -0700
To: IGS Mail Recipients
From: IGS Mail Service
Reply-To: IGS Mail Administrator
Errors-To: IGS Mail Administrator
Sender: IGS Mail Administrator
Subject: No 2006: USNO cable specs -- CORRECTIONS
Status: RO
******************************************************************************
IGS Electronic Mail Fri Aug 28 9:51:26 PDT 1998 Message Number 2006
******************************************************************************
Author: Jim Ray
Subject: USNO cable specs -- CORRECTIONS
IGS Mail #1965, which described the configuration changes made at the USNO
IGS installation on 12 August 1998, contained several errors in the
specifications of the antenna cables. The corrected cable information is
below.
An updated station log is being sent to the IGS Central Bureau.
We apologize for this error.
=========================================================================
Jim Ray e-mail: jimr@maia.usno.navy.mil
U.S. Naval Observatory, EO Dept. phone : 202-762-1444
3450 Massachusetts Avenue, NW fax : 202-762-1563
Washington, DC 20392-5420
=========================================================================
4. GPS Antenna Information
4.1 Antenna Type : DORNE MARGOLIN T
Serial Number : 309
Antenna Height (m) : 0.0
Antenna Reference Point : ARP
Degree Offset from North : oriented North but not measured
Antenna Radome Type : none
Date Installed : 24-APR-1997
Date Removed : (dd-MMM-yyyy hh:mm UT)
Additional Information : Antenna cable 24-APR-1997 to 12-AUG-1998:
* : Intercomp RG-217/U -- physical length
* : 293 feet (89.31 m), mostly exposed to full
* : sun running along rooftop of Bldg 52
: specifications:
: Velocity factor 0.66
: Capacitance 30.8 pf/foot
* : Loss at 1225 MHz 6.5 dB/100 foot
* : Loss at 1575 MHz 7.6 dB/100 foot
: Electrical Length Change versus Temperature:
* : spec is between 0.50 ps/m/C and 1.24 ps/m/C;
* : USNO measurement of similar RG-217 cable
* : gave 0.53 ps/m/C
: Antenna cable 12-AUG-1998 to present:
: Andrew FSJ1-50A (35422-33 phase stabilized)
: 1/4 inch Superflexible Foam Dielectric
* : Heliax -- physical length 296.5 feet
* : (90.37 m), mostly run in ceiling of 3rd
: floor of Bldg 52; measured electrical
: length is 373 +/- 3 ns
: specifications:
: Velocity factor 0.84
: DC resistance 2 to 3 ohms per 1000 foot
: Capacitance, 24.2 pF/foot
: Inductance, .061 uH/foot
: Loss at 1250 MHz 6.77 dB/100 foot
: Loss at 1500 MHz 7.47 dB/100 foot
: Electrical Length Change versus Temperature:
: 400 PPM over (-40 to 30 C) or 5.7 PPM/C
* : => 0.02 ps/m/C
* = corrected items
[Mailed From: Jim Ray (USNO 202-762-1444) ]