[IGSMAIL-2006] USNO cable specs -- CORRECTIONS

[Jim]

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IGS Electronic Mail      Fri Aug 28  9:51:26 PDT 1998      Message Number 2006
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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 at 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) <jimr at maia.usno.navy.mil>]