On 09/03/2017 06:02 PM, Bill Byrom wrote:
For precision timing measurements, I would think that there would be
concern about the double reflections of a badly mismatched low loss
transmission line (such as using 75 ohm line in a 50 ohm environment).
The re-reflected signal will act similar to multipath (as a delayed
aggressor) on all satellite signals equally. The impedance mismatch
delayed reflection aggressor could aggravate timing errors due to
changes in temperature or stress in the cable. Whether this is important
for you depends on how time-nutty you want to get.
See these papers:
Effects of Antenna Cables on GPS Timing Receivers:
http://tf.boulder.nist.gov/general/pdf/1384.pdf
Absolute Calibration of a Geodetic Time Transfer System:
http://xenon.colorado.edu/paperIrevise2.pdf
--
Bill Byrom N5BB
Thank you Bill, very interesting.
Wes, that waveguide is looking better all the time.
It will be difficult to control the temperature of it though.
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