[time-nuts] GPS Antenna Feed Line Decision

Mike Naruta AA8K aa8k at comcast.net
Sun Sep 3 18:27:33 EDT 2017

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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