[time-nuts] Re: Looking at ultra precise 50 km-100 km Electronic Distance Measurement.

[Bob kb8tq]

Hi

Probably the most direct route would be to simply buy a GPSDO with 
the “normal” 10 MHz output. Then build a “synthesizer” to convert that
10 MHz into whatever the radios need.

Since GPSDO’s need to run for a while (days …) to achieve reasonable
accuracy, something based on a light weight Rubidium might make sense.

Bob

> On Jan 22, 2022, at 12:48 PM, Patrick Barthelow <apolloeme at gmail.com> wrote:
> 
> Looking to increase accuracy of a microwave transceiver pair designed to
> measure very long distances  (*up to even 100km, Line of sight)
> They send a microwave carrier, modulated by HF radio modulation sine waves.
> To an identical Transceiver at the far end. Which sends the modulated
> carrier back. and phase comparisons of emitted and returned sigs are
> compared and precisely quantified.   Most instrument specs from the old
> days are still pretty good,  +-  a centimeter or so, and a ppm variation
> with total distance. --In 40-60km  High accuracy stuff  needs good
> meteorology data along the line measured, which affects c = speed of radio
> waves at the time of measurement.
> The Modulation frequencies need to be either monitored continuously and/or
> need to be stable to assigned values.   Trying to modify internal frequency
> reference of a pretty old system to  GPSDO accuracy.
> Anyone here that has done  EDM work in surveying  or Geodesy, etc?
> Best, 73,   Pat Barthelow AA6EG
> apol <apolloeme at gmail.com>loeme at gmail.com
> 
> 
> *"The most exciting phrase to hear in Science, the one that heraldsnew
> discoveries,  is not "Eureka, I have found it!"    but:*
> "That's funny..."  ----Isaac Asimov
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