[time-nuts] Measuring receiver...

[Burt I. Weiner]

Nick,

Welcome to the world of FMT-Nuttery where we strive to make absurdly 
accurate off-air frequency measurements.

I regularly participate in the FMT's.  The "measuring receiver" I use 
is a HP-3586B "Selective Level Meter".  While the 3586 series of 
receivers will only give you 0.1 Hz resolution, there are simple 
methods to use them to get down to 1 mHz (milliHertz) resolution, or 
better.  You'll quickly find out that you're limited by propagation 
between the FMT transmitter and your receive location.

Rather than go into a long dissertation here on how to do this, 
here's a link to the write-up for my preferred FMT Methodology - 
K6OQK FMT Methodology.

See:  http://www.k5cm.com/k6oqk%20fmt%20new.htm

You're probably already familiar with Connie, K5CM's website for all 
things FMT, but in case you're not, take a look at:  www.k5cm.com

I'll be glad to answer any questions you have.  You can either ask 
here or send me a direct e-mail at: biwa at att.net.

Burt, K6OQK


From: Nick Sayer <nsayer at kfu.com>

I'm considering taking a shot at the next ARRL frequency measurement contest.

The assumption going in is that the signal is CW, with at least a 
half minute or so of just solid "on" at one point or another and that 
reception is reasonably good.

I've got a good TIA and excellent references, but that's the easy 
part, it seems to me. It seems to me that what I really need to do is 
make a synthesized heterodyne receiver that can present an accurately 
tuned RF band pass - say, 10 kHz wide with the synthesizer set for
5 kHz steps - to the TIA, with some manually tunable high-pass and 
low-pass filtering to isolate the signal of interest. If the mixer 
got its LO from a synthesizer with a GPSDO reference, it seems to me 
that you could then measure the frequency of the signal of interest 
(now an audio frequency, so you can listen to it too) with the TIA 
(also getting the GPSDO reference) and then do simple math to arrive 
at the actual RF frequency.

Anybody have any thoughts?

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
www.biwa.cc
K6OQK