[time-nuts] Measuring receiver...
brooke at pacific.net
Tue Jun 21 14:28:22 EDT 2016
During W.W.II there were secret methods of "fingerprinting" radio transmitters and separately the operators.
I suspect the transmitter fingerprinting involved things like frequency accuracy, stability, CW rise and decay time,
&Etc. For the operator some from of statistics on the timings associated with sending Morse Code. But. . . I haven't
seen any papers describing this. Can anyone point me to a paper on this?
Brooke Clarke, N6GCE
The lesser of evils is still evil.
-------- Original Message --------
> 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
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