[time-nuts] HF frequency counting receiver

[Mark Spencer]

To echo the point that Jim Lux made in another post...

I'm not sure how those of us who live an appreciable distance from the transmitters can expect to get mili hertz accuracy  in light of the HF Doppler shift over long distance paths with restorting to tactics such as simultaneously monitoring another transmitter that has a precisely known frequency and is located near the target transmitter to determine what the Doppler shift is at a given point of time.   (I'm not 100 percent sure this approach would work but it seems viable to me at first glance.)

I've spent some quality time monitoring WWV, and have read various papers and I am quite convinced that HF Doppler shift is a real issue at times.


All the best
Mark S
VE7AFZ

Sent from my iPhone

> On Jun 20, 2016, at 10:10 AM, Graham / KE9H <ke9h.graham at gmail.com> wrote:
> 
> You need to be able to measure frequency accurately in the milli-Hertz
> range to be competitive in the frequency measuring contests.
> 
> I doubt the Selective Voltmeters have that level of resolution. I think
> they 'only' read to 0.1 Hz.
> 
> --- Graham
> 
> 
> 
> On Mon, Jun 20, 2016 at 11:52 AM, Pete Lancashire <pete at petelancashire.com>
> wrote:
> 
>> Never tried it but a Selective Level Meter aka HP 3586A/B/C ?
>> 
>> On Mon, Jun 20, 2016 at 7:51 AM, Nick Sayer via time-nuts
>> <time-nuts at febo.com> wrote:
>>> 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?
>>> 
>>> 
>>> Sent from my iPhone
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