Re: [time-nuts] HF frequency counting receiver

Hi Yes, indeed doppler is problem. It is not a un-solvable problem. That’s why you need the long audio records to look at. That’s why you go a bit crazy looking at giant long FFT’s. The next layer to it is that your receiver has to stay on that signal for the entire duration of the test. If

Re: [time-nuts] HF frequency counting receiver

On 6/20/16 1:44 PM, Graham / KE9H wrote: The ionospheric Doppler will spread the signal a few tenths of a Hz, YES. so getting millihertz is more random luck of the draw. NO, it is all about how good your averaging method/strategy is, over the period of the test measurement. A lot of the

Re: [time-nuts] HF frequency counting receiver

http://www.cliftonlaboratories.com/off-the-air_frequency_measurement.htm If you peruse http://www.b4h.net/fmt/fmtresults201204.php you will see that HP3336A's also feature regularly. On Jun 21, 2016, at 4:52 AM, Pete Lancashire wrote: > Never tried it but a Selective Level Meter aka HP

Re: [time-nuts] HF frequency counting receiver

On 6/20/2016 11:18 AM, Mark Spencer wrote: I am quite convinced that HF Doppler shift is a real issue at times. Absolutely true Mark. I spent some time looking at this way back when and it is quite possible to observe (in Southern Calfornia) transitory phase shifts on the 10 MHz signal

Re: [time-nuts] HF frequency counting receiver

Most of the folks doing the FMT these days use some sort of audio spectrum analyzer program and estimate the frequency using that. Or use the audio spectrum analyzer to measure the difference between the frequency being measured and the precision reference. You are correct, it is usually not a

Re: [time-nuts] HF frequency counting receiver

> On Jun 20, 2016, at 12:52 PM, Bob Camp wrote: > > Hi > > The cheaters way is to simply use a fully synthesized radio tied to a known > reference frequency. Yeah, that’s what I’ve got in mind. Both the synthesized tuning LO and the second LO would be derived from an external

Re: [time-nuts] HF frequency counting receiver

Hi The cheaters way is to simply use a fully synthesized radio tied to a known reference frequency. Feed the output into one channel of a sound card. Feed the other channel of the sound card with a known frequency tone. Post process it to death with your choice of FFT programs. Another

Re: [time-nuts] HF frequency counting receiver

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

Re: [time-nuts] HF frequency counting receiver

On 6/20/16 10:10 AM, Graham / KE9H 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. --- Gr And

Re: [time-nuts] HF frequency counting receiver

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

Re: [time-nuts] HF frequency counting receiver

On 6/20/16 7:51 AM, Nick Sayer via time-nuts 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.

Re: [time-nuts] HF frequency counting receiver

Nick: You can do it this way, but it requires you to totally understand the mathematics and granularity of ALL of the frequency sources and synthesizers in the superhet receiver. And if there are any audio soundcards or sampling devices involved, the specifications and origin of the sampling

Re: [time-nuts] HF frequency counting receiver

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 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

[time-nuts] HF frequency counting receiver

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