[time-nuts] WWVB Measurements using DSP recovery

[Greg Broburg]

Yes, your idea is very nice.

So, many basement engineers have not moved
into the world of programmable DSP concepts, missing
some basic breadboard circuit and some example
demonstration software to try out. Perhaps your idea
would be the perfect tool to inspire and learn from. The
general nature of this is very good.

Can you show a circuit of what you have done?

Would you recommend the 7200 again or something
else that is better suited?

Many thanks;

Greg


On 3/28/2011 9:56 AM, Poul-Henning Kamp wrote:
> In message<4D90B859.2080907 at comcast.net>, Greg Broburg writes:
>
>> There is a method to recover a very weak signal
>> out of the mud that is fairly easy to build.
> I did this slightly differently:
>
> Take a 1MSPS ADC and average it into 1000 buckets in round
> robin form, one after the other.
>
> This can be done very quickly in an interrupt routine or even in hardware.
> The Aduc72xx family of ARM can do this running a sweat, any DSP
> would have absolutely no trouble doing it.
>
> In Europe use 2000 buckets so you can capture DCF77 also.
>
> By multiplying the buckets with a suitable IQ signal, you can pull
> out any signal of integral kHz frequency you care for, and measure
> its relative phase and change of phase over time.
>
> Here are some experiements I did many years ago with one million
> buckets, so I could demodulate the second pulses:
>
> http://phk.freebsd.dk/loran-c/CW/
>
> I would love to find somebody who can design some proper hardware
> for this, so that we can have an "VLF-All-band Time/Phase Receiver",
> basically a receiver you can ask, at any time, "What is the phase
> of the signal at N kHz, for any value of N you care for.
>
> Poul-Henning
>