[time-nuts] WWVB Dephaser Question

[John C. Westmoreland, P.E.]

Hello Time Nuts,

I'm going to try a two antenna approach - parts are on order.

Buying a 2nd board vs. trying to implement a low-noise amplifier is a wash
for the cost
for the 2nd audio board.

It will require a few board mods - but they are simple.

When I have some interesting results, I will publish them to the group.

Yes, good if not great thread here - have enjoyed the discussion and hope
to see some good
results.

73's,
John
AJ6BC


On Sun, Oct 25, 2020 at 11:40 AM Andy Talbot <andy.g4jnt at gmail.com> wrote:

> That doesn't appear to give you 1/4 the base sampling rate as you suggest
> with "... to sample at 4 times the desired rate..."
> I do something similar on a 1kHz tone, generating I/Q at 1kHz sampling rate
> on a bandwidth up to 500Hz, ie 750 - 1250Hz
> Samples at 4kHz are S1, S2, S3, S4
> Then  I = S1 + S2 - S3 - S4
>          Q = S1 - S2 - S3 + S4   at 1kHz sampling, centred on 1kHz tone
>
>
> See http://g4jnt.com/Coherent_LF_Receiver.pdf where the technique is used
> in a coherent LF receiver.
>
> Andy
> www.g4jnt.com
>
>
>
> On Sun, 25 Oct 2020 at 02:17, jimlux <jimlux at earthlink.net> wrote:
>
> > On 10/24/20 3:53 PM, paul swed wrote:
> >
> >
> > The classic way to get I/Q is to sample at 4 times the desired rate,
> > then, given that your input samples are x(1),x(2),x(3),x(4), etc. the
> > I/Q streams are
> >
> > I(1) = X(1)
> > Q(1) = X(2)
> > I(2) = -X(3)
> > Q(2) = -X(4)
> > I(3) = X(5)
> > Q(3) = X(6)
> > I(4) = -X(7)
> > Q(4) = -X(8)
> >
> > and so forth.
> >
> > This will put your signal right in the middle of the sampling bandwidth.
> >
> >
> >
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