[time-nuts] WWVB Dephaser Question

[Andy Talbot]

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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