Re: [Discuss-gnuradio] Quadrature rate question

[Tom Rondeau]

On Mon, Dec 10, 2012 at 7:40 AM, Martin Braun (CEL) <address@hidden> wrote:

On Mon, Dec 10, 2012 at 01:05:13PM +0100, Martin Braun (CEL) wrote:
> On Mon, Dec 10, 2012 at 09:44:29PM +1000, Phil wrote:
> > A recent post by Markus Gonser had me intrigued and so I
> > experimented with his grc code. The resulting FM receiver does work
> > but it doesn't quite sound right. My guess is that the quadrature
> > rate is not correct at 705.6kHz. Is this the correct rate and if
> > it's not what should it be?
>
> That depends. The quadrature rate is the rate of the incoming I/Q sample
> stream. 705.6 kSps seems unusual, though.

Actually, it's 16*44.1kSps, which isn't that unusual. Still, you need to
get that rate at the input.

MB

Yeah, if you're using a UHD device, you'll ask it for a specific rate. If it can get that rate, everything's fine. If you are asking it for a rate that it cannot achieve, it will give you a warning that you asked for rate X but it was actually set to rate Y. If that's the case, you'll have a sample rate mismatch between the two devices. You'll need to do some resampling to get them to match.

Tom