|
From: | tom x |
Subject: | Re: [Discuss-gnuradio] diminishing returns with increasing frequency offset |
Date: | Fri, 18 Mar 2016 20:01:58 +0100 |
Tom,
you'll need to tell us more about what you're doing and what you've tried.
Cheers,
Martin
On 03/17/2016 03:36 PM, tom x wrote:
> It's strange but the only sampling rate that works is 4 MHz; Packets are
> not decoded when the sampling rate is set above this rate.
>
> Thanks,
> Tom
>
> On Thu, Mar 17, 2016 at 7:33 PM, Martin Braun <address@hidden
> > address@hidden <mailto:address@hidden>> <mailto:address@hidden>> wrote:
>
> What's your sampling rate? The further you go towards the edge of your
> Nyquist zone, the more the anti-aliasing filter might be kicking in.
>
> Cheers,
> Martin
>
> On 03/17/2016 10:23 AM, tom x wrote:
> > Hi,
> >
> > My setup is a USRP N210 receiving from a transmitter sending a few
> > packets a second. (The packets are decoded with Bloessl's 802.15.4 PHY
> > block if it matters)
> >
> > Let's say the transmitter is sending data on frequency f_t.
> >
> > I set the USRP to receive on f_t plus an offset f_o.
> > The next block is a frequency xlating FIR filter centered at -f_o.
> > This is intended to correct the offset.
> >
> > I made a slider block for f_o and allowed it to vary between 0 and
> 3MHz.
> > I need an offset of a few MHz for my application. However, the
> number of
> > packets received seems to drops as I increase f_o. I get almost no
> > packets after f_o is increased over 0.5MHz.
> >
> > The overall purpose of this is to carve two channels out of the
> received
> > bandwidth with two frequency xlating FIR filter blocks, with the USRP
> > tuned between the channels and the filter blocks centered at offsets
> > that put them on the channel peaks. As explained above, if the
> offset is
> > too big, it stops working. Why do you think this is happening?
> >
> > Thanks,
> > Tom
> >
> >
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >
>
>
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