Re: [Discuss-gnuradio] Problem with USRP PSK modulation

[Tom Rondeau]

On Thu, Apr 19, 2012 at 10:41 AM, Vivian Paola Triana Galeano
<address@hidden> wrote:
> I'm using non-differential modulation. But I used differential before and it
> didn't work neither. I think my problem is with the sample rate that I have
> to set in UHD_USRP Sink and Source Blocks. I try to send a wav file that has
> maximum frequency of 12kHz so I set the sample rate at 28kHz, however it
> didn't. I need understand what the sample rate refers to.
>
> Thansks in advance for helping me!

Vivian,

You definitely need to use differential, so make sure you start there
(on both ends of the chain).

Have you just tried using the benchmark_tx/rx examples and got those
working first? Best to understand that and get it working before
trying to do your own thing. At least at that point, you know that
your setup will work and if something goes wrong it's in the new code.

Often, people have problems because the frequency of the transmitter
and receiver radios are too far apart and the receiver cannot lock to
the signal. Make sure you've corrected for any major frequency offsets
(this is a common problem that people bring up on the list, so google
for it if you need more information).

Tom


> 2012/4/19 Tom Rondeau <address@hidden>
>>
>> On Wed, Apr 18, 2012 at 11:32 AM, Vivian Paola Triana Galeano
>> <address@hidden> wrote:
>> > I'm working with USRP1 daughterboard RFX 2400 MHz.
>> > The configuration of the parameter  in UHD_USRP block is sample rate=
>> > 1MHz
>> > Center freq=2.4GHz.
>>
>> Vivian,
>> Are you using differential or non-differential modulation? Over the
>> air, the phase ambiguity at the receiver does not get worked out, so
>> it will only work if you use differentially encoded symbols.
>>
>> Tom
>>
>>
>> > 2012/4/18 Edmar Candeia Gurjao <address@hidden>
>> >>
>> >> Hi Vivian,
>> >>
>> >> give us details about your set up, like what USRP you are using,
>> >> daughterboads and frequency of transmission,
>> >>
>> >> Edmar
>> >>
>> >> 2012/4/18 Vivian Paola Triana Galeano <address@hidden>:
>> >> >
>> >> > I think my problem has something to do with the parameters of the
>> >> > USRP.
>> >> >
>> >> > I  try to send a file modulated with BPSK. So I build a graph like
>> >> > this
>> >> > :
>> >> >
>> >> > File source -> Packet Encoder -> PBSK MOD -> PBSK DEMOD -> Packet
>> >> > Decoder ->
>> >> > File sink
>> >> >
>> >> >
>> >> >
>> >> > and i really get the correct output file with thee right
>> >> > constellation.
>> >> >
>> >> > If I put a USRP source and USRP sink into graph, I don't receive
>> >> > anything.
>> >> > I hope anyone can help me. Thanks
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > Discuss-gnuradio mailing list
>> >> > address@hidden
>> >> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> ---------------
>> >> Edmar Candeia Gurjão
>> >> Universidade Federal de Campina Grande.
>> >> 1 574 387 0195
>> >> http://ecandeia.dee.ufcg.edu.br
>> >
>> >
>> >
>> > _______________________________________________
>> > Discuss-gnuradio mailing list
>> > address@hidden
>> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>> >
>
>