discuss-gnuradio
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx


From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx
Date: Wed, 27 Oct 2010 14:32:33 -0400
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7

On 10/27/2010 02:11 PM, Hongliang Zhang wrote:
> Hi everyone,
>
> I made a test for UHD blocks today, and I found a problem as follows:
>
> I take two USRP2 boards for my test. One is used as transmiter and the other
> board is set to be receiver.And I use UHD Simple Sink and UHD Simple Source
> blocks for transmiting and receiving respectively. 
>
> sampling frequency = 195.312K (which is the minimum sampling frequncy of the
> system). 
> gain=0
> The transmitted signal is a AM modulated sine signal. 
> The frequency of orignal sine wave (the message signal) is 10K Hz.
> The frequency of carrier signal (center frequency for modulation at
> transmitter board) is 2.42 GHz, and I use the same frequency at the receiver
> board for demodulation.
> Amplitude of transmitted signal is 0.05.
>
> I connect the two boards together, and I add a scope to observe the period
> of the received demodulated signal. The problem is the period is about
> 0.000045, which means the frequency of the signal I received is not 10 KHz,
> but about 2.2 KHz.
>
> I have used the same external reference clock and PPS signal for both of the
> boards, so I think they are set up correctly. Why do I get a received signal
> with different frequency from what I transmit? 
>
> Does anyone meet the similar problem before? How may I solve the problem?
>
> Thanks so much for every help and suggestions in advance.
>
> Best regards,
> Hongliang
>
>
>
>   
What daughterboards are you using?

Can you share your (GRC) flow-graphs with us--makes it easier to spot
problems.

I hope that you're using an attenuator between the transmitter side and
receiver side.

My guess is that there's a sample-rate issue somewhere on the receive
side, like the scope sink
  hasn't been told the correct sample rate, so it's displaying
incorrectly, etc.




-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org





reply via email to

[Prev in Thread] Current Thread [Next in Thread]