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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
- [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Hongliang Zhang, 2010/10/27
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx,
Marcus D. Leech <=
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Hongliang Zhang, 2010/10/28
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Jason Abele, 2010/10/28
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Josh Blum, 2010/10/28
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Hongliang Zhang, 2010/10/29
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Jason Abele, 2010/10/29
- Re: [Discuss-gnuradio] Problem of using UHD blocks as Tx & Rx, Hongliang Zhang, 2010/10/30