[Top][All Lists]

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

Re: [Discuss-gnuradio] nonexisted peaks USRP N210 Connection

From: Ben Hilburn
Subject: Re: [Discuss-gnuradio] nonexisted peaks USRP N210 Connection
Date: Thu, 2 Aug 2012 11:49:30 -0700

Sema -

There will always be some DC feed-through in radio equipment, so depending on your application, it may be important that you tune the LO outside of your passband.  UHD provides the capability for advanced LO tuning, which attempts to do this all for you.  An example of this is shown below:

//advanced tuning with tune_request_t
uhd::tune_request_t tune_req(target_frequency, lo_offset);
You should request your frequency of interest in place of the 'target_frequency' field, and tell it how far away you want the LO to be in the 'lo_offset' field.  UHD will compensate for everything in the chain (LO offset, DSP frequency offset, etc.,), and will tune each component to the appropriate frequency.  Try using this to move the DC component out of your passband.

You can find full documentation on this here:

Once you have tuned the LO away, play with your gain settings to improve your SNR.


On Thu, Aug 2, 2012 at 6:12 AM, s k <address@hidden> wrote:
Hi All,

I want to do a transmit receive application with USRP Network series, with USRP N210s. I have used WBX TX/RX as transmitter and TVRX2 TX/RX part as receiver. I used 206MHz as center frequency. Here is my transmitter blocks

 Satır içi resim 4

And my receiver blocks in GRC

  Satır içi resim 3

My receiver graph before transmitter begin to transmit:

  Satır içi resim 2  

My transmitter graph when i begin to transmit, first one is zoomed up part

Satır içi resim 5

and zoomed in down part.

Satır içi resim 6

And finally my receiver graph is the following graph. As you see there is a DC peak that i didn't send in the transmitter end.

   Satır içi resim 1

I tried so much time but each time i saw this peak when i work in this frequency (also other high frequencies). When i shift center frequency a little bit then four of them shifting together. So it is together with other three.

What is the reason of this peak. İs it because of transmitter or receiver? When i use relatively low frequencies as center frequency (for example 50MHz or 60MHz) then the DC peak is disappearing. (I attached the images.)

Any help would be kindly appreciated.


Discuss-gnuradio mailing list

reply via email to

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