Re: [Discuss-gnuradio] IF value of the RF front end

[Jamie Wo]

Hi Nick,

Thanks for your reply. 

But I am not sure whether I understand what you said. My understanding is that the WBX converts RF signal into baseband signal directly, while for TVRX2, the RF signal is converted into low IF signal firstly by TVRX2 and then converted into basebad signal by USRP's FPGA. Am I right?

Then, what is the sampling rate should I set to sample the signal of interest. For example, FM radio signal at 106.3MHz. 

Best regards,
Jamie

On Wed, Jul 11, 2012 at 12:34 AM, Nick Foster <address@hidden> wrote:

Jamie,

WBX is a direct-conversion receiver, meaning there is no IF: it is a quadrature receiver where the LO frequency is equal to the RF frequency.

TVRX2 is a low-IF receiver using a 12.5MHz IF.

Both daughterboards can be treated as zero-IF direct conversion receivers for tuning purposes, as the digital downconverter in the USRP's FPGA will downconvert any residual IF to baseband before returning samples to the host. In other words, when you tune the USRP to 2.2GHz, the resulting samples will have a center frequency of 2.2GHz.

If you have a need to tune the LO frequency separately from the DDC/DUC frequency, you can do that using the advanced tuning parameters: http://files.ettus.com/uhd_docs/manual/html/general.html#two-stage-tuning-process

Best,

Nick

On Mon, Jul 9, 2012 at 11:14 PM, Jamie Wo <address@hidden> wrote:

Hi all, 

As far as I know the maximum sampling rate for USRP N210 is 25M sps. To receive signal with high frequency, such as 300 MHz to 2.2 GH, the RF front end converts the RF into IF, so the ADC can sample the IF signal. My question is what  the IF value is for daughter-board WBX?  Where can I reset the immediate frequency of the daughter-board, such as WBX and TVRX2?

It may be a simple question, but I cannot find the answer. Any explanation will be appreciated.

Best regards,

Jamie

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