Re: [Discuss-gnuradio] Gain and Sample Rate Setting

Hi,
what Jeon writes is correct so far, but two comments:
> You can check XCVR2450's dsp rate

XCVR2450 is your daughterboard, not your USRP. The mainboard has a master clock rate. 100M is a good example, because it's the MCR of the USRP N2x0.

> But in case of LFTX, LFRX, it is 200k.

As explained above, it's not a feature of the daughterboard, but of your USRP. My assumption would be the minimum rate for you is 100M/512 = 192.something kHz

And as Jeon pointed out, you should see a warning on the console, saying which sampling rate was actually used.
Now, I'm not quite sure what tools you're using that use the uhd_interface.uhd_transmitter and uhd_interface.uhd_receiver, but if it's one of the benchmark_* scripts, you will need to adjust symbol rate or samples_per_symbol, or likely both, to yield a valid sampling rate.

Best regards,
Marcus

On 30.08.2015 23:42, Jeon wrote:

Note before the text: my answer might have some incorrect terminologies.

I am unable to know how to set the sample rate and sps for my device.

1. DSP rate should be an integer multiple of sampling rate

You can check XCVR2450's dsp rate by `uhd_usrp_probe` command. Let's say it is 100M (not a true value!)
If you set sampling rate to 30k, 100M/30k = 3.333k, not an integer

2. There is some lower limit of sampling rate

Since I've never used XCVR2450, I don't know the exact value of it.

But in case of LFTX, LFRX, it is 200k.

If 50k that you've set is below such lower limit, you can see warning message on the console.

Regards,
Jeon.

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