[USRP-users] rx_samples_to_file issue

Marcus D. Leech mleech at ripnet.com
Wed Oct 1 23:57:06 EDT 2014


On 10/01/2014 11:46 PM, gsmandvoip wrote:
> Yes I am running single channel, but when trying to achieve my desired 
> sampling rate without _4rx.rbf, it says, requested sampling rate is 
> not valid, adjusting to some 3.9M or so.
> sorry for misleading info I gave earlier, I have i3, with 32 bit and 
> i7 with 64 bit, but getting same result on both machines
>
> Here is my command to capture signal:
>
> ./rx_samples_to_file --args="fpga=usrp1_fpga_4rx.rbf, subdev=DBSRX"  
> --freq "$FC" --rate="$SR" $FILE --nsamps "$NSAMPLES"
>
> and here is its output:
>
> Creating the usrp device with: fpga=usrp1_fpga_4rx.rbf, subdev=DBSRX...
> -- Loading firmware image: /usr/share/uhd/images/usrp1_fw.ihx... done
> -- Opening a USRP1 device...
> -- Loading FPGA image: /usr/share/uhd/images/usrp1_fpga_4rx.rbf... done
> -- Using FPGA clock rate of 52.000000MHz...
> *Error: LookupError: IndexError: multi_usrp::get_tx_subdev_spec(0) 
> failed to make default spec - ValueError: The subdevice specification 
> "A:0" is too long.*
> The user specified 1 channels, but there are only 0 tx dsps on mboard 0.
>
>
Don't use the _4rx image if you don't need it.

The USRP1 only does strict-integer resampling, and with a master clock 
(NON STANDARD FOR USRP1) of 52.000MHz, 4Msps is not a sample rate
   that it can produce.   Try 5.2Msps or 4.3333Msps.

At 5.2Msps, it's recording at roughly 20.8Mbytes/second, so your system 
needs to be able to sustain that for at least as long as the capture lasts.


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