Re: [Discuss-gnuradio] usrp2_rx_cfile.py issue

[Tom Rondeau]

On Thu, Nov 17, 2011 at 6:41 PM, Hasan Rajib Imam <address@hidden> wrote:

Hello Nick,

Thanks for your reply.

"you can use Gnuradio blocks such as the decimating FIR filter to
decimate additionally by however much you like."

Could you please tell me how can I do the above thing? Actually I am very new to gnuradio. I will really appreciate your help.

Thanks.

Hasan,

You can use the gr.fir_filter_XXX(decim, taps) or gr.fft_filter_XXX(decim, taps). The taps are generally defined using gr.firdes.low_pass_2(gain, sample rate, bw, transition, attenuation, window). The 'decim' parameter for these blocks is an integer.

fft_filter:

http://gnuradio.org/doc/doxygen/classgr__fft__filter__ccc.html

fir_filter:

http://gnuradio.org/doc/doxygen/classgr__fir__filter__ccc.html

firdes:

http://gnuradio.org/doc/doxygen/classgr__firdes.html

Tom

 

On Fri, Nov 18, 2011 at 1:29 AM, Nick Foster <address@hidden> wrote:

On Thu, Nov 17, 2011 at 8:28 AM, Nick Foster <address@hidden> wrote:
> On Thu, Nov 17, 2011 at 2:33 AM, hasanimam <address@hidden> wrote:
>>
>> Hello all,
>>
>> I am here once again and would like to bother you a bit.
>> I am using the usrp2_rx_cfile.py command to get the IQ data from usrp2. I am
>> using the following command
>>
>> sudo python usrp2_rx_cfile.py -f 800M -d 496 -s -v -N 10
>> /home/gnuradio4/Desktop/observed_data/test.dat
>>
>> And I am getting the following output:
>>
>> Network interface: eth0
>> USRP2 address: 00:50:c2:85:35:7d
>> Using RX d'board id 0x0053
>> Rx gain: 15.75
>> Rx baseband frequency: 800M
>> Rx DDC frequency: 0
>> Rx residual frequency: 0
>> Rx decimation rate: 512
>> Rx sample rate: 195.312k
>> Receving 10 samples
>> Writing 16-bit complex shorts
>> Output filename: /home/gnuradio4/Desktop/observed_data/test.dat
>>
>> In the above, it shows that the sample rate is 195.312k. I want to raise
>> this rate but it seems that decimation rate has a limit upto 512 so i cant
>> do that.
>> Can you suggest me any other way to raise the sample rate?
>> In fact I want the time difference between each sample to be around 100us,
>> but sample rate 195k gives me 5us.
>
> "Decimation" means the ratio by which the 100MHz main clock is
> divided. 100MHz / 512 = 195.312kHz. Try using a lower decimation.

Oh, I think I misunderstood your question, sorry -- you don't want to
raise the SAMPLE rate, you want to raise the DECIMATION. In that case,
you can use Gnuradio blocks such as the decimating FIR filter to
decimate additionally by however much you like.

--n

>
> --n
>
>>
>> Thank you.
>>
>>
>> --
>> View this message in context: http://old.nabble.com/usrp2_rx_cfile.py-issue-tp32860995p32860995.html
>> Sent from the GnuRadio mailing list archive at Nabble.com.
>>
>>
>> _______________________________________________
>> Discuss-gnuradio mailing list
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>
>

--
Hasan Rajib Imam
University of Electro-Communication, Japan
1st year Masters Student
Email: address@hidden
Contact No: (+81)80-5004-5931

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