[Discuss-gnuradio] fft_bin resolution in usr_spectrum_sense.py
Hello, I am trying to detect energy on 10kHz size channel or less resolution. With the fft_size 1024, 8MHz /1024 = 7.815 kHz is FFT frequency resolution. I have a question in here. Of the returned value, (i.e. the center frequency = 2.5G) m.data, m.data[1] shows the energy of 2.5G to 2.5007G, m.data[2] for the energy 2.5007G to 2.5014G Etc. Is it connect understanding? Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] fft_bin resolution in usr_spectrum_sense.py
Hello, I am trying to detect energy on 10kHz size channel or less resolution. With the fft_size 1024, 8MHz /1024 = 7.815 kHz is FFT frequency resolution. I have a question in here. Of the returned value, (i.e. the center frequency = 2.5G) m.data, m.data[1] shows the energy of 2.5G to 2.5007G, m.data[2] for the energy 2.5007G to 2.5014G Etc. Is it connect understanding? Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] data from adc
Thanks Sebastiaan. Now I know what the decimation means. Then, if I decimate by 4 or 8, how I can get the sampled values before reaching fft bins. What I want to do is to measure the noise power. Thanks, Kyungtae -Original Message- From: Sebastiaan Heunis [mailto:sheu...@gmail.com] Sent: Monday, January 18, 2010 1:11 PM To: Kyungtae Kim Cc: Gnuradio Subject: Re: [Discuss-gnuradio] data from adc Kyungtae Do you mean directly after it is sampled, before any of the DDC functions? Then the answer is no. You will have to decimate by a factor of at least 4 when using real sampling and 8 when using complex sampling to be able to get the data over the USB link (for the USRP1). Sebastiaan -- Sebastiaan Heunis Radar Remote Sensing Group, University of Cape Town, South Africa Tel: +27 72 950 9370 On Mon, Jan 18, 2010 at 7:46 PM, Kyungtae Kim wrote: > Hi, > > > > Is there a way to get the data from ADC directly? I can find some examples > to get it with using FFT, however without FFT, I wonder how it can be > gotten. > > > > Thanks, > > Kyungtae > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] measuring noise power
If you mean usrp_spectrum_sense.py and usrp_fft.py, then, usrp_spectrum_sense.py in Gnuradio/gnuradio-examples/python/usrp, usrp_fft.py in Gnuradio/gr-utils/src/python/, if your install gnuradio is Gnuradio. Thanks, Kyungtae From: Marcus D. Leech [mailto:mle...@ripnet.com] Sent: Monday, January 18, 2010 2:11 PM To: Kyungtae Kim Cc: discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] measuring noise power On 01/18/2010 01:22 PM, Kyungtae Kim wrote: Thanks, I tried to find the example, however I couldn't in the gnuradio directories. Could you let me know where I can find the sample code? Thanks, Kyungtae From: discuss-gnuradio-bounces+kyungtae=nec-labs@gnu.org [mailto:discuss-gnuradio-bounces+kyungtae=nec-labs@gnu.org] On Behalf Of Marcus D. Leech Sent: Monday, January 18, 2010 1:06 PM To: discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] measuring noise power On 01/18/2010 12:36 PM, Kyungtae Kim wrote: Hi, I am looking for a way to measure noise power through usrp1. I tried to test with usrp_spectrum_sense.py, however I am not sure the power values measured is correct, because it is not same values shown as the graph from usrp_fft.py. I wonder if someone helps me out for this. Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio Try building a little app using GRC using gr_complex_to_mag_squared(), then run it through an averager. Or the gr_probe_avg_mag_sqrd_c() Block. Pretty straightforward. Should be quite accurate. gr-radio-astronomy/src/python/usrp_ra_receiver.py computes total power, using a long-term averager. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] usrp_spectrum_sense.py
Hi, In my experimentation, the measured power depends on fft_size and dwell_delay in usrp_spectrum_sense.py while measuring noise power, the larger those values results in higher measured power even if it is normalized based on the fft_size like this. 20*math.log10(math.sqrt(bin)/tb.fft_size) - 20*math.log10(tb.fft_size) -10*math.log(tb.power/tb.fft_size/tb.fft_size) I wonder it is normal operation. Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] measuring noise power
Thanks, I tried to find the example, however I couldn't in the gnuradio directories. Could you let me know where I can find the sample code? Thanks, Kyungtae From: discuss-gnuradio-bounces+kyungtae=nec-labs@gnu.org [mailto:discuss-gnuradio-bounces+kyungtae=nec-labs@gnu.org] On Behalf Of Marcus D. Leech Sent: Monday, January 18, 2010 1:06 PM To: discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] measuring noise power On 01/18/2010 12:36 PM, Kyungtae Kim wrote: Hi, I am looking for a way to measure noise power through usrp1. I tried to test with usrp_spectrum_sense.py, however I am not sure the power values measured is correct, because it is not same values shown as the graph from usrp_fft.py. I wonder if someone helps me out for this. Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio Try building a little app using GRC using gr_complex_to_mag_squared(), then run it through an averager. Or the gr_probe_avg_mag_sqrd_c() Block. Pretty straightforward. Should be quite accurate. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] data from adc
Hi, Is there a way to get the data from ADC directly? I can find some examples to get it with using FFT, however without FFT, I wonder how it can be gotten. Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] measuring noise power
Hi, I am looking for a way to measure noise power through usrp1. I tried to test with usrp_spectrum_sense.py, however I am not sure the power values measured is correct, because it is not same values shown as the graph from usrp_fft.py. I wonder if someone helps me out for this. Thanks, Kyungtae ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
