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Re: [Discuss-gnuradio] [spectrum sense bug][usrp]


From: Heitor Araujo
Subject: Re: [Discuss-gnuradio] [spectrum sense bug][usrp]
Date: Fri, 4 Mar 2016 17:35:25 +0000

Hi Marcus

Yes, I'm using two USRP N210, one for transmitting the signal and the other to receive the signal.

-First, to transmit the signal, executed the uhd_tx_dpsk.grc code, example of gnuradio (is attached the image of the diagram and the signal).

https://goo.gl/3LAJ9N
https://goo.gl/OmYkom

The sampling rate is 1 MHz and the center frequency is 700.3M.


-On a different computer, I executed the usrp_spectrum_sense.py code as follows:
sudo ./usrp_spectrum_sense.py 699M 702M --fft 512 the output and the code are attached

code ( https://goo.gl/YxH12D )
output ( https://goo.gl/iwIoqV )

Also performed a receiver code into gnu radio (imagem) and the signal is received correctly.

https://goo.gl/03dGMR
https://goo.gl/V48NeU

I am very grateful for the help.

Best regards,
Heitor



Subject: Re: [Discuss-gnuradio] [spectrum sense bug][usrp]
To: address@hidden; address@hidden
From: address@hidden
Date: Thu, 3 Mar 2016 12:40:20 +0100

Ah, so you're using another USRP to transmit?

I can't reproduce this right now (not close to USRPs), but could you send an email with the output of usrp_spectrum_sense attached, and also the full verbatim command line used to launch it?

Best regards,
Marcus

On 03/02/2016 09:58 PM, Heitor Araujo wrote:
Hi Marcus,

When the N210 is transmitting, LEDs A,D,E,F are on. When the N210 is receiving, LEDS C,D,E,F are on.
I run the uhd_fft script and the USRP detected the signal on the right frequency (The frequency that it was trasmitted - 700.68).

Command to transmit: uhd_siggen -f 700681250.0


To: address@hidden
From: address@hidden
Date: Wed, 2 Mar 2016 21:09:40 +0100
Subject: Re: [Discuss-gnuradio] [spectrum sense bug][usrp]

Hi Heitor,

if the same applies to you just displaying e.g. 10MHz of bandwidth with uhd_fft, you probably have a hefty oscillator offset, either on the N210 10MHz reference or your signal generator.  What generates your signal, and which LEDs are active on your N210?

Best regards,
Marcus

On 02.03.2016 21:06, Heitor Araujo wrote:
Hi

I'm trying to do a basic spectrum sense with a USRP N210 kit and gnuradio.

I made a literature research and noted that the “usrp_spectrum_sense.py” code was used in some articles. But when transmit some signal in a certain frequecy and execute the “usrp_spectrum_sense.py”, the signal is found by the code, but it appears in another frequency (usually about 1Mhz ahead). And also the bandwidth of the received signal is different from the transmited signal (It seems it depends of the sample rate of the transmited the signal).

sudo ./usrp_spectrum_sense.py 699M 702M --fft 512 and execute the "uhd_tx_dpsk.grc" in gnuradio to transmit the signal from 700.2M tom 700.4M. The signal is detected in 700.7M to 701M.

Thanks









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