Re: [Discuss-gnuradio] usrp_spectrum_sense.py input parameters in USRP B200

[Marcus Müller]

Hi Soumaya,

the B200 tunes slower and might need up to half a second when tuning further.

You should hence minimize the amount of tuning, and instead of 4MS/s use a higher rate, a larger FFT size, and tune less often.

The power normalization is truly, 100%, arbitrary. Since these dB are all "relative to digital 1", they only have linear relation with real-world powers.

Best regards,

Marcus

On 01/13/2017 11:40 AM, Soumaya el barrak wrote:

Dear all,

I am working with USRP B200 for spectrum sensing, I want to scan the band from 2.4 to 2.5 Ghz, I use fft size 256, and sample_rate 4M, and tune _delay 0,001s. I am not sure if the parameters are correctely chosen because when I try to scan another band without wireless activities, I still receive hight power levels. Can anyone has any idea about where I am mistaken ? 

Also, in the formula used to calculate the PSD : 

 Power_dB = 10*math.log10(m.data[i_bin]/tb.usrp_rate); 

Normally it is the magnitude squared averaged , I want to know why it is averaged by the usrp_rate ?  

Thank you in advance !

Soumaya  

--

EL BARRAK Soumaya

Telecommunication & Networking Engineer / Phd Student

Innovative Technologies Laboratory

National School of Applied Sciences of Tangier - (ENSA Tanger)

Abdelmalek Essaâdi University -  Morocco

Tel : (+212) 6 65 9 625 40/ (+ 39) 327 198 5064

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