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

---------- Forwarded message ----------
From: Soumaya el barrak <address@hidden>
Date: 2017-01-16 10:32 GMT+01:00
Subject: Re: [Discuss-gnuradio] usrp_spectrum_sense.py input parameters in USRP B200
To: Marcus Müller <address@hidden>

Hi Marcus,

Thank you so much for your reply, I followed your recommendations, I used a sample-rate of 8MS/s and FFT-size 1024 and I kept the tune-delay and dwell-delay at 0.25 s. But I still receive some strange power values while scanning the 2.4 GHz band.

I also obtained high power picks while tuning from one center frequency to another. Could you please explain for me where I am mistaken? And what is the explanation of those power picks?

Best..

Soumaya

2017-01-13 14:46 GMT+01:00 Marcus Müller <address@hidden>:

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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EL BARRAK Soumaya

Telecommunication & Networking Engineer / Phd Student

Innovative Technologies Laboratory

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

Abdelmalek Essaâdi University - Morocco