Rtl_power

Main forum to discuss RTL-SDR related topics.
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enetsec
Posts: 4
Joined: Sun May 20, 2018 3:53 am

Rtl_power

Post by enetsec » Sun May 20, 2018 4:01 am

Hi folks, I am using rtl_power with the parameters of 144 to 145 step of 500k however it appears 3 results in DBm whit same sinal -25.1, -25.1, -25.1 in CSV file. what this means ? 144, 144.5 and 145 mhz? right ?
I have not yet understood the operation of this tool.
Tks

rtlsdrblog
Site Admin
Posts: 2397
Joined: Mon Nov 19, 2012 11:54 pm

Re: Rtl_power

Post by rtlsdrblog » Sun May 20, 2018 9:21 am

Can you please paste the exact command that you're using, and what it is that you're trying to achieve?

enetsec
Posts: 4
Joined: Sun May 20, 2018 3:53 am

Re: Rtl_power

Post by enetsec » Sun May 20, 2018 3:54 pm

Hi rtlsdrblog, im use Rtl_power -f144M:145M:500k file.txt

Number of frequency hops: 1
Dongle bandwidth: 1000000Hz
Downsampling by: 1x
Cropping by: 0.00%
Total FFT bins: 2
Logged FFT bins: 2
FFT bin size: 500000.00Hz
Buffer size: 16384 bytes (8.19ms)
Reporting every 10 seconds
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
Tuner gain set to automatic.
Exact sample rate is: 1000000.026491 Hz

return result

2018-05-20, 15:52:32, 144000000, 145000000, 500000.00, 4481024, nan, nan, nan
2018-05-20, 15:52:42, 144000000, 145000000, 500000.00, 4984832, nan, nan, nan

thanks for help

rtlsdrblog
Site Admin
Posts: 2397
Joined: Mon Nov 19, 2012 11:54 pm

Re: Rtl_power

Post by rtlsdrblog » Sun May 20, 2018 11:04 pm

But what exactly are you trying to achieve? You need to set the integration time (-i) and the exit timer too (-e) if you want to do a long term scan with rtl_power. Right now you're getting one shot of results only.

I'd suggest reading this guide first http://kmkeen.com/rtl-power/.

enetsec
Posts: 4
Joined: Sun May 20, 2018 3:53 am

Re: Rtl_power

Post by enetsec » Sun May 27, 2018 4:27 pm

I want to measure the radio signals to use these values ​​separately
example
144.000 -25
144.500 -35
145.000 -10
I asked some questions for the site support email but no answer
Thank you for your attention and patience.

rtlsdrblog
Site Admin
Posts: 2397
Joined: Mon Nov 19, 2012 11:54 pm

Re: Rtl_power

Post by rtlsdrblog » Sun May 27, 2018 10:47 pm

Sorry i'm still not clear on exactly what you're trying to achieve. Are you wanting to measure 3 frequencies exactly? But what bandwidth are those signals etc?

rtl_power measures an integrated power value over a bandwidth.

At the moment you're getting three integrated power values over 500kHz. That might not be enough resolution to differentiate a narrowband signal. Reduce the step to something like 5kHz and try again. Then plot the results to see what you got.

Try the examples in the guide first http://kmkeen.com/rtl-power/.

I've not received any emails from you yet, but regardless it's better to discuss issues like this in the forum so anyone else can help too.

enetsec
Posts: 4
Joined: Sun May 20, 2018 3:53 am

Re: Rtl_power

Post by enetsec » Sat Jul 07, 2018 6:11 am

Hello, I think I've misunderstood my goals. my idea was to treat the data as this application does.
https://github.com/covertcodes/freqwatc ... eqwatch.py
I see that this application uses data extracted from rtl_power and sends it to a database,I think to do the same.
however I do not understand how the frequency is bound to the signal in the .csv file
https://drive.google.com/file/d/1I3FDXA ... sp=sharing
I use Step 5k on image(print) , my understanding in print is correct ?
thanks the help

rtlsdrblog
Site Admin
Posts: 2397
Joined: Mon Nov 19, 2012 11:54 pm

Re: Rtl_power

Post by rtlsdrblog » Sun Jul 08, 2018 11:12 am

rtl_power simply 'bins' a frequency range, and measures the power over that bin. So if your bin is set to 0.1 MHz, it will measure 0.1 MHz chunks of the spectrum, and output the power for each one in the csv file.

jongud
Posts: 1
Joined: Thu Jun 13, 2019 6:32 pm

Re: Rtl_power

Post by jongud » Thu Jun 13, 2019 6:39 pm

Hello.
I'm having similar problem.
I am trying to measure the power on a specific VHF channel with 18 KHz bandwidth at 144.900 MHz (using it to compare antennas)

I use this command:
$ rtl_power -f 144891K:144909K:18K -g 10 -i 1

I get these results every second:
2019-06-13, 18:36:38, 144891000, 144909000, 9000.00, 761670, -12.65, -12.65, -12.65

Since I am asking for 18KHz bin, why does it produce three columns of results?

Thanks,
TF3LM

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