Re: [Discuss-gnuradio] GNU Radio flow graph for Spectrum sensing

[Marcus Müller]

Hi Rodrigo (once again),

one of the wise elders reminded me that in the FFT, power is but
proportional to the input power in time domain, due to a factor of
fft_length occuring when forward-backward transforming.

Greetings,
Marcus

On 14.08.2014 11:29, Marcus Müller wrote:
> Hi Rodrigo,
>  both is right, due to Parseval's Theorem stating that energy of a
> signal in time and frequency domain is equivalent.
>
> Regarding "File is large": of course it is; I don't know what sampling
> rate you're using, but assume you have 1MS/s of complex float, that will be
> 2*32bit*10^6/s = 8MB/s of data.
>
> Regarding "it cannot be opened": Opened by what? Maybe you're not aware of:
> http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#What-is-the-file-format-of-a-gr_file_sink-How-can-I-read-files-produced-by-a-file-sink
>
> Greetings,
> Marcus
> On 13.08.2014 23:29, Rodrigo Rozário wrote:
>> Hi Martin,
>>
>> I am generating by the following flowgraph:
>>
>> RTL2832 source -> FFT -> File Sink
>>
>> I tried too:
>>
>> RTL2832 -> File Sink
>>
>> Is it right?
>>
>>
>>
>>
>> 2014-08-13 9:00 GMT-03:00 Martin Braun <address@hidden>:
>>
>>> How are you generating those files?
>>>
>>>
>>> On 08/12/2014 01:30 AM, Rodrigo Rozário wrote:
>>>> Hi guys,
>>>>
>>>> I'm trying to configure a spectrum analyzer with GNU Radio and I had a
>>>> many problems. I tried a lot of ways to do it but all of them failed.
>>>>
>>>> More specifically, I need to get information about the FFT and store it.
>>>>
>>>> I tried the following:
>>>> - I get data from the block RTL2832 and store it: this is generates a
>>>> very big file data end a can't open. In a file of a few seconds of
>>>> storage (50Mb) I can't recognize the power values.
>>>>
>>>> - I try to store and after open it on a editor, but not work.
>>>>
>>>> I think that there is any problem in the format of the data stored. Can
>>>> you help? Anyone already can do it?
>>>>
>>>>
>>>> --
>>>> /*Rodrigo Rozário */
>>>> /CREA-DF - 21339/D-DF - Professional Registration/
>>>> /Engenheiro de Redes de Comunicação - //Network Engineering/
>>>> /Universidade de Brasília - //University of Brasília/
>>>> /
>>>> /
>>>>
>>>>
>>>>
>>>>
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