Hi Larry,
in addition to what Kim said:
You'll have to consider that what the Qt frequency sink and what a
frequency to voltage converter does are pretty different things:
- The freq-to-volt converter takes a signal and (ideally) gives
you a reading determining the (somehow defined) strongest
frequency in your signal. So it's "one signal over a lot of time
in, one number out", if you want so.
- The Qt frequency sink takes in a period of signal, and shows
you all the frequencies' magnitudes it can detect at once. It's
"one signal over a lot of time in, a set of a lot of frequency
magnitudes out".
So the core question is: What do you really want to do,
mathematically?
Because I find that highly cool, here's what's happening inside the
Qt frequency sink, even if that might be unrelated to your problem:
- takes in a vector of N samples
- Computes a discrete Fourier transform (using FFTw's fast
fourier transform algorithms) of length N
- computes the square of the magnitude, the logarithm of that,
normalizes each of the N complex result values
- optionally: averages each bin individually
- regularly updates the plot with the N-vector of PSD
Best regards,
Marcus
On 04.11.2015 13:15, larry ho wrote:
Hi
I am new to linux and GNU Radio,
I am trying to create a frequency to voltage converter, I
tried looking into the source code of QT GUI Frequency Sink
to get an idea how it detects frequency. However, it seems a
little complicated, is there any particular function i
should look out for in the coding? Or are there any
alternative in creating a frequency to voltage converter.
Greatly appreciative if any advise can be provided. Thank
you.
Regards
Larry
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