On Sun, Aug 6, 2017 at 1:57 PM, John Ackermann N8UR <j...@febo.com> wrote:
> I also have a QT Frequency Sink as eye candy, and notice that its display
> is about 6dB different than the Log Power FFT output. I can think of a
> number of reasons why that could be, but my simple question is... is there
> an appropriate way to adjust one or the other to align their readings?
> (Later I'll send the log power results into a calibration routine to
> convert to dBm based on measured results.)
> Also while I'm at it, there's a "Reference Scale" parameter in the Log
> Power FFT, set by default to "2". Is there a way to use this parameter to
> align the two readings? I tried changing it to "1" but that threw an error
> at runtime.
I took a look at logpwrfft's code and the first thing that is done to that
number is ref_scale/2, so you need to pass in a float (1.0) rather than an
integer to not get it truncated to zero. Sounds like something to fix.
> Also, there doesn't appear to be any window applied (or at least apparent)
> in the Log Power FFT block. Is there a way to window the output?
The GRC definition for the block doesn't let you set it but there actually
is a parameter win which defaults to Blackman-Harris.
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