Theoreticaly you can gain 5.2dB by going from 3 to 10 sec. dot length.
sample rate.
Rik
Only if the resolution of the waterfall analysis software is 3 times
less.
Does Spectran use the same windowing function as Spectrogram ?
Depending on which window is used, the effective bandwidth of a spectrum
display can be from one to three FFT bins, trading off display
sidelobes against effective bandwidth.
.........
I installed a 1Hz bandwidth filter in the RA1792 over the weekend, by
mixing the 455kHz second IF down to 32765 Hz, followed by a ladder
filter made from 5 watch crystals, then mixing back up to 455kHz with
the same local oscillator so it's own instability cancels out. This LO
needs to be tuneable to interpolate over the 10 Hz step size of the Rx.
Results are interesting to say the least !
AGC action is completely destroyed as the 1Hz filter has a group delay
of over a second and so the AGC loop goes wildly unstable - hence manual
gain control is essential.
All signals sound like a perfect audio tone - even static crashes sound
like a carrier with slow fading on it ! Loran lines are tones in this
BW. But it really does bring signals out of the noise, even in the
severe thunder storms of the last few days.
Andy G4JNT
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