Message-ID: <00ce01bf6777$e2542e00$0600a8c0@main>
From: "Dave" <dave@picks.force9.co.uk>
To: rsgb_lf_group@blacksheep.org
References: <LPBBJIAEFBFDMPGAFFKBAEFBCAAA.g3xtz@rgcomms.demon.co.uk>
Subject: LF: Re: Narrow Bandwidth reception
Date: Tue, 25 Jan 2000 20:36:30 -0000
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Dear all.

I was the other half of the QSO which started this debate, on 73kHz, I don't
need FFT to work Graham on 136!
I started with the 86Hz bandwidth but my PC runs so slowly that the
characters were too short. Reverting to the next one up (about 172Hz) it was
an easier copy. I imagine that a PC with more number-crunching ability would
help here!

I always use the 30dB scale as it emphasises small signal-level differences
better. Incidentally, I still like the old greyscale representation that the
original version did. Black for no signal getting lighter the stronger the
signal. Some of the colour schemes just seem to confuse.

We must try a comparison of Spectran against Spectrogram one day too...

73, Dave G3YXM

> I would like to know other users experiences using the Spectrogram
programs.
> I have frequently found that I am only able to detect the weakest stations
> using a sample rate of 5.5k with a FFT size of 16384. This gives an
> on-screen bandwidth of 86 Hz. If I attempt to see more of the band, either
> by increasing the sample rate, or decreasing the FFT size, I am unable to
> detect the signal that I know is there.  This seems fairly obvious, in
that
> decreasing bandwidth should improve signal to noise, but I wonder if all
> users have the same results?
>
> 73 de Graham B. Phillips.  G3XTZ.
>
>
>