Seems like it would be a simple matter to amplitude modulate the noise
spectrum with a 1 to 5 Hz sine wave in order to simulate the speech
envelope. A more complicated, but perhaps more realistic implementation
would be to combine a 1 to 5 Hz gaussian noise spectrum with a
200 - 3000 Hz gaussian spectrum with the syllabic component weighted
appropriately. Probably not that hard for an experienced DSP person
to put together. A .WAV file could be then distributed via the internet
and played via soundcard with the repeat function activated.
73 de Mike, W4EF.............................
----- Original Message -----
From: "Ian White, G3SEK" <G3SEK@ifwtech.com>
Sent: Thursday, September 20, 2001 2:32 AM
Subject: Re: [AMPS] IMD
> Peter Chadwick wrote:
> >Tom says:
> >>Are you saying the wideband noise causes the power supplies to
> >>waddle around at a syllabic rate?
> >It had better, even if it means modifying the noise source.
> It's true in principle that white noise contains equal components at all
> frequencies, but it doesn't contain the very strong components at
> syllabic rates that speech does.
> The frequency spectrum of speech looks like a huge peak at about 1-5Hz
> (higher for auctioneers) but then virtually nothing until about 200Hz.
> It's the strength of that syllabic-rate peak that troubles so many power
> 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
> 'In Practice' columnist for RadCom (RSGB)
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