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To: <>
Subject: [AMPS] IMD
From: Mike" < (Mike)
Date: Thu, 20 Sep 2001 09:24:27 -0700
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" <>
To: <>
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
> supplies
> 73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
>                           'In Practice' columnist for RadCom (RSGB)
> --
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