On Sep 22, 2005, at 12:09 PM, Peter Chadwick wrote:
> >With 0db attenuation, take the S meter reading at the adjacent
> frequency, tune to the fundamental frequency, add attenuation as
> needed to give the same S-meter reading as before. The # of db of
> attenuation
> is how many db down the total IMD is.<
>
> ?
>
> Even this depends on how accurately you can set the S meter to the
> same place.
So, do not use a meter that has sticky bearings.
> If we have a meter range to S9 + 40, and even 4 dB per S point, that's
> a 76dB range. So to set to 1dB, you have to get the meter to within
> around 1.5% of the same value - and on a speech signal, too.
The IMD level produced by the transmission of human speech can not be
found by a 2-tone IMD test. I use a steady "ahhhhhhhhh".
>
> 73
>
> ?
>
> Peter W6/G3RZP
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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