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Re: DSP, good use on satellites?



Jeremy,

At 10:03 AM 12/8/99 -0500, Jeremy Cowgar - KB8LFA wrote:
>As most of you know, I am new to satellites... Last night I made my 10th
>contact, after experiencing difficulties with my N-connector on the 70cm
>link :( Caused me to miss two passes! )
>
>Anyways, I would like to ask if using a DSP would reduce the noise that is
>created when kicking on the pre-amp? I have a mirage 70cm pre-amp (mounted
>at the mast), and noise is little, but then when I kick the pre-amp on,
>noise is an S2-3, however signals go from being almost (very very very
>close) to undetectable to S7-9 (That's with my RG-8 50' run since last night
>I had difficulties with my 9913 run - connector - Will be fixing tonight,
>hopefully).

I always run a little DSP on all the satellites, and a lot of DSP on 
AO10.  My FT847 has audio section DSP, and for the LEOS I leave it in NR 
(noise reduction) mode.  For AO10 I kick in a Timewave DSP-9 and use the 
random noise reduction setting.

One thing I've discovered is that a good set of communications headphones 
help with voice fidelity on the birds.  Many stereo High Fidelity 
headphones have too wide an audio response. Headsets designed for 
communications center their audio response in the voice part of the audio 
spectrum.

A simple test for your headphones is to listen to a 2M repeater which 
passes a PL tone.  Can you hear the tone in the headphones?  If so, your 
headphones (or speaker) have too broad an audio response, and a narrow 
audio filter, or DSP will help.

One thing a preamplifier WILL do, is also amplify the noise.  If it 
amplifying ambient noise (white noise) a DSP unit will be very effective in 
lessening the din.

73, Mike


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