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From: hbrown@voicenet.com
Subject: Re: REALITY CHECK!
Date: Fri, 6 Dec 1996 07:20:53 -0500 (EST)
Phil,

Thanks again for your reply.

I have to differ with you on your reply on how to determine the interferance levels that SS has on CW and other modulations and likewise their empacts on various methods of SS. Yes, it take both analysis and expermentation to determine the noise levels to the 1 or 2 db levels (maybe not even for higher amounts of uncertanty) but that is not the point.

We would like a starting point and I am frustrated in not being able to get there. If you recall the comments sent to the FCC in response to the ARRL request to allow SS modulation on the lower vhf bands stated by both AMSAT responses and others that noise floors on systems designed for EME and terrestrial weak signal modes will suffer with large (was it up to 20 dB increases?). This was using simple calculations not claiming 0.1 dB accuracies and none of us expect anyone to predict to this close.

Now, I am sure that the company that you work for has the ability to make analytical estimates on these impacts since they are selling systems that must live in the real world with non SS interferance so there must be something in the professional literature that can get us to the answers we yearn for. No, I don't expect your company to give any trade secrets here or perform the analysis for us but could you tell us where to look?

I am sure that us weak signal (and sometimes weak brained) group would like to have commercial comunications quality systems and we do when we don't shoot for the difficult but we are mainly in the weak signal hobby cause it's hard. Give us more capablity and we will move the records up a notch. We will welcome SS if it gives us a greater capability but this means longer distance improvements, not higher S/N improvements that fall apart like FM does at low S/N below the treashold.

Can you point us twards the tools/analysis that may have been done on this noise level concern that we have so we can get on and mutually determine what places SS has in amateur radio?

73, hARRY, w3iit
>>
>>What do you, as an expert on spread-spectrum communications, predict will
>>happen to our noise floor on the various V/UHF amateur bands as heard on our
>>typical narrowband receiver systems when one or more ss stations operate on
>>the same band utilizing whatever transmission parameters might be expected
>>to be considered normal by other ss users?
>
>This question can only be answered by analysis and experimentation
>using real numbers for location, propagation constants, antenna gains
>and patterns, power levels, receiver system temps, processing gains,
>etc. The same can be said for *any* amateur communications t at share
>the same amateur band, whether these communications are narrowband or
>wideband.
>
>Phil

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