[Fwd: Re: [BC] FAA RF rulemaking]

[Robert Meuser]

-------- Original Message --------
Subject: 	Re: [BC] FAA RF rulemaking
Date: 	Wed, 28 Jun 2006 09:47:34 -0400
From: 	Robert Meuser <Robertm at broadcast.net>
Reply-To: 	robertm at nyc.rr.com
To: 	Broadcasters' Mailing List <broadcast at radiolists.net>
References: 	<200606262325.k5QNP8gs093168 at mail1.mx.voyager.net> 
<5.0.0.25.2.20060627083136.04c12ca0 at pop.ais.net> 
<000a01c69a55$d22bc7a0$0300a8c0 at cd2176218a> 
<7.0.1.0.2.20060627201117.0422dda0 at oldradio.com> 
<003001c69aa4$dd056470$0300a8c0 at cd2176218a>



As Mike points out, it is well documented that NAVCOMM interference is a 
receiver problem. When the receiver overloads, it is usually a combination of 
two or more stations most often above 107.1 that are the culprits. As a simple 
example stations on 107.1 and 107.9 will mix the receiver generated second and 
third harmonics to produce 105.5 and 109.5 as intermod products.

As Paul mentioned, better receivers are the proper solution.

R

Dave Dunsmoor wrote:
>     Well, my experience has been spurs, (energy generated and radiated well
> outside the frequency of interest). Say perhaps a transmitter on 93.7
> generated a ninth harmonic that landed directly on top of one of a cell
> tower's channels. Or one that generated "extra" channels up and down the FM
> band. In another case, a spur landed right on, (or close to) the VOR
> frequency, and the FM had to be shutdown until it's IPA was repaired Anyway,
> that's where I heard the problem was.
> 
>     IMD is slightly different, but can cause similar problems, and that is
> usually avoided by frequency and siting selections.
> 
> Dave
> 
> 
> 
>> At 06:54 PM 6/27/2006, Dave Dunsmoor wrote
>>> It's been my experience that NAV and Comm frequencies
>>> are not bothered by "overload" so much but by RFI from transmitters
> outside
>>> the NAV/COMM frequency bands. Specifically FM transmitters, and they do
>>> generate spurs occasionally.
>>          Are you talking about intermod products, Dave?
> 
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