Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!rpi!night From: night@pawl.rpi.edu (Trip Martin) Newsgroups: sci.electronics Subject: Re: naive question about RF propagation (anecdote) Message-ID: Date: 18 Jan 90 14:14:38 GMT References: <6671@tekgvs.LABS.TEK.COM> <6857@wpi.wpi.edu> Organization: Rensselaer Polytechnic Institute, Troy NY Lines: 20 reynhout@wpi.wpi.edu (Hagbard Celine) writes: > From what I understand now, the AM signal dropped considerably, allowing a >lower-power broadcast at the AM demodulation circuit's RESONANT frequency to >be picked up. This is done quite intentionally. For some reason, 660Hz comes >to mind, but this doesn't sound right, and I don't know enough about rf to >say one way or another....but I'm sure someone (almost everyone?) out there >does... It has nothing to do with the AM demodulation circuit's resonant frequency (I assume you mean the IF). Basically, the traffic report signal was strong enough to make it through all the filters in the AM receiver (these filters tend to be poor anyhow, compared to most other kinds of radios), and still be strong enough to reach the detector with decent strength. Since you're in a long tunnel, it doesn't have to fight off other stations. -- Trip Martin KA2LIV Trip_Martin@mts.rpi.edu night@pawl.rpi.edu night@uruguay.acm.rpi.edu ** Murphy's Law of Thermodynamics: Things get worse under pressure **