Date: Thu, 18 Jun 1998 08:35:55 -0500 From: David Kelly <dkelly@nebula.tbe.com> To: hackers@FreeBSD.ORG, multimedia@FreeBSD.ORG Subject: Re: X-10 Mouse Remote patch Message-ID: <199806181335.IAA01488@PeeCee.tbe.com> In-Reply-To: Your message of "Thu, 18 Jun 1998 08:50:20 EDT." <199806181250.IAA26015@skynet.ctr.columbia.edu>
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Bill Paul writes: [...] > It's the taxi drivers (sometimes gypsy drivers, sometimes medallion > cabs; it varies). Many taxi drivers in NYC have illegal CB radio systems > in their cabs. By illegal, I mean CB radios that have been modified to > tune outside the normal CB frequency allocation and used together with RC > amplifiers. FCC rules dictate that CB radio transmitters are only allowed > 4 watts output power using AM and 12 using SSB, but it's not uncommon to > find amplifiers that boost the output to 100, 200 or 500 watts or more. > (These amplifiers are often cheaply built, badly shielded, and have less > than adequate output filtering. A lot of the time they're little more > than a big heat-sink with transistors attached.) One of the problems is the cheap CB radio transmitter. FCC specs dictate maximum spurious emissions (off frequency) two ways: absolute and attenuation from the fundamental frequency. At the moderately low power of a CB the absolute spec often governs. Then you run it thru an amplifier and get very strong signals off frequency. In any case there are always strong signals off frequency with high powered transmitters as the mandated attenuation is only 60 dB. Combine CB'ers love of speech processors driving their radios into distortion and emit even more spurious emissions. Sheilding of radio and/or amp has little to do with the transmitted garbage. If the X10 mouse transmitter and receiver are anything like the ones I've torn apart for X10 A/C house controls, then give up. Your problem isn't "evil" CB'ers or amateur radio operators, but possibly the world's cheapest radio. X10 used RC (resistor/capacitor) circuits to establish their frequency. Receiver was 5 or 10 MHz wide. And most any signal on any frequency would interfere. -- David Kelly N4HHE, dkelly@nebula.tbe.com ======================================================================== Whom computers would destroy, they must first drive mad. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message
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