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| Re: Canarsie CBTC (98079) | |||
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Re: Canarsie CBTC |
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Posted by SelkirkTMO on Mon Jun 13 12:28:00 2005, in response to Re: Canarsie CBTC, posted by RonInBayside on Mon Jun 13 12:10:40 2005. Nah buddy ... "de rigeur" ... nothing special here, and frequency hopping has its own issues. Sure, interference on a SPECIFIC frequency isn't so much an issue, but frequency hopping requires a GENEROUS and FLAT bandpass filter, even though THAT is a lot easier too these days. But if you have BROADBAND noise such as an arc'ing insulator nearby, all bets are off. Ever hear a sizzling sound from a nearby third rail in humidity? That'd KNOCK IT OUT. That's "wideband noise" for ya. :)The ONLY thing "frequency hopping" was good for was the old Russkie jamming stations and typical 1960's "countermeasures" ... if you happened to hit a frequency that had a carrier on it, you'd DWELL there short enough to get most of the signal through. It's AMAZING how much "leakage" can screw with "frequency-agile" ... Lemme put it to you THIS way ... PASNY comes by here every so often and sprays chemicals on the bigass power towers that run through my property. BEFORE they do so, my SATELLITE goes byebye and we're talking 3920 MHZ ... WAY above NYCTA ... and even there, when the insulators are arcing, reception can REALLY suck. At *LOWER* frequencies, well ... STILL ... I'm *mainly* busting chops because of "techno-blind-faith" ... sure a vendor in a pinch will try to make the sale through "cob-jobs" but there are serious inherent flaws with RF links, especially when an interference source is WAYSIDE ... since the electronics are UNDERCAR, that's only CLOSER to that source than the power towers and my pizza pan which are separated by a few hundred feet. INCHES are different. :( |
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