Date: Tue, 23 Jan 2001 07:48:29 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: dmlb@dmlb.org (Duncan Barclay) Cc: grog@lemis.com (Greg Lehey), freebsd-chat@FreeBSD.ORG, kris@FreeBSD.ORG (Kris Kennaway), brad.knowles@skynet.be (Brad Knowles), keichii@peorth.iteration.net, tlambert@primenet.com (Terry Lambert) Subject: Re: GSM vs. CDMA (was: VCD (was Re: cvs commit: src/sys/dev/ata Message-ID: <200101230748.AAA14547@usr08.primenet.com> In-Reply-To: <XFMail.010123020900.dmlb@computer.my.domain> from "Duncan Barclay" at Jan 23, 2001 02:09:00 AM
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> >> Yes, I saw that. I was more thinking about who you would be > >> pissing off if you turned one of these things on in the U.S. > >> near a military base. > > > > Hmm. Yes, I wonder what would happen. I wonder how long it would > > take them to work out what was going on. > > A GSM phone will not transmit anything until it find a beacon being > transmitted by a basestation. There is a scanning procedure that > looks at all possible frequencies in use by all GSM networks (in a > given band), followed by a timing acquistion, followed by reading > of various informational packets transmitted in the beacon. The > whole procedure is documented in the GSM 05.08 and 05.10 standards. > > The US military would not know anyone was using a phone because the phone > would just not do anything apart from saying "no network". When I was in about third grade, I had a ham radio receiver (I collected broken electronics and other things, which I would then fix or scavenge for parts; I built my first robot in fifth grade). One interesting effect that I quickly latched onto to get PBS programming on the television instead of "The Brady Bunch" was that you can use one receiver to selectively jam specific frequencies from being usable by another (if you tell my sisters, I will, of course, deny this). All it takes is a strong receiver (actually, when they make you turn off your electronics in a plane, it's to keep them from interfering with the on-board ILS receivers, not just so people will actually use the GTE "AirPhone"). The point is, if the British can detect unlicensed televisions, I think the U.S. Military can find a cell phone that looks like a scanner trying to listen to their frequencies. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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