Date: Sun, 21 Jan 2001 22:35:15 -0600 (CST) From: David Scheidt <dscheidt@enteract.com> To: Greg Lehey <grog@lemis.com> Cc: "Michael C . Wu" <keichii@iteration.net>, Brad Knowles <brad.knowles@skynet.be>, freebsd-chat@FreeBSD.ORG Subject: Re: Mobile phone coverage (was: VCD (was Re: cvs commit: src/sys/dev/ata atapi-cd.c)) Message-ID: <Pine.BSF.4.21.0101212221400.55216-100000@shell-2.enteract.com> In-Reply-To: <20010122135650.Q3066@wantadilla.lemis.com>
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On Mon, 22 Jan 2001, Greg Lehey wrote: :On Sunday, 21 January 2001 at 21:10:08 -0600, Michael C . Wu wrote: :> On Mon, Jan 22, 2001 at 03:42:45AM +0100, Brad Knowles scribbled: :>> At 12:35 PM +1030 2001/1/22, Greg Lehey wrote: :>> :>>> That's not the issue here. BTW, for the USA you need a three-band :>>> phone. That is, incidentally, the only kind of phone which will work :>>> just about anywhere (I'm not sure about Israel and Korea). :>> :>> Uhh, I think you need more than that. Let's count: :>> :>> AMPS/NAMPS :>> US TDMA (1900Mhz? 900Mhz?) :>> US CDMA (1900Mhz? 900Mhz?) :>> US GSM (1900Mhz) :> :> US 1900 and 900 The US is 1900 and 800, not 900. The 900 Mhz freqs used by GSM in the rest of the world are the property of the US military. To be honest, I'm not sure there are any AMPS band GSM carriers in the US. Maybe Bell South DCS? :I've been looking at web pages, and it doesn't sound to me that 3G is :a new transmission technology, just something that climbs on the back :of one. Is there any reason why it should be tied to CDMA and not to :GSM? Yes. CDMA has much better use of bandwidth. All users of a CDMA channel use it simultanously, not time multiplexed. The data travelling across the air interface are encoded with a walsh code, which allows the receiver to pick out each data stream, because some mathmattecian was bloody clever. I'm unable to find a good web reference right at the moment, but CDMA is clearly a better choice than any of the TDMA solutions. David To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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