GSM and TDMA

On Thu, 7 Jul 2005 21:39:06 -0400, "Gregory W. Ernest"
<Gernest@optonline.net> wrote:

>I am planning to send a cell phone as a gift to someone who lives in a
>country that doesn't have gsm networks. I know that gsm and tdma are built
>on the same underlying technology. My question is will a gsm phone work a
>tdma network?
>
Both phones used Time Division Multiple Access technology to operate,
but that beyond the underlying theory of operation, a GSM and a
TDMA/D-AMPS phone have next to nothing in common. There are some dual
mode phones aroung (GAIT IIRC). For example the underlying data rate
on GSM is 9600 bits per second or 14,400 bits per second (depends upon
how you want to look at), and a GSM phone uses a channel 200Khz wide,
and operates the transmitter 217 times per second. A D-AMPS phone uses
a 30Khz channel, and has an underlying data rate of 7200bits per
second, and operates at a much lower transmitter rate. The frame
formats, modulation scheme etc share essentially nothing.

Keep in mind that there are two versions of TDMA, D-AMPS and and a
very close relative, IS-136. D-AMPS has the ability for complete
coexistance on an AMPS network, IS-136 does not. (D-AMPS uses analog
signaling for control that is identical to AMPS, IS-136 uses digital
signaling for control which an AMPS network will not understand).