On Wed, 29 Oct 2003 08:53:39 +0100, "Meindert Sprang"
wrote:

Apart from that, the cellphone system works with datapackets in very tight
time-slots. The system compensates for the distance between the tower and
the phone (TA: Timing Advance) with a TA value between 0 and 63, for every
550 meters the phone is further away from the tower. This imposes a hard
limit on the maximum distance of 550 x 63 = 34.6km or 18.7 miles. So no
matter how high your antenna is and how much power you have available, 18,7
miles is the limit.

This is true for GSM, but not for AMPS and IS-95 CDMA widely used in
North America. I have no idea about distance limits for D-AMPS which
is TDMA, but it will fall back to AMPS anayway.

In Sweden we have some extended range GSM sites allowing up to 70km
distance, but they don't cover the majority of the coastline. This can
be a problem sometimes, that's why i have an old NMT450 cell phone
installed as well. With an antenna 18 m up, and 15W TX at 450 MHz, the
range is impressive, to say the least.


/Marcus

--
Marcus AAkesson
Gothenburg Callsigns: SM6XFN & SB4779
Sweden
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