[ltp] Re: Linux-Thinkpad digest, Vol 1 #632 - 27 msgs

[T. Ivarsson]

From: James Knott <james.knott@rogers.com>
> morpheus wrote:
> > As I said, I'm a pilot, not an RF engineer.  As I recall, though, the
> > report used a particular model of Nokia phone and noted that at maximum
> > output it drew 4 amps of current, so that's the number that stuck in my
> 
> I still don't know where you got that number from.  Hand held cell 
> phones are limited by law, to about 600 mW average power.

Well, the limited output power depends on what technology you are discussing (GSM, TDMA, UMTS, or CDMA) and the mobile's powerclass. I can only speak for CDMA (and AMPS - analog) when I say that the almost exclusively used max output power is 200mW. The specifications (e.g., ANSI-95 and IS-2000) for the technologies specifies the output power for mobiles. The only thing regulators ("the law") specifies is the amount of allowed interference outside the mobiles frequency spectrum - and in some countries the amunt of radiation allowed from a health perspective.

Back in the days in the US, there were mobiles used (especially AMPS) that had an output power of 3W - add to that that some people installed an antenna on the car that provided an additional ~1dB gain. So the number '4' is not improbable, the unit is most likely Watts though...

GSM mobiles (and TDMA) are notorious for interfereing with hearingaids and radios. This is because they use a very bursty transmission process when establishing contact with a base station. This means that the mobile is turning its transmitter on and off, which in turn cause interference (transmitters/amplifiers don't like to be turned on and off rapidly). You can hear this if your GSM/TDMA mobile is close to a radio and you are just about to receive a call.

Sorry for venturing off-topic, but I'm an RF/cellular engineer and picky with details :)

T.
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