All Cellphones Are Beautiful! Even those with >33dBm output power.

By SN | | 2 minutes

Preface

I definately love useless reflections about various stuff including RF. Some time in past, I was wondering, what is the RF power limit for User Equipment used in mobile networks… From some source, I heard that 33 dBm is an absolute max for a user equipment at GSM900. However, as it turns out, it’s not true - there is already more informations on that “here”

GSM900 max RF power
That's actually very interesting.

Where are those devices, which have >1W of output power at GSM frequencies?

… definately not in our pockets:). I haven’t found any of such devices, till this day.

BEHOLD

I just bought Siemens S1 autotelefon. A German phone, which supports D-Netz - which is basically German way of saying GSM900.

siemens P1
Siemens P1 - front view
siemens P1
Siemens P1 - rear view

According to the “specs”, it has max. 5W output power

siemens P1
Specs

Since, it’s giant GSM phone, I was more than happy to be able to disassemble it and take a closer look at the technology itself

siemens P1
Transmitter board, part 1 (RF PA, and frequency duplex filter visible)
siemens P1
Transmitter board, part 2(PMB2200T - integrated mixer-modulator visible)
siemens P1
Receiver board, part 1 (MC12022SLB - prescaler and TBB200G - PLL synthesizer visible)
siemens P1
Receiver board, part 2 (PMB2400T - GSM receiver, and LP295 - voltage regulator visible)
siemens P1
Receiver board, part 3 (oscillators visible)
siemens P1
Receiver board, part 4
siemens P1
Digital board, part 1
siemens P1
Digital board, part 2

Summary

That’s pretty interesting device, which may give an insight - just because it’s made from discrete components - how do 2G devices work. I’d like to tinker with a firmware, however reverse engineering of the FW is pretty hard stuff. Let’s see in the future:).