Nokia 8550 サービスマニュアル

NSM–3/3D

System Module

PAMS Technical Documentation

Page  39

Issue 4  02/2002

 Nokia Corporation

This RF module takes care of all RF functions of EGSM/DCS1800 dual-
band engine. RF circuitry is located on one side of the 8 layer tranceiver–
PCB. PCB area for the RF circuitry is about 15 cm2. The RF design is
based on the first dualband direct conversion RF–IC ”Hagar”. So there is
no intermediate frequency and that means the number of component is
much lover than before and there shall be much less interference prob-
lems than previously.

EMC emissions are taken care of using metallized plactic shield,  which
screens the whole transceiver. Internal screening is realized with isolated
partitions. At least the VCO is isolated. The baseband circuitry is located
on the same side of the same board.

Battery voltage, idle mode

3.9 V

Regulated supply voltage

2.8 +/– 3% V

Voltage reference

1.5 +/– 1.5% V

Operating temperature range

–10...+55 deg. C

Absolute maximum voltage

4.8 V

Receive frequency range

925 ... 960 MHz / 1805 ... 1880 MHz

Transmit frequency range

880 ... 915 MHz / 1710 ... 1785 MHz

Duplex spacing

45 MHz / 95 MHz

Channel spacing

200 kHz

Number of RF channels

174 / 374

Power class

4 (EGSM900) / 1 (DCS1800)

Number of power levels

15 / 16