User Guide

Rx AM suppression (GSM)

Context

Rx AM suppression is used to tune the AM suppression capabilities of the GSM receiver.

AM suppression is related to ability of the receiver to operate when there is a disturbing AM modulated signal

near the received channel signal frequency.

RFIC has tunable compensation circuit which has an effect on the AM suppression ability.

In Rx AM suppression, a continuous useful signal accompanied with an AM modulated signal 10MHz above

the current channel is fed to the antenna. RFIC control word values are iterated until a minimum RSSI signal

is found.

Steps

1. Connect the module jig’s GSM connector to the signal generator.

2. From the "Operating mode" dropdown menu, set mode to "Local".

3. From the Tuning menu, choose GSM -> Rx AM Suppression.

4. Select GSM900 band (or GSM850 on RM-24).

5. Click Start.

6. Connect the signal generator to the phone according to the frequency and modulation parameters

displayed in the pop-up window:

Frequency 952.46771MHz / 1852.86771MHz / 1970.06771

MHz (depending on the band used)

Power level -25 dBm / -26 dBm / -29 dBm (increase by cable

and jig attenuations)

Modulation AM

AM modulation depth 90%

RM-10;RM-24

RF Troubleshooting and Manual Tuning Guide Nokia Customer Care

Issue 1 COMPANY CONFIDENTIAL Page 7 –33