User Guide

PAMS
Technical Documentation
WinTesla User Guide
NHD–4
Page 34
Original 11/97
RSSI
This step consist of tuning the analog mode reference value for the
receiver signal strength meter.
This tuning is needed if FM detector (D1); any parts of RX–chain; duplex
filter or saw filter has been changed
Note: Take into account any cable loss.
Description of Tuning
This tuning records the RSSI values for low and high power received
signals. This is done by feeding a –95 dBm signal into the AMPS receiver
at channel 384 with modulation of 8 kHz FM, 1 kHz audio. The RSSI
voltage generated by the AMPS receiver IC (D1) routes to the MCU, pin
58. The MCU reads the RSSI value resulting from its onboard A/D
converter. For the –65 dBm input signal this digital value is stored in
EEPROM as RSSI_HI. This process is repeated for a –65 dBm
modulated input signal, and the stored value is termed RSSI_LO. The
RSSI values read by the MCU are 10 bit numbers.
Analog RSSI level tuning steps:
– Using the JBS–7 service jig, replace the standard battery of the phone
with the dummy battery BTS–4.
– Apply +6.0 V to dummy battery.
– Connect signal generator to antenna connector at 881.52 MHz (chan-
nel 384) using modulating frequency 1.0 kHz with a deviation of 8.0
kHz and level of –95 dBm.
– Select ” Tuning – RSSI”.
– The program reads the reference value stored on phone together with
the reference value read from A/D converter.
– A/D converter value should be between 0 – 255.
– Press <Tune> to store values to the phone and exit or <Cancel> to exit
without storing.
– Connect signal generator to antenna connector at 881.52 MHz (chan-
nel 384) using modulating frequency 1.0 kHz with a deviation of 8.0
kHz and level of –65 dBm.
– A/D converter value should be between 0 – 255.
– Press <Tune> to store values to the phone and exit or <Cancel> to exit
without storing.