Nokia 8390 Manuales De Servicio
PAMS Technical Documentation
System Module & UI
NSB-8
Issue 1 01/02
ãNokia Corporation
Page 35
Settling time requirement comes also from the start up-time allowed. When transceiver
is in sleep mode and "wakes" up to receive mode, there is only about 5 ms for the AFC-
voltage to settle. When the first burst comes in system clock has to be settled into +/-
0.1 ppm frequency accuracy. The VCTCXO-module requires also 5 ms to settle into final
frequency. Amplitude rises into full swing in 1... 2 ms, but frequency set tling time is
higher so this oscillator must be powered up early enough.
is in sleep mode and "wakes" up to receive mode, there is only about 5 ms for the AFC-
voltage to settle. When the first burst comes in system clock has to be settled into +/-
0.1 ppm frequency accuracy. The VCTCXO-module requires also 5 ms to settle into final
frequency. Amplitude rises into full swing in 1... 2 ms, but frequency set tling time is
higher so this oscillator must be powered up early enough.
DC-compensation
DC compensation is made during DCN1 and DCN2 operations (controlled via serial bus).
DCN1 is carried out by charging the large external capacitors in AGC stages to a voltage
which cause a zero dc-offset. DCN2 set the signal offset to constant value (RXREF 1.35
V). The RXREF signal is used as a zero level to RX ADCs.
DCN1 is carried out by charging the large external capacitors in AGC stages to a voltage
which cause a zero dc-offset. DCN2 set the signal offset to constant value (RXREF 1.35
V). The RXREF signal is used as a zero level to RX ADCs.