NSW-6
System Module SE2
PAMS Technical Documentation
Page 11
Issue 1 12/99
Nokia Mobile Phones Ltd.
Baseband Module, Functional Description
Modes of Operation
The phone has the following main operating modes
– Analog mode, on 800 MHz band
– Analog Control Channel
ACCH
– Analog Voice Channel
AVCH
– Digital mode, on 800 MHz band
– Digital Control Channel
DCCH
– Digital Traffic Channel
DTCH
– Digital mode, on 1900 MHz band
– Digital Control Channel
DCCH
– Digital Traffic Channel
DTCH
– Out Of Range –mode
OOR
– Locals mode
Analog Control Channel mode (ACCH
)
On analog control channel the phone receives continuous signalling
messages on Forward Control Channel (FOCC) from base station, being
most of the time in IDLE mode. Only the receiver part is on. Occasionally
the phone re–scans control channels in order to find the stronger or
otherwise preferred control channel.
Also registration (TX on) happens occasionally, whereby the phone sends
its information on Reverse Control Channel (RECC) to base station and
the phone’s location is updated in the switching office.
If a call is initiated, either by the user or base station, the phone moves to
analog voice channel or digital traffic channel mode depending on the
orders by the base station.
Analog Voice Channel Mode (AVCH)
The phone receives and transmits analog audio signal. All circuitry is
powered up except digital rx–parts. In this mode the DSP does all the au-
dio processing and in the Hands Free (HF) mode it also performs echo–
cancellation and the HF algorithm. COBBA performs the AD–conversion
for the MIC signal, and the DA–conversion for the EAR signal.
