NSW-6
System Module SE2
PAMS Technical Documentation
Page 12
Issue 1 12/99
Nokia Mobile Phones Ltd.
With audio signal also SAT (Supervisory Audio Tone) is being received
from the base station. The SAT signal can be 5970 Hz, 6000Hz or 6030
Hz, the frequency being defined by the base station. DSP’s DPLL phase
lock loops to SAT, detects if the SAT frequency is the expected one and
examines the signal quality. DSP reports SAT quality figures to MCU reg-
ularly. The received SAT signal is transponded (transmitted back) to base
station.
The base station can send signalling messages on Forward Voice Chan-
nel (FVC) to the phone, by replacing the audio with a burst of Wide Band
Data (WBD). Typically these are handoff or power level messages. Sys-
tem Logic RX–modem is used for receiving the signalling message burst,
after which it gives interrupt to MCU for reading the data. During the burst
audio path must be muted; MCU gives message to DSP about this. MCU
can acknowledge the messages on Reverse Voice Channel (RVC), where
DSP sends the WBD to transmitter RF.
Also Signalling Tone (ST) can be transmitted to acknowledge messages
from base station. DSP sends ST after MCU’s command.
On Analog Voice Channel MCU uses sleep mode (HW DEEP SLEEP)
most of the time, but other circuits are fully operational.
Digital Control Channel Mode (DCCH)
On digital control channel (DCCH) DSP receives the paging information
from the Paging channels. DSP sends messages to MCU for processing
them.
Each Hyperframe (HFC) comprises two Superframes (SF), the first as
the Primary (p) and the second as the Secondary (s) paging frame. The
assigned Page Frame Class (PFC) defines the frames which must be re-
ceived, and thus it also defines when the receiver must be on; i.e. the
basic power consumption is defined at the same time.
The phone employs sleep mode between received time slots. Then DSP
sets the sleep clock timer and MCU, DSP and RF including VCXO are
powered down. Only sleep clock and necessary timers are running.
From DCCH phone may be ordered to analog control channel or to ana-
log or digital traffic channel.
Digital Traffic Channel Mode (DTCH)
Digital Voice Channel
On digital voice channel DSP processes speech signal in 20 ms time
slots. DSP performs the speech and channel functions in time shared
fashion and sleeps whenever possible. Rx and tx are powered on and off
according to the slot timing. MCU is waken up mainly by DSP, when
there is signalling information for the Cellular Software.
