
1996 Oct 29
90
Philips Semiconductors
Objective specification
GSM signal processing IC
PCF5083
9.4
Software applications
This section contains examples for several basic GSM
channels. For every example the procedures to be
executed within the DSP are shown in the form of tables.
The first column contains the TDMA frame number fn in
which the EXEC_PROC messages should be sent to the
DSP. The 2nd column shows the corresponding
procedures with all parameters. Parameters in uppercase
are constants, lowercase parameters are variables. The
3rd column contains the number words N
W
to be
transmitted to the DSP within frame fn (PACKET message
assumed). The columns RX and MX contain the number of
I and Q pairs to be sampled in the receive and monitoring
timeslots of TDMA frame fn. Column TX contains the
number of bits to sent to the GMSK modulator within the
transmit timeslot. The tables are based upon the general
rule that an EXEC_PROC message for a procedure that
starts execution in TDMA frame n has to be sent in TDMA
frame N
1.
Unless otherwise noted, the corresponding
PROC_RETURN message will be available at the latest at
the end of TDMA frame N+1, i.e. if the messages are read
by the SC at beginning of every TDMA frame, the
PROC_RETURN message will be available in frame
N + 2. Start and end of a TDMA frame are defined by the
falling edge of the FRAME_INT signal produced by the
timer core.
9.4.1
R
ECEIVING A
CCH
BLOCK
Table 67 shows how to receive a CCH block and to
perform monitoring of two neighbouring cells in parallel. It
is assumed that the CCH block has to be received in the
frames N to N + 3. Note that the TX timeslot is used for
monitoring in this example.
Table 67
Procedures to be started for receiving a CCH block
Note
1.
Procedures to be started via EXEC_PROC in TDMA frame FN.
fn
PROCEDURES
(1)
N
W
RX
TX
MX
N
1
CP_rx_normal_burst (CCH_CMI_BUFF1, tsc, agc_gain1);
CP_power_measure (agc_gain2)
CP_power_measure (agc_gain3)
CP_rx_normal_burst (CCH_CMI_BUFF2, tsc, agc_gain1);
CP_power_measure (agc_gain2)
CP_power_measure (agc_gain3)
CP_rx_normal_burst (CCH_CMI_BUFF3, tsc, agc_gain1);
CP_power_measure (agc_gain2)
CP_power_measure (agc_gain3)
CP_rx_normal_burst (CCH_CMI_BUFF4, tsc, agc_gain1);
CM_decoder_CCH( );
CP_power_measure (agc_gain2)
CP_power_measure (agc_gain3)
15
N
15
149
80
80
N + 1
15
149
80
80
N + 2
18
149
80
80
N + 3
149
80
80