PMR Signalling Processor
CMX881
1.6.20.2 PROGRAMMING REGISTER Block 1 – Selcall Setup:
$C8 (P1.0)
Voice band tones Tx Level
Bit:
15
1
14
1
13
0
12
1
11
10
9
8
7
6
5
4
3
2
1
0
P1.0
Voice band tones Tx level
Emph
Bits 11 (MSB) to 1 (LSB) set the transmitted Selcall, DTMF, Audio Tone and MSK signal level (pk-pk)
with a resolution of VDD(A)/2048 per LSB (1.465mV per LSB at VDD(A)=3V). Valid range for this value is
0 to 1536.
Bit 0 controls Rx Selcall de-emphasis. When set to '0' the signal going to the Selcall tone detector is not
de-emphasised. When voice processing is enabled in the Mode register, de/pre-emphasis is enabled in
the Audio & Device Address register and this bit (b0) is set to '1', signals going to the Secall tone detector
are de-emphasised in accordance with Figure 6.
$C8 (P1.1)
Selcall Detect Bandwidth and Audio Band Detect Threshold
Bit:
15
0
14
1
13
0
12
1
11
10
9
8
7
6
5
4
3
2
1
0
Selcall detect
P1.1
0
Audio band detect threshold
bandwidth
The ‘detect threshold’ bits (bits 9 to 4) set the minimum Selcall and/or MSK signal level that will be
detected. The levels are set according to the formula:
Minimum Level = Detect Threshold × 3.63mV rms at VDD(A) = 3V
The Selcall detected bandwidth is set in accordance with the following table:
BANDWIDTH
Bit 3
Bit 2
Bit 1
Bit 0
Will Decode
±1.1%
Will Not Decode
±2.4%
1
1
1
1
0
0
0
0
0
0
1
1
0
1
0
1
±1.3%
±2.7%
Recommended for EEA ⇒
±1.6%
±2.9%
±1.8%
±3.2%
$C8 (P1.2-18) Programmable Selcall Tones
Bit:
15
0
14
1
13
0
12
1
11
0
10
9
8
7
6
5
4
3
2
1
0
P1.2-18
Programmable Selcall Tone
N (see below)
R (see below)
These words set the programmable Selcall tones used in transmit and receive. The frequency is set in
bits 11-0 for each word according to the formula:
N = Integer part of (0.042666 x frequency)
R = (0.042666 x frequency - N) x 6000 / frequency (round to nearest integer)
Example: For 1010Hz, N = 43, R = 1. The programmed tones must only be set to frequencies from
400Hz to 3000Hz.
2004 CML Microsystems Plc
44
D/881/7
CMLMICRO [ CML MICROCIRCUITS ]
