Sub-Audio Signaling Processor
Page 15 of 24
MX805A
5.2.5 Write to CTCSS TX Frequency/NRZ Baud Data Rate Register –A/C 73 (7B ) followed by 2
H
H
bytes of Command Data.
The information loaded to this register will set either the:
(a) CTCSS TX Tone Frequency
(b) NRZ TX Baud Rate
(c) NRZ RX Baud Rate
f
CTCSS OUT
R
R
NRZ TX
NRZ RX
The chosen mode for this register (a, b, or c) is determined by the MX805A modes enabled by the Control
Register, as shown in Table 8.
Control Register Bits
MX805A Mode
Enabled
CTCSS TX/NRZ Baud Rate
Register Function
7
6
5
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
CTCSS Decode
NRZ Decode
NRZ RX Baud Rate
CTCSS Decode
CTCSS TX Frequency
NRZ TX Baud Rate
CTCSS TX Frequency
NRZ TX Baud Rate
NRZ RX Baud Rate
NRZ RX Baud Rate
NRZ Encode
CTCSS Encode and Decode
NRZ Encode & CTCSS Decode
NRZ & CTCSS Decode
NRZ Decode
Table 8 CTCSS Frequency/NRZ Baud Rate Register Configurations
5.2.5.1 Data Format
Data is transmitted to this register as 2 bytes of Command Data in the form illustrated in the diagram below.
This register is not affected by the General Rest Command (01H) and may adopt any random configuration at
power-up.
(Command Data)
(MSB) - Loaded First
(Command Data)
(LSB) - Loaded Last
Byte 1
Byte 0
15
9
7
1
14
13
12
11
10
8
6
5
4
3
2
0
P
"0"
Q
CTCSS TX Frequency/NRZ Baud Rate Register
Figure 7: Format of the CTCSS TX Frequency/NRZ Baud Rate Register
5.2.5.2 Command Words P and Q
The two words, P and Q, loaded to this register are interpreted as:
P = a binary number to set the TX Sub-Audio Lowpass filter bandwidth (applicable to NRX and CTCSS
modes).
Q = A binary number to set the frequency r baud rate of the selected functon.
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