FX818 데이터 시트보기 (PDF) - CML Microsystems Plc

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FX818

CTCSS Signalling Processor

CML Microsystems Plc 

CTCSS Signalling Processor

FX818

SUB-AUDIO CONTROL Register (Hex address $80)

This register is used to control the functions of the device as described below:

CTCSS TX ENABLE

and DECODER

ENABLE

(Bits 7 and 6)

These two bits enable and disable the CTCSS decoder (Rx) or transmitter (Tx)

according to the table below:

Tx

Bit 7

0

0

1

1

Rx

Bit 6

0

1

0

1

Function

Tx disabled, Rx disabled

Tx disabled, Rx enabled

Tx enabled, Rx disabled

Tx enabled, Rx enabled

CTCSS FAST

DETECT ENABLE

(Bit 5)

(Bits 4, 3, 2, 1 and 0)

When this bit is "1", the "FAST CTCSS DETECT" or "FAST CTCSS

PREDICTIVE" mode is enabled, depending upon the setting of FAST CTCSS

MODE (Bit 3 SUB-AUDIO SET-UP Register, $82). When this bit is "0", both

"FAST CTCSS DETECT" and "FAST CTCSS PREDICTIVE" tone detectors are

disabled.

Reserved for future use. These bits should be set to "0".

SUB-AUDIO SET-UP Register (Hex address $82)

This register is used to define the CTCSS parameters, as described below:

CTCSS DECODER

BANDWIDTH

(Bits 7, 6, 5 and 4)

These four bits set the bandwidth of the CTCSS tone decoder according to

the table below:

Bit 7

1

1

1

1

1

1

1

1

Bit 6

0

0

0

0

1

1

1

1

Bit 5

0

0

1

1

0

0

1

1

Bit 4

0

1

0

1

0

1

0

1

BANDWIDTH

Will Decode Will Not Decode

±1.1%

±2.4%

±1.3%

±2.7%

±1.6%

±2.9%

±1.8%

±3.2%

±2.0%

±3.5%

±2.2%

±3.7%

±2.5%

±4.0%

±2.7%

±4.2%

FAST CTCSS MODE

(Bit 3)

When CTCSS FAST DETECT ENABLE (Bit 5 SUB-AUDIO CONTROL Register,

$80) is "1", this bit selects the "FAST CTCSS DETECT" or the "FAST CTCSS

PREDICTIVE" mode, according to the table below:

© 1997 Consumer Microcircuits Limited

9

D/818/4

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