CMX881(2002) Просмотр технического описания (PDF) - CML Microsystems Plc

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Компоненты Описание

производитель

CMX881
(Rev.:2002)

Baseband Processor for PMR and Trunked Radios

CML Microsystems Plc 

PMR Signalling Processor

CMX881

Section

CONTENTS

Page

1.0 Features ........................................................................................................................1

1.1 Brief Description ............................................................................................................1

1.2 Block Diagram ...............................................................................................................6

1.3 Signal List......................................................................................................................7

1.4 External Components ....................................................................................................9

1.4.1 PCB Layout Guidelines and Power Supply Decoupling....................................10

1.4.2 Modulator Outputs...........................................................................................11

1.5 General Description .....................................................................................................12

1.5.1 Sleep Mode.....................................................................................................13

1.5.2 Auxiliary ADC..................................................................................................13

1.5.3 Receive Mode .................................................................................................14

1.5.4 Transmit Mode ................................................................................................21

1.5.5 FFSK/MSK Data packeting..............................................................................25

1.5.6 C-BUS Operation ............................................................................................27

1.6 C-BUS Register Description.........................................................................................28

1.7 Application Notes.........................................................................................................46

1.7.1 CRC and Parity information.............................................................................46

1.8 Performance Specification...........................................................................................47

1.8.1 Electrical Performance ....................................................................................47

1.8.2 Packaging .......................................................................................................57

Table

Page

Table 1 Concurrent Rx Signalling Modes Supported by the CMX881........................................ 14

Table 2 CTCSS Tones ............................................................................................................. 17

Table 3 DCS Modulation Modes............................................................................................... 17

Table 4 DCS 23 Bit Codes ....................................................................................................... 18

Table 5 Selcall Tones............................................................................................................... 19

Table 6 Concurrent Tx Modes Supported by the CMX881 ........................................................ 21

Table 7 Data Frequencies for each Baud Rate ......................................................................... 24

Table 8 DTMF Tone Pairs and Corresponding Tx Programming Codes.................................... 25

Table 9 Maximum Data Transfer Latency................................................................................. 26

Figure

Page

Figure 1 Block Diagram..............................................................................................................6

Figure 2 Recommended External Components ..........................................................................9

Figure 3 Power Supply Connections and De-coupling............................................................... 10

Figure 4 Modulator output components to achieve -100dB/decade roll-off ................................ 11

Figure 5 Rx Audio Filter Frequency Response.......................................................................... 15

Figure 6 De-emphasis Curve for TIA/EIA-603 Compliance ....................................................... 15

Figure 7 Low Pass Sub-Audio Band Filter for CTCSS and DCS ............................................... 16

Figure 8 25kHz Channel Audio Filter Response Template........................................................ 22

Figure 9 12.5kHz Channel Audio Filter Response Template..................................................... 22

Figure 10 Audio Frequency Pre-emphasis Template ................................................................ 23

Figure 11 Modulating Waveforms for 1200 and 2400 Baud FFSK/MSK Signals ....................... 24

Figure 12 C-BUS Transactions................................................................................................. 27

© 2002 CML Microsystems Plc

4

D/881/2

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