TABLE OF CONTENTS
PAGE
1. INTRODUCTION............................................1-1
2. SEA 157S SPECIFICATIONS.................................2-1
2.1 General............................................2-1
2.2 Transmitter........................................2-1
2.3 Receiver...........................................2-2
2.4 Mechanical.........................................2-2
2.5 DSC controller.....................................2-3
3. OPERATING THE SEA 157S..................................3-1
3.1 Front Panel Controls...............................3-1
3.2 Display............................................3-1
3.3 Push To Talk.......................................3-1
3.4 Radiotelephone Operating System Functions..........3-2
3.5 Digital Selective Calling Operating System.........3-7
3.6 Using Test, Calibration and Diagnostic Utilities...3-13
3.7 USA Frequency List.................................3-14
3.8 International Channel list.........................3-15
3.9 Weather Channel list...............................3-16
4. INSTALLATION............................................4-1
4.1 Preliminary Check..................................4-1
4.2 Shelf or Overhead Mounting.........................4-1
4.3 Bulkhead Mounting..................................4-1
4.4 Power Supply Wiring................................4-1
4.5 Antenna Wiring.....................................4-1
4.6 External Speaker Wiring............................4-2
4-7 NMEA 0183 and RS232 Wiring.........................4-2
5. THEORY OF OPERATION.....................................5-1
5.1 Frequency Synthesizer..............................5-1
5.2 Modulation Circuit.................................5-2
5.3 Main Receiver......................................5-2
5.4 Transmit Amplifier Chain...........................5-5
5.5 Antenna Interface Circuits.........................5-5
5.6 Automatic RF Power Control (APC) and TX Logic......5-6
5.7 TX Logic Detector..................................5-6
5.8 Power and Audio Circuits...........................5-6
5.9 Microcomputer Circuitry............................5-7
5.10 Keypad/Keypad Lighting.............................5-8
5.11 Display/Display Lighting...........................5-8
6. MAINTENANCE.............................................6-1
6.1 General............................................6-1
6.2 Recommended Test Equipment.........................6-1
6.3 Basic Performance Tests............................6-2
6.4 Transmitter Alignment..............................6-3
6.5 Receiver alignment.................................6-6
7. Block Diagram/Schematics............................7-1/7-9
