Table of Contents
3.1.2.5
3.1.2.6
3.1.2.7
3.1.2.8
3.1.3
Receiver Back-End............................................................................................................3-6
3.1.3.1
3.1.3.2
3.2
Command Board ............................................................................................................................3-8
3.2.1
3.2.2
Serial Input/Output IC ........................................................................................................3-8
3.2.3
Power-Up/-Down Sequence ..............................................................................................3-9
3.2.4
Regulators .......................................................................................................................3-10
3.2.5
Reset Circuits ..................................................................................................................3-10
3.2.6
3.2.7
3.2.8
Received Audio ...............................................................................................................3-12
3.2.9
Microphone Audio ...........................................................................................................3-12
3.2.10 Transmit Deviation ..........................................................................................................3-13
3.2.11 RS-232 Line Driver..........................................................................................................3-13
3.2.12 Flash Programming .........................................................................................................3-13
3.2.13 Encryption Voltages ........................................................................................................3-13
3.3
ASTRO Spectra VOCON Board...................................................................................................3-15
3.3.1
General............................................................................................................................3-15
3.3.2
Controller Section ............................................................................................................3-15
3.3.3
Vocoder Section ..............................................................................................................3-17
3.3.4
RX Signal Path ................................................................................................................3-18
3.3.5
TX Signal Path ................................................................................................................3-21
3.3.6
3.3.7
Vocoder Bootstrap...........................................................................................................3-24
3.3.8
3.3.9
Controller Memory Map ...................................................................................................3-24
3.3.10 Vocoder Memory Map .....................................................................................................3-26
3.3.11 MCU System Clock .........................................................................................................3-28
3.3.12 DSP System Clock ..........................................................................................................3-28
3.3.14 VOCON Board Signals....................................................................................................3-29
3.4
3.4.1
General............................................................................................................................3-38
3.4.2
3.4.3
3.4.4
3.4.5
3.4.6
3.4.7
3.4.8
3.4.9
3.5
Voltage Control Oscillator.............................................................................................................3-47
3.5.1
VHF Band........................................................................................................................3-47
3.5.1.1
3.5.1.2
3.5.1.3
3.5.1.4
6881076C25-E
Loop Filter ................................................................................................................3-5
Auxiliary Control Bits ................................................................................................3-5
Second VCO ............................................................................................................3-6
Power Distribution ....................................................................................................3-6
First IF ......................................................................................................................3-6
ABACUS II IC ...........................................................................................................3-7
General...................................................................................................................3-47
DC Voltage Supplies ..............................................................................................3-47
VCO........................................................................................................................3-47
Synthesizer Feedback............................................................................................3-48
vii
September 5, 2008