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September 5, 2008
6881076C25-E
3-40
Theory of Operation:
ASTRO Spectra Plus VOCON Board
When transmitting, the microphone audio is passed from the command board to the MC145483
CODEC (U402), which incorporates an analog-to-digital (A/D) converter to translate the analog
waveform to a data stream. The data is made available to the DSP through the Serial Audio Port
(SAP) of the Patriot IC. In the converse way, the DSP writes speaker data samples to a D/A in the
CODEC (U402) through the SAP. The CODEC (U402) provides an analog speaker audio signal to
the audio power amplifier on the command board.
Figure 3-15. ASTRO Spectra Plus VOCON Board – Vocoder Section
Modulation
Out
Speaker
D/A
ABACUS
Interface
Mic
A/D
PATRIOT
U300
FLASH
U301
2M x 16
Address/Data/
Control
Command Board
Encryption
Board
SRAM
U302
256k x 16
GPIO
SPI
22.5k x 32
SRAM
SSI - BBP
DSP 56600
KRSIC
ADDAG
CODEC
SSI - SAP
Command
Board
Summary of Contents for ASTRO Digital Spectra
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Page 6: ...September 5 2008 6881076C25 E iv Document History Notes ...
Page 20: ...xviii List of Tables September 5 2008 6881076C25 E Notes ...
Page 24: ...September 5 2008 6881076C25 E xxii CommercialWarranty Notes ...
Page 48: ...September 5 2008 6881076C25 E xlvi Model Numbering Charts and Specifications Notes ...
Page 142: ...September 5 2008 6881076C25 E 3 82 Theory of Operation Power Amplifiers Notes ...
Page 434: ...September 5 2008 6881076C25 E Glossary 10 Notes ...
Page 440: ...Index 6 September 5 2008 6881076C25 E Notes ...
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