Figure 3-15. Astro Spectra Plus Vocon Board - Vocoder Section - Motorola ASTRO Digital Spectra Plus Detailed Service Manual
Uhf & vhf 800 mhz mobile radios
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Also See for ASTRO Digital Spectra Plus:
- Service manual (426 pages) ,
- User manual (174 pages) ,
- Instruction manual (114 pages)
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3-40
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.
Command Board
KRSIC
ABACUS
Interface
Figure 3-15. ASTRO Spectra Plus VOCON Board – Vocoder Section
September 5, 2008
Theory of Operation: ASTRO Spectra Plus VOCON Board
PATRIOT
U300
SPI
SSI - BBP
GPIO
ADDAG
Modulation
Out
Address/Data/
Control
22.5k x 32
SRAM
DSP 56600
Mic
SSI - SAP
A/D
CODEC
Speaker
D/A
FLASH
U301
2M x 16
SRAM
U302
256k x 16
Encryption
Board
Command
Board
6881076C25-E
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Troubleshooting
