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Voice System Specifications
Voice System Specifications
ITU ADPCM Voice System (950-0385 or 950-0386)
Parameter Description
Audio In/Out 8-bit PCM with u-Law companding to 12 bits
Time division PCM multiplexed audio highway
Audio Bandwidth 200 Hz to 3400 Hz, +/- 1 dB
Recording Method Transcoding to 4-bit ADPCM at 32Kbits/sec
Double buffers for each channel
DMA transfer to hard disk for permanent storage
Storage Files in protected partition of hard disk
End-of-file indication for precise audio cutoff
Message Length No minimum
Maximum limited only by mass memory capacity
(although the paging terminal may limit voice recordings to a more
practical size)
End of Message Precision replay without wasting voice time
Pause Compression Software selectable
Performed before disk transfer to conserve activity
Fast audio attack prevents initial syllable cutoff, also minimizes
noise falsing
Selectable decay rate allows customized pause length
Operation Standard card = 14 independent channels
High capacity card = 28 independent channels
Each may be recording or playing
Entirely software controlled by the paging terminal, no special
training required for callers
Diagnostics and error recovery provided by the paging terminal
control software
LED Indicators One LED to show voice memory activity
One LED to show program memory activity
Two LEDs for test information
Four LEDs to indicate channel activity
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