Digital Voice Systems VC-20-ATC-10B Especificaciones descargar pdf (Pagina 12)

FAA20 Embedded NEXCOM Vocoder

Board Manual

This manual has been prepared for the Federal Aviation Administration.

FA100-00107 (March 2004) – Rev 1.0.0 Page 6

Table 1: DIN Signals

SIGNAL PIN DIR DESCRIPTION

NIBBLE SIGNALS

ENC3

ENC2

ENC1

ENC0

C15

C16

O Encoder Data: The compressed voice data is proved as

a sequence of nibbles from the ATC-10B encoder. A

total of 25 nibbles is provided every vocoder frame. The

first nibble is a control nibble that is nominally set to 0000

(binary). The subsequent 24 nibbles contain the 96-bit

encoded voice data packet. Each nibble is output on the

rising edge of ENCCK. The FMEN encoder frame pulse

is used to initiate the nibble sequence.

ENCCK A5 I/O Encoder Clock: The encoder clock controls the transfer

of encoder data (ENCx). This signal must be 9600 Hz ±

0.05%. The ENCx, FMEN, GO and RUN are

synchronous with the rising edge of this clock. Either

internal or external clock can be used.

FMEN C6 I/O Encoder Frame Enable (active high): The frame enable

is set high for one ENCCK period to begin the transfer of

encoder data. The frame enable is pulsed high once

every 20 ms (normal rate) and delineates the encoding

window. . Either internal or external frame enable can be

used.

DEC3

DEC2

DEC1

DEC0

C18

C19

I Decoder Data: The compressed voice data is provided

as a sequence of nibbles to the ATC-10B decoder. A

total of 25 nibbles is provided every vocoder frame.

Each nibble is read on the falling edge of DECCK. The

FMDE encoder frame pulse is used to initiate the nibble

transfer sequence.

DECCK A10 I/O Decoder Clock: The decoder clock controls the transfer

of decoder data (DECx). This signal must be 9600 Hz ±

0.05%. Either internal or external clock can be used.

FMDE C11 I/O Decoder Frame Enable (active high): The frame enable

is set high for one ENCCK period to begin the transfer of

encoder data. The frame enable is pulsed high once

every 20 ms (normal rate) and delineates the decoding

window. Either internal or external frame enable can be

used.

AUDIO SIGNALS

AVI A29 I Analog Speech Input: The analog voice input signal is

filtered with a bandpass filter (100 – 3700 Hz) and

sampled at 8 kHz by a 16-bit codec. The signal should

not exceed ±1 volts peak-to-peak.

AVO C29 O Analog Speech Output: A digital-to-analog converter

operating at 8 kHz generates the analog voice output

signal. The signal is bandpass filtered (100 – 3700 Hz)

and should not exceed ±1 volts peak-to-peak.

PCM SIGNALS

DX B6 O Serial Transmit Data: Linear 16-bit PCM voice is output

from the FAA20 at a rate of 8000 samples/second. Each

sample is transmitted serially (MSB first) beginning with

the rising edge of the SCLK after the FSX signal is

detected.

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 108 109

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