Digital Voice Systems VC-20-ATC-10B, Руководство пользователя

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Section 6 – VC-20™ ATC-10b Vocoder Board Advanced Features
VC-20

ATC-10b Vocoder Board User’s Manual
page 9
The Speech Compression Specialists
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VFRO VFRO is the analog speech output produced by passing the decoder output through a 16
bit linear codec. VFRO has an analog bandwidth of 100 Hz. - 3600 Hz., and it is
constrained to be /- 1.5 volts.
RUN RUN is a status signal that signifies that the VC-20™ - ATC-10b is encoding and
decoding speech. This signal drives the green LED. Each data frame is divided into an
encoder window and a decoder window. The RUN signal is active within each
respective window when the VC-20™ - ATC-10b is encoding or decoding speech (see
figure 6). RUN is synchronous with TXCK.
RESX RESX is the reset status output signal. It is active when the VC-20-MTR is being reset.
The VC-20™ - ATC-10b is reset under three conditions: during power-up, as a result of
DINRS being asserted, or as a result of a Watch-Dog Timer reset. This signal is an
active low output. RESX is the VC-20™ - ATC-10b 's actual hard-reset signal;
whereas, RESET is a software flag that is synchronous with TXCK.
DINRS DINRS is a VC-20™ - ATC-10b reset signal. An active high level on DINRS for a
duration of at least 300ns will reset the VC-20™ - ATC-10b. DINRS will generate
RESX and RESET. The VC-20™ - ATC-10b will pull this signal to its inactive state
(low) when it is not being driven by an external source (it may be left unconnected if not
being used).
VAD The VAD signal must be held low to enable the onboard Voice/Silence detection and
comfort noise generation. This signal is sampled on the falling edge of the first clock
cycle of each 20 ms encoder frame. If left unconnected, this signal is pulled internally to
the disabled state (high).
DTMF_DET The DTMF_DET flag is activated by the encoder if it detects a DTMF tone on VRXI.
The DTMF_DET is brought high on a rising edge of TXCK and held high for four clock
cycles. During this time the DTMF data is output on DTMF_DAT. The DTMF_DET
flag is only output once for each continuous DTMF tone that is detected. DTMF_DET
can only be active during the first four clock cycles of a 20 ms data frame.
DTMF_DAT If the VC-20™ - ATC-10b detects a DTMF tone, it outputs four bits of data identifying
the tone on the DTMF_DAT signal (see Section 3.7). The data is output during the four
clock cycles when DTMF_DET is high. The data is synchronous with the rising edge of
TXCK. This signal should be ignored when DTMF_DET is inactive.