Digital Voice Systems VC-20-ATC-10B Specifikace stáhnout pdf (Strana 20)

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 14

3. Select the proper adapter configuration (SW3).

This switch setting is important for configurations that use the PCM

interface. If the host system can support both the 8 ksps and 6.67

ksps digital frame rates, set SW3=OFF. If on the other hand, the

host system only supports the standard 8 ksps voice sample rate,

enable the adapter, i.e. set SW3=ON.

4. Select the truncated timing switch (SW4) to the OFF position.

This switch can be used to initially setup the FAA20 in truncated

timing mode. This typically is not desirable, but could be helpful for

system test or demonstration purposes.

5. If VC20 mode has been selected and the PCM interface will be used

with the vocoder, set the PCM route enable switch (SW5) to the ON

position. Otherwise, set the position to OFF.

4.3 Setting up Flash Configuration Parameters

It is recommended that the FAA20 flash configuration parameter settings be

reviewed and updated as required to insure FAA20 interoperability. The

flash configuration parameters settings are accessible via the FAA20

terminal command interface.

To communicate with the FAA20 terminal port for the first time, set up a

terminal to work at 115,200 bps, 8 data bits, 1 stop bit, no parity, no flow

control. The terminal communication parameters can be changed and

saved to flash memory, as required.

To view the current configuration, type the ‘CFG’ command which lists all

configuration parameters. For a list of the default settings, refer to Section

8.3.3.

Since the desired configuration setup is up to the FAA20 integrator, detailed

setup instructions are not provided. However, the following sections

provide additional information which may be helpful in selecting the

appropriate flash configuration.

4.3.1 Timing Configuration

In order to achieve the best audio quality, the proper timing configuration

must be used. The following items provide timing configuration guidance.

• Clocking (CLKSRC, CLKRATE, FRAMESIZE). Either internal or

external clock (CLKSRC) must be selected for the NIB clock

interface and the optional PCM interface. Since the FAA20 vocoder

is intended to be part of a larger system, external timing is usually

selected. If external clock is selected, the CLKRATE and

FRAMESIZE can be ignored: CLKRATE and FRAMESIZE. If

internal clock is selected, you must insure that the normal and

truncated timing modes support 8 ksps and 6.67 ksps for linear

voice, respectively. In addition, the frame rates for compressed

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Digital Voice Systems VC-20-ATC-10B Specifikace Strana 20

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