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AMBE-3000F™ Vocoder Chip Users Manual

Version 3.4, April, 2014

O Management

Figure 38 Front End Output Filter Mask

This document assumes that the A-to-D converter produces digital samples where the maximum digital input level (+3 dBm0)

is defined to be +/- 32767, and similarly, that the maximum digital output level of the D-to-A converter occurs at the same

digital level of +/- 32767. If a converter is used which does not meet these assumptions then the digital gain elements shown in

Figure 36 Vocoder Front End should be adjusted appropriately. Note that these ass

umptions are automatically satisfied if 16

bit linear A-to-D and D-to-A converters are used, in which case the digital gain elements should be set to unity gain.

An additional recommendation addresses the maximum noise level measured at the output reference points shown in Figure 36

Voc

oder Front End with the corresponding inputs set to ze

ro. DVSI recommends that the noise level for both directions should

not exceed -60 dBm0 with no corresponding input. In addition, the isolation from cross talk (or echo) from the output to the

input should exceed 45 dB which can be achieved via either passive (electrical and/or acoustic design) or active (echo

cancellation and/or suppression) means.

5.11 Interfacing a codec to the AMBE-3000F™ Vocoder chip

5.11.1 The Texas Instruments General purpose TLV320AIC14

The Texas Instruments’ TLV320AIC14 codec presents a simple low cost solution for use with DVSI’s AMBE-3000F™

vocoder chip. This example provides information on interfacing theTLV320AIC14 to the AMBE-3000F™ Vocoder chip SPI

interface.

(Subject to Change) Page 55

DVSI CONFIDENTIAL PROPRIETARY

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Digital Voice Systems AMBE-3000 Spezifikationen Seite 65