Digital Voice Systems AMBE-3000 Especificações descarregar pdf (Página 64)

AMBE-3000F™ Vocoder Chip Users Manual

Version 3.4, April, 2014

O Management

Figure 36 Vocoder Front End

It is recommended that the analog input gain be set such that the RMS speech level under nominal input conditions is 25 dB

below the saturation point of the A-to-D converter (+3 dBm0). This level, which equates to -22 dBm0, is designed to provide

sufficient margin to prevent the peaks of the speech waveform from being clipped by the A-to-D converter.

Figure 37 Front End Input Filter Mask

The voice coder interface requires the A-to-D and D-to-A converters to operate at an 8 kHz sampling rate (i.e. a sampling

period of 125 microseconds) at the digital input/output reference points. This requirement necessitates the use of analog filters

at both the input and output to eliminate any frequency components above the Nyquist frequency (4 kHz). The recommended

input filter mask is shown in Figure 37 Front End Input Filter Mask, and the recommended output filter mask is shown in

Figure 38 Front End Output Filter Mask. For proper operation, the shaded zone o

f the respective figure should bound the

frequency response of the front-end input and output.

(Subject to Change) Page 54

DVSI CONFIDENTIAL PROPRIETARY

1 2 ... 59 60 61 62 63 64 65 66 67 68 69 ... 110 111

Sem comentários

Digital Voice Systems AMBE-3000 Especificações Página 64