Specifications

Net-2000™ VCU Users Manual
Version 4.0, December, 2013
VO
IP Mode
APC
O Standard Vocoder Mode
The Full-Rate mode is compatible with the current APCO P25 standard. The P25 standard vocoder has a total data
bit rate of 7200 bps. Of these bits 4400 bps is voice data and 2800 bps is Forward Error Correction (FEC). The
vocoder can be selected with or without FEC.
Figure 14 APCO Standard Vocoder Selection
The APCO Enhanced Vocoder is DVSI’s new vocoder technology. The APCO Enhanced vocoder in the Net-
2000™- P25 VCU offers the flexibility of data rate, FEC and Bit stealing selection. of 3600 bps. This new vocoder
is designed to be particularly robust and perform exceptionally well even under the presence of bit errors and
acoustic background noise conditions.
Figure 15 APCO Enhanced Vocoder Selection
4.3.1 APCO Enhanced Vocoder Bit Stealing
The APCO Enhanced vocoder offer the ability to steal up to six bits from the vocoder. This mode can be used to
transmit user data in-band.
4.3.2 APCO Enhanced Vocoder Additional Features
As part of Half-Rate vocoder mode the Net-2000™ VCU offers the ability to decode up to 8 bits of Soft Decision
Forward Error Correction. This feature is ideal for testing and evaluating degraded channel conditions and/or
significant bit errors.
In addition to the enhanced FEC capability the Net-2000™ VCU Half-Rate vocoder provides voice activity
detection and DTMF Knox Tone detection and regeneration. See Section 4 Protocol for more information.
(Subject to Change) Page 18
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