Digital Voice Systems Net-2000-P25, Руководство пользователя

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Net-2000™ Voice Codec Unit
User’s Manual
Page 1
DVSI Confidential Proprietary
Section 1 – Net-2000™ VCU Introduction
Net-2000
TM
VCU Introduction
General Information
The Net-2000™-P25 voice codec unit (VCU) incorporates Digital Voice Systems, Inc. (DVSI) latest
advancement in voice compression technology to bridge analog speech I/O to an Ethernet network.
The Net-2000™-P25 VCU supports both the standard Full-Rate APCO P25 vocoder as well as
DVSI’s new Half-Rate voice compression vocoder proposed to APCO. This makes it an ideal
evaluation module for a variety of digital mobile radio communication systems.
DVSI’s new Half-Rate Vocoder operates at 2450 bps and includes integrated forward error
correction (FEC) to raise the total channel rate to only 3600 bps. DVSI designed the 3600 bps Half-
Rate Vocoder as an extension to the standard 7200 bps Full-Rate IMBE™ Vocoder that is currently
used throughout P25.
Features
•
Net-2000™ VCU incorporates both the current APCO standard Full-Rate vocoder and the
proposed Half-Rate voice compression vocoder
•
Real-time, full-duplex communications via the Ethernet interface to another Net-2000™-
P25 VCU unit.
•
A built-in web server for easy selection and control of the audio I/O
•
The Net-2000™- P25 VCU’s RS-232 serial port can be used as a console terminal to allow
low-level system setup.
•
The Net-2000™- P25 VCU can handle information from a DHCP server when available on a
Local Area Network (LAN).
•
The embedded user interface allows the operation software to be field upgradeable.
Interfaces
To meet a wide variety of communication system requirements the Net-2000™- P25 VCU contains
two interfaces for speech input and output and an Ethernet connection for the channel data
interface. The Net-2000™-P25 VCU analog interface includes a 4-wire and a handset for input and
output of uncompressed speech. The speech I/O is easily managed with the Net-2000™- P25
VCU’s built-in web server control.
For a channel connection, the Net-2000™ VCU provides a 10Base-T Ethernet interface for
connecting directly to a Local Area Network (LAN). This configuration can be used to create a real-
time full duplex Voice Over Internet Protocol (VOIP) Ethernet based vocoder communication system
between two Net-2000™ VCUs. Alternatively, the Net-2000™ VCU can Loopback the VOIP
information back to itself for voice monitoring and evaluation applications.
When two Net-2000™-P25 communicate, each converts the input analog speech into digital speech
samples, encodes the speech using the selected APCO Full-Rate or Half-Rate mode and then
sends the compressed bit stream out as UDP packets over the Ethernet interface. Simultaneously,
the compressed bit stream of UDP packets from the other Net-2000™-P25 are read in from the
Ethernet interface and decoded back in to digital speech samples. The decoded samples are
converted back into analog speech via the AIC-10 codec whose output is sent to both the handset
and line-level output connections.