VC-55™-PR Dual Rate
Single Channel Vocoder Board
*New*       *New*


Digital Voice Systems, Inc. (DVSI), the leader in low-bit-rate high-quality voice compression technology, introduces a new vocoder board. The VC-55™-PR Voice Codec Board is a full-duplex real-time voice processing board incorporating DVSI's latest advancements in voice compression technology. The VC-55™-PR is ideally suited for a variety of applications including: digital mobile radio communication systems, wireless telephony, voice monitoring / recording / storage systems and also, testing and evaluation of DVSI vocoder performance. The compact board design is engineered for seamless integration into new or existing OEM systems.

The VC-55™-PR hardware incorporates DVSI's patented voice compression vocoder software geared toward the next generation of APCO Project 25 (P25) digital mobile radio communication systems. Providing the best in voice compression performance, the VC-55™-PR integrates an enhanced dual rate (7200/3600 bps) APCO P25 implementation. The VC-55™-PR includes a number of additional features, such as: Noise Suppresion, Silence Frame Generation and support for DTMF tones.

The enhanced full-rate 4400 bps vocoder with 2800 bps of integrated Forward Error Correction (FEC) significantly improves voice performance and provides a number of other vocoder advancements while remaining fully interoperable with the existing APCO Project 25 vocoder standard (TIA-102BABA). The enhanced half-rate APCO P25 vocoder operates at 2450 bps with 1150 bps of FEC to maximize system resources and improve channel efficiency by doubling the number of public safety communication channels. This low-bit-rate vocoder is fully interoperable with the new half-rate vocoder proposed by DVSI for APCO Project 25 Phase II.

The standard VC-55™-PR is designed as a stand-alone voice processing board. The stand alone board is equipped with a separate connectors for audio I/O, handset, power and a RS-232 serial interface capable of one channel of compressed voice data.

The VC-55™-PR is equipped with a high performance audio codec allowing for analog audio input from the stereo jack and handset connections. The digitized speech is encoded, converted into a data bit stream and then output to the RS-232 serial interface. At the same time, the board can receive compressed data, decode and convert it into an analog signal for output to the stereo jack and handset connectors. The encoder and decoder are fully asynchronous.

A real-time, full-duplex communication link between two VC-55™-PR boards can be established by connecting a cable to each board's RJ-45 connector. The VC-55™-PR implements an asynchronous RS-232 serial interface as the compressed voice data channel using a protocol designed by DVSI. Once a link is established, voice communication between the two boards can be performed using either the handset or stereo jack input.

The VC-55™-PR Voice Codec Board is easy to set up and run. Each board is shipped with the software loaded and ready to go. When power is applied to the board, the VC-55™-PR boots from the on board flash and is ready in seconds. The board is equipped with LED indicators for quick determination of the board's operational status.

The VC-55™-PR is an economical hardware solution for customers who want to gain access to APCO Project 25 (P25) land mobile radio vocoder technology. By integrating the enhanced vocoder software into a hardware platform DVSI can offer a package without the licensing fees or royalties associated with software only solutions. With off-the-shelf availability, the VC-55™-PR provides a cost-effective voice compression vehicle that reduces the time and up front engineering expenses associated with new product development.


VC-55™-PR Vocoder Board Technical Specifications:

Name Type Description
Analog In 3.5mm Stereo Jack Audio from Mic In
Analog Out 3.5mm Stereo Jack Audio out to Spkrs / amp
Handset RJ-11 Full Duplex Communication
USB USB Type2 Configuration of board parameters
RS-232 RJ-45 Channel Data
  Input Voltage 5V or 3V DC
Input Current 250 ma
Physical Size:
3.1875 X 2.1875 inches


Optional Accessories Kit 

As a convenience, DVSI offers an optional accessories kit. This kit is equipped with the basic items that simplify getting started with the VC-55™ -PR Vocoder Board. The accessories kit includes the following:
Item Description
Power Adapter AC to 5 Volt DC
Handset with cord  Connects to RJ11 Connector
      Download VC-55™-PR Manual