DVSI Rate Converter Software

Rate Converter Software

Introduction

To facilitate the delivery of innovative products that support AMBE® vocoder communication systems DVSI developed the parametric rate converter, vocoder repeater and frame analyzer software. The parametric rate converter software promotes seamless interoperability between AMBE® vocoder communication networks such as, wireless radio or satellite links, wire connected phone lines, and Ethernet networks including the Internet. With the vocoder repeater function the effective transmission range can be extended to avoid gaps in coverage area as well as remove unwanted errors in data stream. Its frame analyzer function helps propagate efficient data transmission.

Efficiently and effectively expanding digital mobile radio communication networks depends greatly on the voice compression vocoder capabilities and how it handles wireless transmission conditions and background environmental noise. DVSI is continuously advancing voice compression technology and its ability to provide high quality intelligible voice in a variety of conditions and background noise environments. With DVSI’s parametric rate converter / repeater technology there is no need to employ encoding/decoding tandeming that could result in severe degradation in performance, increased processing delays and losses in voice quality and intelligibility.

Mission critical wireless communication is not segregated solely to law enforcement and emergency first responders. Any industry that relies on digital wireless communication, from energy/utilities, to large university campuses or transportation systems, or manufacturing facilities and even amateur radio demand high quality voice and intelligibility. It is considered mission critical to them. These communication systems employ different standards such as DMR, DpMR, Globastar, Terrastar, Full Rate and Half Rate P25, NXDN at various data rates. However, the one thing they have in common is they all implement the AMBE® Vocoder technology. When there is a need to expand or communicate between any of these systems, the best way to avoid the detrimental effect of encoder/decoder tandeming is to employ a parametric rate converter/repeater.

DVSI's rate converter software has the flexibility to convert or repeat to/from at virtually any data rate between 2000 bps and 9600 bps. The versatility of speech and/or FEC rates permits optimization within custom system requirements while delivering and maintaining excellent voice quality along with superior robustness to bit errors without adding significant delays.

Software Operation

The parametric rate converter software processes the incoming data bit stream without converting it to speech as part of the conversion process (i.e., it does not use tandeming). Instead, the MBE model parameters are used as the intermediate stage between bit rates. The synthesis and the analysis of speech is not performed. This approach avoids multiple stages of tandeming where in most situations leads to the loss of voice quality, intelligibility, and delay.

Similar to the parametric rate converter software the “Repeater capability” in the software does not convert the incoming data bit stream to speech as part of the process. The input data bit stream can be FEC Decoded to fix bit errors and then FEC encoded before re-transmitting the repaired frame. Without the need to process MBE model parameters and voice-decode or voice-encode there is no tandeming and no algorithmic delay that can degrade voice quality and hamper network performance. Additionally, the repeater function can be set to ‘FEC decode only’ to give access to transmitted data or ‘FEC Encode only’ for the injection of data into network data stream.

Key benefits of the Rate Converter Software are:

• Convert between any two AMBE® Vocoder rates (including custom rates).
• Eliminates Encoder / Decoder Tandeming issues (No need to voice synthesis to PCM and re-encode).
• Minimizes delays.