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- Overview: EV6180/EV6380
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- Robust Advanced Low Complexity Waveform Interpolation (RALCWI)
- CMX608: Half-duplex RALCWI Vocoder
- CMX618: Half-duplex RALCWI Vocoder with Integrated Voice Codec
- CMX638: Full-duplex RALCWI Vocoder with Integrated Voice Codec
- Near Toll Quality RALCWI Coding Algorithm
- Multiple Bit-Rate Modes:
- 2050, 2400 or 2750 bps
- 3600 bps with FEC Enabled
- 4-bit Viterbi Soft Decision Decoding
- Integrated Voice Codec (CMX618 and CMX638 only)
- Integrated Input and Output Channel Filters
- 20ms, 40ms, 60ms and 80ms Packet Lengths
- No Licensing or Royalty Payments
- Ancillary Audio Functions:
- Voice Activity Detector
- Comfort Noise Generator
- DTMF and Single Tone Regeneration
- 1.8V Low-power Operation, 3.3V Tolerant I/O
- Small 48-pin LQFP and VQFN Packages
- Digital PMR, LMR, Voice Radio
- Digital Trunking
- DMR TDMA
- DMR FDMA, dPMR
- Digital-voice Scrambling and Encryption
- Digital WLL
- Voice-storage and Playback Systems
(Answering Machines, Annunciators) - Messaging Systems
- VoIP Systems
- Voice Pagers
- Regenerative Digital Voice Repeaters
Package Styles:
- CMX608Q3 - 48-pin VQFN
- CMX618L4 - 48-pin LQFP
- CMX618Q3 - 48-pin VQFN
- CMX638L4 - 48-pin LQFP
- CMX638Q3 - 48-pin VQFN
Supply Requirement:
The CMX608/CMX618/CMX638 are flexible, high integration, high performance, RALCWI (Robust Advanced Low Complexity Waveform Interpolation) Vocoders, offering near toll quality voice at very low bit rates.
A Forward Error Correction (FEC) engine provides optimum performance in real life applications.
The RALCWI Vocoder comprises four independent functions which are selectable by the host: Voice Encoder, FEC Encoder, Voice Decoder and FEC Decoder. The CMX608 and CMX618 are half-duplex Vocoders and the CMX638 is a full-duplex Vocoder with integrated voice CODEC.
The CMX618 includes an integrated voice CODEC, offering a complete analogue voice to low bit rate vocoded data function, with integrated channel filters removing the need for external components, whereas the CMX608 requires an external voice CODEC.
The CMX608, CMX618 and CMX638 all operate from a dual power supply (1.8V and 3.3V) and are available in both 48-pin LQFP (L4) and 48-pin VQFN (Q3) packages.
In encode mode, the voice encoder uses a 20ms voice frame size with 3 programmable bit rates:
2050bps, 2400bps or 2750bps. The optional FEC encoder performs channel coding of the encoded voice
(2050bps, 2400bps or 2750bps, depending on the selected mode) and forms an encoded, interleaved
bit-stream of 3600bps (216 bits per 60ms packet or 288 bits per 80ms packet).
The FEC operation utilises a packet of either 3 or 4 x 20ms Vocoder frames to provide optimum error
correction performance.
In decode mode, the optional FEC decoder performs de-interleaving and channel decoding of the
coded bit-stream (216 bits per 60ms packet or 288 bits per 80ms packet) and forms an error-corrected
bit-stream of encoded voice at 2050bps, 2400bps or 2750bps rate, depending on the selected mode.
The FEC decoder can optionally use "soft decision" metrics to improve its decoding ability.
The voice decoder then converts the error-corrected bit-stream back into a digitised voice signal.
Soft Decision Decoding (SDD), Discontinuous Transmission detection (DTX), Voice Activity Detection
(VAD) and Comfort Noise Generation (CNG) functions are also included, to further enhance the overall
performance. Single (STD) and Dual (DTMF) Tones can be detected and sent separately in the coded
bit-stream, then regenerated at the far end.
