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MELPe - enhanced Mixed-Excitation Linear Predictive

Vocoders by Adaptive Digital

ADT MELPe SPEECH CODER New! C55x

DESCRIPTION

Adaptive Digital's enhanced-MELP (MELPe) the new Federal Standard, is a low bit rate vocoder supporting 2400, 1200 and 600 bps. It can operate at half the rate of the MELP standard.

Enhancements include: Improved encoding/decoding, transcoding between 2400, 1200 and 600 bps bit streams, and noise preprocessing for removing background noise.

MELPe provides better quality than all older military standards, especially in noisy environments such as battlefield, vehicles and aircraft. MELPe is suitable for use by OEM customers for VoIP, telecom, military, secure voice & radio, and other low bit-rate compressed speech applications.

MELPe vocoder is also known as military standard MIL-STD-3005 and NATO STANAG 4591

Coding Rate: 2400, 1200, and 600 bpsMELPe

Sampling Rate: 8 kHz

FEATURES

  1. Functions are C-callable
  2. Multiple channel capable
  3. Optional noise preprocessing
  4. Transcodes between rates
  5. C64x xDM Compliant: ensures easy codec implementation and integration for DaVinci™ Technology

FRAME SIZE

The Melpe coder frame size is dependent on the Encode/Decode rate

Rate Frame Size (Samples) Frame Size (msec.)
600 bps 720 90 .0
1200 bps 540 67.5
2400 bps 180 22.5

 

AVAILIBILITY

ADT MELPe is available on the TMS320C6000™ DSP Family

C55x™ DSP Generation

MIPS (Peak) CPU Resource Requirements
Software 600 bps 1200 bps 2400 bps
Encode Decode Encode Decode Encode Decode
MelpE 28 18 36 14 26 18
Noise Preprocessor (NPP) 21 18 21
Total 67 68 65

 

Rate 2400 and Rate 1200 only
All memory usage is given in bytes.

C55x Memory Resource Requirements Rate 2400 and Rate 1200 only
Software Program Memory Channel Scratch Tables Data
Encoder 65k 6560 6984 84k 1k
Decoder 1600
NPP 11968

Rate 2400, Rate 1200 and Rate 600

C55x Memory Resource Requirements Rate 2400, Rate 1200 and Rate 600
Software Program Memory Channel Scratch Tables Data
Encoder 77k 6560 6984 162k 1k
Decoder 1600
NPP 11968

 

Update October 18, 2009


FUNCTIONS

MELPE_ADT_initEncode (…) Initializes the MELPe encoder
MELPE_ADT_initDecode (…) Initializes the MELPe decoder
MELPE_ADT_encode (…) Executes the MELPe encoder
MELPE_ADT_decode (…) Executes the MELPe decoder
NPP_ADT_init (…) Initializes the Melpe noise pre-processor
NPP_ADT_process (…) Executes the Melpe noise pre-processor

APPLICATIONS

Military communications requiring a lower bit rate, used in narrow band channels.

 



 

PRODUCTS