Analog Signal Compression & Decompression by using ADSP Processor

Shrenik Suresh Sarade


The analog speech signal is digitized by sampling. For maintaining the voice quality, each sample has to be represented by 13 or 16 bits. The compression is nothing but to reduce the original data bits from higher bits to lower bits with good quality of signal as compared to original signal and decompression is reconstructed original signal from the compressed signal.
Adaptive differential pulse code modulation is very useful & efficient for compression & decompression designed by Bell labs in 1970 for the reduction of bits of Analog signal. The ADPCM uses the difference techniques of next samples of original signal & predicted signal of last sample.
The analog speech signals are amplified by the pre-amplifier and fed to the CODEC for analog to digital conversion. The CODEC transmits the digitized signal to the ADSP 2105/2115 processor, which then compresses the speech data using the ADPCM techniques and store in RAM. When the processor is interrupted, it reads the compressed data from RAM expands the data and send the data to CODEC. CODEC are used for the conversion of digital signal data to analog signal data which amplified by amplifier and output applied for the speaker. The ADPCM algorithms are going to use in ADSP processor, the compressed signal is stored in RAM, that signal is applied to the speaker & going to check the quality of signal with original signal. That stored compressed signal is then applied to the decompression techniques of ADPCM in ADSP processor.
The ADSP-2100 processor is a digital signal processing (DSP) with high speed processing applications built in single chip. That contains the computation units, address data generators & on chip program & data memory, serials ports that operate on 25 Mhz with 40ns instruction cycle time.
This project played very important role because this project is going to use in different application, like data transfer from one place to another place by using wire in computer application. In communication field this compression techniques is very useful to stores the data with less memory.

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