What IS Delta Modulation?
A Delta Modulation (DM) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance. In DM each segment of the approximated signal is compared to the preceding bit and successive bits are determined by this comparison.
Features of Delta Modulation include:
- The quantization design is simple.
- The analog signal is approximated with a series of segments.
- It require simpler implementation
- The design of the modulator and demodulator is simple
- The bit rate can be decided by the user.
What Is Differential Pulse Code Modulation (DPCM)?
Differential pulse code modulation (DPCM) is a technique of analog to digital signal conversion. This technique samples the analog signal and then quantizes the difference between the sampled value and its predicted value, then encodes the signal to form a digital value.
Features of DPCM Include:
- As a signal encoder, it uses the baseline of pulse-code modulation (PCM) but adds some functionalities based on the prediction of the samples of the signal.
- The input can be an analog or a digital signal.
- The numbers of levels are fixed.
- Requires relatively less bandwidth
|BASIS OF COMPARISON||DELTA MODULATION (DM)||Differential Pulse Code Modulation (DPCM)|
|Application||DM is generally used in speeches and images.||DPCM is mostly used in videos and speeches.|
|Feedback||In DM, feedback only exists in transmitter.||In DPCM, Feedback exists in both transmitter and receiver.|
|Signal To Noise Ratio||DM has poor signal to noise ratio.||DPCM has fair signal to noise ratio.|
|Distortion And Quantization Error||Slop over-load distortion and granular noise exist in DM.||Slop over-load distortion and quantization noise exist in DPCM.|
|Number Of Bits||In DM, only one bit is used per sample.||In DPCM, more than one but less than PCM (Pulse Code Modulation) bits are used.|
|Efficiency||DM is less efficient than DPCM.||DPCM is more efficient than DM.|
|Levels/Step Size||In DM, step size is fixed.||In DPCM the numbers of levels are fixed.|
|Transmission Bandwidth||DM requires lowest bandwidth.||DPCM requires less bandwidth than PCM.|