2 April 2020

Difference between DM and ADM

What is DM?

Delta modulation is a scheme to permit the use of a simple quantizing strategy for constructing the encoded signals which are oversampled purposely, to increase the correlation between adjacent samples of the signal, as seen in the differential pulse code modulation method(DPCM).


What is ADM?

This modulation is a refined form of delta modulation. This method was introduced to solve the granular noise and slope overload error caused during the delta modulation method. This modulation is exactly similar to delta modulation except that the step size is variable according to the input signal in adaptive delta modulation whereas it is a fixed value in delta modulation.


Here this article gives the difference between delta modulation and adaptive delta modulation to better understand this topic.


Difference between DM and ADM:


  • DM stands for delta modulation while in ADM stands for adaptive delta modulations.
  • Both are used for only one bit per one sample, 
  • In Delta, the modulation step size is kept fixed and cannot be varied while in Adaptive delta modulation according to signal variations step sizes varies.
  • Complexity in implementation is simple in both systems.
  • Feedback exists in the transmitter while using delta modulation, while ADM feedback exists.
  • Both having the lowest bandwidth is required.
  • In Delta modulation quantization error and distortion is dependent on when Slop overload distortion and granular noise are present while in adaptive delta modulation Qulanatization noise is present but other errors are absent. 
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