What is the advantage of using Pulse Code Modulation over Delta Modulation?

Question

Is DM less acceptable for encoding analog signals that represent binary because DM merely approximates the signal? Would there be bit errors?

Thanks for your help! Low-tech answers only please :D

Answer 1

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Answer 2

Delta modulation is a form of signal compression that tries to reduce the amount of bits that needed to be transmitted by not transmitting the whole value of the signal at every moment, but only the difference between the current value and the previous value. The receiver keeps adding the (possibly negative) incoming values to an accumulator, so the original signal can be recovered.

For signals that change slowly, this is a very good idea: the difference can be expressed with a lower number of bits.

There are two disadvantages of DM: if the signal changes abruptly, the difference could exceed the allocated number of bits, and if a transmission error occurs, the accumulator stores a wrong value and the error is propagated to all following samples.

Methods exist to mitigate both types of error: adaptive DM dynamically changes the number of bits allocated to the delta, and the "true" value of the signal can be periodically transmit to realign the accumulator and reduce the impact of error propagation.