Advantages of Delta Modulation | disadvantages of Delta Modulation
This page covers advantages and disadvantages of Delta Modulation. It mentions Delta Modulation advantages or benefits and Delta Modulation disadvantages or drawbacks.
What is Delta Modulation?
It is also known as Delta Pulse Code Modulation or DPCM. Unlike PCM, here actually difference between m(t) and m^(t) is transmitted. Hence it is known as delta modulation. In delta modulation, a multi-bit difference value is stored or transmitted as per requirements.
As shown in the block diagram, we do not transmit D(t) but transmit only its polarity as determined at each sampling rate. Here P0(t) is obtained by multiplying input pulse train Pi(t) by +1 or by -1 depending on polarity only and not magnitude of D(t). Refer Delta modulation vs PCM vs ADPCM >> for more information.
In Delta modulation we have applied D(t) in place of m(t) as used in PCM. This kind of system is feasible to implement.
Benefits or advantages of Delta Modulation
Following are the benefits or advantages of Delta Modulation:
➨In Delta modulation electronic circuit requirement for modulation at transmitter and for demodulation at receiver is substantially simpler compare to PCM.
➨In delta modulation, amplitude of speech signal does not exceed maximum sinusoidal amplitude.
➨PCM has sampling rate higher than nyquist rate. The encode signal contains redundant information. DPCM can efficiently remove this redundancy.
➨DPCM needs less number of quantization levels and hence less number of bits are needed to represent them.
➨Signaling rate and bandwidth of DPCM or delta modulation is less than PCM technique.
Drawbacks or disadvantages of Delta Modulation
Following are the drawbacks or disadvantages of Delta Modulation:
➨If changes in signal is less than the step size, then modulator no longer follow signal. Thus produces train of alternating positive and negative pulses.
➨Modulator overloads when slope of signal is too high.
➨High bit rate.
➨It requires predictor circuit and hence it is very complex.
➨Its practical usage is limited.
PCM vs DPCM vs ADPCM
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