What does DM stands for?
What does DM stands for? Correct Answer Delta modulation
Explanation:
Delta Modulation (DM):
It is used to reduce the bandwidth or bit rate.
- It is considered as a 1 bit DPCM. So, the encoder is a 1 bit ADC, i.e. only 1 sample is used in DM.
- The encoder output is either 1 or 0
- Two quantization levels are used + Δ and - Δ
DM uses past information for modulation.
The block diagram is shown below:
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|
Parameter |
PCM |
Delta Modulation (DM) |
DPCM |
|
Number of bits |
It can use 4, 8, or 16 bits per sample |
It uses only one bit for one sample |
Bits can be more than one but are less than PCM |
|
Level/Step size |
Step size is fixed |
Step size is fixed and cannot be varied |
A fixed number of levels are used. |
|
Quantization error or Distortion |
Quantization error depends on the number of levels used |
Slope overload distortion and granular noise is present |
Slope overload distortion and quantization noise is present |
|
The bandwidth of the transmission channel |
The highest bandwidth is required since the number of bits is high |
The lowest bandwidth is required |
The bandwidth required is lower than PCM |
|
Signal to Noise ratio |
Good |
Poor |
Fair |
|
Area of Application |
Audio and Video Telephony |
Speech and images |
Speech and video |
