Difference between Pulse Code Modulation (PCM) and Delta Modulation (DM)

PCM stands for Pulse Code Modulation and DM stands for Delta Modulation. PCM is basically used for reworking analog to digital signals and DM is a conversion technique between analog and digital signals. In this article, we will discuss these two topics and also see the differences between these PCM and DM.

What is Pulse Code Modulation (PCM)?

Pulse Code Modulation is the technique used for reworking analog signals into digital signals. PCM has a good or sensible signal-to-noise ratio. For transmission, Pulse Code Modulation wants high transmitter bandwidth. PCM technique is split into three elements, initial is the transmission at the provision end, second regeneration at the transmission path and conjointly the receiving end. 

Advantages of Pulse Code Modulation (PCM)

• High Noise Immunity: PCM signals are also less likely to be distorted by noises or interferences as compared to analog signals which is why PCM is normally used in long distance transmissions.
• Efficient Digital Signal Processing: PCM has been found to be compatible with many current digital systems for processing, storing and transmission hence can interface easily with these systems.
• Data Compression: Nevertheless, there are some compression techniques that can be applied for PCM signals so as to decrease the data width that shall be transmitted without significant loss in quality.
• Error Detection and Correction: As PCM is a digital signal, therefore the technique of error detection and correction can be implemented which makes the data transmission is more reliable.
• High Quality: PCM supplies significantly superior quality sound and video signal transmission and exhibits a wide range of applications in CDs, telephone line communication, digital audio systems, etc.

Disadvantages of Pulse Code Modulation (PCM)

• High Bandwidth Requirement: PCM uses a wide bandwidth in its transmission since the signal is usually sampled in this format so as to provide high quality.
• Complexity: PCM systems are relatively more complicated than analog modulation schemes since encodings and decoding of the various signals employed in the system under development are elaborate.
• Quantization Error: Another factor which PCM brings in is the existence of quantization error through the rounding of the signal values when converting from analog to digital.
• High Power Consumption: Because of the high processing demands, users have typically reported that PCM systems are power-hungrier and hence not very suitable for low power conditions.

What is Delta Modulation(DM)?

Delta modulation is an analog to digital and digital to analog signal conversion technique. Delta modulation is employed to realize high signal to noise ratio. It uses one bit PCM code to realize digital transmission of analog signal. With delta modulation, instead of transmit a coded illustration of a sample solely one bit is transmitted, that merely indicates whether or not the sample is larger or smaller than the previous sample. it's the best type or simplest type of Differential Pulse Code Modulation. Delta modulation signal is smaller than Pulse Code Modulation system. If signal is large, the next bit in digital data is 1 otherwise 0. 

Advantages of Delta Modulation

• Simplicity: Compared to PCM; delta modulation is easier to design and implement, therefore its implementation is easier and cheaper.
• Lower Bandwidth: DM uses fewer band width than PCM because it only sends information of the difference between two samples.
• Efficient for Slowly Varying Signals: Delta Modulation employs a high level of resolution for signals that may change slowly with time hence applicable to some selected low bandwidth signals.
• Reduced Hardware Complexity: DM poses modest demands for the encoding and decoding circuits thus making it less costly and less power efficient.

Disadvantages of Delta Modulation

• Slope Overload Distortion: The main drawback of the DM is the slope overload where the input signal rapidly varies and creates large tracking errors due to a small step size.
• Granular Noise: If the step size is larger, then granular noise occurs and this again degrades the signal quality specially the slow changing regions.
• Lower Quality: A number of times, DM has been found to offer a lower signal quality in comparison to PCM where fidelity audio or video transmission is being envisaged.
• Limited Applications: As the above analyses discussed, the DM has a lower signal accuracy than RM, thereby less often adopted for high-quality material transmissions, thereby restricting its applications.

Difference Between Pulse Code Modulation (PCM) and Delta Modulation (DM)

Conclusion

PCM and DM are used to convert the analogue signals in to the digital from yet they differ a lot in some of the areas such as complexity, signal quality and band width. PCM provides richer signal representation and is used in those applications, which demand fine differential, for example, digital audio and telephony. While on the other hand, DM is comparatively easier and lessens bandwidth usage but has higher odds of errors and is not effective for high quality signals. DM and PCM both have different applications in a system to transmit data; the choice between the two depends with the needs of the system in terms of signal quality and required bandwidth of the communication channel.