PCM has much better noise immunity as compared to PAM, PWM and PPM systems.



Explanation:


- Pulse Code Modulation (PCM) is a digital modulation technique that represents analog signals by sampling and quantizing them into discrete values. It is widely used in various communication systems for transmitting voice, video, and data signals.


- PCM has better noise immunity compared to other modulation techniques such as Pulse Amplitude Modulation (PAM), Pulse Width Modulation (PWM), and Pulse Position Modulation (PPM). This is because of the following reasons:


1. Quantization: PCM quantizes the analog signal into discrete levels. This quantization reduces the effects of noise since the receiver can easily distinguish between the different levels, even in the presence of noise. In PAM, PWM, and PPM systems, noise can cause errors in the demodulation process as the receiver needs to accurately measure the amplitude, width, or position of the pulses.


2. Digital Representation: PCM represents the analog signal in a digital format, where each sample is represented by a binary code. The digital representation allows for error detection and correction techniques to be applied, improving the overall noise immunity. In contrast, PAM, PWM, and PPM systems do not have inherent error detection and correction mechanisms.


3. Noise Shaping: PCM can also employ noise shaping techniques, such as delta modulation or adaptive delta modulation, to further improve noise immunity. These techniques reduce the effects of quantization noise by shaping the noise spectrum to frequencies where it is less perceptible. PAM, PWM, and PPM systems do not have built-in noise shaping mechanisms.


PCM does not contain any information in the width or the position of the pulses.



Explanation:


- The reason stated is correct. In PCM, the information is not contained in the width or position of the pulses, but rather in the amplitude or level of the sample. The width and position of the pulses are irrelevant in PCM since the analog signal is sampled and quantized into discrete levels.


- The key information in PCM is the amplitude or level of each sample, which is represented by a binary code. This binary code carries the information of the analog signal and is used for transmission and reception.


- In contrast, PAM, PWM, and PPM systems encode information in the width or position of the pulses. The receiver needs to accurately measure the width or position of the pulses to decode the information, which can be susceptible to noise and errors.


- By not relying on the width or position of the pulses, PCM avoids the problems associated with noise-induced errors in PAM, PWM, and PPM systems. This further contributes to the better noise immunity of PCM.


Therefore, both Assertion (A) and Reason (R) are true, and Reason (R) provides the correct explanation of Assertion (A).