Explain Pulse Code Modulation
Pulse Code Modulation (PCM) is a digital representation technique used for converting analog signals into digital signals. PCM converts the continuous-time analog signal into a discrete-time signal, represented by binary numbers, which can be easily processed by digital systems.
In PCM, the analog signal is sampled at a regular interval to obtain a sequence of numbers that represents the amplitude of the signal at each sampled point. Then, the amplitude values are quantized into a finite number of levels (usually represented by binary numbers). The quantization error between the actual amplitude value and the quantized value is then rounded off to the nearest level.
The resulting digital signal is a sequence of binary numbers, each representing the amplitude of the signal at a particular point in time. These binary numbers are transmitted or stored for playback and can be converted back into an analog signal by using a digital-to-analog (DAC) converter.
PCM is widely used in telecommunications, audio recording and playback, and other digital signal processing applications. One of the main advantages of PCM is that it provides high-quality and reliable signal transmission with minimal distortion.
Pulse Code Modulation (PCM) is a method used to digitally represent an analog signal. It is a widely used technique in telecommunications and digital audio applications. PCM works by sampling an analog signal at regular intervals, and then converting each sample into a binary code.
Here is a step-by-step breakdown of how PCM works:
1. Sampling: The first step in PCM is to sample the analog signal. This involves measuring the amplitude of the analog signal at regular intervals. The sampling rate determines how frequently these samples are taken.
2. Quantization: After sampling, the analog signal must be quantized. This step involves converting the continuous range of amplitudes obtained from sampling into a discrete number of levels. The number of levels is determined by the bit resolution of the PCM system. For example, an 8-bit PCM system will have 256 possible levels.
3. Encoding: Once the amplitudes have been quantized, they are then encoded into binary code words. Each level is assigned a unique binary code.
4. Transmission: The encoded binary code words are transmitted as a digital signal. The digital signal can be easily transmitted over various digital communication systems, such as fiber optic cables or wireless networks.
5. Decoding: At the receiving end, the digital signal is decoded back into analog form. The binary code words are converted back into their corresponding amplitude levels.
6. Reconstruction: Finally, the reconstructed analog signal is obtained by using a low-pass filter to smooth out the discrete level transitions. This removes any high-frequency components introduced during quantization, resulting in a close approximation of the original analog signal.
Overall, PCM allows for the accurate representation of analog signals in a digital format. It provides a method to store, transmit, and reproduce analog signals reliably, making it an essential technique in modern telecommunications and digital audio systems.