Pulse Modulation. Pulse modulation is a type of modulation in which the signal is transmitted in the form of pulses. It can be used to transmit analogue information. In pulse modulation, continuous signals are sampled at regular intervals. Pulse modulation can be classified into two major types.
Pulse Code Modulation Advantages
Analog signal can be transmitted over a high- speed digital communication system. Probability of occurring error will reduce by the use of appropriate coding methods. PCM is used in Telkom system, digital audio recording, digitized video special effects, digital video, voice mail.Pulse modulation methods are used to transfer a narrowband analog signal, such as a phone call, over a pulse stream. Some schemes use a digital signal for transmission, making them essentially an analog-to-digital conversion. Pulse-amplitude modulation (PAM).
PWM signals are used for a wide variety of control applications. Their main use is for controlling DC motors but it can also be used to control valves, pumps, hydraulics, and other mechanical parts.
Definition of pulse time modulation
: modulation of the time intervals between successive pulses of constant duration and amplitude in accordance with a signal specifically : a system of multiplex high-frequency transmission using this method of modulation.Modulation allows us to send a signal over a bandpass frequency range. If every signal gets its own frequency range, then we can transmit multiple signals simultaneously over a single channel, all using different frequency ranges. Another reason to modulate a signal is to allow the use of a smaller antenna.
Advantages of Pulse Amplitude Modulation (PAM):
No complex circuitry is required for both transmission and reception. Transmitter and receiver circuitry is simple and easy to construct. PAM can generate other pulse modulation signals and can carry the message or information at same time.Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. Though PCM is a more general term, it is often used to describe data encoded as LPCM.
Quantization is the process of converting a continuous range of values into a finite range of discreet values. This is a function of analog-to-digital converters, which create a series of digital values to represent the original analog signal.
Of them all, the digital modulation technique used is Pulse Code Modulation PCM. A signal is pulse code modulated to convert its analog information into a binary sequence, i.e., 1s and 0s. Instead of a pulse train, PCM produces a series of numbers or digits, and hence this process is called as digital.
Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications.
Pulse-code modulation, abbreviated "PCM," is a form of digital signal that is used to represent analog data. Depending on the model of television you watch, switching the audio output to PCM may improve the sound quality of the television's speakers.
A signal is pulse code modulated to convert its analog information into a binary sequence, i.e., 1s and 0s. The output of a PCM will resemble a binary sequence. The following figure shows an example of PCM output with respect to instantaneous values of a given sine wave.
Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. In a PCM stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps.
A signal is pulse code modulated to convert its analog information into a binary sequence, i.e., 1s and 0s. The output of a PCM will resemble a binary sequence. Instead of a pulse train, PCM produces a series of numbers or digits, and hence this process is called as digital.
PCM audio, whether it is input or output, consists of samples. A single sample represents the amplitude of one channel of sound at a certain point in time. A frame consists of exactly one sample per channel. If there is only one channel (Mono sound) a frame is simply a single sample.
The advantages of PCM transmission speak for themselves:
constant signal/noise ratio by digitization of the signal. multiple use of one transmission-channel by multiplexing. interference free signal transmission, low susceptibility to crosstalk. direct acquisition and processing of the received digital PCM signal to aThe quality of a Quantizer output depends upon the number of quantization levels used. The discrete amplitudes of the quantized output are called as representation levels or reconstruction levels. The spacing between the two adjacent representation levels is called a quantum or step-size.
BPCM = R = n* Bandwidth of PCM signal depends on the bit rate and the pulse shape. For no aliasing i.e. the Nyquist rate : fs= 2B, where B is the bandwidth of the analog signal that is to be converted.
