Does anyone know how the PCM regulator works?

1) What is a PCM regulator?

2) Only know that PCM is pulse code modulation.

PCM is the English abbreviation of Pulse Code Modulation, namely.

The process of pulse sampling, digital quantization, and encoding of dialogue tones.

**The frequency band of the voice signal is limited to 300Hz-3400Hz, in order to analogue the voice message.

The first thing to do is to pulse sample (time quantization) of the analog signal, and determine it according to the sampling.

The frequency of the sampling pulse of the voice signal shall be at least twice the frequency of the speech signal, as specified in the standard.

for 8khz. The amplitude quantification of the sampled PAM pulses is then performed, and the amplitude of each pulse is performed.

Expressed in 8 bits, the PCM encoding rate of each ** signal is 8k 8 bits = 64kb s.

30 channels are connected frame by frame consisting of 1 frame synchronization signal and 1 signaling signal.

The rate of the digital bitstream - the PCM base group (primary group) is 64 kb s 32 = 2048 kb s.

3) A few words to remember in the fundamentals of PCM:

PCM is the abbreviation of pulse code modulation technology;

According to the sampling theorem, the sampling rate of each voice is 8kHz.

For each PAM signal, the A-law-thirteen polyline nonlinear code is adopted, 8 bits;

PCM base group frame supports 30 channels, and the encoding rate of each channel is 64kbits.

The PCM base group frame structure is 32 time slots, in which TS0 is the frame synchronization time slot, TS16 is the signaling time slot, TS1 TS15, and TS17 TS31 are the channel time slots.

The transmission rate of the PCM base group is .

3. PCM regulator RC: accept the automotive ECU PWM signal and drive the regulator. li:

Connect the car ECUFeedback the working status of the regulator and adjust the PWM input. 3. Lin or C:

An upgraded version of the PCM regulator. The PCM control was changed to a programmable load response control feature with a bidirectional communication interface.

Pulse code modulation is to convert an analog signal with continuous time and value into a digital signal with discrete time and discrete value and transmit it in the channel. Pulse code modulation is the process of sampling analog signals, and then quantifying the amplitude of the sample value.

Sampling, which is a periodic sweep of analog signals, turns a continuous signal in time into a discrete signal in time, and sampling must follow Nyquist's sampling theorem. The analog signal should also contain all the information in the original signal after being sampled, i.e. the original analog signal can be restored without distortion. The lower bound of its sampling rate is determined by the sampling theorem.

The sampling rate is 8kHz.

Quantization is to discretize the amplitude of the instantaneous value obtained by sampling, that is, to use a set of specified levels, and express the instantaneous sampling value with the nearest level value, usually expressed in binary.

Quantization error: The difference between the quantized signal and the sampled signal. The quantization error manifests as noise at the receiving end, which is called quantization noise.

The higher the number of quantization stages, the smaller the error, and the more corresponding binary code bits, the higher the transmission rate and the wider the frequency band. In order to keep the quantization noise as small as possible and the number of code bits required is not too large, the non-uniform quantization method is usually used for quantization. The quantification interval is determined according to the different intervals of the amplitude, and the quantification interval of the interval with small amplitude is small, and the quantization interval of the interval with large amplitude is large.

An analog signal is sampled and quantized to obtain a quantized pulse amplitude modulated signal, which is only a finite number.

Encoding is a set of binary code sets to represent each quantized value with a fixed level. However, in practice, quantization is done at the same time as the coding process, so the coding process is also known as the modulo-digital transformation, which can be denoted as a d.

The voice signal is first sampled by an anti-aliasing low-pass filter and turned into a sampling signal with 8kHz repetition frequency (i.e., a discrete pulse amplitude modulated PAM signal), and then the continuous PAM signal is quantified into a signal with a limited amplitude value by the "rounding" method, and then converted into binary code after encoding. For **, CCITT specifies a sampling rate of 8kHz, and each sampling value is coded with 8 digits, that is, there are a total of 2 8=256 quantified values, so the standard digit rate after PCM coding for each channel is 64kb s. In order to solve the problems of large quantization error and poor sound quality of small signals in uniform quantization, a nonlinear quantization method with uneven selection of quantization interval is adopted in practice, that is, the quantization characteristics are densely layered and the quantization interval is small in small signals, and sparse in large signals and large quantization intervals.

In practice, two logarithmic forms of compression are used: a-law and law, a-law coding is mainly used in 30-32-way primary group systems, and law coding is mainly used in 24-way primary group systems. A law PCM is used in Europe and China, and law PCM is used in North America and Japan.