Home / Electronics Articles / Advantages, disadvantages and There are some disadvantages of PCM (pulse code modulation) which are given below, Difference between PCM and DPCM ยท Difference between pulse. Answer to Briefly describe an advantage and a disadvantage of using differential pulse code modulation (DPCM) over pulse code modu. This page covers advantages and disadvantages of mentions PCM Also refer advantages and disadvantages of DPCM >> and ADPCM >> techniques.

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Each code has the same number of bits and requires the same length of time for transmission. Code number is in the form of binary representation.

Input signal is compared to the integrated output and delta signal risadvantage between the input signal and the pulse signal is brought to quantizer.

Advantages and disadvantages of dpcm system –

Basic concept of delta modualation can be explained in the DM block diagram shown in Fig 3. The magnitude of a quantum is also called the resolution. Histogram of PCM sampled image Fig 5.

The facts that were mentioned in this paragraph are applicable to signals in general not just image and video signals. This necessitates transmitting several identical PCM codes, which is redundant. The rounded off error is called the called the quantization error Qe. DPCM compression depends on the prediction technique, well-conducted prediction techniques lead to good compression rates, in other cases DPCM could mean expansion comparing to regular PCM encoding.

In this type of modulation, analog data is sampled and ot before being represented to digital binary form. For nad ADC to accurately convert a voltage to a binary code, the voltage must be relatively constant so that the ADC can complete the conversion before the voltage level changes. Feedback Privacy Policy Feedback. Disaevantage purpose of a sample-and-hold circuit is advvantage periodically sample the continually changing analog input voltage and disadvantags those samples to a series of constant-amplitude PAM voltage levels.


Formally written, DPCM dieadvantage method can be conducted for intra-frame coding and inter-frame coding. So, output signal contains bipolar pulses. The output signal contains information about sign of signal change for one level comparing to previous time interval.

To determine the PCM code for a particular sample voltage, simply divide the voltage by the resolution, convert the quotient to an n-bit binary code, and then add the sign bit.

The good side of the ADPCM method is minimal CPU load, but it has significant quantization noise and only mediocore compression rates can be achieved 4: Basic concept of DPCM – coding a difference, is based on the fact that most source signals show significant correlation between successive samples so encoding uses redundancy in sample values which implies lower bit rate.

Difference between PCM and DPCM

But, modeling such optimization is very complex so optimization of those two components are usually optimized separately. Delta modulation D elta m odulation DM is a subclass of differential pulse code modulation. Mathematically, the minimum Nyquist sampling rate is: Consequently, the minimum sampling rate is equal to twice the highest audio input frequency.

The PCM code shown in Table is a three-bit sign- magnitude code with eight possible combinations four positive and four negative. In PCM, the analog speech waveform is sampled and converted directly into a multibit digital code by an Analog to Digital converter. If the current sample is smaller than the previous sample, a logic 0 is transmitted. Can be reduced by increasing the step size. Design of DPCM system means optimizing the predictor and quantizer components, because the quantizer is included in prediction loop there is complex dependancy between the prediction error and quantizaton error so joint optimization should be performed to assure optimal results.

DM encoder Input signal is compared to the integrated output and delta signal difference between the input signal and the pulse signal is brought to quantizer.

In both coding intra- and inter- frame the value of target pixel is predicted using the previously-coded neighboring pixels.

Advantages and disadvantages of dpcm system

PCM is by far the most prevalent form of pulse modulation and will be discussed in more detail. The advatage difference between adjacent steps is called the quantization interval or quantum. My presentations Advnatage Feedback Log out. Images and video signals are examples of signal which have above mentioned correlation. If you wish to download it, please recommend it to your friends in any social system. If the magnitude of the sample exceeds the highest quantization interval, overload distortion also called peak limiting occurs.


As it can be noticed in DM there is a feedback by which the output signal is brought to the integrator which integrates and the bipolar pulses forming a pulse signal which is being compared to the input value. Because it’s necessary to predict sample dcm DPCM is form of predictive coding. The digital code is stored in the memory and which is later re-called for the playback.

PWM and Disadvwntage are used in special-purpose communications systems mainly for the military but are seldom used for commercial digital transmission systems.

Anx conducted on signals with correlation between successive samples leads to good compression ratios. Therefore, as shown in the figure, each sample voltage is rounded off quantized to the closest available level and then converted to its corresponding PCM code. In PCM, we represent each quantized level by a code number and later transmit the code number rather than sample value itself. Because the range of sample differences is typically less than the range of individual samples, fewer bits are required advantagw DPCM than conventional PCM.

davantage The smaller the magnitude of a quantum, the better smaller the resolution and the more accurately the quantized signal will resemble the original analog sample. Quantizer generates output according to difference signal if difference signal is positive quantizer generates positive impulse, and if the difference is negative quantizer generates negative signal.

Another example would be an audio signal with a low-biased frequency spectrum.