The Delta modulation (DM or Δ-modulation) is an analog-to-digital or digital-to-analog signal conversion. Its main features are: The term digital signal is used to refer to more than one concept. ... An analog or analogue signal is an allergy continuous in both time and amplitude. ...

• the analog signal is approximated with a series of segments;
• each segment of the approximated signal is compared to the original analog wave to determine the increase or decrease in relative amplitude, *the decision process for establishing the state of successive bits is determined by this comparison,
• only the change of information is sent, that is only an increase or decrease of the signal amplitude from the previous sample is sent whereas a no-change condition causes the modulated signal to remain at the same 0 or 1 state of the previous sample.

To achieve high signal-to-noise ratio, delta modulator can use oversampling technique, that is the analog signal is sampled at a rate several time higher than Nyquist rate, and then a decimation filter which enhance the resolution lowering the output frequency. The ASCII codes for the word Wikipedia represented in binary, the numeral system most commonly used for encoding computer information. ... Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering concept defined as the ratio of a signal power to the noise power corrupting the signal. ... In signal processing, oversampling is the process of sampling a signal with a sampling frequency significantly higher than twice the bandwidth or highest frequency of the signal being sampled. ... The sampling frequency or sampling rate defines the number of samples per second taken from a continuous signal to make a discrete signal. ...

Derived from of delta modulation are continuously variable slope delta modulation, delta-sigma modulation, and differential modulation. The Differential Pulse Code Modulation is similar. In telecommunications, modulation is the process of varying a periodic waveform, i. ... Continuously variable slope delta modulation (CVSD or CVSDM) is a voice coding method. ... The Delta-Sigma (ΔΣ) modulation is a kind of analog-to-digital or digital-to-analog conversion. ... Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code. ...

Principle

Fig. 1 - Block diagram of a Δ-modulator/demodulator

Delta modulation is based in quantizing not the absolute value of the input analog waveform, but only the difference between the current and the previuos step. Let's examine a system block diagram. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ...

The modulator is made by a quantizer which converts the difference between the input signal and the average of the previous steps. In its simplest way, the quantizer can be realized with a comparator referenced to 0 (two levels quantizer), whose output is 1 or 0 if the input signal is positive or negative. The demodulator is made by an integrator (like the one in the feedback loop) which averages the steps, and its output is filtered with a low pass filter The term filter may refer to: A device to separate mixtures. ...

Bibliography

• Steele, R. (1975). Delta Modulation Systems. London: Pentech Press. ISBN 0-4708-2104-3.