# Incremental modulation

## Research Course

The basic principle of delta modulation is proposed in 1946, it is one of the simplest differential pulse code. Early language delta modulation encoder is composed of discrete components. With the development of analog integrated circuits technology, in the late 1970s there has been amplification of syllabic modulator monolithically integrated amount, 80s instantaneous companding monolithically integrated, single-chip comprising the switched capacitor filter and a switched capacitor integrator, continuously improve the degree of integration, the volume of the delta modulation encoder is reduced, reducing power consumption.

## works

Simple delta modulation (DM) of the principle shown in FIG. FIG: x ( n ) denotes analog signal n sampled values; Min ( n ) denotes x ( n ) of the predicted value; Benjamin ( n ) represents an approximation of the n th sample values, Min ( n ) = Benjamin ( n -1); d ( n ) samples representing x difference ( n ) and its predicted value Min ( n ) of, d ( n ) = x ( n ) - Min ( n ); Lu ( n ) denotes the quantizer output value , if the difference d ( n ) is positive, Lu ( n ) = Jian, Jian called the order of magnitude; if d ( n ) is negative, Lu ( n ) = - Jian.

delta modulation delta modulation systems transmit digital form end rule: If the quantizer output Lu ( n ) = Jian, the digital c ( n ) = 1, also known as "1" code; otherwise Lu ( n ) = - Jian, the digital c ( n ) = 0, also known as "0" code. In the receiving side, an order of magnitude from a digital solution Lu '( n ), which decoding rule is: the received "1" code, c ' ( n ) = 1, gives the order of magnitude Lu '( n ) = Jian; received "0" code, c ' ( n ) = 0, gives the order of magnitude Lu '( n ) = - Jian. Xun output signal samples ( n ) = Lu '( n ) + Lu' ( n -1). If the transmission channel without error i.e. c ( n ) = c '( n ), the receive end Xun (n) same as ( n ) and Benjamin transmit end, and the holding circuit after a low pass filter to restore the original sampled analog signal. An actual circuit, the integrator can be used to implement the functions of adding and delay units; available amount and polarity switch to the generator stage quantizer composition; and sampling, the digital portion may be formed to constitute a shift register.