SU511691A1 - Delta Modulation Analog-to-Discrete Converter - Google Patents

Description

one

 The invention relates to communication technology and can be used to convert an analog telephone signal into 1 digital form.

 The analog-to-discrete transform is known; The driver is using adaptive delta; modulations containing a sequentially connected integrator, comparator, and pulse; modulator, as well as the elements And the master oscillator.

: However, the known analog-to-discrete converter has large quantization noise and free channel noise, j. The aim of the invention is to reduce i noise by quantizing free channel noise.

For this, both outputs of the pulse mode are connected to the analyzer inputs, the outputs of which are connected to the corresponding inputs of the shift register and the first input of the AND element, the outputs of the shift register are connected to the first inputs of the other AND elements, and the second inputs of all the AND elements are whose input is connected to

2

I exit the master oscillator, and you: moves 3, aments AND through the element OR plug-EA to the set points of two triggers; the control inputs of which are connected to the outputs of the n-shulz modulator, and the outputs - with the corresponding inputs of integ; ratorg ... with additional output

 the distributor is connected to the clock inputs of the I shift shift register, the analyzer and the pulse

j whom modulator

i This is explained in the drawings.

On: fpg. 1 shows a structural electrical converter circuit; in fig. 2 "": time diagrams.

 Analog converter converter with; using adaptive delta modulation; tions contains serially connected; integrator 1, comparator 2, and pulse modulator 3, both outputs of which are CCPP -

: to the inputs of the analyzer 4, the outputs of which are respectively connected to nepaoNty; the input element And 5 and the inputs of the shift register ira 6, the outputs of which are connected to the first I inputs of elements And 7 8, 9 and 10,

Claims (5)

 the second inputs of which and the element 5 are connected to the corresponding outputs of the distributor 11, which is connected to the output of the master oscillator 12, and the outputs of the elements 5, 7-1O through the element OR 13 are connected to the installation inputs of two flip-flops 14 and 15 controlling the inputs of which are connected to the outputs of the pulse modulator 3, and the outputs to the corresponding inputs of the integrator 1. An additional output of the distributor 11 is connected to the clock inputs of the shift register 6, the analyzer 4 and the pulse modulator 3. Analog-discrete converter otaet follows. The adaptation algorithm of the analog-discrete converter is modified by connecting the inputs of elements 5, 7-10 of the various outputs of the distributor 11 with ten outputs. The following adaptation algorithm is used: 1. The number of different discrete quantization steps is five. 2. If the sign of each subsequent quantization step coincides with the sign of the previous one, then the quantization steps change sequentially: А.2Д ЗА, D. А 9А, where А is the minimum quantization step. 3. When changing the sign of the difference between the input analog signal (see Fig. 2, c and the step signal of the approximation (see Fig. 2, d) to the opposite, the quantization tag also changes sign, and in absolute value has the following values: D .2D. D "2 D-step after step D2 ZD - A., Dz 4D - D.-2D, D4 6L - Dz-4D, D 9A--. 4. The constant level is displayed by alternating the quantization step D "2D with different signs. An analog input signal (see Fig. 2, is fed to the input of comparator 2, in which a difference signal is generated between the analog signal and an approximation signal (see Fig. 2, d), which is fed to another input of comparator 2 from the integrator 1 output. Difference signal from the output of comparator 2 enters the pulse modulator 3, where, in accordance with the sign of the difference signal, pulse sequences are formed (see Fig. 2, e and 2, e), carrying information about the increments of the original function in clock points. These pulse sequences are supplied in line with z, to the input of the analyzer 4 and to the control inputs of the triggers 14 and 15. The analyzer 4 decides to increase or decrease the quantization step in accordance with the adaptation algorithm by comparing the sign of the adjacent pulses of the pulse sequence (see Fig. 2, e). 4, pulse sequences f, -t, -l J p -P and f c-H are formed. The first output of the analyzer 4 is a pulse of the sequence g, rewriting information from the fourth or third bits of the shift register 6 to the second, if the sign of the subsequent row aga quantization is opposite to the sign of the previous one. At the second output of analyzer 4, an impulse of sequence f appears, register 6 to the right, if the characters match. At the third output of analyzer 4, a pulse of the sequence -C appears, setting the shift register 6 to the initial state after each shift cycle. At the fourth output of the analyzer 4, the sequence -f is formed, fed to the first input of the element AND 5. The input of the distributor 11 is supplied with a pulse sequence from the output of the master oscillator 12. The distributor 11 generates a clock frequency f supplied to the clock inputs of the shift register 6, the analyzer 4 and the pulse modulator 3, and the pulse sequences f, fg -PD. Q, fg. specifying the time positions of the rising edges of the pulse sequences (see Figs. 2, a and 2, b) applied to the inputs of the integrator 1. The pulse sequences T, 3 J4 6 9 of the respective outputs of the distributor 11 are fed to the second inputs of the And 5, 7 elements 10 respectively. The first inputs of the elements AND 7-10 from the outputs of the shift register 6 are supplied with pulse sequences fn - i J and 7 JHlO, respectively. The impulses of sequences, f.Q alternately open the elements AND 5, 7-1О, skip the impulses of the corresponding sequences f, fg. f4 f 6 9 ° ™ Pb are then combined on the element OR 13 and fed to the installation inputs of the flip-flops 14 and 15. At the outputs of the flip-flops 14 and 15, pulse sequences (see Fig. 2, a and 2, b) of variable duration are formed, which enter the inputs of the integrator 1. When a positive pulse arrives at one input of integrator 1, the voltage at its output rises linearly to a value directly proportional to the pulse duration, and when the pulse arrives at the other input it decreases linearly. A step signal of approximation is formed at the integrator output (see Fig. 2, d). Analog-to-discrete converter using an adaptive VT delta module iiJj iliili Fig. 1, comprising a series-connected integrator, a comparator and a pulse modulator, as well as AND elements and a master oscillator, characterized in that, in order to reduce quantization noise and free channel noise, both outputs of the pulse modulator are connected to the analyzer inputs, outputs which are connected to the corresponding inputs of the shift register and the first input of the element And, the outputs of the shift register are connected to the first inputs of the other elements And, and the second inputs of all elements And are connected to the corresponding outputs It is an input whose input is connected to the output of the master oscillator, the outputs of the AND elements through the OR element are connected to the setup inputs of two triggers, the control inputs of which are connected to the outputs of the pulse modulator, and the outputs of the corresponding integrator inputs. connected to the clock inputs of the shift register, analyzer and pulse modulator. about 4i " "Ti" -b