SU762159A1 - Multichannel voltage to code converter - Google Patents

Description

The invention relates to the measurement technique and the technique of analog-digital conversion, can be used as an information converter for electronic digital computing devices.

A known converter that automatically takes into account zero-level drift. The converter consists of two comparison elements, a sawtooth voltage generator and a trigger. One input. ¹

one of the elements And grounded, and the other is connected to the output of the sawtooth generator. The output of this reference element is filed on the bus "'Disable' trigger bus permission which is connected to the output of the primary reference element transducer Such construction provides improved accuracy, without requiring holding head adjustment works regu- ₂ £ ΐ. |.

The disadvantage of the converter is the use of a large number in it.

precision items.

²

A converter is also known that contains a channel switch, a pulse-width modulator, a zero-level correction node, a reference frequency generator, a number-impulse-co-code converter, a control unit, and sources of measured voltages. The outputs of the sources of measured voltages are connected to the corresponding inputs of the channel switch, one input of which is connected to the common bus, and the output connected to the input of a pulse-width modulator.

The output of the pulse-width modulator is connected to the first input of the zero-level correction unit, the second input of which is connected to the output of the reference frequency generator. The number of pulses of the transducer input is a code connected to the output of the zero level correction node. The third input of the zero level correction node is connected to the first output of the control unit [2),

The disadvantage of this device lies in the low conversion accuracy. since it does not take into account the errors3

This is caused by the nonlinear dependence of the code on the measured voltage.

The purpose of the invention is to improve the accuracy of conversion by reducing the nonlinearity coefficient.

This goal is achieved by the following: a device containing a channel switch, a pulse-width modulator, a zero level correction unit, a reference frequency generator, a number of pulses-code converter, a control unit, and sources of measured voltages whose outputs are connected to the corresponding switch inputs channels, one input of which is connected to the common and bus, and the output is connected to the input of a pulse-width modulator, the output of which is connected to the first input of the zero-level correction node, the second input of which n with the output of the reference frequency generator 20, the inverter input number of pulses — the code is connected to the output of the zero level correction node, to the third input of which is connected to the first output of the control unit, an element H, 25 an inverter, a counter and a reset node, the output of which is connected to the reset bus the counter, and its output is connected to the fourth input of the zero-level correction node and through the inverter is connected to the

the first input element And the second input of which is connected to the output of the reference frequency generator, and the third - with the output of the pulse-width modulator, the output of the element And is connected to the input 35 of the counter, the converter inputs the number of pulses of the code, the reset node and the channel switch are connected respectively to the second , the third and fourth outputs of the block. controls. 40

FIG. 1 is a block diagram of a multichannel converter; in fig. 2 - timing diagram of the device.

The converter contains a commutator of 1 channel, a pulse-width modulator 2, a zero-level correction node 3, a reference frequency generator 4, a converter 5 number of pulses – code, a control unit 6, sources 7 measured _{5 τ} voltages and χ 4, and χ _2ί ··· »And x _n coincidence element 8, inverter 9, a counter 10, a reset unit 11.

Knots and blocks of multichannel trans. raeovatelya interconnected sledu- ₅₅ yushim manner. The outputs of the sources 7 measured voltages Ιΐχ ^,

connected to the corresponding inputs

switch 1 channel, one input is 159 4

ryo grounded. The output of the switch 1 channels connected to the input of the pulse-width modulator 2, the output of which is connected to the first input of the node 3 zero-level correction. The second input of the node 3 zero level correction is connected to the output of the reference frequency generator 4. The input of the converter 5 is the number of pulses code connected to the output of the node 3 zero level correction. The third input of the node 3 zero-level correction is connected to the first output of the control unit 6. The output of the reset node 11 is connected to the reset bus of the counter 10. The output of the counter 10 is connected to the fourth input of the node 3 zero level correction and through the inverter 9 is connected to the first input of the And 8 element, the second input of the And 8 element is connected to the output of the reference frequency generator 4, the third with the output of the pulse-width modulator 2, the output of the coincidence element is connected to the input of the counter 10. Inverter 5 inputs, pulse code-code, reset node 11 and switch 1 are connected to outputs 2, 3 and 4, respectively, of control unit 6.

The device operates in two modes: measurement mode and storing the value of the zero level of the converter and the input voltage conversion mode. '

In the mode of measuring and storing the value of the zero level, a channel is connected to the input of the pulse-width modulator 2, the input of which is grounded. In the initial position, the counter 10 and the node 3 zero level corrections are in the nulet · state. The signal from the control unit 6 gives permission to memorize the value of the zero level to the node 3 of the zero level correction. With the arrival of the leading edge of the pulse from the output of the pulse-width modulator.2 to the input element And 8 pulses of the generator 4 of the reference frequency arrive at the counter 10. After the specified number of pulses of the generator 4 of the reference frequency is entered into the counter 10, a signal appears at its output , which prohibits the further arrival of pulses at its input and allows the arrival of pulses of the generator 4 of the reference frequency to the node 3 of the zero level correction. In node 3 zero level correction, the number of pulses is stored until the next poll of the zero channel.

5,7621

Thus, the width of the output pulse of the pulse-width modulator with its grounded input corresponds to the following equivalent number of pulses: more (20-30 times), ₅ recorded in the counter 10, equal to the transfer ^- coordinates (see Fig. 2), and less recorded in block 3 of the zero level correction, equal to the drift of the zero level. YU

As a node. 3 zero level corrections can be used, for example, a reversible counter.

In the input voltage conversion mode of 13χ _l, switch 1 of the channels begins polling these voltages. In this case, before each polling of the information channel, the counter 10 is reset to zero by using the reset node 11, and the signal from the output of the control unit 20 switches the zero level correction node 3 to subtract the current value of the zero drift from the previously recorded value. With the arrival of the leading edge of the pulse from the output of the 25-pulse-width modulator 2, element 8 is triggered. Pulses of the reference frequency generator 4 arrive at the input of counter Y. 9 stops the flow of the oscillator 4 of the reference frequency to the counter 10 and allows the flow of pulses to the node 3 of the correction 35 of the zero level. Generator 4 pulses of the reference frequency arrive at node 3 of the zero level correction until their number equals the current value of the zero drift of the converter, then they enter the number of pulses and code in converter 5. Before polling the next information channel ϋχ4 _{+ 4, the} counter 10 is reset to the zero position. 45

The goal in a multichannel converter is achieved by reducing the nonlinear dependence between the measured voltage and the code in the converter the number of pulses-code.

Node 3 zero level correction, together with counter 10, transfers the origin (point 0) to the zero point value point (point 0). Ubu ~ ₅₅ lichiv value of the zero level and the sensitivity of the transducer, achieve a reduction in the conversion time 1 _P p in the code to a value of 1 _x and therefore

(see Fig. 2) decreases the nonlinearity of the output code M _x .

The converter can be used in measurement technology, in information transmission systems. It is simpler, more reliable, more economical, does not require high-qualification adjustment work and the use of precision elements while maintaining high accuracy of conversion.

Claims (1)

Claim Multi-channel voltage-code converter containing a channel switch, pulse-width modulator, zero-level correction node, reference frequency generator, number-of-pulse-code converter, control unit and measured voltage sources, the outputs of which are connected to the corresponding inputs of the channel switch, one input of which is connected with a common bus, and the output is connected to the input of a pulse-width modulator, the output of which is connected to the first input of the zero-level correction node, the second input of which is connected to the output home of the reference frequency generator, the converter input the number of pulses-code is connected to the output of the zero-level correction unit, the third input of which is connected to the first output of the control unit, characterized in that the element And, inverter, counter and the reset node, the output of which is connected to the meter reset bus, its output is connected to the fourth input of the zero level correction node and through the inverter is connected to the first input of the And element, the second input of which is connected to the generator output of ornoy frequency, and the third - a yield of a pulse width modulator, and an output of the counter is connected to the input transducer input pulse number code, and reset the switch unit channels connected respectively to the second, third and fourth outputs of the control unit.