RU2231922C1 - Analog-to-digital converter - Google Patents

Abstract

FIELD: measurement technology and computer engineering.

SUBSTANCE: analog-to-digital converter that can be used in data monitoring, acquisition, and processing systems has conversion channels, each incorporating voltage-to-frequency converter and counter, timer and adder.

EFFECT: enhanced speed and measurement technology of analog-to-digital converter.

1 cl, 2 dwg

Description

The invention relates to electrical and computer technology and can be used in control systems, collection and processing of information using computer technology.

Known analog-to-digital Converter containing a voltage-frequency Converter and the block selection of the conversion range (see patent US 4357999, H 03 M 1/00, 1982). The disadvantage of this device is its low speed.

Closest to the proposed device is an analog-to-digital converter with converting voltage to frequency, containing a voltage-frequency converter, the input of which is the measured voltage, and the output is connected to the input of the counter, which is in counting mode, a fixed time interval specified by the shaper fixed time interval the output of which is connected to the counter resolution input of the counter. The structural diagram of the prototype is shown in figure 1 (Pairing sensors and input devices with IBM PC computers. / Ed. By W. Tompkins, J. Webster. M .: Mir, 1992, p.205-206).

This conversion method is characterized by low speed, but good noise immunity.

The task of the invention is to increase the speed of the analog-to-digital Converter or measurement accuracy.

The problem is achieved by the fact that in a known analog-to-digital converter (ADC) containing a voltage-frequency converter, the input of which is the measured voltage, and the output is connected to the input of the counter, which is in counting mode, a fixed time interval specified by the shaper of a fixed time interval (timer), the output of which is connected to the counter resolution enable input, a second conversion channel is introduced based on the voltage-frequency converter, the input of which is measured voltage, and the output is connected to the counter input, which is in counting mode, a fixed time interval specified by the shaper of a fixed time interval, the output of which is connected to the counter resolution enable input of the counter, and an adder, the inputs of which are connected to the outputs of the counters, and an analog digital conversion.

The invention is illustrated in figure 2, which presents a structural diagram of the invention.

The device contains (see figure 2) two voltage-frequency converters 1 and 2, two counters 3 and 4, a timer 5 and an adder 6.

Voltage-frequency converters (VFDs) are designed to convert the input measured voltage to frequency, and VFDs convert asynchronously, independently of each other.

Counters 3 and 4 count the pulses from the output of the IF. Moreover, the counters are in counting mode for the time specified by the timer.

Timer 5 generates a count resolution signal that arrives simultaneously at counters 3 and 4.

The adder 6 summarizes the counting results of the counters and at its output generates the result of the analog-to-digital conversion upon completion of the pulse counting mode.

However, despite the fact that the introduced blocks are standard units of analog and digital technology, their introduction provides a new technical result - increasing the speed of the device or the accuracy of measurements. The claimed invention allows to reduce the conversion time of the measured voltage due to the use of the second channel.

The device operates as follows.

The measured voltage U _{Vx is} supplied simultaneously to the input of each voltage-frequency converter 1 and 2, at the output of which a sequence of pulses is formed, the repetition rate of which is proportional to the value of the input voltage. Voltage-frequency converters (VLF) operate independently of each other with an individual voltage-frequency conversion coefficient.

Timer 5 generates control signals, with the help of which the modes of zeroing, counting and storage are provided for counters 3 and 4.

Counters 3 and 4 count the number of pulses from the outputs of the respective voltage-frequency converters for a fixed time interval. From the outputs of the counters, the result of the count goes to the input of the adder.

The adder 6 summarizes the results of the counters and at its output generates the result of analog-to-digital conversion.

Assume that the steepness of the IF conversion is such that, at an input voltage of 1 V, the output pulse repetition rate is 1 kHz. The counter at a time interval of 1 s will record 1000 pulses.

Assume that the steepness of the VLF conversion of each channel is the same. At a time interval of 0.5 s, the counters will count 500 pulses, and at the output of the adder, the result of the sum from two counters will be equal to 1000 pulses. In this case, the conversion was carried out in less time with the same accuracy.

Thus, in the proposed two-channel ADC, the same result of the known analog-to-digital conversion is obtained in half the time.

If we parallelize n channels containing IF filters, counters, and reduce the conversion time by n times, then the sum of the results of counting the counters of all channels is formed at the output of the adder, while the speed of the analog-to-digital converter increases with the same accuracy.

If the conversion time is left unchanged, the introduction of n channels can improve the accuracy of analog-to-digital conversion.

раз.It is known that a possible deviation between the arithmetic mean value of a series of measurements and the true value is characterized by the standard error of the result of n measurements, which implies that presenting the result from a series of n measurements as an arithmetic mean allows reducing the standard error in

time.

This circumstance is one of the important ways to increase the accuracy of measurements and reduce random errors. This method is especially effective when automating measurement processes or when performing calculation operations directly in the blocks of measuring devices (Improving the accuracy of measurements in communication technology. S.M. Vernik, F.V. Kushnir, R.P. Rudnitsky. M .: Radio and communication 1981, p. 57).

Claims (2)

1. An analog-to-digital converter containing a voltage converter is a frequency at the input of which a measured voltage is supplied, and the output is connected to the counter input, and a timer, the output of which is connected to the counter resolution enable input, characterized in that one additional channel is introduced into it, the voltage containing the converter — frequency and counter, as well as the adder, the inputs of the first and additional voltage – frequency converters being combined, the output of the additional voltage – frequency converter being connected to ode additional counter, the second input of the additional counter is connected to the timer output, and the counter outputs are connected to adder inputs. 2. The analog-to-digital converter according to claim 1, characterized in that n-2 channels are additionally introduced into it, each of which contains a voltage-frequency converter and a counter, the inputs of all n voltage-frequency converters being combined, the outputs of n-2 converters voltage - frequency are connected to the inputs of n-2 counters, the inputs of all counters are connected to the output of the timer, and the outputs of n-2 counters are connected to the inputs of the adder.

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