SU1541779A1 - Method and apparatus for converting analog quantity into code - Google Patents

Abstract

The invention relates to the field of telemetry and can be used in signal transmission time of pulse modulation through a communication channel and in code-pulse devices. A device comprising a linearly varying voltage generator 2, a comparator 3, a reference frequency pulse generator 8, a communication channel 14, a first pulse counter 11, a first key 9, a control unit 13, a reference pulse generator 1, and implementing an analog value conversion method the measuring time interval and the digital code, in order to increase the accuracy and noise immunity due to the additional measuring time interval, which allows you to control the reliability of the result, introduced the first 4 and second 5 pulse generators, the second key 10, the element OR 6, the distributor 7 pulses, the second counter 12 pulses. 2 sp.f-ly, 3 Il.

Description

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The invention relates to the field of telemetry and can be used in signal transmission time of pulse modulation through a communication channel and in code-pulse devices.

The purpose of the invention is to improve the accuracy and noise immunity.

Figure 1 shows the block diagram of the device; fig 2 is the time diagram of his work; Fig 3 is a block diagram of the algorithm functioning and microprocessor "

The device contains a generator 1 of reference pulses8 a generator of 2 lines ™ Cho of varying voltage, a comparator 3} first 4 and second 5 pulse formers 9 elements1 OR 69 distributor 7 impulses, generator 8 pulses of the reference frequency, first 9 and second 10 keys, first 111 and the second 12 pulse counters, Control unit 13 g performed on the microprocessor, and the communication channel 14.

The device works as follows

The generator 1 generates a sequence of signals with a period selected from the condition that it must be equal to or more than twice the maximum time interval proportional to the maximum value of the input signal (Fig 2a), which is fed to the inputs of generator 2 linearly varying the voltage that forms the triangular form of voltage 1 (.2c), and the shaper of 4 pulses, which is triggered along the front of incoming pulses (fig26). At the moments of equality of the analogous value and the linearly increasing voltage (), the 3S comparator is triggered from the output of which the pulses (FIG. 2g) are fed to the input of the imaging unit 5 pulses (ph2d)

The pulses () through the element OR 6 through the channel 14 h 3 “arrive at the first input of the distributor 7, The value of the analog value is proportional to the time interval formed by these pulses

The installation of the distributor 7 and the counters 11 and 12 of the initial state occurs after a brief signal Reset () from the first output of the block 13. At the same time, the keys 9 and 10 are open, the counters And and 12 are reset,

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At the moment of arrival at the information input of the distributor 7, the pulse triggers and generates a signal to close the key 9 (FIG. 2h), which connects the counting input of the counter 1 1 to the output of the generator 8 pulses of the reference frequency. Counter 11 starts counting these pulses (Fig, 2k).

When the second pulse arrives at the information input of the distributor 7, it operates (Fig. 2m), the key 9 opens and the switch closes the key 10. At the same time, the counter 11 stops and the counter 12 starts counting (Fig. 2L). 7 its next triggering leads to the opening of the key 10 and stopping the counter 12. Subsequent pulses arriving at the information input

the 7S distributor does not cause a change in its state until block 13 outputs a next Reset signal, asynchronous with respect to the input pulses. At the same time, its period is chosen by the obviously large period of input signals.

Before issuing an alternate signal, the reset unit 13 reads from counters 11 and 12 a code combination equivalent to time intervals, which are formed by three successive pulses arriving at the information input of the distributor 7. Next, the block-13 processes and checks the counting results for compliance with the selected period of input signals. If the test result is positive, then a smaller or equal digital value from the obtained counting results uniquely corresponds to the analog value being converted; if negative, the sequence of conversions is repeated until a positive result is obtained.

The device can be divided (conditionally) into two parts: the transmitter and the receiver- Nick, interconnected by a communication channel. They work independently, I can turn it on or off at any time. After switching on, the receiver is ready to receive impulses arriving at its input from the transducer via the communication channel, it comes only after the block 13 () forms a short pulse Reset (fig.2g) .

The form coming from the transmitter is shown in Figure 2e. If we consider any three consecutive impulses, then we can see that they form two different and time-lags. Conventionally, the smaller one is called the main one (with the duration te), and the larger one is called ADDITIONAL (with a DURATION

t) i The interval value is proportional to the analog value being converted (the process of its formation is illustrated in fig. 2a-e). The tc interval is denoted by the concept of the main time interval.

The sum of the intervals tft and to determines the value of the period of the sequence of reference pulses T, i.e.

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The period T does not depend on the current value of the analog value and is selected once when setting up the generator 1 (Fig 2a).

Considering Figs., It can be noted that the first impulse of the time interval t0 is always formed at the moment the saw starts (Fig. 2c), and the second impulse at the time of the operation of the comparator 3 with equal instantaneous values of the saw and the analog value (shown by the horizontal line, Fig. 2c) o This shows that with decreasing analog in size, the second impulse of the time interval tQ approaches the first, and with increasing -. moves, however, it always has m, it is

× 2 or 2 taking into account (I) receive

tflЈT / 2. (3)

Expression (3) allows the receiver to detect the time interval to from two intervals recorded by the counters AND and 12.

The interference immunity of the method is due to the verification of the condition (1) at the receiver. Interference pulses can be fed to the receiver input interspersed with transmitter pulses. However, the sum of the intervals recorded by counters And and 12, formed by three pulses successively arriving at the receiver input (among which at least one interference impulse), is necessarily less than the period T known to the receiver. If the interference impulse randomly cancels the working impulse.

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or one of the pulses will cease to be formed in the transmitter due to its malfunction, or if the analog value goes out of the transmitter's working area, then check Yu JQ

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K for the sum of the t0 and to intervals in the receiver will show that this sum exceeds T0, and the result of the conversion will be discarded as erroneous. Thus, at the expense of a preselected time interval in the device implementing the method of a single communication channel for transmitting the signals forming the time intervals and checking the results of the conversion, accuracy is increased and high noise immunity is ensured.

Claims (3)

1. A method of converting an analog value into a code, comprising forming a sequence of reference pulses with a period longer than a predetermined time interval proportional to the maximum value of the input signal, simultaneously forming a linearly varying voltage and the main measuring voltage on the leading edge of each reference pulse. time interval, the input signal is compared with a linearly varying voltage, and at the moment of their equality the formation of the main the measuring time interval, simultaneously with the formation of the main measuring time interval, form the main code proportional to it, determine the output code proportional to the input signal, characterized in that, in order to improve accuracy and noise immunity, after the formation of the main measuring time interval is formed, an additional time interval equal to the time between the end of the main measuring time interval and a subsequent rising edge of the reference pulse with simultaneous formation of an additional code, the additional measurement proportional to the time interval, after which the summation is carried out the main and additional kodos, carry out a control comparison of the obtained sum with a given code, proportional to the period of the reference pulse sequence, if they are equal, the code proportional to the shorter measuring time interval is selected for the output code value, and if the inequality is not the control comparison is repeated for subsequent basic and additional measurement time intervals until the moment of their equality, and the period of the trace of the reference, pulses is chosen to be equal to or more than twice the value uw (a predetermined time interval, 2 A device for converting an analogue --- go value into a code containing a generator of linearly varying voltage, comparing the reference frequency generator of the first counter of pulses, the first key of the control unit, the output of the generator of the alternating voltage of the comparator the second input of which is the input bus; the counting input of the first counter is connected to the output of the first key, the injector input of which is connected to the output of the reference frequency generator, is distinguished by so that, in order to increase accuracy and noise immunity, the first and second pulse formers, the reference pulse generator, the OR element, the pulse distributor of the second key and the second pulse counter, whose counting input is connected to the output of the second key, whose information input is connected to the output of the pulse generator of the reference frequency, and the control input is connected to the first output of the pulse distributor, the second output of which is connected to the control input of the first key, and the information input through the channel connection is connected to the output of the OR element, the first and second inputs of which are connected to the outputs of the comparator and the reference pulse generator, respectively, through the corresponding first and second pulse shapers, the inputs of the pulse distributor and the first and second counters are combined and connected to the first output of the control unit, the first and the second inputs of which are connected respectively to the outputs of the first and second pulse counters, and the second output is the output bus output generator reference pulses The c is connected to the input of the generator of a linearly varying signal. (Start J sum calculation Interdamb 1, Read t0 I Read to J. Calculate the sum Zt ta + tg Formation of a pulse "Reset I Select signal a" Reset 2. pause 3.dio signal „Reset