SU860306A1 - Converter of time intervals to digital code - Google Patents

Description

The invention relates to a measuring technique and can be used in various fields of science and technology for measuring the time interval between pulses. The limescale converter is a digital code containing a reference frequency generator connected to the first inputs of two matching elements, the second inputs of which are connected to the corresponding outputs of the control trigger, and the outputs of the matching elements are connected to the counting inputs of two pulse counters, the outputs of which bits are connected respectively to the first inputs of the elements of coincidence, the second inputs of which are connected to the buses of the polling of the counters, the source of the sequences of pulses, the element rzhki, two elements of coincidence and a trigger, the counting input of which is connected to the output of the source of pulse sequences, and the outputs of the additional trigger are connected to the first inputs of two additional elements of the match, the second inputs of which are connected through the delay element to the output of the reference frequency generator, and the outputs of the additional elements of matching are connected respectively, to the control inputs to the fl j flip-flop trigger. The disadvantage of the known converter is the limitation of the accuracy of the conversion of time intervals to digital th code due to fast counters. The closest in technical essence to the present invention is a time interval converter into a digital code comprising a control trigger, a reference frequency generator connected in series, a coincidence element and a counter, as well as a polling circuit, with a single output of the control trigger being connected to the second input of the coincidence element 2 . A disadvantage of the known converter is low accuracy, which can be increased by increasing the frequency of the reference oscillator. Increasing the frequency of the reference oscillator is often accompanied by the need to take additional circuit design and engineering measures to eliminate the influence of high-frequency pickups from the generator on the converter elements.

The purpose of the invention is to reduce the conversion error.

The goal is achieved by the fact that a time converter into a digital code containing a control trigger, a reference frequency generator, a counter, an output (which is connected to the input of the polling unit, delay elements are added, and a pulse train distributor, and the output of the reference frequency generator is connected to the first input of the pulse train distributor directly and with its second input through the delay element; the direct output of the control trigger is connected to the third gate of the distributor pulse sequences, the outputs of which are connected to the R and S vhodag4 counter.

FIG. 1 is a block diagram of a time converter into a digital code; in fig. 2 is a block diagram of a pulse train distributor; Fig. 3 shows time diagrams of the operation of the converter and diagrams of the error of converting time intervals into a digital code.

The converter of time intervals into a digital code contains a counter, 1, polling unit 2, a generator 3 of the reference frequency, the output of which is connected to the first input 4 of the distributor 5 of the pulse sequence and through the delay element 6 to the second input 7 of the distributor 5, the third input 8 of the distributor 5 is connected to the output of the control trigger 9 having the inputs 10 Start 11. The stop, the first 12 and the second 13 outputs of the distributor are connected respectively to the S and R inputs of the counter 1.

The pulse train distributor contains the triggers 14 and 15, the outputs of which are connected to the first inputs of the matching elements 1-18, respectively, the second inputs of the matching elements 16 and 17 are combined. And they are the first input 4 of the distributor 5, the second inputs of the matching elements 18 and 19 are combined The second input 7 of the distributor 5, the third inputs of the matching elements 1619 are combined with the R inputs of the flip-flops 14 and 15 and are the third input 8 of the distributor 5.

the output of the matching element 17 is combined with the S input of the trigger 15 and is connected to the first input of the element OR 20, the output of which is the first output 12 of the distributor 5, and the second. the input of the element OR 20 is connected to the output of the element 19 of the match and to the S input of the trigger 14. The outputs of the elements 16 and 18 of the match are connected to the inputs of the element OR 21, the output of which is the second output 13 of the distributor 5.

The time interval to digital converter works as follows.

In the initial state, when the distributor 5 pulse sequence 5 is in effect, the inhibitory potential acts from the control trigger 9, which keeps the distributor triggers 14 and 15 in the zero state and prohibits the passage of pulses of the reference frequency generator 3 acting on the inputs 4 and 7 of the distributor 5 to its outputs are 12 and 13. When the first impulse of the time interval (A) arrives at the input 10, the control trigger 9 switches (Ug) and removes the prohibition from the R inputs of the triggers 14 and 15 and the matching elements 16-19.

Since the moment of switching of the control trigger 9 is not synchronized with the pulses of the generator 3 of the reference frequency, depending on its position relative to the pulses acting on the inputs 4 (and) and 7 (and,) of the distributor 5, the signal is either at the output of the coincidence element 17 , or at the output of the element 19 coincidence, on the second inputs of which permitting potentials act from the flip-flops 14 and 15. Elements 16 and 18 coincide are closed on the inputs connected to the single outputs of the flip-flops 14 and 15.

When switching control. the trigger 9 (Fig. 3) is first shown on the output signal of the coincidence element 19, which switches the trigger 14 lU. ) and, passing through the element OR 20 to the output 12 of the distributor 5 (and 0), switches the first trigger of the counter 1 to the state 1 (ibc |) via the S input. The trigger 14 switches over, removes the ban from the element 16, matches and locks element 17 matches, resulting in signals

from the output of element 16 match- {b

neither through the OR element 21 passes to the second output 13 of the distributor 5 and to the R input of the first trigger of the counter 1, switching it to the zero state.

Claims (2)

Since the outputs of the distributor 5 of the pulse sequences are connected to the separate inputs of the first trigger of counter 1, the first trigger of counter 1 switches with the pulse frequency of generator 3, which is equivalent to an increase in the frequency of generator 3 in a known device, and therefore a decrease in the time interval error in digital code. FIG. Figure 3 shows the time diagrams of the error d t due to the random and uniform appearance of the first pulse () of the time interval at any time between the quantization pulses. and errors ut ,, due to the random moment of arrival of the second pulse of the time interval (U -, - j) between the quantization pulses. When delaying quantization pulses in the delay module by the value of t} | --Mr, where T. is the quantization period, t..t,, and since the errors q t and l t have a uniform distribution density in the intervals | p,, - I then the total error in converting time intervals to a digital code will be distributed according to Simpson's law with a maximum error value ± -. Thus, the proposed converter allows, with a period of following quantization pulses T, to obtain a conversion error that is two times smaller than in the known device. A special feature of the distributor 5 of pulse sequences in the converter is that, regardless of the position of the pulses at inputs 4 and 7 relative to the switching moment of the control trigger, the first pulse always appears on the first 12 stroke of the distributor 5 and switches the first trigger of the counter 1 in a single state. If the distributor did not have such a feature, in the event of the first pulse appearing at the second outlet of the distributor 13, half the production period would be lost, since the zero state of the first trigger of counter 1 would be confirmed, and this would increase the error l t to + Ttt and would not allow to increase accuracy. Therefore, the described feature of the distributor 5 directing the first output pulse to output 12 is necessary to reduce the error in converting time slots to a digital code. If trigger 9 does not switch: between pulses 1) 4.-UT r as in FIG. 3, and between pulses U -1) 4, the operation of the former will be explained in the same time diagrams of FIG. 3 if we change the designations U- and U replaced by Uf g & U on Uyg Note that the shift of the sequences of pulses U4 7 by the value of C :: is realized without difficulty. Thus, if generator 3 generates pulses with a squaring power of two, then the holding element 6 is an inverter. If generator 3 generates a sinusoidal oscillation, then a half-period delay is ensured by the formation of pulses (i, for example, from a positive half-wave, and pulses Uj from a negative half-wave of a sinusoid.) the reference frequency, the counter, the output of which is connected to the input of the polling unit, characterized in that, in order to reduce the conversion error, a delay element is inserted into it and distributed pulse sequence, the output of the reference frequency generator is connected to the first input of the pulse train distributor directly and to its second input through a delay element, the direct output of the control trigger is connected to the third input of the pulse train distributor, whose outputs are connected to the R and S inputs of the counter Sources of information taken into account in the examination 1. The author's certificate of the USSR 573797, cl. G 04 F 10/04, 1971. 2. Gitis E, and. Information converters for electronic digital computing devices, M., Energie, 1975, p., 235-239. % I TO .z - i