SU1013904A1 - Time interval meter - Google Patents

Abstract

MEASURING TIME INTERVALS, containing a clock sequence generator, the first output of which is connected to the first input of the synchronizer, a start-stop trigger, the first input of which is connected to the bus., Start-impulses, input trigger, first resolution block, two distinct blocks, first pulse generator The time-to-voltage converter, the output of which through an amplifier is connected to the first input of the analog-to-digital converter, characterized in that, in order to improve the measurement accuracy, the second resolution unit, OR element, second and third pulse shapers, two switches, addition and subtraction unit and command generation unit, the second output of the clock sequence connected to the inputs of the first resolution unit and the second pulse shaper, the control input is connected to the output of the element OR, the first Input of the first pulse generator and the control input of one third pitpt-f-.1 MSJiilMKT.i I i a54RfftiTX4 ibHtBfeM i-jf: -i-, its impulse driver, the input of which is connected to the third generator output The act sequence and the input of the second resolution block, the control-input of which is connected to the second synchronizer input, the control input of the first resolution block and the start-stop trigger output, the second input of which is connected to the output of the first pulse shaper, the input of the time-amplitude converter and the second analog input a digital converter, the output of which is connected to the first input of the command generation unit, and the information outputs are connected to the first group of inputs of the addition and subtraction unit; “L group of inputs of which are connected to the outputs of the first switch, the first and second groups of inputs of which are connected to the outputs of the bits of the first and second counting blocks, respectively, the installation inputs of which are combined and connected to the start-pulse bus, the first INPUT of the OR element, the first input of the trigger and installation co-o of the input of the command generation unit, the outputs of which are connected to the third group of inputs of the block, addition - subtraction, the second input of the command generation unit, is connected to the stop pulse bus , The second input of OR I riJt.Il, and the second input of the input trigger -I whose output is connected to zapre1Gge-1-rotating the stop-start entry Trigg P- |. Pa, the outputs of the second and third pulse formers are connected respectively to the first and second inputs of the second switch, the third input of which is connected to the input of the first switch and the synchronizer output, the output of the second switch connected to the second input of the first pulse shaper, outputs

Description

Boro and the second resolution blocks are connected to the counting inputs of the first and second counting blocks, respectively.

The invention relates to a measuring technique and can be used to measure the time intervals of fast processes and repetitive processes, as well as in automatic control systems. It is known a device that allows to measure time intervals with high accuracy, which contains a start trigger, a clock generator (frequencies, time expander, discriminator, resolution circuit, recalculation device, and overflow circuit Cl. However, the known device has a low conversion speed. the time interval between the start and stop pulses in a digital code and low accuracy. The closest to the invention to the technical essence is the time-digital 1 converter, which uses time - amplitude is a code containing a clock generator connected in series, a synchronizer, two time-digit converters and an electronic computer. Each of the converters that have one common input connected to the synchronizer output and the Stop input to the other input, respectively. and Stop 2, corresponding to the beginning and end of the measured time interval, consists of a synchronizer, one of the outputs of which is connected in series by a prohibition scheme and the first eschetna. a circuit that counts a whole number of pulses of the clock frequency corresponding to the measured interval, and connected in series to the second output are a time-amplitude converter, an amplifier, an analog-to-digital converter, the second is recalculated to a circuit in which a number proportional to the time value is written additions of the measured interval not considered in the first recalculation scheme C2. However, the known device for measuring time intervals does not allow accurate measurement of the temporal characteristics of fast-repeating processes, and its realization is (COMPLETE technical problem. The aim of the invention is to improve the measurement accuracy. The goal is set by the fact that the time interval meter containing the generator clock sequence, the first output of which is connected to the first input of the synchronizer, the start-stop trigger, the first input of which is connected to the start-impulse bus, the input rigger, first resolution block, two conversion blocks, first pulse shaper, time converter - amplitude, the output of which is connected via an amplifier to the first input of an analog-digital converter, the second block, resolutions, OR element, second and third pulse shapers, two switches, an addition and subtraction unit and a command generation unit, the second output of the clock sequence generator being connected to the inputs of the first resolution unit and the second pulse generator, the control input of which is one with the output of the OR element, the first input of the first pulse generator and the control input of the third pulse generator, whose input is connected to the third output of the clock sequence generator and the input of the second resolution block, the control input of which is connected to the second synchronizer input, control input of the first resolution block , and the start-stop trigger output, the second input of which is connected to the output of the first pulse shaper, the time-amplitude input to the second input of the analogue-ti an output converter, the output of which is connected to the first input of the command generation unit, and information outputs are connected to the first group of inputs of the addition and subtraction unit, the second group of inputs of which is connected to the outputs of the first switch, the first and second groups of inputs of which are connected counting blocks, respectively, the installation inputs of which are combined and connected to the start-pulse bus, the first input of the OR element, the first input of the trigger input and the installation input of the block generating commands whose outputs are connected to the third group of inputs of the addition block. pulse drivers are connected respectively to the first and second inputs of the second switch, the third input of which is connected to the input of the first switch and the output of the synchronizer, the output of the second switch The controller is connected to the second input of the first pulse generator, the outputs of the first and second resolution blocks are connected to the counting inputs of the first and second counters, respectively.

The drawing shows a block diagram of the meter time intervals.

The meter contains a start-stop trigger 1, the first driver 2 pulses, the first 3 and. the second 4 resolution blocks, the clock sequence generator 5, the first b and the second 7. counting blocks, the first switch 8, the adding and subtracting block 9, the element 10 OR, the second 11 and the third 12 pulse formers, the second switch .13, the time converter 14 - amplitude , amplifier 15, analog-to-digital converter 16, block 17-formation of commands, the synchronizer 18 and the input trigger 19.

The general principle of the meter operation is to measure the measured interval with an accuracy of a clock frequency pulse period by applying recalculated blocks of these pulses to the input and in addition to measuring the time intervals between the Start pulse and the second counted clock frequency pulse, and also the Stop pulse and the second counted pulse clock frequency. In this case, two independent channels are used for the change, to the inputs of which two clock sequences are shifted one for the half of the period relative to the other. In the subsequent selection of one of the channels, this completely eliminates the uncertainty resulting from the measurement that occurs when the counting front of the pulses of the clock frequency and the starting pulse coincide. The time interval tj is defined by the formula

S,

whereT, the duration of the first and second pulses at the output of shaper 2;

TD - the period of the clock sequence; N is the counting unit code. 6. If the start-up pulse arrives at the front of the sequences arriving at the synchronizer, it is occasional; This way will choose the channel, but in this case both channels will be far enough from the failed situations. The device works as follows.

The pulse Start arriving at the meter transfers the triggers 1 and 19 to one state and also through element 10 ILI starts the shaper 2. Also blocks 6, 7 and 17 nullify with this pulse. High level from the output, trigger 1 gives permission to block 3 and 4, and the input of blocks 6 and 7 will begin to receive pulses from the outputs of generator 5. Pulse Start through element 10 OR will also allow the operation of FOEMERS 11 and 12, to the other inputs of which receive the same (respectively, 9 sequences and yejiea blocks 3 and 4 to the inputs of recalculating;, blocks 6 and 7. At the same time, at the output of 11 and 12 pulses will be generated, which will correspond to the second after the pulse Start counting the front of the clock pulses arriving at their inputs. The counting unit 7 can both count the pulse with the coinciding counting front and not count, t ie in the end result there is uncertainty, which the synchronizer 1B allows, which inputs together with the high: level from the output of the trigger 1 receives the clock sequence from: generator 5. If the positive front impulse output from the latch 1 coincides with the high level of sequence supplied to the input synchronizer, the synchronizer 18 decides that the most far from the channel situation of uncertainty in t kotorlly input unit 6 and the generator 11, and delivers ija. the inputs of the switches 8 and 13 are high, which corresponds to the fact that the outputs of the colliders 8 and 13 are under-. The outputs are correspondingly block 6 and driver ll. If ; the positive edge of the pulse from the trigger 1 output coincided with the low level of the sequence input to the synchronizer 18, the synchronizer would take the opposite solution and the outputs of the switches 8 and 13 would be connected to the outputs of the counting unit 7 and the driver 12 If positive the front of the pulse from the output of the trigger 1 falls on the front of the sequence fed to the input of the synchronizer 18, the level at the output of the synchronizer 18 can be both low and high, respectively, the switches 8 and 13 can be in any and two states, but in this case both channels will be far from undetermined .sosto Nij. Negative front pulse output from the switch 13, the driver 2 sets the input level to low; Thus, at its output a pulse was formed, the duration of which is determined by the start pulse and the second counting pulse of the clock sequence, for which uncertainty is eliminated. From the output of the imaging unit 2, the pulse arrives at the imager 14 time — the amplitude, at the output of which the level corresponding to the duration of the input pulse is given. This level is amplified by amplifier 15 and fed to an analog-to-digital converter 16, which converts it into binary code. The code then goes to block 9 of addition - subtraction and is stored there.

Subsequently, the Stop pulse through element 10 OR again starts the driver 2 and also enables the drivers 11 and 12. The synchronizer-18 uses the Stop pulse does not work, therefore the meter continues to work according to the previously selected clock sequence. Again, the negative front of the impulse from the output of the former 11 through KCMNtya-aTOp 13 resets the former 2, the needlepulse from the exit of which, in turn, with its negative front resets the trigger tag as Stoy resets the trigger IS, which removes the ban of the stripper 1. Low output 1 prohibits further passage clock pulses through blocks 3 and 4 on the blocks and recalculated blocks 6 7. Their counting stops. Output pulse 2 comes

the converter 14, where its length npeoopasseTCH is again in damage, which is further amplified and generated in the converter 16, the binary code S from the remote JM again goes to block 9 of addition - subtraction, where the corresponding mathematical operations are performed on it. , CL Pulse Stop situation of uncertainty can not be, since the recalculation blocks 6 and 7 continue to count regardless of the 1RH and Imguls Stop. Uncertainly, HHDCTb can occur only 3 two cases x, i.e. two possible

the option of forming pulses at the outputs of the formers 11 and 12, in which the negative edges of the generated pulses will be spaced apart from each other for the period of the clock frequency. In any case, it is the negative fronts of these pulses that determine the stopping of the counting of blocks 6 and 7, therefore both options are taken into account by counting ones: blocks b and 7.

The command generation unit 17 operates as follows.

After the conversion process is completed in the analog-digital converter 16, a write pulse appears at one of its outputs, which is fed to the input of block 17. When it arrives at the output of block 17, a command is generated that corresponds to storing information received at the input of block 9 from the output of the converter 16. Upon arrival at one of the outputs of the pulse 17 unit, a command is formed at its output to add the code combination from the output of the switch 8 and previously stored. Finally, upon the arrival of the second write pulse from the output of the converter 16, the output of block 17 forms a subtraction command from the result that was in block 9 before this binary combination, coming to block 9 from the output of converter 16. The final result is as follows:

, -1) 2% iN2-N3) A ,,

where is the binary code

block;

N, first and second, respectively, binary code combinations at the output of converter 16, 2 is the number by which the time interval equal to the period of the clock frequency / K is coded in converter 16 is the conversion factor that is determined during calibration of the meter. Calibration is similar to that described in the known device CGG; . Thus, a number is obtained that is proportional to the measured interval between the Start and Stop shlpuls.

The proposed meter makes it possible to increase the accuracy of measuring time intervals, it is technologically advanced, most of the nodes can be made completely by integrated technology in the form of an LSI easily interfaced with a computer. Start Stop

Claims (1)

TIME INTERVAL METER, containing a clock generator, the first output of which is connected to the first input of the synchronizer, a start-stop trigger, the first input of which is connected to the _£ bus of start pulses, an input trigger, the first resolution block, two counting blocks, the first pulse shaper, time-amplitude converter, the output of which through the amplifier is connected to the first input of the analog-to-digital converter, it is important that, in order to increase the measurement accuracy, a second a permission unit, an OR element, a second and third pulse shaper, two switches, an addition / subtraction unit and a command generation unit, the second output of the clock generator being connected to the inputs of the first permission block and the second pulse shaper, the control input of which is connected to the output of the OR element, the first input of the first pulse shaper and the control input a third of its pulse shaper, the input of which is connected to the third output of the clock generator and the input of the second resolution block, the control input of which is connected to the second input of the synchronizer, the control input of the first resolution block and the output of the start-stop trigger, the second input of which is connected to the output of the first pulse shaper, the input of the time-amplitude converter and the second input of the analog-to-digital converter, the output of which is connected with the first input of the command generation unit, and the information outputs are connected to the first group of inputs of the addition - subtraction unit, the second ·. group of inputs of which is connected to the outputs of the of the first switch, the first and second groups of inputs are connected to the outputs of the bits of the first and second conversion blocks, respectively, the installation inputs of which are combined and connected to the start-pulse bus, the first input of the OR element, the first input of the input trigger and the installation input of the command unit, outputs which is connected to the third group of inputs of the block, addition - subtraction, the second input of the block forming commands connected to the bus stop pulses, the second input of the OR element; and the second input of the input trigger, <the output of which is connected to the inhibit I input of the start-stop trigger-i ra, the outputs of the second and third pulse conditioners are connected W CO O> respectively, to the first and second inputs of the second switch,. the third input of which is connected to the input of the first switch and the output of the synchronizer, the output of the second switch is connected to the second input of the first pulse shaper, outputs per1013904. of the first and second resolution blocks, respectively, of the first and second, are reconnected with the counting inputs of the counting blocks.