SU1250976A1 - Method and apparatus for measuring frequency of pulse signals - Google Patents

Abstract

The invention relates to electrical measuring and computing techniques and can be used to measure the frequency (period) of electrical signals. The purpose of the invention is to improve the accuracy of measuring the frequency and period of the pulse signals. The essence of the proposed method is as follows. A reference reference is given.

Description

The time interval during which the first cycle of measuring the number N of pulses of an unknown signal is carried out. In subsequent cycles, the interval duration is increased by a random value uniformly distributed over a certain interval. The number of measurements in which the number of pulses is greater than that determined in the first cycle is recorded. The maximum value of the ratio of time intervals is determined using the appropriate formula, the period and frequency of the signals are determined. By determining the exact location of the N + 1 pulse, the error in the selection of the counting end is eliminated.

The invention relates to electronic measuring and computing equipment and can be used to measure the frequency (period) of electrical signals.

The purpose of the invention is to improve the accuracy of measuring the frequency and period of pulse signals by statistically processing the results of multiple measurements with a varying measuring time interval.

FIG. 1 shows a temporary diagram illustrating the essence of the proposed method in FIG. 2 is a block diagram of an apparatus for implementing the proposed method for measuring the frequency (period) of pulse signals.

The device contains (Fig. 2) block

Formation, selector 2, counter

3, indicator A, control block 5, time stamp generator 6, crystal oscillator 7, crystal oscillator 8, frequency setting control element 9, frequency divider 10, keys

II and 12, random voltage generation unit 13, floating frequency generator 14, counter 15, register 16, digital-to-analog converter 17, voltage divider 18.

In the device, the output of the forging unit 1 is connected to the input of the selector 2, another input of which is connected to the output of the control unit 5, the input of which is connected to the output

50976

those. the aim of the invention is achieved. A device for implementing the method includes a shaping unit t, a selector 2, a control unit 5, a time stamp generator 6, an indicator 4, a crystal oscillator 7, a crystal resonator 8, a frequency divider 10, a key 11, a counter 15, a register 16, a digital-to-analog converter 17 , divider 18 voltage. In order to achieve the goal, a frequency setting controlled element 9, a key 12, a random voltage generating unit 13 are additionally introduced. Unit 13 contains a floating frequency generator 14, as well as blocks 15-18, 2 Cp. f-ly, 2ip.

Key 11, and the reference frequency input is connected to the output of the time stamp generator 6, consisting of a series-connected crystal oscillator 7 and a frequency divider 10, the output of the selector 2 is connected to the input of the counter 3, the output of which is connected to the input of the display 4, the output of the block 1 of the formation is connected to the information input of the control unit 5, the synchronization output of which is connected to the control input of the crystal oscillator 7, and in series to the circuit of the crystal oscillator 8 a frequency driver yppaan e is connected to the element 9 controlling the stroke through the key 12 is connected to the output of the random voltage generating unit 13, consisting of a floating frequency generator 14, the output of which is connected to the input of the counter 15, the outputs of which are connected to the inputs of the register 16, the outputs of which are connected to the corresponding inputs of the digital-to-analog converter 17, the output of which is connected to the voltage divider 18, the output of which is the output of the random voltage generating unit 13, and the input of which is the control input of the register 16.

The essence of the proposed method of measuring the frequency of the unknown im312

The signal pulse is as follows.

During the first measurement cycle, the number of pulses N of unknown frequency (Fig. 1) is contained, which is contained in the reference time interval. The following (N + 1) -ft pulse does not fall into this Interval. In subsequent measurement cycles (Fig. 1), the duration of the reference pulse increases by a random value, uniformly distributed in the inter

vale & t

Wlkf

at the same time in each cycle

the measurement value of this random variable turns out to be different and constant during a given cycle. In the process of repeated measurements, an (N + 1) -ro pulse overlaps or does not occur with an increased pulse duration of the measurement interval. In this case, two time domains are formed, into which the given front enters the increased by a random value pulse of the measurement interval. The ratio between the extents of these regions and is determined by the location of the (N - (- l) -ro pulse within the interval. As can be seen from the graph of Fig. 1, the pulse appearance time is equal to (N + 1) Tj, where T is unknown the period is equal to

T, (NH)

T, ut.

where Tj is the unknown period of measurement e-

my pulse frequency; T is the duration of the reference pulse without an accidental increase;

it is the duration (duration) of the time domain.

The multiplicity of measurements makes it possible to view the whole process statistically and to determine the relationship between the durations of regions through the probability of events. The duration of the time domain at can be determined by the expression

at at

aw with

П П П (П

at

Max

P is the maximum value of a random variable by which the reference time interval is increased, the number of measurements

five

0

n, is the number of measurement, with

which number of pulses during the reference time interval, extended by a random value, would be greater than or equal to N + 1.

Then the period of the measured pulse frequency is defined as:

TPA. „.,

pnp

15

 N + 1

and its frequency is expressed as the reciprocal of

f. : i20

five

0

five

0

five

0

five

Thus, having fixed after the first measurement the number of pulses equal to N for the duration of the reference interval, increasing the reference interval by a random amount and determining the number n, in subsequent measurements, at which the readings will be greater than or equal to (N + 1) and the maximum the deviation of the random variable At, by which the reference pulse is increased, it is possible to determine the unknown period and frequency of the measured pulse signals.

By determining the exact location of the (N + 1) -ro pulse, the discretization error of the count end is eliminated, i.e. the aim of the invention is achieved.

The proposed device works as follows

In the initial state, the keys 11 and 12 are open.

When the power supply of the device is turned on, the initial installation of the control unit 5, the counter 3, the indicator 4 (the power supply circuit and the initial reset are not indicated in the functional diagram of Fig. 2 are not indicated).

On the input bus, the measured pulse signals are fed to the input of the Formation block, at the output of which pulses of standard amplitude and duration appear with a period equal to the period of the measured pulse signals. These pulses are fed to the input of the selector 2 and the input of block 17 up5

Equal. The measurement process begins with pressing key 11, from which the enabling signal enters the start input of control unit 5. The control unit 5 generates a single pulse of a predetermined duration, which is input to the input of the selector 2 and permits the transmission to the output of the selector 2 of standard pulses with an un- BtcTHbjM period. A single pulse of a predetermined duration is formed by the pulses of time stamps arriving at the input of the reference frequency of the control unit 5 from the generator output of 6 time stamps. The time stamps are pulse signals of a stable frequency defined by a crystal oscillator 7. A burst of pulses passed through selector 2 fills counter 3, which at its output converts it to a binary code, which is induced by indicator 4. For a temporary input input; m-pulses and the beginning of the reference pulse of a given duration, the pulses from the output of the forming unit 1 are additionally fed to the information input of the control unit 5, which synchronizes the start of the quartz oscillator 7 at the time of the start couple.

The described operation of the device is similar to the operation of the prototype.

After the first measurement, the number of pulses in the indicator 4 is equal to N.

After the key 12 is closed, the second measurement cycle is performed, and the measurement process is similar to the first cycle. Its difference lies only in the fact that the period of the quartz oscillator 7 increases and, consequently, the interval between the time stamps increases, and accordingly the duration of the reference pulse opening the selector 2 increases. The increase of this pulse occurs by some random value. This is achieved by the fact that when key 11 is pressed, a random voltage value appears at the output of the random voltage generating unit 13, which remains constant during one measurement cycle and during this cycle the input of the frequency defining control element 9 enters. by increasing its capacity and

25

097F. "

thereby reducing the resonant frequency of the crystal oscillator 7, which leads to an increase in the duration of the reference pulse. With the 4-5 indicator, a new indication of the number of pulses is recorded, recorded in counter 3,

The next key press 11 causes the appearance on block 13.

10 forming a random voltage of a new value, which through a closed key 12 is fed to the input of the frequency defining controlled element 9. In this measurement cycle, an increase in the pulse duration occurs by another random value that does not exceed the specified maximum value. Since the random voltage generation unit 13 generates a random voltage value according to a uniform law, therefore, the frequency setting controllable element 9 will be controlled according to a uniform law, causing a corresponding decrease in the frequency of the quartz oscillator generator 7. Zheniyakh 13 works as follows.

30 The unstable frequency produced by the generator 14 of the floating frequency is fed to the counting input of the counter 15. In the process of entering unstable pulses

35, the counter 15 is periodically filled and reset. This value of the codes on the input of counter 15 maintains a different time depending on the frequency of the input pulses.

40 Upon receipt of w pulse at the entrance

The random voltage generation unit 13, which is the control input of the register 16, records in it the code values that

45 were at the output of counter 16 at the time of the survey. This value is stored in register 16 and is fed to the input of a digital-to-analog converter 17. The contents of register 16 each time

50 changes when a new pulse arrives at its input. The random nature of the code values memorized each time in register 16 and arriving at the input of a digital-to-analog 55 converter 17 is explained by the lack of correlation between the time parameters of clock pulses on the input of counter 15 and the time for 7

In this case, when the permissive signal arrives at the input of the random voltage generating unit 13, the random value of the voltage appears at the output of the key 1t, which then goes to the frequency-controlled variable element 9 and saves constant during this measurement cycle.

The main advantage of the proposed method and device compared to limestone is to improve the accuracy of frequency and period measurements by reducing the end-to-end discretization error,

Claims (3)

1. A method of measuring the frequency of pulse signals, which is taken into account in calculating the number of pulses at an unknown frequency over a known time interval, characterized in that, in order to improve accuracy, the counting of pulses of unknown frequency is performed repeatedly, and after the first counting of the number of pulses during a known time interval at each subsequent price the duration of a known time interval is increased by a random value with a uniform distribution law, and the unknown frequency of the pulse signals is determined from the expression N + 1 T - max P de T - the duration of the reference (known) time interval; , - maximum value random value of the increase in the reference time interval N is the number of pulses of unknown frequency contained in the reference time interval; 509768 n is the number of measurements / P (is the number of measurements in which the number of pulses during the reference time interval increased by a random value would be greater than or equal to N + 1. 2. Device for measuring the frequency of the pulse signals, containing a forelock, the output of which is connected to the first input of the selector, the second input of which is connected to the output of the control unit, the first input of which is connected to the output of the first key, and the second input to 5 is connected to the time marker generator slot, consisting of a series-connected crystal oscillator and a frequency divider, and the output of the selector is connected to the counter input20 ka whose output is connected to the input indicator, and the output of the forming unit is connected to the third input of the control unit, the second output of which is connected to the control input of the quartz oscillator, characterized by the fact that, in order to improve the accuracy, it is connected in series to the quartz resonator circuit included in the quartz oscillator frequency -ead control element, the control input of which is connected via a second key to the output of a random voltage forcing unit whose input is connected to the output the first key. 3. The device according to claim 2, characterized in that the random voltage generating unit comprises a floating frequency generator, the output of which is connected to the counter input, the outputs of which are connected to the register inputs, the outputs of which are connected to the corresponding inputs of the digital-analog converter, the output of which is connected to a voltage divider, the output of which is the output of a random voltage generating unit, and its input is the control register input. A t .one J tMOKC