SU763805A1 - Digital electric signal frequency and period meter - Google Patents

Description

one

The invention relates to the field of electrical measuring equipment and can be used to measure changes in a wide dynamic frequency range, as well as a period of electrical signals with a predetermined error.

A device for digital measurement of the signal period is contained, which contains pulse counters of the reference frequency, by which the difference in the number of filling reference bars in each of the adjacent intervals is calculated, with the output of the re-sample signal by quantization of the period when this difference does not exceed the specified error Ij.

The disadvantage of the device is the inconsistency of the relative measurement error in the frequency range.

The digital frequency meter is known, it contains four counters with the corresponding keys on the inputs, a code comparison unit connected between the outputs of the third and fourth counters, divide frequency and control unit p.

The frequency meter does not provide a constant error in a wide dynamic range, and the redundancy

2

measurement time at the end of the dampl: -; ob: a does not allow to produce; measure with max. speedy11

The aim of the invention of Blutches is the improvement of metrological characteristics ;;.; devices and expansion eio fu; -: rational Bozmoknostei.

Set a goal. M that in the meter, co, g

10, the first pulse counter, which is connected to the code comparison output, the inputs of which are respectively connected to the discharge: Rg-; and the outputs of the second and third counters: 15 pulses, the second and third lights ,. informational inputs of which are connected by a melody and connected to the generator output of the reference frequency, and the output of the second key is connected to

20 input of the second counter pulses, a frequency divider and the unit is 1-1 I, the first input of which is connected to the information input of the first key and connected to the source of measurement

25 signals, the first three outputs of the control unit are connected respectively to the control inputs of the indicated keys, and the fourth output is connected to the control input of the processor, the output of the third key is connected to the code

The frequency target, the output of which is connected to the input of the third counter, the output of the code comparison circuit is connected to the second input of the control unit whose fifth output is connected to the input of the generator of the reference frequency.

The drawing shows a block diagram of the meter.

The meter contains an exemplary frequency generator 1, a control unit 2, keys 3-5, a frequency divider b pulse counters 7-9, a comparison circuit of codes 10 and a processor 11.

Before starting the measurement, all elements of the meter are reset, the unit 8 is brought into the counter 8, and the division factor in the frequency divider b is set to the required accuracy:

K -. where sg is zsodanna error

ABOUT

measurements. With the beginning of the first period of the measured frequency, the control unit 2 imposes a synchronization pulse to the generator 1 start and opens the keys 3,4 and 5, as a result of which the counter 7 starts counting the pulses divided by K times the reference frequency, the counter 8 starts the pulses of the reference frequency, and the counter 9 - impulses of unknown frequency. With the arrival of the impulse of the end of the first period of unknown chaty, block 2 closes key 4, fixing in the counter 8 the number Nj, which is prohortional to the value of the period of the measured frequency

Tx

.T, b, - ,,

where A, - 1 - / l, L

quantization error.

By key 3 ,. the frequency divider b, the counter 7 and the comparison circuit of the codes 10 form a time measurement interval ±, over which the counter 9 counts the pulses of the measured frequency

N, CT,

m

At the moment of comparing the code of the counter 7 with the code stored in the counter 8, according to the signal of the circuit 10, the control unit 2 closes the keys 3 and 5 and delivers a control signal to the input of the processor 11. By this time, the counter 9 will have the code

. ,,

where A is the quantization error of the data interval. Processor II, based on the signal from block 2, determines the final measurement result

D, g

- L.-CHK 1

  N-iTo

With a slow.m. measurement of the measured frequency, the condition

, 4K (liA,),

which provides an almost constant relative error, the value of which does not exceed the one specified in a wide measuring range;

d c-i-.

so n

The formation of a measurement interval proportional to the result of quantization of the first period of an unknown frequency allows to ensure a high instrument performance. The value of the result of quantizing the First period of an unknown frequency makes it possible to judge the magnitude of the period, and when the condition is satisfied, f i f characterizes the magnitude of the measured period with a sufficiently high accuracy. Obtaining preliminary information about the magnitude of the measured frequency period at the beginning of the measurement cycle is an important condition for the effective use of some automatic control systems.

Depending on the set task, the algorithm of the operation of the control unit 2 can also be programmed. Using the proposed meter, it is also possible to make a separate measurement of both the frequency and the period of the electrical signals.

The proposed digital meter for the frequency and period of electrical signals has a number of advantages over the known ones. The formation of a new connection in the meter allows the use of a higher model frequency, which is practically limited by the time the code sets in counter 8. Synchronization of the model frequency generator allowed to increase the upper limit of measurement, which in the meter is determined by the condition fn 4 fg. The synchronization of the beginning of the measurement by the arrival of the first period of the measured frequency and the increase in the result of the period quantization by one provide the formation of a measurement interval equal to or greater than the time required to measure the unknown frequency with a given accuracy.

ayupvd la invention

A digital meter for the frequency and period of electrical signals containing the first pulse counter, the input of which is connected to the output of the key, the code comparison unit, the inputs of which are respectively connected to the discharge outputs of the second and

the third pulse counters, the second and third keys, the information inputs of which are interconnected and connected to the output of the generator of the reference frequency, and the output of the second

the key is connected to the input of the second pulse counter, a frequency divider and a control unit, the first input of which is connected to the information input of the first key and connected to the source of the measured signal, the first three outputs of the control unit are connected respectively to the control inputs of the keys, and the fourth output is connected to the control processor input, characterized in that, in order to improve the metrological characteristics of the device and expand its functional

capabilities, the output of the third key is connected to the input of a frequency divider, the output of which is connected to the input of the third counter, the output of the code comparison circuit is connected to the second input of the control unit, the fifth output of which is connected to the generator input of the reference frequency.

Sources of information taken into account in the examination

1. Author's certificate of the USSR; 5,31090, cl. G 01 R 23/00, 1975.

2. USSR author's certificate number 461383, cl. G 01 R 23/10, 1973.

F

kil

Claims (1)

A digital meter for the frequency and period of electrical signals, comprising a first pulse counter, the input of which is connected to the key output, a code comparison unit, the inputs of which are respectively connected to the bit outputs of the second and third pulse counters, and the second and third switches, the information inputs of which are interconnected and connected to the output of the reference frequency generator, and the output of the second key is connected to the input of the second pulse counter, the frequency divider and the control unit, the first input of which is connected to the information m is the input of the first key and connected to the source of the measured signal, the first three outputs of the control unit are connected respectively to the control inputs of the keys, and the fourth output is connected to the control · input of the processor, characterized in that, in order to improve the metrological characteristics of the device and expand its functionality, the output of the third key is connected to the input of the frequency divider, the output of which is connected to the input of the third counter, the output of the code comparison circuit is connected to the second input of the control unit, the fifth output which is connected to the input of the reference frequency generator.