SU1302208A1 - Digital frequency meter - Google Patents

Abstract

The device relates to the field of digital electrical engineering. The purpose of the invention is to improve the accuracy of measuring low and infrared frequencies. The digital frequency meter includes a measurement interval imager 1, a reference frequency generator 2, pulse formers 3 and 5, a register 8, and a pulse counter 4. The introduction of the Controlled Frequency Divider 7, the pulse counter 6 and the formation of new functional connections enable one to achieve the set goal. 1 il. from about yu oo 00

Description

This invention relates to a digital electrical measuring technique.

The purpose of the invention is to improve the accuracy of measuring low and infra-low frequencies.

The drawing shows the functional diagram of the device.

The digital frequency meter consists of a generator of 1 measurement interval, a generator 2 of the reference frequency, a first generator of 3 pulses, a first counter of 4 pulses, a second generator of 5 pulses, a second counter of 6 pulses, a controlled frequency divider 7, register 8,

The first input of the measurement interval imager 1, which is the input of the device, is connected to the counting input of the first counter of 4 pulses, the second input is connected to the reference frequency geder 2, and the output is connected to the control input of the first counter of 4 pulses and the input of the first imager of 3 pulses, the output which is connected to the input Record re-. the horn 8 and the input of the second driver 5 Pulses, the output of which is connected to the input of the zero setting of the first counter of 4 pulses,

 The inputs of the controlled frequency divider 7 are connected to the outputs of the first counter of 4 pulses, the control input is connected to the generator 2 of the reference frequency, and the output is connected to the counting input of the second counter 6 of the pulses, the control input of which is connected to the output of the measuring interval 1 of the measurement interval, the installation input the zero is connected to the output of the second form, - the generator of 5 pulses, and the outputs under the uchey to the inputs of the register 8,

The digital frequency meter works as follows.

The shaper 1 of the measurement interval forms the time interval T, the beginning of which coincides with the first pulse of the measured frequency f. The pulse counter 4 calculates the number of periods of the measured frequency that were laid in the time interval T, t, e. during the time interval T, the code N j in the counter 4 pulses gradually increases as each successive pulse arrives. As a result, the output frequency of the controlled frequency divider 7 is changed according to the following law:

f b ifc. N

where N is the maximum dividing ratio of the controlled divider 7 frequency,

The pulses from the output of the controlled divider 7 frequency are counted for the time interval T by the second counter 6 pulses. After the time interval T ends, a pulse from the output of the first pulse generator 3 records the result in register 8. A pulse from the output of the second pulse generator 5 sets the zero in counters 4 and 6 pulses and prepares for the beginning of the next measurement cycle of the interval imager 1 measurements. The value N .. takes on successively 1,2,3 ,,,,, i.e. forms an arithmetic progression, so the number of pulses N in the counter 6 at the end of the measurement

(1 + 2 + 3 +,

N

N,)

hri

)

ftt

(one)

or N

n „

N. (M, About i-- -% iibt,

N is an integer number of periods T, laid down in the measurement interval

a.t is the difference between the time interval T and the integer number of periods T, i.e.

 T

- N T

t x

. Ni

(2)

Solving equation (2) with respect to N and substituting the result in equation (1), we obtain

P

  fo. + fo.Iu.fx /, tЛГч

2N 2N

Nominal conversion function

N -, f.j

Measurement error with expression

one

S - f

Thus, in comparison with the known device ;, the error of which is estimated by the expression

S -----, at T f 1 the error

2 | CHC proposed digital frequency meter

always less.

Claims (1)

Invention Formula A digital frequency meter containing a shaper of the measurement interval, the first input of which, being the device input, is connected to the counting input of the first pulse counter, the second input is connected to the reference frequency generator, and the output is connected to the control input of the first pulse counter pulses, the output of which is connected to the input of the register and the input of the second pulse generator, the output of which is connected to the input of the zero of the first counter 10 15 22084 pulses, characterized in that, in order to improve the accuracy of measuring low and infra-low frequencies, a second pulse counter and a controlled frequency divider are introduced, the inputs of which are connected to the first inputs of the first pulse counter, the control input is connected to the generator, the reference frequency, and the output connected to the counting input of the second pulse counter, the control input of which is connected to the output of the measurement interval imager, the input of the zero setup is connected to the output of the second pulse imager, and the outputs are connected to the inputs of the register tra.