SU1503022A1 - Method and apparatus for determining instant values of electric signal frequency - Google Patents

Abstract

The invention relates to information and measurement technology. The purpose of the invention is to improve the measurement accuracy. The method of measuring the instantaneous values of the frequency of an electrical signal includes the operation of forming two periodic sequences of pulses shifted by a time interval Τ, not exceeding half the follow-up period, shifting the electrical signal to a constant level, measuring the instantaneous values of electrical signals, subtracting the latter from the measured results of the instantaneous values signal and calculating the frequency value. The output signal is fed to the input of the adder 1, the reference voltage from the source 2 of the reference voltage. Through the switch 3 and the analog-to-digital converter 4, the signal goes to the arithmetic unit 23. The installation of the trigger 8 is accomplished by pressing the Start button 21 or from the external start terminal 20. The switch 19 selects the operation modes. The counting of the clock pulses of the generator 5 is carried out in the counter 14 pulses. The result through the register 22 is sent to the recording-recording device 23. The device also contains a frequency divider 6, triggers 7, 8, a driver 9 pulses, delay blocks 10, 11, AND-NOT elements 12, 13, a controlled frequency divider 15, setpoint 16 division ratio. 2 sp.f. 3 il.

Description

31503022

to the arithmetic unit 23. The installation of the trigger 8 is accomplished by pressing the Start button 21 or from the external trigger terminal 20. Switch 19 selects operating modes. The counting of the clock pulses of the generator 5 is carried out in the counter 14 pulses. The result through the register 22 is sent to the recording and registering device 24. The device also contains a frequency divider 6, triggers 7, 8, a pulse shaper 9, delay blocks 10, 11, AND –NEC elements 12,13, a controlled frequency divider 15, master 16 division ratio. 2 sp.f-ly, 3 Il.

The invention relates to information and measuring technology and can be used for its intended purpose in instantaneous frequency meters, in frequency control devices, in devices for measuring non-electrical quantities by generator (frequency) methods.

The aim of the invention is to improve the measurement accuracy.

Fig. 1 shows a block diagram of a device for measuring the instantaneous frequency of an electrical signal in Fig. 2 — timing diagrams explaining the method and operation of the device; Fig. 3 is a block diagram of an arithmetic unit.

The essence of the method of measuring the instantaneous values of the frequency of electric

0o, ts-1

AO

+ 2

- pulse duration, g - next period (To 1 / fg);

where is L t T

UQ, is a constant value. Then, a secondary sequence of short rectangular pulses (Fig. 2d, second operation of the method) is formed, shifted relative to the perU, (t) - (1 +

ABOUT

A second electrical signal is generated (Fig. 26, third operation of the method)

Ul (

(four)

in advance of a given and distinguishable measuring instrument of a constant level and, much smaller, for example, the amplitude value of the signal (O, i.e. and and „.

The investigated electrical signal (1) is shifted by the value of a constant

Whose signal is as follows.

Assume that it is necessary to measure instantly the frequency of the electrical signal with high accuracy (Fig. 2a).

(one)

a, (t) (2; rf ,, t (f),

where f |. - instant frequency value; Uj (t)

and

instantaneous voltage value;

initial phase shift; amplitude value of the signal.

To solve this problem, a periodic sequence of short rectangular pulses is formed (Fig. 2c, the first operation of the method)

sin (n U t V / TO)

nutT / T.

Cos) (2)

howl for an interval of time; not exceeding half the period of their pursuit. Assume that the shift C is equal to 0.5 Td (FIG. 2d), then the second sequence of short rectangular pulses will be described by fusion (with and „- Un, and„, constant values)

j V i UD

sin (n ti tT / To)

nut

IT / T

Cos n (g, t +7). (3)

the level of the second electrical signal (2) (the fourth step of the method). p the result is a biased electrical signal (figd),

U (t) sin (27.f ,; t -lfo (5)

The instantaneous values of the electrical signal (5) are measured at time t ;, t, j, t f. (The fifth step of the method), the instantaneous value of the electrical signal (4) is measured at time t ;, t, t

(t e

51503022

(FIG. 2d), delayed relative to 11 g 0.5 Iff (pole

to times t and tj at time Ci operation of the method). Since the transform function of the real N meter is described by

N S (1 + p tl + UN, where and is the amplitude of the sample,

(6)

Sy and LN are multiplicative and additive components of conversion errors,

then the measurement results are instant 15

the signal values (5) will be described by the defenses

N, ll (tj) s (1 + p -t-AN;

N: .. U, (t; -,) S (l + y) + uN;

(

N ,,, U, (t.4,) S (1 p + UN, a of the signal (4) - by discharge

N

(ti

 3

u5

 a, (t, v.) s (i + p

 Ul.i (t; ,,) S (1 -f p + UN j

- ulj (t ,, 5) s (1 -t-j) -t- un.

Since,) tt2 (t, -,)

TO expressions (10) - (12)

25 (10)

(11) (12) 30

Ul (t;, 5) and „, take the form

one

f.

The described method measures the elimination of the additive typographic component of the measurement. Acting (19) we substitute the value (18) taking into account (7) - (9) and (finally,

27th

arccos

sin (2) cos,; - To,,. ,,, 4

. -.-.- .. l-j-ch-g;

(,; t ;,)

since f. j (t;) / 2, a (.

As can be seen from expression (20), the measurement result of the instantaneous values of the frequency of the electrical signal does not contain the additive and multiplicative components of the measurement error. The time moments С ;, | Чг and - 1 + 5 measurements of the amplitudes of the samples can be chosen arbitrarily at any interval of the electric signal under study. The number of frequency measurements per period and the frequency range of the signals under study are limited by the speed of the instantaneous amplitude measurement process and the processing time of the results of intermediate measurements. In practice, the processing time of the results of intermediate measurements is very short and amounts to hundreds of nanoseconds. If a

 DO S (t -f p + UN j (13) Uo S (1 + f) +, (1A) Uo S (1 + y) + UN, (15)

Then, the measurement results (13) - (15) are subtracted, respectively, from the previous measurement results (7) - - (9) of the instantaneous values of the shifted electrical signal (5) (the seventh operation of the method). The result is

N-- N

1 + 1)

(sixteen)

razhe7)

N;

N

l o

N, N,

- N, 4, i

44 t + 5

(17) (18)

(8) (9)

The instantaneous frequency of the electric signal. (20) is calculated by

formula

f, i

N

b;

one

arccos

r-N i-l-NlL) 2N ;,

(nineteen);

The described method of measurement ensures the elimination of the additive and multiplicative components of the measurement error. Indeed, in expression (19) we substitute the values (16) - (18) taking into account (7) - (9) and (5) and as a result we finally get

the speed of the instantaneous amplitude measurement process is 40 lt 0.1-0.5 µs, then the frequency range of applicability of the described method is from thousand hertz

to megahertz, i.e.

10 10 - Hz.

The device implementing the method (FIG. 1) contains an adder 1, a source 2 of the reference voltage, a switch 3, an analog-digital converter 4, a generator of 5 clock pulses, a divider 6 frequencies, triggers 7 and B, a driver 9 pulses, blocks 10 and 11 delays, AND-NOT elements 12 and 13, pulse counter 14, controlled frequency divider 15, dividing ratio sensor 16, decoder 17, OR-NOT 18 element, switch 19 operating modes, external start terminal 20, Start button 21 , register 22, arithmetic

unit 23, registration-registrar another device 24.

The arithmetic unit 23 includes six registers 25-30, three subtractors 31-33, an adder FOR, two digital division units 35 and 36, a functional converter 37, a second unit 38, a number, and a second decoder 39.

The first input of the adder 1 is connected to the input terminal, the second input of the adder 1 is connected to the same input of the switch 3 and connected to the first output of the source 2 of the reference voltage. The output of the adder 1 is connected to the first input of the switch 3, the output of which is connected to the input of the analog-digital converter 4

The output of the analog-to-digital converter 4 is connected to the output of the driver 9 pulses.

The control input of the switch 3 is connected to the output of the trigger 7, the counting input of which is connected to the input of the formulator 9 pulses and connected to the output of the AND-NO element 12, to which the counting input of the pulse counter 14 is connected.

The outputs of the pulse counter 14 are connected to the control inputs of the arithmetic block 23 and the inputs of the decoder 17. The output of the decoder 17 is connected to the control input of the register 22 input of the zero setting of the trigger 8 and through the first block 10 of the delay 10 to the input of the zero of the counter 14 impulses.

The direct output of the second trigger 8 is connected to the first input of the element AND-NO 12, the second input of which is connected to the generator output 5 clock pulses, to which the input of the frequency divider 6 is connected.

The output of the frequency divider 6 through the block 11 of the delay is connected to the first input of the element AND NOT 13, the second and third inputs of which are connected respectively to the inverse output of the trigger 8 and the first output of the operation mode switch 19. I

The output of the NAND unit 13 is connected to the counting input of the controlled frequency divider 15, the setup inputs of which are connected to the outputs of the setting unit 16 of the division factor.

The output of the controlled divider 15 chatot is connected to the first input of the element lUTM-HE 18, the output of which is under

five

0

five

ABOUT

"

e

five

five

The key is connected to the input of the zero setting of the trigger 7 and the installation input of the trigger unit 8, the second and third inputs of the element OR NOT 18 are connected to the same outputs of the switch 19 modes of operation.

The first input of the switch 19 of operation modes is connected to the second output of the source 2 of the reference voltage. The second, third and fifth inputs of the switch 19 of the operation modes are connected and connected to the ground bus. The fourth input through the Start button 21 is connected to the second input of the source 2 of the reference voltage, and the sixth input of the operation mode switch 19 is connected to the external trigger terminal 20.

The inputs of the arithmetic unit 23 are connected to the outputs of the analog-digital converter 4, and the outputs are connected via a register 22 to the inputs of the reading and recording device 24 and are digital outputs of the device for measuring the instantaneous values of the frequency of the electric signal under study.

In the arithmetic unit 23 (FIG. 3), the same inputs of the registers 25-30 are combined and are the inputs of the block 23. The control inputs of the registers 25-30 are connected by means of the first to the sixth outputs of the section 39, the inputs of which are the control inputs of the arithmetic block 23.

The outputs of registers 25-27 and 29 are connected to the inputs of the Reduced subtractors 31, 32 and 33, respectively. The outputs of the registers 26, 28 and 30 are connected to the inputs of the Subtractable subtractors 31, 32 and 33, respectively

The codes of the subtractors 31 and 33 are connected to the inputs of the adder 34, whose outputs are connected to the inputs of the Divisible first digital division block 35, the inputs of which are connected to the outputs of the second subtractor 32,

The outputs of the digital division unit 35 are connected via the functional (arc cosine) converter 37 to the Divisible inputs of the second digital division unit 36, the inputs of which Divider are connected to the outputs of the setpoint 38 of the number. The outputs of the second digital division unit 36 are the outputs of the arithmetic unit 23.

The device for measuring the instantaneous values of the frequency of the electrical signal operates as follows.

Fla the first input of the adder 1 receives the investigated electrical signal (1), the instantaneous value of the frequency of which is to be measured. The second input of the adder 1 from the first output of the source 2 of the reference voltage receives the second electrical signal (A) of a constant level. The output signal (5) of the adder 1 is fed to the first input of the switch 3, the second input of which receives the signal (4) from the first output of the source 2 of the reference voltage (Fig. 1).

Consider the mode of single measurement with manual (RU) or automatic (AU) control of the operation of the device. For this purpose, the operation mode switch 19 is shifted to the position opposite to that indicated in FIG. As a result, the output of the output pulses of the frequency divider 6 to the first input of the element OR NOT 18 is prohibited. The trigger 8 is set to the unit state manually by pressing the Start button 21 or automatically by applying a pulse corresponding to the logical unit to the external trigger terminal 20 .one).

The control pulses from the second and third outputs of the operation mode switch 19 are received through the second (with manual) or third (with external control) inputs of the OR-NE 18 element to the input of the trigger unit 8 installation.

The control pulses do not arrive at the first input of the element 18, since in the indicated position of the operation mode switch 19, the third input of the NAND 13 element is supplied with a zero potential that prohibits the passage of the specified pulses from the output of the frequency divider 6.

When the resolving potential arrives from the output of the trigger 8 to the first input of the element AND-NOT 12, the clock pulses from the generator 5 successively appear at the output. These pulses are fed to the counting input of the trigger 7, through which the digital output of the device is controlled by 55 switch 3. As a result, signals (1) and (4) are alternately fed to the input of a digital-to-digital converter.

It shows the measurement result code of the instantaneous frequency of the studied electrical signal. Using a counting device 9, connected to the output of the element IS-NOT 12, strobe pulses are formed from a periodic sequence of rectangular pulses that control the operation of the analog-digital converter 4. At the time of arrival of these pulses to the gate input of the analog-to-digital-to-digital converter 4, the instantaneous values of this or that electrical signal are converted and outputted to the memory registers of the arithmetic Lloka 23, 5 Arithmetic operation control This unit 23 is implemented by applying clock pulses from the output of the NANDI element 12 to the counting input of the counter 14, the output code of which controls the equality of the arithmetic unit 23.

From the outputs of the analog-to-digital converter 4, the codes of the numbers of expressions (7) and (13), (8) and (14), (9) and (15) are received at the inputs of the arithmetic unit 23.

Processing of the results of intermediate measurements is carried out in a dynamic mode with the arrival of every 0 clock pulse in the counter 14.

Since only six clocks are needed to carry out the measurement process, after passing the sixth pulse, the pulse counter 14 is zeroed. This is accomplished by decoding the output code of counter 14 using decoder 17. When the sixth pulse arrives, a pulse appears at the output of decoder 17, which sets the second trigger 8 to zero and thus prohibits the passage of clock pulses through the IS-NOT element 12. On the other hand , the output pulse 5 of the decoder 17 is fed to the control input of the register 22 and thus, writes the measurement result (19) to the register 22. And, finally,. through the delay unit 10, the output pulse Q of the decoder 17 is fed to the input of the zero setting of the counter 14, it is folded after six clock pulses. As a result, the output of the register is 22, and therefore.

five

0

It shows the result code for measuring the instantaneous frequency of the studied electrical signal. Using a counting device15

At 24, the measurement result indicates with a decimal number system. When the Start Button 21 is pressed again, the measurement process is similarly repeated.

If the measurement of the instantaneous values of the frequency of the studied signals is necessary to be carried out automatically, then to do this, set the switch 19 of the operation modes to

1 shown in FIG. As a result, pulses in counter 14 are codes of numbers N; .2. The NRs are recorded in registers 27 and 28, respectively. Before the fifth clock pulse arrives, the code of the number is subtracted

15 Nj from the code of the number N; . The subtraction result is fed to the input of the Divider of the digital division block 35.

Upon receipt in the counter 14 pt th and sixth clock pulses

On the third input of the second element IS-NOT 13, the resolving potential will arrive. In this case, the second and third inputs of the SH-NE 18 element are grounded.

A clock pulse from the output of the frequency divider 6 through the second block 11 of the delay and the element IS-NOT 13 will go

on the counting input of a controlled dividend, there is a record of codes of numbers Nc and 15 frequencies. The installation inputs of the controlled frequency divider 15 from the output of the setting device 16 receive the code of the division factor Cl of the follow frequency of the input pulses. With K. 1, the measurement process will be repeated each time, since the element OR of the NO-18 will receive the input of the unit of the second trigger 8

and registers 29 and 30 respectively. Before the next pulse arrives, the codes of the numbers N and N are summed; in the sum of 25 34. Then the half-sum of the numbers N ;, N; j is divided by the value of the number N using the first digital division block. The result of the division is converted into a functional (arcosa-delayed transient transition time f) matrix matrix converter 37 in trigger 8 every seventh clock J generator of generator 5. If the division factor of the frequency divider is equal to seven or ten, the measurement process will be repeated when with every eighth or eleventh cycle pulse.

With KQ 1 (for example), the measurement process will be carried out at intervals of

type and is fed to the input of the Divisible second digital block 36 division, to the input of the Divider which receives the code number-N (, 271 from the output of the setpoint 38.

As a result, a measurement result code defined by expression (19) appears at the output of the second zipper block and, consequently, at the output of the arithmetic unit.

35

40 M

meas

K | t h

where K,

1C d - dividers division factors of 6 and 15 frequencies,

f - following frequency

about

clock pulses. From the output of the analog-to-digital converter 4, the number codes arrive at the combined inputs of the registers 25-30. When the first clock pulse arrives at counter 14, the first output of the decoder 39 shows a signal allowing recording the number NJ to register 25. When the second clock pulse arrives at counter 14 on the second output of the decoder 39 according to the Wits signal, allowed (Ii record the number

12

N

; v, to register 26. Before the arrival of the third clock pulse, subtractor 31 subtracts

the number code from the number N code; , and the result of the subtraction goes to one of the inputs of the adder 34.

Similarly, when entering the third and fourth clock

pulses in the counter 14 codes of numbers N; .2. SIGs are written to registers 27 and 28, respectively. Before the fifth clock pulse arrives, the code of the number is subtracted

Nj from the code of the number N; . The result of the subtraction is input to the Divider of the digital division block 35.

Upon receipt of the 14th and sixth clock pulses in the counter, recording of codes of numbers Nc is realized

and registers 29 and 30 respectively. Before the next pulse arrives, the codes of the numbers N and N are summed; in summer 25 34. Then the half-sum of the numbers N ;, and N; j is divided by the value of the number N using the first digital block 35 of division. The result of the division is converted to functional (arccosi

type and is fed to the input Divisible second digital block 36 division, to the input of the Divider which receives the code number-N (, 271 from the output of the setter 38.

As a result, the output of the second digital division unit, and the investigator; but, and at the output of the arithmetic unit, according to it, the measurement result code defined by expression (19).

The exclusion of additive and multi-. The predictive components of the error, achieved by introducing into the device an adder, an automatic switch, two triggers, a pulse former, an NANDI item, a counter and a decoder, increase the accuracy of measuring the instantaneous frequency values of the electrical signal.

five

0 M

50

Claims (1)

1. A method for measuring the instantaneous frequency values of an electrical signal, comprising forming a periodic sequence of high frequency pulse pulses with a stable period of time, measuring the instantaneous values of the counter 1303 (V electric hygiene at the time of short impulses and determining the frequency by the formula one 2-7T. a g s: s o s i , 2nt .) where T is the period of following short pulses; f, .- - frequency controlled  L 1 electrical signal, Ni ,, n ;, and N ;, the measurement results ix, are also distinguished by the fact that, in order to improve the measurement accuracy, they form a second periodic sequence of short pulses, shifted relative to the first by an interval of time not exceeding half of their follow-up period, a predetermined constant level, to which the investigated electric signal is shifted, the instantaneous values of the second electric signal are measured at the moments of the following short pulses of the second periodic sequence short pulses, subtract the measurement results from the corresponding measurement results of the instantaneous values of the displaced electrical signal, and the obtained intermediate measurement results are used to determine the instantaneous magnitude of the frequency values of the electrical signal under investigation. as the values of N ;,, Nj, Ni ,. 2, Device for measuring instant The values of the frequency of the electrical signal, containing a clock pulse generator, the first and second delay blocks, an A / D converter connected in series, an arithmetic unit, a register, and a K11 are a device that differs in order to improve accuracy, a switch is inserted into it , the first and second triggers, the first rt, the second NAND elements, the OR OR NOT element, the frequency divider, the driver of the pulses, the controlled frequency divider, the dividing coefficient setter, the mode switch, Source of the reference voltage, the pulse counter, decoder, and an adder whose first input Con YU 15 20 25 ZO 35 40 45 ,, five The second input is connected to the second input of the switch and connected to the first output of the voltage source, the output of the adder is connected to the second input of the switch, whose input is connected to the input of the analog-digital converter, the gate input of which is connected to the output of the pulse generator, the circuit control switch is connected to the outputs of the first trigger, the counting input of which is connected to the input of the pulse shaper, with the output of the first AND-NOT element and the counting input of the pulse counter, the outputs connected to the control inputs of the arithmetic unit and to the inputs of the decoder, the output of which is connected to the control input of the register, the zero input input of the second trigger, and through the first eduder unit to the installation input of the pulse counter, the second output of the second trigger is connected to the first input of the first element IS-NOT, the second input of which is connected to the output of the clock pulse generator and to the input of a frequency divider, the output of which is second to the second delay unit connected to the first input of the second element IS-NOT, the second and third the inputs of which are connected respectively to the inverse output of the second trigger and the first output of the operating mode switch, the output of the second IS-NOT element is connected to the counting input of the controlled frequency divider, the setup inputs of which are connected to the outputs of the dividing coefficient controller, the output of the controlled frequency divider is connected to the first input of the element OR NOT, the output of which is connected to the input of the zero setting of the first trigger and to the installation input of the unit 1 of the second trigger, the second and third inputs of the STI element are NOT connected to The second-named outputs of the operating mode switch, the first input of which is connected to the second output of the voltage source, and the second, third and fifth inputs of which are combined and connected to the ground bus, the fourth input through the Start button is connected to the second output of the voltage source, and The sixth input of the mode switch is connected to the external start terminal. - Edaktor C, Baker Compiled by Yu.Minkin Tehred M.Hodanich Order 5081/55 Circulation 714 ZNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 113035 Production and Publishing Combine Patent, Uzhgorod, st. Gagarin, 101 Imv LaiMJULt .t "Mj Proofreader M. Pojo Subscription