SU1531016A1 - Digital meter of low frequencies - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure low frequencies. The purpose of the invention is to expand the measurement range. The measured signal with frequency FX is fed to the second input of the 3 period meter, where, after passing through the trigger 6, from its inverse output it is fed to the first input of the 7 even periods meter and the second input of the 8 meter of odd periods. The signal from the direct output of the trigger 6 is fed to the first input of the meter 8 and the second input of the meter 7. The inverse output of the trigger 6 is connected to the first input of the And element, to the second input of which the output of the frequency divider is connected. The forward output of trigger 6 is connected to the enable input of the register. In a binary counter, pulse counting is performed. Information from the busses 9 is fed to the control inputs of the controllable divider. Upon completion of the measurement, a code proportional to the FX is generated at the output of the meter. The input of the frequency divider is connected to the output of the master oscillator. Each of the meters 7 and 8 also contains a driver and a delay element. 4 il.

Description

SL

CO

Mr

V / V oijue- Htfu L / iv- mfMfAtt 1 L / l LOM fftn

fm / o)

Ci

4U (/

This invention relates to a measurement technique and is intended to measure low frequencies.

The purpose of the invention is to expand the range of measured frequencies.

FIG. 1 shows a block diagram of a digital low-frequency meter; in fig. 2 - block diagram of the meter even (odd) periods; in fig. 3 - functional scheme of the period meter; figure 4 is a timing diagram of the meter.

The digital low frequency meter comprises a series-connected clock generator 1 and a frequency divider 2, a period meter connected in series 3, a controlled divider 4 and a period meter 5, the output of which is the output of a digital low frequency meter. The second input of the period 3 meter is the input of a digital low frequency meter. The first, second and third outputs of the splitter 2 frequency are connected to the first inputs of the meter 3 periods, the controlled splitter 4 and the meter 5 period.

Each of the meters 3 and 5 of the period contains a trigger 6, a meter 7 even periods, a meter 8 odd periods and information bus 9 information transfer. Inverse trigger output 6 is connected to the first input of the meter 7 even periods and the second input of the meter 8 odd periods. The direct output of the trigger 6 is connected to the first input of the meter 8 odd periods and the second input of the meter 7 even periods. The third inputs of the meter 7 even periods and the meter 8 odd periods are combined and connected to the first and third outputs of the divider 2 frequencies, respectively.

Similar outputs meter 7 even periods and meter 8 odd periods are combined information buses 9 information transfer.

Trigger input 6 is in the case of a 3-period meter input of a digital low-frequency meter | and in the case of a period meter 5, by its second input. Bus 9 information transfer connected to the output of each of the gauges 3 and 5 period. Each of gauges 7 and 8 even and odd

five

0

five

0

five

0

five

0

five

periods consists of an element And 10, a binary counter 11, a register 12, a driver 13 and a delay 14 delay. The input of the former 13 and the first input of the element 10 are interconnected and are the first input of the period meter 3 (5), the enabling input of the output of the information of the register 12 is the second input of the period meter 3 (5), the third input of which is the second input of the AND element ten.

Shaper 13 its output is connected to the input of the delay element 14 and the clock input of the register 12. The output of the element And 10 is connected to the counting input of the binary counter 11, the installation input of which is connected to the output of the delay element 14. The outputs of the counter 11 are connected to the inputs of the register 12.

Digital low-frequency meter works as follows.

The measured signal with frequency f (Fig. 4a) is fed to the second input of the meter 3 periods, where, having passed through trigger 6, is converted into a phase signal with frequency 12 and pulse duration TX 1 / fx (Fig. 46, c). The signal from the inverse output of the trigger 6 is fed to the first input of the meter 7 even periods and to the second input of the meter 8 odd periods. The signal from the direct output of the trigger 6 is fed to the first input of the meter 8 of odd periods and to the second input of the meter 7 even periods. The first input of the meters 7 and 8 is allowing for measuring periods, the second input is allowing for outputting the measurement result to the data bus 9, and the third input is intended for supplying counting pulses with frequency fy coming from the first output of splitter 2 frequency.

Thus, the first and second inputs of the meters 7 and 8 are supplied in antiphase. Suppose that the arrival of the next pulse of the monitored signal at the inverting output of flip-flop 6 leads to a high-level signal (Fig. 4b), which goes to the first input of the meter 7 and, respectively, to the first input of the And 10 element, to the second input of which through the third input The meter 7 receives counting sy frequencies f with divider 2 frequencies.

five

At the same time, at the output of element And 10, pulses of frequency f, arriving at the counting input of binary counter 11, appear (Fig. 4d). At the same time, the low level signal (Fig. 4c) from the direct output of flip-flop 6 through the second input of meter 7 is fed to the enable input of EZ register 12 and holds it, the outputs are in the off state (high impedance state at the output). Upon the arrival of the next pulse of the measured signal, trigger 6 of the meter 3 periods changes its state when it reaches the opposite one. At the same time, the low level sys- tem from the inverted output of the trigger 6 prohibits the passage of counting pulses through an AND 10 element and the number of pulses in the counter 1 1 accumulates

L T, T, -1.

At the same time at the signal transition: the inverse output of the trigger 6 from the high level in the LOW-shaped form 13 forms a short pulse with the duration of the Hcfig. Before), arriving at the synchronization input from the register (12), according to which information from counter 11 is overwritten into register 12, and a high level signal from the direct output of trigger 6 through the second input of meter 7 connects the outputs of register 12 to the data bus 9. Pulse from the output of the former 13, having passed through the delaying element 14 through time and t sets the counter 11 to the state O.

At the same time, after a change in the state of trigger 6 in meter 8, the same processes begin to repeat as in meter 7 (Fig. 4c, e, g, i) since gauges 7 and 8 are made the same. Thus, on bus 9 there is information for each period of the input signal.

Information from women 9 goes to the control inputs of the controlled divider 4, the counters input of which receives pulses of frequency f from the instant output of divider 2. At the output of controlled divider 4, the signal appears

f. ,

nf2 2 -f,

where n is the resolution of the control digits about in about 141 to one L.

Q g 0

5 o

..

five

five

166

This signal is applied to the input of period meter 5. Since meter 5 is made the same as meter 3, the processes,, described above, occur in it.

Pulses of frequency fj are fed to the meter from the third output of divider 2. Upon completion of the measurement, a binary code is generated at the output of meter 5, numerically equal to

 f

In fj / fnp f, - 7 g, g 2.

As can be seen from the above, the value of code B is proportional to the measured value of f.

When satisfied

f-l, oh.

1) 12

where k is the number that determines the number of significant digits (bits) of the number B,

its value is numerically equal to the measured value f ,.

The use of a digital low-frequency meter allows you to expand the range of measured frequencies while maintaining the required speed, which is achieved by providing the ability to automatically change the measurement time TyJ, while changing i without first reconfiguring the parameters of the digital low-frequency meter.

So, for example, with a counter capacitance of 11 2 16384 f,, f,, fj 6.1035 MHz, the minimum measured frequency ffc and 6.1036 Hz, the maximum measured frequency 247 Hz at measuring time 1.006 / fx Tmcm 1 , 9997 / fX.

Claims (1)

Invention Formula A digital low frequency meter containing a master oscillator, a frequency divider, the first and second period meter, characterized in that, in order to expand the range of measured frequencies, a frequency divider control is introduced into it, the master oscillator is connected to the input of a frequency divider, the first output of which connected to the first input of the first period meter, the second input of which is the hole of the digital low frequency meter, the second output of the frequency divider 1, is connected to the first input of the controlled frequency divider, the second input It is connected to the output of the first the period meter, the third output of the frequency divider is connected to the first input of the second period meter, the second input of which is connected to the output of the controlled frequency divider. fie. one I one $ & FIG. ABOUT i Jl Tl c T AND .IJL, -J F l f1 / e