SU427289A1 - LOW FREQUENCY DIGITAL FREQUENCY METER - Google Patents

Description

This invention relates to a radio measuring technique. The frequency meter can be used in radio measuring devices for frequency measurement, as well as in frequency-code converters of automatic devices for measuring and monitoring the state of radio-electronic systems.

Low frequency digital frequency meters are known, which include a pulse shaper, a time selector, an integral part counter of the measured frequency, an indicator, a reference frequency generator, and a reference time interval shaping circuit.

The purpose of the invention is to improve the measurement accuracy in the low frequency region.

The proposed frequency meter is characterized in that it is provided with two additional time selectors, a control selector of a time selector, a divider 10 times, a pulse counter, controlled by a frequency divider, a hertz fraction counter, and a memory for storing and reproducing a time interval.

The drawing shows the block diagram of the device.

The frequency meter contains an electronic counting frequency meter 1, which includes a pulse shaper 2, a time selector 5, an integer counter for the measured frequency 4, an indicator 5, a reference frequency generator 6, and a time interval shaping circuit

7; time selector control circuit 8, the first additional time selector 9, a divider 10 times 10, a pulse counter 11, a controlled frequency divider 12, a second additional time selector 13, a fractional part counter of the measured frequency 14 and a time domain storing and reproducing circuit 15. Frequency meter works as follows.

In the initial state, the signal of the studied low frequency fx arrives at the device input, the pulse generator of the reference frequency 6 generates signals, the counters 4, 11 and 14 are in the initial state, at which

counters // and 14 are written in zeros, and on counter 4 is the number “-1.

The formation circuit 7, the control circuit 8, the memory and reproduction circuit 15 are also in the initial state, with

which all three time selectors are 3, 9 and IS

are closed. The number 10 (where n is the desired integer

number) set in divider 10 by any of

known methods.

Upon admission to the formation scheme

time interval 7 is a signal (for example, from some programming device not shown in the drawing), as a result of which time selector 3 is opened to the pulses of the measured frequency. The first pulse from pulse generator 2 passes through the time selector 3 to the counter - and transfers it to the state in which zero is written on the counter. The same pulse arrives at the time interval formation circuit 7, where, starting from the moment of its occurrence, the reference meter (second) interval is formed. All other pulses of the output measured sequence that have passed through the time selector 3 during the second measurement interval, arrive at counter 4, where their number is equal to the integer part of the measured frequency.

From the output of the temporal collector 3, the read pulses with a period Tk are fed to the timing selector control circuit 8, which generates a rectangular pulse with duration Tx, received; . The number of pulses placed in the time interval Tx is divided by / ("in the frequency divider 0, and then fed to the pulse counter 11. The counter sets on the controlled frequency divider a division factor equal to the number of pulses that have fired on the counter. As a result The output of the controlled frequency divider 12 receives signals from the pulse generator of the reference frequency 6, divided by frequency a certain number of times.

The control input and the output of the time selector 3 are connected to the inputs of the circuit 15 for storing and reproducing the interval t. The functions of this circuit include the memorization and subsequent reproduction of the interval-time At between the last counting pulse and the end of the second measurement interval. This interval, in the form of a duration of a rectangular pulse, is reproduced at the output of the circuit 15 immediately or some time after the end of the second measurement interval. A rectangular pulse of length At from the output of the circuit / 5 arrives at the time selector 13, opens it for the pulses from the output of the controlled frequency divider 12, and the pulses through the selector arrive at the counter 14 fractions Hz, where their number is proportional to the fractional part of the total value of the input frequency .

By selecting the division factor Yui of the divider 10 with an appropriate choice of the frequency Ret and the capacitance of the pulse counter 11, the accuracy of the measurement of the frequency fx can be improved by n orders of magnitude.

Subject invention

A low-frequency digital frequency meter containing an electron-counting frequency meter, which includes in series

the connected pulse generator, a time selector, to the other input of which the output of the reference frequency generator, the counter of the whole measured frequency, and

An indicator characterized in that, in order to improve the measurement accuracy, it is equipped with two additional time selectors, a divider 10 times, a pulse counter controlled by a frequency divider, a fractional counter of the measured frequency, a memory for storing and reproducing a time interval and a control circuit, which is connected to the output of the main time selector, and the output is sequentially

connected by a first additional time selector, a divider 10 times, a pulse counter, controlled by a frequency divider, a second additional time selector, a fractional counter of the measured frequency and an indicator, the control input of the first additional time selector and the controlled frequency divider connected to the generator output the reference frequency, the control input of the second time selector is connected to the output of the time memory and playback circuit, and the inputs of the last connection respectively, to the outputs of the circuit for forming the time interval and the main time

selector.

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f N