SU1023249A1 - Electromechanical filter resonance frequency measuring device - Google Patents

Description

The invention relates to a radio metering technique and finds application in the creation of instruments j intended for measuring resonant frequencies of electromechanical filters (EMF) in the course of their tuning. Devices are known based on the capacitive method of exciting and recording oscillations of mechanical resonators, in which the EMF resonator is one of the capacitor plates. When a voltage is applied to this capacitor with a frequency close to or equal to the resonance frequency, the second and third harmonics appear in the signal spectrum, the amplitudes of which are maximal when the frequency of the excitation coincides with the resonant frequency ij. The disadvantages of these devices are low sensitivity and low accuracy. The closest to the proposed technical entity is a device containing a series-connected generator, a linear key and an electromagnetic sensor with a measured EMF, the second generator output is connected to the input of an electron-counting frequency meter, the sensor output is via a second linear key and a broadband amplifier is connected To the oscilloscope input, the linear key control inputs are connected to the anti-phase outputs of the clock generator 2. A disadvantage of the known device is low measurement accuracy. The purpose of the invention is to improve accuracy and productivity. The goal is achieved by the fact that in a device for measuring the resonant frequencies of an EMF containing the first linear key and electromagnetic sensor with the measured EMF, which are connected to the generator, the generator output is connected to the input of the electron-counting frequency meter, the output of the electromagnetic sensor through the second linear key and a broadband amplifier connected to the input of the oscilloscope, control inputs; linear switches connected to the antiphase outputs of the JTopa time switch; consecutive amplifiers are entered in series detector, first memory block, first threshold block, first dual-channel switch, integrator and second threshold block, a second dual-channel switch, a second memory block and a differential amplifier, as well as an adder and counting trigger, the first output of which is connected to the first one the entrance of the second two. channel switch, the second input of the latter is connected to the output of the amplitude detector, the input of which is connected to the second output of the broadband. amplifier, at. the second trigger output is connected to the first input of the adder, the second input of which is connected to the integrator output, the output of the second threshold unit is connected to the second input of the first two-channel switch, the third input of the last is connected to the output of the differential amplifier, the output of the counting trigger is connected to the input of the clock generator, and the output the adder is connected to the input of the generator. The drawing shows a block diagram of a device for measuring the resonant frequencies of an EMF. The device consists of a generator 1, an electron-counting frequency meter 2, a linear switch 3, a clock generator 4, an electromagnetic sensor 5 with the measured EMF b, a linear key 7, a broadband amplifier 8, an oscilloscope 9, an amplitude detector 10, a counting trigger 11, an adder 12 memory unit 13, threshold unit 14, dual-channel switch 15, integrator 16, threshold unit 17, dual-channel switch 18, memory unit 19, and differential amplifier 20.. The device works as follows. in a way. The high frequency voltage from the generator 1 is fed to the input of the electron-counting frequency meter 2 and the linear key 3. The switching of the linear key 3 is carried out by the clock generator 4. The voltage at the output of the key 3 is radio pulses whose frequency is equal to the frequency of the generator 1. These the radio pulses are fed to the input of the electromagnetic sensor 5 and excite oscillations in one of the selected EMF 6 resonators. All other resonators are damped. After the end of the radio pulse, the damped oscillations of the response of the resonator from the sensor .5 are fed to the input of the second linearly: 7 key, which is controlled by the antiphase voltage of the clock generator 4. Therefore, only the exponential responses of the measured resonance appear at the output of the key 7. These responses, amplified by a wideband amplifier 8, are fed to the input of an oscilloscope 9, which plays an auxiliary role and serves to roughly determine the frequency band in which the resonances of the tunable EMF are. From the output of the wideband amplifier 8, the exponential responses also arrive at the input of the detector, highlighting their envelopes.

The frequency of generator 1 is modulated by the meander coming from the counting trigger 11 through the adder 12. Switching the trigger 11 occurs at the moment of closing the key 3. Therefore, the process of setting the frequency of the generator 1 ends until a radio pulse appears at the output of the key 3. The frequency of the neighboring radio pulses differs by the value of the selected deviation . If the frequency of oscillator 1 is outside the measured resonance band, then there are no effective responses and the voltage at the output of block 13 is below the response threshold of block 14. Therefore, the two-channel switch 15 is switched to the position at which the input of the integrator 16 is connected to the output of block 17. Block 17 has two symmetric opposite polarity ppdra, and the voltage at the output of the integrator 16 is a triangular pulses that rearrange the average frequency of the generator 1. When the generator 1 is tuned, its frequencies fall into the band of the measured resonance and the output of the amplitude detector 10 appear exponential pulses. The amplitudes of these pulses are remembered by block 13, block 14 is triggered, and switches the TLD. The channel switch 15. The frequency inverter of the generator 1 is linearly terminated. Since the measured EMF 6 is excited by radio pulses having different frequencies S at two adjacent clock periods, if, for example, the average frequency of the generator is lower than the frequency of the measured resonance, the exponential response corresponding to the higher frequency of filling of the radio pulse will be greater in amplitude. These responses pass through the dual-channel switch 18 and arrive at block 19,

which memorizes separately the amplitudes of responses corresponding to higher and lower filling frequencies of p1 radio pulses. The difference in these amplitudes is extracted and amplified by the differential amplifier 20 and through

.Open channel. Two-channel com. mutator -15 is fed to the input of the integrator 16, which leads to further restructuring of the average frequency

0 of the generator 1. When the frequency of the generator 1 coincides with the frequency of the measured resonance, the amplitudes of the exponential responses become the same, and the frequency tuning is fine. Since the electron-counting frequency meter 2 measures the average purity of the generator, its indication. equal to the frequency of the measured resonance. The time constant of the block 13 is chosen such that the holding time of the VII voltage at its output is longer than the time of a single tuning of the EMF resonators. This allows the EMF 6 to be repeatedly disconnected from sensor 5, to adjust by resizing.

5 resonators and then automatic frequency measurement. This improves performance tuning and measurement. If the resonant frequency in the tuning process is strong

0 changed, i.e. there are no responses at the output of the amplitude detector 10, the voltage at the output of block 13 will fall below the trigger threshold of block 14, and the search process will repeat

5 and output a new value of frequency.

Since in this device the responses obtained on the slopes of the frequency response of the measured resonance are compared in the measurement process, the measurement accuracy will be higher than that of the prototype. In addition, due to the automation of adjustment, the subjective error of the operator itself is excluded.

Claims (1)

DEVICE FOR MEASURING RESONANT FREQUENCIES OF ELECTROMECHANICAL FILTERS, containing a series-connected generator, a first linear key and an electromagnetic sensor with a measured electromechanical filter, a second output of the generator connected to the input of an electronically-counted frequency meter, the output of the electromagnetic sensor through a second linear key and a broadband amplifier connected to the input of the oscilloscope the control inputs of the linear keys are connected to the antiphase outputs of the clock generator, which is especially important in order to povsheniya accuracy and productivity has been entered 'series-connected amplitude detector, the first memory block, a first threshold unit, the first dvuhbanalny switch, an integrator and a second threshold unit _{L of} serially connected second, dual-channel switch, the second memory block, and a differential amplifier, and the adder and counter a trigger, the first output of which is connected to the first input of the second two-channel switch, the second input of the latter is connected to the output of the amplitude detector, the input of which is connected connected to the second output of the broadband amplifier, while the second output of the counting trigger is connected to the first input of the adder, the second input of which is connected to the output of the integrator, the output of the second threshold block is connected to the second input of the first two-channel switch, the third input of the last is connected to the output of the differential amplifier, the output of the counting the trigger is connected to the input of the clock generator, and the output of the adder is connected to the input of the generator.