SU779948A1 - Device for measuring magnetic receiver conversion coefficient - Google Patents

Description

The invention relates to the field of * magnetometry, is intended to measure the conversion coefficient of devices containing magnetic receivers under conditions of strong interference, as well as to monitor the operability of such devices.

A device for measuring the conversion coefficient of magnetic receivers is well-known, containing a master oscillator and a magnetic field source with a magnetic receiver [1].

Since the interference directly affects the measurement results, their accuracy is low, and such devices can only be used in cases where the field of the monitored signal significantly exceeds the noise field. However, in most cases this condition is not feasible. 2Q A device for determining the conversion coefficient of broadband magnetic receivers is also known. It contains a magnetic field source, a magnetic receiver, a master oscillator, amplitude and synchronous detectors, a selective amplifier, an adder and a switch [2], which makes it possible to eliminate the influence of interference on the result of measuring the conversion coefficient.

COEFFICIENT MEASUREMENTS R R P T B I

MAGIC RECEIVERS ί - ------- I (ffeSiSS. 'Yr.' Thy I

However, such a device is not allowed. It is possible to measure the conversion coefficient in those cases when the interference field exceeds the limit threshold — the field at which the overload of the electronic circuit of the magnetic receiver occurs. Since even in laboratory conditions interference, for example industrial, can cause overloading of the magnetic receiver, 10 the use of the described device is limited.

The purpose of the invention is to increase the noise immunity when measuring the conversion coefficient of the magnetic receivers.

This goal is achieved by the fact that a device containing a master oscillator, an adder and a magnetic receiver sequentially connected to a magnetic field source is equipped with a series-connected zero-organ, phase shifter, (key, memory element, low-pass filter and amplifier, the output of which is connected to the second input , an adder, the first input of which is connected to the input of the phase shifter.

In the drawing (shows a structural diagram of the proposed device.

Magnetic receiver 1 is placed in a magnetic field created by source 2. The output signal of the magnetic receiver is switched by a normally connected key 3, a memory element 4, a low-pass filter 5 and an amplifier 6 to one input of the adder 7, the other input of which is connected to the master oscillator 8, and the output is connected to a magnetic field source. The generator is also connected through a phase shifter 9 to the input of the null organ 10, and the output of the latter is to the control input of the key,

The device operates as follows.

Magnetic receiver 1 is affected by two 'interference fields and a control signal field created by source 2. A control signal is supplied to magnetic field source 2 from the output of master oscillator 8 through an adder 7.2Q. In magnetic receiver 1, magnetic fields are converted to voltage proportional to them. The signal from the output of the master oscillator 8 is also fed to the input of the phase shifter 9, which eliminates the phase shift between this voltage and the voltage caused by it at the output of the magnetic receiver 1. At zero transition times, the voltage of the control signal supplied to the input of the zero-organ 10 from the phaser - 30 of the switch 9, at the output of the zero-organ short pulses are generated, which are fed to the control input of the normally open key 3 and open it. The signal input of the key 3 is supplied with the voltage from the output of the magnetic receiver 1. Since the voltage of the control signal and the voltage caused by it ........... are different in phase with the output of the magnetic receiver, then when the key 3 is open, the response to the control signal at the output of the magnetic receiver is equal to 'Liu, and at the input of the storage element 4, only the interference voltage acts. Thus, at the output of the storage element 4, a sequence of samples is formed, the envelope of which is proportional to the noise. The storage element 4, which in the simplest case is a capacitor, serves to highlight the envelope of the sequence of samples. When you open the key 3 at the output of the storage element 4 is set to a voltage equal to the interference voltage. This ”П P; ё: yryazheyye is preserved until the arrival of a new“ control ”pulse, during the action of which a new value of the interference voltage is set at the output of the memory element 4, etc. At the output of the storage element 4, a step voltage is generated, the low-frequency component of which

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which is proportional to the noise. This component extracted by the LPF 5 is set in amplifier 6 and supplied through the adder 7 to the magnetic field source 2, thereby forming a negative feedback circuit for pomehe.Dlya ensuring effective noise suppression is necessary, ^z 8 to the generator frequency at, least twice the the frequency of the highest harmonic of the interference spectrum. Otherwise, the interference and control spectra overlap and it is impossible to separate them using filter 5. The conversion coefficient of the magnetic receiver 1 is defined as the ratio of the measured voltage at the output of the device to the known magnetic field strength created by the source 2.

The introduction of deep negative feedback on the interference in this device allowed to significantly increase the noise immunity when measuring the conversion coefficient of the MAG receiver. As shown by the results of an experiment conducted on an existing laboratory mock-up, the device’s operability was preserved under the conditions of industrial noise, the value of which was 50 times higher than the threshold limit of the magnetic receiver.

Such a high noise immunity makes it possible to use the present invention when measuring the conversion coefficient of magnetic receivers and monitoring the operability of various devices containing magnetic receivers under conditions of strong interference.

Claims (2)

Mai-receiver 1 is placed in the magnetic field created by the source 2 The output signal of the magnetic field is transmitted through successively connected normally open key 3, memory element 4, low-frequency filter 5 and amplifier 6 to one input of adder 7, the other input of which is connected to master oscillator 8 , and the output - with a source of magnetic field. The generator is also connected via a phase shifter 9 to the input of the null organ 10, and the output of the latter is connected to the control input of the key. The device works as follows. The magnetic receiver 1 is affected by two fields of interference and the field of the control signal generated by source 2. The control signal enters source 2 of the magnetic field from the output of the master oscillator 8 through a 7 V adder of the magnetic receiver 1 and the magnetic fields are transformed into proportional voltages. The master oscillator 8 is also fed to the input of the phase shifter 9, which eliminates the phase shift between this voltage and the voltage generated by it at the output of the magnetic flux 1. At the time of the zero crossing, the voltage control one signal input to the input zero-body 10 with the phase shifter 9, the output of the zero-organ expression batyvayuts short pulses, which are applied to a control input Normal open but the key 3 and open it. The signal input of the key 3 is supplied; the voltage is from the output of the magnetic field 1. Since the control voltage of the signal and the voltage caused by it at the output of the magnetic field is in-phase, at the moment when the key 3 is open, the response to the control signal of the magnetic field is equal to the signal equal to : storage element 4, interference voltage is valid. Thus, the Hai output memory element 4 forms a sequence of samples, the envelope of which is proportional to the interference. The memory element 4, which in the simplest case is a capacitor, serves to select: 1 the envelope of the sample sequence. When opening the key 3 at the output of the storage element 4 is set for example | a tension equal to the voltage. This voltage is stored until the arrival of a 15GB control signal pulse, during which a new value of the interference voltage is set at the output of the storage element 4, and so on. At the output of the memory element 4, a step voltage is formed, the low frequency component of which is proportional to the interference. This component is extracted by a low-frequency filter 5, installed by amplifier 6, and fed through a mmattor 7 to a magnetic field source 2, thereby forming a negative feedback loop for interference. To ensure effective suppression of the interference, it is necessary that the oscillator 8 is at least. at least twice the frequency of the higher harmonic of the interference spectrum. Otherwise, the interference and pilot spectra overlap and it is impossible to separate them using filter 5. The conversion factor of magnetic field 1 is defined as the ratio of the measured voltage at the output of the device to the known magnetic field strength generated by source 2. The introduction of deep negative feedback on the interference in this device allowed us to significantly increase the noise immunity when measuring the conversion factor of magnetic receivers. As shown by the results of an experiment conducted on an operating laboratory mock-up, the operability of the device was maintained under conditions of industrial interference, the magnitude of which was 50 times higher than the limit of the magnetic flux limit. Such a high noise immunity makes it possible to use the present invention in measuring the conversion factor of the magnetic receivers and monitoring the operability of various devices containing magnetic receivers under conditions of strong interference. The invention of a device for measuring the conversion factor; an magnetic receiver comprising a series-connected master oscillator, an adder and a magnetic receiver with a magnetic field source, characterized in that, in order to increase the noise immunity, it is equipped with a series-connected phase shifter, null organ, a key that stores entom, .filter low frequency and amplifier, whose output is connected to the second input of the adder, the first input of which is connected to the input of the phase shifter. Sources of information taken into account during the examination 1. USSR author's certificate No. 491112, cl. G 01 R 33/00, 1975. 2. USSR Author's Certificate No. 509846, C 01 R 33 / 00.1975.