RU-2804284-C1 - COMPENSATOR FOR HARMONIC INTERFERENCE IN A LOW-FREQUENCY SIGNAL

RU2804284C1RU 2804284 C1RU2804284 C1RU 2804284C1RU-2804284-C1

Abstract

FIELD: railway transport. SUBSTANCE: means for compensating for interference in the signal of track circuits or automatic locomotive signaling. Compensator for harmonic interference in a low-frequency signal contains a notch filter that suppresses a signal voltage with a frequency of 25 and/or 75 Hz, an amplifier with adjustable gain and a three-winding transformer, the two primary windings of which have the same number of turns and are connected in opposite directions. The notch filter is made in the form of an inductor and a capacitor connected in parallel. In this case, the secondary winding of the isolation transformer of the track circuit or the output of the receiving locomotive coils of the automatic locomotive signaling is connected to one input winding of the three-winding transformer and is connected to the second input winding of the three-winding transformer through a notch filter and an amplifier with adjustable gain. The output winding of the transformer is connected to the input of the signal receiver. EFFECT: increasing the noise immunity of track circuit receivers and automatic locomotive signaling. 1 cl, 1 dwg

Inventors

SHAMANOV VIKTOR INNOKENTEVICH
Denezhkin Dmitrij Valerevich

Dates

Publication Date: 20230926
Application Date: 20230220

Claims (1)

A compensator for harmonic interference in a low-frequency signal of rail circuits or automatic locomotive signaling, containing a notch filter made in the form of a parallel-connected inductor and capacitor, which suppresses the signal voltage with a frequency of 25 and/or 75 Hz, characterized in that, in order to increase the noise immunity of rail receivers circuits and automatic locomotive signaling due to an increase in the degree of noise suppression, it is additionally equipped with an amplifier with adjustable gain and a three-winding transformer, the two primary windings of which have the same number of turns and are connected counter-currently, with the secondary winding of the isolating transformer of the track circuit or the output of the receiving locomotive coils of the automatic locomotive alarms are connected to one input winding of a three-winding transformer and through a notch filter to an amplifier with an adjustable gain, the output of which is connected to the second input winding of a three-winding transformer, connected by its output winding to the input of the signal receiver.

Description

Field of technology to which the invention relates The invention relates to the field of railway automation and telemechanics and improves the noise immunity of signal receivers in track circuits and in automatic locomotive signaling systems by compensating for harmonic interference. State of the art There are known devices for suppressing interference in track circuits and in automatic locomotive signaling systems [1]. However, they do not provide the required degree of attenuation of interference that has a wide frequency range and a large change in amplitudes over time. A device is known for compensating interference in an automatic locomotive signaling receiver, connected to the receiver input, equipped with a notch filter, an inverting transformer with a transformation ratio equal to unity, and a summing three-winding transformer [2]. However, the quality of noise suppression by this device depends on the efficiency of the notch filter and the amount of harmonic noise power loss in the inverting transformer. The invention relates to the field of railway automation and telemechanics and can be used in equipment for track circuits and automatic locomotive signaling. This equipment uses electrical filters on resonant circuits built on inductors and capacitors. This is due to the fact that signal currents in track circuits and automatic locomotive signaling have carrier frequencies in the lower part of the audio range, at which such filters are most effective. Disclosure of the Invention The objective of the invention is to increase the noise immunity of track circuit receivers and automatic locomotive signaling by increasing the degree of suppression of interference from traction current while eliminating the need to make complex circuit or design changes for this purpose. The task is achieved by the fact that the noise compensator is additionally equipped with an amplifier with an adjustable gain and a three-winding transformer, the two primary windings of which have the same number of turns and are connected counter-currently, and the secondary winding of the track circuit isolating transformer or the output of the receiving locomotive coils of the automatic locomotive signaling are connected to one input winding three-winding transformer and through a notch filter to an amplifier with adjustable gain, the output of which is connected to the second input winding of the three-winding transformer, connected by its output winding to the input of the signal receiver. Brief description of drawings The drawing shows a block diagram of the interference compensator. Carrying out the invention The device contains an amplifier with an adjustable gain 1, the input of which, through a notch filter, made in the form of a parallel-connected inductor 2 and a capacitor 3, is connected to the secondary winding of the isolating transformer of the track circuit or to the receiving locomotive coils of the automatic locomotive signaling, to which one input is also connected winding of a three-winding transformer 4, its second input winding is connected back to back with its first winding and connected to the output of an amplifier with adjustable gain 1, and the output winding of the transformer is connected to the input of the signal receiver 5. The device works as follows. The voltage on the secondary winding of the track circuit isolating transformer or at the output of the receiving locomotive coils of the automatic locomotive signaling, each of which contains the sum of the voltages of the useful signal and interference goes to a notch filter, which significantly attenuates the useful signal Therefore, almost only noise voltage is supplied to the input of the variable gain amplifier. which, after amplification, is fed to one of the input windings of a three-winding transformer. The second input winding of this transformer receives a signal containing the sum of the voltages of the useful signal and interference . Since the input windings of the transformer are connected back-to-back, its output signal is equal to the difference between the signals . As a result, the compensator significantly reduces interference in the signal received from the rail line. The notch filter to some extent attenuates interference at frequencies close to the tuning frequency of the notch filter, i.e. to the frequency of the useful signal. Tuning with a variable gain amplifier makes it possible to equalize the voltages on the harmonics of the interference at the inputs of the second and first windings of the transformer, thereby increasing the efficiency of noise compensation. Thus, supplying the noise compensator with the indicated elements ensures a significant reduction in powerful interference from alternating traction current in rail lines, especially growing when the train flow thickens or the movement of heavy trains. This ensures a reduction in failures in the operation of signal receivers in track circuits and in automatic locomotiv