JPS6044179B2 - Track circuit transmitter/receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a track circuit transmitting/receiving device used in a railway signal safety system.

In recent years, the density of vehicles has been increasing rapidly as transportation capacity has increased.

As a means of increasing vehicle density, it is necessary to increase the speed of vehicles (electric vehicles) and strengthen their high acceleration and deceleration performance, and from the viewpoint of energy conservation, chopper control vehicles are being introduced. Therefore, on the track, a phenomenon appears in which the return current flowing through the wheels of the electric car gradually increases as the electric car current increases. For this reason, the noise level increases rapidly near the orbit.
This is beginning to have an adverse effect on various signaling devices that utilize tracks as part of their circuit configurations. The noise generated near the track described above can be roughly divided into two types: induced noise from the chopper control device and arc noise due to the electric car current generated at the contact surface between the electric car wheels and the track.

In particular, the latter arc noise is in the same frequency band 2 [kHz2] as the signals superimposed on the orbit by various control devices for track circuits, as shown in Fig. 1, an example of its frequency spectrum.
At 10 [kHz2], each harmonic component exists at a uniform level, making it close to so-called random white noise. For this reason, conventionally used filters such as bandpass filters are no longer able to easily remove the random noise mentioned above, and even if such random noise occurs, it is no longer possible to remove it stably. There is a need for a track circuit transmitter/receiver that operates in the same way.

Therefore, the present invention was made in view of the above circumstances, and its purpose is to provide a track circuit transmitting/receiving device that has high noise resistance and operates stably even when random noise occurs. It is in.

In order to achieve such an object, the track circuit transmitting/receiving device according to the present invention calculates an autocorrelation function φ(d) of a signal detected from the orbit, and determines if this autocorrelation function φ(τ) is a predetermined value or more. Only when the vehicle is not on the track within a predetermined range is it determined.

In other words, as shown in the graph of FIG. 2, the autocorrelation function φ, (τ) of random noise has the characteristic that the lag τ is small except around τ=0.

On the other hand, if a sinusoidal AC signal of a predetermined frequency Fc is supplied to the track and a track current is detected at a certain distance from this supply point, the vehicle will If the detection signal from the orbit does not exist in the section between the two points), the detection signal from the orbit will have the same frequency as the sinusoidal AC signal.

Therefore, the autocorrelation function φ of the detection signal in this case. (τ)
As shown in the graph of Figure 3, (7) n times period
Oh! (It has periodicity such that it becomes RlJ when n=1, 2, 3, etc.).

Therefore, the autocorrelation function φ(
When determining τ), if the lag τ is set to n times the time interval of one cycle of the sine wave AC signal frequency FO, the autocorrelation function φ( τ) indicates the maximum value.

Therefore, the autocorrelation function φ(
If τ) is determined at a predetermined level by setting τ=lock·n, the presence or absence of a vehicle can be discriminated regardless of random noise. Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 4 is a diagram showing an embodiment of a track circuit transmitting/receiving device according to the present invention. In the same figure, transmitter 1 is oscillator 0S
1,0S2, modulator MDl power amplifier PAl transformer T
.

The sine wave alternating current signal with a frequency FO outputted from the oscillator 0S1 is converted to a frequency F. ．．
amplitude modulated by a square wave signal. Therefore, the alternating current signal of frequency FO is intermittently outputted from the modulator at the blue cycle. The AC signal output from the modulator is amplified in power by the power amplifier PA and applied to the track RL via the transformer L. On the other hand, the receiver 2 includes an autocorrelation function calculator ACFCl level discriminator LDl rectifier RE, which is composed of a loop antenna LPl transformer T1, bandpass filters BPFl amplifiers A1 and A2, a delay circuit DL, a multiplier, and an integrator 1.
It has a Cl relay R.

In such a configuration, if the vehicle TR does not exist between the application point of the AC signal by the transmitter 1 and the arrangement position of the loop antenna "LP," the loop antenna LP is not affected by the AC signal applied by the transmitter 1. A voltage of a predetermined level is induced.

This induced voltage signal of the loop antenna LP is supplied to the bandpass filter BPF via the transformer T1 as an orbital current detection signal. Then, in this bandpass filter BPF, unnecessary components outside the band are removed, and the amplifier A
1 to the autocorrelation function calculator ACFC.
The signal of frequency Fc input to the autocorrelation function calculator ACFC is directly supplied to one input terminal of the multiplier M, and is also delayed by ln time in the delay circuit DL and then supplied to the other input terminal of the multiplier M. supplied to

Here, when the vehicle TR is not on a trajectory within a predetermined range, the signal input to the autocorrelation function calculator ACFC is defined as Xc(t), and the delayed signal obtained from the output of the delay circuit DL is defined as XO(t- τ) (where τ = lock n), in the multiplier M, Xc(t) XO(t
−τ) is being multiplied.

Then, the output signals of this multiplier M are XO(t) and XO(t
-τ) is integrated at the blue time interval in the integrator 1 and weighted with a predetermined weighting coefficient w(ty). Therefore,
The autocorrelation function calculator ACFC outputs an autocorrelation function output φ as shown in the following first equation when the vehicle TR is not on a trajectory within a predetermined range.

(τ) is output. Autocorrelation function output φc in this case
(τ) is φ.

(τ)=1 is 1/F. ．． It is obtained as an alternating current signal that appears with a period of . On the other hand, when the vehicle T comes to exist on the orbit within a predetermined range, the AC signal from the transmitter 1 is transmitted to the vehicle T.
Shorted by the R wheel.

Therefore, only random noise components are generated in the loop antenna LP. Under these conditions, the noise signal input to the autocorrelation function calculator ACFC is
N(t), and the output signal of the delay circuit DL is XN(t-τ)
When expressed as , the autocorrelation function calculator ACFC outputs an autocorrelation function output φN(τ) as shown in the second equation. In this case, since the lag τ is set to blue n, the autocorrelation function output φN(
τ) will be small.

Therefore, the output φ(τ
) at a predetermined reference level, it is possible to know whether the vehicle is moving on a trajectory within a predetermined range, regardless of random noise.

Therefore, the autocorrelation function output φ(τ) of the autocorrelation function calculator ACFC is at the discrimination reference level φ. When a larger autocorrelation function φ(τ) is input, a “H” level discrimination signal is output, and when an autocorrelation function φ(τ) with φo≧φ(τ) is input, a “L” level discrimination signal is output. The reference level φ is input to a level discriminator that outputs a signal. compared to For example, the autocorrelation function φ, (γ) of random noise is the second
If it is as shown in the figure, the reference level φ. isφ
. Set to ≧0.2. Then, the autocorrelation function φ(τ) when the vehicle is not on a trajectory within a predetermined range is a coefficient φ that becomes RlJ at a period of time. Since (τ),
The level discriminator outputs an AC signal in which the repetition period of the 66W5 level and the 6'LO level is different. This AC signal is supplied to the rectifier REC via the amplifier A2 and rectified. As a result, a rectified output of a predetermined voltage level is obtained from the rectifier REC, and the relay R is driven by this rectified output. Then, the contact of relay R causes the car W! T
It can be known that R does not exist on the orbit within the predetermined range. On the other hand, the autocorrelation function φ(τ) when the vehicle m exists on a trajectory within a predetermined range is the coefficient φN(τ) expressed by the second equation above, and this coefficient φN(τ)
is the reference level φ. When compared with ≧0.2, φN(
τ) くφ. There is a relationship between For this reason, the level discriminator LD
The output signal becomes a continuous DC signal at "°L" level.

As a result of this, relay R is no longer driven. In other words, even if random noise occurs, relay R will not be driven, and even though the vehicle is on the trajectory within a predetermined range, relay R will be driven due to the influence of random noise. Therefore, an erroneous detection as if the car 11FI'R does not exist cannot occur. Note that in this case, for noise resistance, it is better to have a larger lag τ when determining the autocorrelation function φ(τ).

As can be seen from the above explanation, the present invention detects the presence or absence of a vehicle by utilizing the difference between the characteristics of the autocorrelation function of random noise and the characteristics of the autocorrelation function of a sine wave AC signal. It is something. A sinusoidal AC signal for checking the presence or absence of a vehicle is intermittently applied to the track. Therefore, it is possible to obtain a track circuit transmitting/receiving device that has excellent noise resistance, always operates stably even when random noise occurs, and always operates on the fail-safe side.

This is extremely effective in preventing various accidents caused by increased vehicle speeds and increased vehicle density. In the above-described embodiment, the autocorrelation function calculator is constructed of an analog type, but it may be replaced with a digital type.

[Brief explanation of drawings]

Fig. 1 is a graph showing an example of the frequency spectrum of random noise, Fig. 2 is a graph showing the autocorrelation function of random noise, Fig. 3 is a graph showing the autocorrelation function of a sinusoidal AC signal, Fig. 4 FIG. 1 is a diagram showing an embodiment of the present invention. 1...Transmitter, 2...Receiver, 0S1,
0S2...Oscillator, MD...Modulator, PA
...Power amplifier, RL ... Orbit, LP
......Loop antenna, BPF...Band pass filter, Al, A2...Amplifier, DL...
...delay circuit, M...multiplier, I...
...Integrator, ACFC...Autocorrelation function calculator, LD...Level discriminator, REC...
rectifier.

Claims (1)

[Claims] 1 A transmitter that repeatedly and intermittently supplies an alternating current signal of a predetermined frequency to the orbit, a detector that detects the orbital current and is placed at a certain distance from the intermittent supply point of the alternating current signal, and a predetermined signal that is detected from the detection signal of this detector. means for removing unnecessary components; and multiplying the output signal of the means by a delayed signal delayed by an integral multiple of one cycle time of the alternating current signal, and applying the multiplication output to the time interval of the intermittent supply. an autocorrelation function calculator for calculating the autocorrelation function output of the output signal by integrating according to the output signal; a level discriminator for discriminating the output signal level of the autocorrelation function calculator at a predetermined level; and a receiver comprising a rectifier for rectification, and the output signal of the rectifier is used as a detection signal indicating the presence or absence of a train between the intermittent supply point of the alternating current signal and the arrangement point of the detector. A transmitting and receiving device for the track circuit.