JPS6047140B2 - Track circuit transmitter/receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to the audio frequency band or several tens of KHz to several hundred KHz.
The present invention relates to a track circuit transmitting/receiving device using the H2 frequency band and using a track or a guide wire as a transmission path.

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. For this reason, on tracks, this phenomenon appears as a return current flowing through the wheels of electric cars, which 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 wheel and the track.

In particular, the latter arc noise is in the same frequency band 2 [KE2] to the signals superimposed on the orbit by various control devices for the orbit circuit, as shown in Fig. 1, an example of its frequency spectrum.
In No. 10 [KH2], 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.
There is a need for a track circuit transmitting/receiving device that operates stably even when such random noise occurs.

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

In order to achieve such an object, the track circuit transmitting/receiving device according to the present invention combines a predetermined number of modulation signals having different frequencies to form two sets of modulation signals, and uses these two sets of modulation signals. modulates a carrier signal of a predetermined frequency,
The modulated signal is sent to the receiver side via the transmission path, and the receiver side demodulates the modulated signal and then detects the frequency components constituting the demodulated signal. Obtain two sets of detection signals corresponding to the previous and previous two sets of modulation signals, only having the same frequency components as the constituent frequency components of the set of modulation signals,
The exclusive OR of these two sets of detection signals is taken, and this exclusive OR output signal is used as the output signal of the track circuit transmitting/receiving device.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 is a block diagram showing an embodiment of a track circuit transmitting/receiving device according to the present invention. In the figure, the handset 1 includes oscillators 0s1 to 0sn and 0Sc, a combinational circuit CNW,
Analog selector ASl Sequence controller SQl
consisting of a modulator MDl power amplifier PAl transformer MT;
The output signal of power amplifier PA is applied to track RL via transformer MT.

On the other hand, the receiver 2 has a loop antenna LPl transformer ITl
Bandpass filter BPFl Amplifier A1 Demodulator DEMl
Filters FLl to FLl rectifiers RECl to RECn, decoders DECl exclusive OR circuits XORl to XOR. n
This exclusive OR circuit XORl−~XORm
The output signals 0T1 to 0Tm are sent out as output signals of the track circuit transmitting/receiving device.

In such a configuration, the combinational circuit CNW receives the outputs from the oscillators 0S1 to 0Sn, respectively. Based on the modulation signals of different frequencies f1 to Fn, for example, the following first
As shown in the table, two sets of first and second modulation signals Fml, f are obtained by combining a predetermined number of modulation signals with frequencies f1 to Fn.
m2 and the input terminal 11 of the analog selector AS,
Supply to i2.

Analog selector AS is sequence controller SQ
The modulation signal F. input to the input terminal 11, i2 is controlled by the select control signal SL applied from the input terminal 11, i2. ．． l,f
．． ．． 2 is alternately selected, and this is used as the modulation signal/signal F. n to the modulator MD. Then, the modulator MD becomes the oscillator 0S0
The carrier wave signal Fc output from the modulated signal F.
．． (frequency modulation or amplitude modulation). In this case, the modulated signal F. is Fn. Since the waveform of the modulated signal obtained from the modulator changes alternately, the waveform of the modulated signal obtained from the modulator changes alternately. The modulated signals F, . . After being power amplified in the power amplifier PA, it is applied to the track RL via the transformer MT. In such a state, if the vehicle TR does not exist between the application point of the modulated signal FmO and the arrangement position of the loop antenna LP, the loop antenna LP does not include the handset 1.
A voltage of a predetermined level is induced by the applied modulated signal Fn,c. This induced voltage signal of the loop antenna LP is supplied to the bandpass filter BPF via the transformer IT as an orbital current detection signal. Then, unnecessary components outside the band are removed by this bandpass filter BPF, and the resultant signal is inputted to the demodulator DEM via the amplifier A.
The demodulator DEM demodulates the track current detection signal input from the amplifier A, and sends the demodulated signal to the filters FLl to FLn.
supply to. The filter characteristics of the filters FLl to FLr) are determined corresponding to the output frequencies f1 to Fn of the oscillators 0S1 to 0Sn. Therefore, the first modulation signal F
．． If the constituent frequency components of the first modulated signal F.nl and the second modulated signal Fm2 are as shown in Table 1 above, the first modulated signal F. ．． At the modulation operation timing according to l, the filter FLl
- the output signal appears only on FL3, and the second modulated signal F.
．． At the modulation operation timing according to 2, filters FL3 to F
An output signal appears only in L5. This filter FLl~F
1-. The output signals of rectifiers RECl to REC. After being converted into a DC signal at the DC signal, the signal is input to the decoder DEC. The decoder DEC uses a filter F to determine what frequency components the demodulated output signal of the demodulator DEM consists of.
It detects based on the output signals of Ll to FL, and has output terminals 1 to r corresponding to the types of combinations of the combinational circuit CNW in the transmitter 1. And output terminal 1
The output conditions for ~r are as shown in Table 2 below, for example. Therefore, the frequency f1~ in the combinational circuit CNW
If the combination of the modulation signals Fn is set such that output signals are obtained at output terminals 1 and 2 of the decoder DEC, for example, the modulation signals F. ．． At the modulation operation timing 2, output signals are obtained alternately at output terminals 1 and 2. Therefore, if the output signals of output terminals 1 and 2 are input to the exclusive OR circuit XORl, a continuous "H" level DC signal can be obtained from this circuit XOR. From XORl, the demodulated output signal of the demodulator DEM is the first modulated signal F.
．． ．． l consists of frequency components corresponding to the second modulation signal Fm2, and only when these components appear alternately does it become a continuous "
A high level DC signal is obtained. On the other hand, when the vehicle TR exists on the orbit within a predetermined range, the modulated signal F. . is shorted by the vehicle of vehicle TR.
Therefore, no induced voltage is generated in the loop antenna LP, and as a result, the output signal of the exclusive OR circuit XORl is “
The signal becomes L level. Therefore, exclusive OR circuit
From the output signal of ORl, it can be determined whether the vehicle TR is on a trajectory within a predetermined range.

As is clear from the above, the present invention checks whether the constituent frequency components of the demodulated signal of the orbit detection current are the same as the components determined by the combinational circuit of the transmitter. This is to check.

Therefore, even if the first stage check operation malfunctions for some reason, the transmission of an erroneous output signal in the next complementarity check is prevented. This eliminates the possibility of sending out erroneous output signals due to non-complementary noise in which the frequency components change moment by moment, such as random noise, and provides excellent noise resistance. It is possible to obtain a track circuit transmitting/receiving device that always operates stably even when 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.

[Brief explanation of drawings]

FIG. 1 is a graph showing an example of a frequency spectrum of random noise, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1... Transmitter, 2... Receiver, 0S1 to 0Sn, 0
S0...Oscillator, CNW...Combination circuit, SQ
...Sequence controller, Immediately...Modulator, PA
...Power amplifier, LP...Loop antenna, D
EM...Demodulator, FLl to F1-R. ... Filter, RECl to RECn... Rectifier, DEC... Decoder, XORl to XOR. ．． ...Exclusive OR circuit.

Claims (1)

[Claims] 1. In a track circuit transmitting/receiving device that uses a track or a guide wire as a signal transmission path, a predetermined number of modulation signals with different frequencies are combined to form two sets of modulation signals, and these two sets of modulation signals are used. a transmitter that alternately modulates a carrier wave signal of a predetermined frequency and sends the modulated signal to the transmission path; and a detector that is placed at a certain distance from the transmission point of the modulated signal and that detects orbital current. , a demodulator that demodulates a signal obtained by removing predetermined unnecessary components from this detector output signal, and a frequency component constituting this demodulator output signal is
A frequency component detector that outputs two sets of detection signals corresponding to the two sets of modulation signals only when the frequency components are the same as constituent frequency components of the two sets of modulation signals, and two sets of detection signals output from the frequency component detector. 1. A track circuit transmitting/receiving device, comprising: a receiver comprising an exclusive OR circuit which receives as input, and an output signal of the exclusive OR circuit is used as an output signal of the track circuit transmitting/receiving device.