EP0282932B1 - Frequency-modulated track current circuit - Google Patents

Frequency-modulated track current circuit Download PDF

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Publication number
EP0282932B1
EP0282932B1 EP88103941A EP88103941A EP0282932B1 EP 0282932 B1 EP0282932 B1 EP 0282932B1 EP 88103941 A EP88103941 A EP 88103941A EP 88103941 A EP88103941 A EP 88103941A EP 0282932 B1 EP0282932 B1 EP 0282932B1
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European Patent Office
Prior art keywords
track
frequency
circuit
modulated
transmitter
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EP88103941A
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German (de)
French (fr)
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EP0282932A2 (en
EP0282932A3 (en
Inventor
Helmut Uebel
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Alcatel Lucent Deutschland AG
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Alcatel SEL AG
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B61RAILWAYS
    • B61LGUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
    • B61L1/00Devices along the route controlled by interaction with the vehicle or train
    • B61L1/18Railway track circuits
    • B61L1/181Details
    • B61L1/188Use of coded current

Definitions

  • the invention relates to a track circuit according to the preamble of claim 1.
  • Electronically controlled drives of rail vehicles especially chopper or phase control, generate an extensive harmonic spectrum in the drive current.
  • the drive reverse current flowing through the rails can disrupt track circuits; in the worst case, it is even conceivable that a track section is incorrectly released.
  • the operational safety of track circuits can be increased by using coded track circuits.
  • the track currents of AC-powered track circuits can be modulated, for example, in amplitude, in phase or in frequency. With the aid of the modulation, coding can be transmitted from the track circuit transmitter to the track circuit receiver. Of the Track circuit receiver then checks the coding in addition to the track voltage level and only reports the corresponding track section if it is correct. Normally, the electronic drives of the traction vehicles cannot replicate this coding, so that an incorrect track vacancy detection is excluded.
  • a circuit arrangement for operating a frequency-modulated, coded track circuit is known, for example, from the journal Signal und Draht 74 (1982), 7/8, pages 151 to 160.
  • a certain bit pattern is generated in the track circuit transmitter, which is fed as a frequency-modulated signal to the rail section to be monitored.
  • the transmitter emits an upper or lower cut-off frequency when a bit with the logic state 1 or 0 is present.
  • the track circuit receiver demodulates the track voltage and compares the bit pattern with a stored target bit pattern. If the target bit pattern corresponding to the bit pattern sent corresponds to a track vacancy signal. If the level of the received signal is too low or the bit patterns do not match, the track section remains reported as occupied.
  • a disadvantage of the known circuit arrangement is that the realization of the track circuit receiver is complex because of the required, signal-technically reliable checking of the bit pattern.
  • a bandpass filter must be used in the receiver, the bandwidth of which is greater than the frequency deviation of the track voltage and which, in order to avoid disturbing amplitude modulation at the output of the filter, has an approximately linear frequency response within its bandwidth.
  • the relatively large filter bandwidth causes a certain susceptibility to faults in the track circuit. Even if the malfunctions due to the code check no longer cause false free messages, they can still reduce the availability of the track circuit.
  • the invention has for its object to provide a frequency-modulated track circuit that works interference-free and is constructed much simpler than the above-mentioned known track circuit.
  • the circuit arrangement according to the invention is characterized in that simple known and proven devices such as e.g. the tube track relay (see e.g. DE-PS 10 98 982, in particular Fig. 1) can be used, which only need to be supplemented by the bandpass filter on the input side.
  • a frequency generator that can be modulated in frequency and is controlled by a code generator is used as the track current circuit transmitter.
  • the tracking of the center frequency of the bandpass filter allows the use of an extremely narrow-band bandpass filter, so that the entire arrangement can hardly be disturbed.
  • the drawing shows the block diagram of a circuit arrangement for track vacancy detection of a double-rail insulated track section 4 using a conventional tubular track relay 8.
  • the track current circuit transmitter 2 has a modulation input ME and a track voltage output GA.
  • a code generator 1 is connected to its modulation input ME as a modulator, while its track voltage output GA is connected to a feed point 3 of a track section 4.
  • the tubular track relay 8 has a mains voltage input NE and a track voltage input GE as well as an output GF for track vacancy detection and an output GB for track occupancy reporting.
  • the signals of the outputs can e.g. be displayed in a signal box.
  • the mains voltage input NE of the tubular track relay 8 receives its voltage from the track voltage output GA of the track current circuit transmitter 2 via a connection 9. For this purpose, this voltage must have a level sufficient for the operation of the tubular track relay.
  • the track voltage at an exit point 5 of the track section 4 passes via a low-pass filter 6 to the signal input SE of a comb filter 7 and from its signal output SA to the track voltage input GE of the tubular track relay 8.
  • the comb filter 7 additionally has a reference voltage input RE, which is connected to the track voltage output GA of the track circuit transmitter 2 connected is.
  • the proven tubular track relay used in systems of the Deutsche Bundesbahn can be used as the tubular track relay 8. This gives a track vacancy signal at its output GF when the voltage at its track voltage input is a predetermined one Threshold value is exceeded and its phase does not deviate by more than 15 ° from the voltage at the mains input. If the voltage at the track voltage input is below the threshold, a track occupancy message is issued at the GB output. If the two voltages at the inputs NE and GE have a phase difference of more than 15 °, interference voltages reach the input GE or the tubular track relay 8 has an internal defect, either the simultaneous output of a free and a busy message takes place or none of them Outputs activated. The latter two states are to be interpreted as a fault.
  • a circuit as described in the magazine Electronics, November 22, 1973, pages 118 to 119, or any other clocked filter can be used as the comb filter 7.
  • Such a circuit requires an external reference frequency which corresponds to the desired center frequency f0 of the filter.
  • Comb filters have a comb-shaped frequency response, where there are maxima at integer multiples of the center frequency f0, so their frequency response continues periodically. Depending on the design of the comb filter, the reference frequency must first be multiplied.
  • the use of the transmitter output voltage or a voltage that is altered in height, with its frequency and in phase voltage, to operate the tube track relay and as a reference for the adjustable comb filter enables the receiver to be designed to be very narrow-band, because through the common modulation of the transmitter center frequency and the reference frequency of the Comb filter eliminates the need to receive a frequency band that is wider than the frequency swing.
  • a very narrow-band receiver as can be achieved by connecting a comb filter, is practically no longer disruptive.
  • the filter settling time which is known to be long for narrow-band filters, prevents a response to higher-frequency interference. Otherwise, it is hardly noticeable, since the comb filter is not clocked, but only changed in frequency in accordance with the modulation signal. Only when the filter input voltage changes in amplitude, as occurs when the track section is occupied or cleared, can the large settling time appear with a delay. However, with a permitted delay of 0.5 s when the track section is occupied or cleared, it is still possible to set the bandwidth of the comb filter to 1 Hz.
  • Interferences that could also be caused by integer multiples of the filter center frequency are caused by the low-pass or bandpass filter 6 connected upstream of the comb filter, which has an upper limit frequency of 1.5 times the comb filter center frequency and all higher multiples of the comb filter Center frequency blocked, switched off.
  • An additional gain in interference immunity can also be achieved in that the track circuit frequency is not generated independently of the drive circuit, but is in a fixed, non-integer ratio to the drive current frequency. This prevents accidental correspondence between the track circuit frequency and harmonics of the drive current frequency.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Train Traffic Observation, Control, And Security (AREA)
  • Circuits Of Receivers In General (AREA)
  • Amplitude Modulation (AREA)
  • Transmitters (AREA)
  • Details Of Television Scanning (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Superheterodyne Receivers (AREA)
  • Amplifiers (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

A circuit is described in which the bandwidth of the track circuit receiver (8) is design to be so narrow that it is virtually impossible for it to be subjected to interference. To permit interpretation of the frequency-modulated track voltage, the frequency deviation of which far exceeds the bandwidth of the receiver, the narrow band characteristic is achieved by means of an adjustable bandpass filter (7), the centre frequency of which is controlled so that it precisely follows the frequency of the track circuit transmitter (2). For this purpose, the output signal from the track circuit transmitter is fed to the track circuit receiver via a special lead (9). <IMAGE>

Description

Die Erfindung betrifft einen Gleisstromkreis gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a track circuit according to the preamble of claim 1.

Elektronisch gesteuerte Antriebe von Schienenfahrzeugen, insbesondere Chopper- oder Phasenanschnittssteuerungen, erzeugen ein umfangreiches Oberwellenspektrum im Triebstrom. Der durch die Schienen fließende Triebrückstrom kann in diesen Fällen Gleisstromkreise stören, im ungünstigsten Fall ist sogar die fälschliche Freimeldung eines Gleisabschnittes denkbar. Die Betriebssicherheit von Gleisstromkreisen läßt sich durch den Einsatz codierter Gleisstromkreise erhöhen. Die Gleisströme wechselstromgespeister Gleisstromkreise können z.B. in der Amplitude, in der Phase oder der Frequenz moduliert werden. Mit Hilfe der Modulation ist eine Codierung vom Gleisstromkreissender zum Gleisstromkreisempfänger übertragbar. Der Gleisstromkreisempfänger überprüft dann zusätzlich zum Gleisspannungspegel die Codierung und meldet nur bei deren Richtigkeit den entsprechenden Gleisabschnitt frei. Normalerweise können die elektronischen Antriebe der Triebfahrzeuge diese Codierung nicht nachbilden, so daß eine fälschliche Gleisfreimeldung ausgeschlossen ist.Electronically controlled drives of rail vehicles, especially chopper or phase control, generate an extensive harmonic spectrum in the drive current. In these cases, the drive reverse current flowing through the rails can disrupt track circuits; in the worst case, it is even conceivable that a track section is incorrectly released. The operational safety of track circuits can be increased by using coded track circuits. The track currents of AC-powered track circuits can be modulated, for example, in amplitude, in phase or in frequency. With the aid of the modulation, coding can be transmitted from the track circuit transmitter to the track circuit receiver. Of the Track circuit receiver then checks the coding in addition to the track voltage level and only reports the corresponding track section if it is correct. Normally, the electronic drives of the traction vehicles cannot replicate this coding, so that an incorrect track vacancy detection is excluded.

Eine Schaltungsanordnung zum Betrieb eines frequenzmodulierten, codierten Gleisstromkreises ist z.B. aus der Zeitschrift Signal und Draht 74 (1982), 7/8, Seiten 151 bis 160 bekannt. Bei dieser Schaltung wird im Gleisstromkreissender ein bestimmtes Bitmuster erzeugt, welches als frequenzmoduliertes Signal dem zu überwachenden Schienenabschnitt zugeführt wird. Dazu gibt der Sender bei Vorliegen eines Bits mit dem logischen Zustand 1 oder 0 eine obere bzw. untere Eckfrequenz ab. Der Gleisstromkreisempfänger demoduliert die Gleisspannung und vergleicht das Bitmuster mit einem gespeicherten Soll-Bitmuster. Bei Übereinstimmung mit dem dem gesendeten Bitmuster entsprechenden Soll-Bitmuster erfolgt eine Gleisfreimeldung. Ist der Pegel des empfangenen Signals zu niedrig oder stimmen die Bitmuster nicht überein, so bleibt der Gleisabschnitt besetzt gemeldet. Nachteilig an der bekannten Schaltungsanordnung ist, daß die Realisierung des Gleisstromkreisempfängers wegen der erforderlichen, signaltechnisch sicheren Überprüfung der Bitmuster aufwendig ist. Im Empfänger muß ein Bandpaßfilter verwendet werden, dessen Bandbreite größer als der Frequenzhub der Gleisspannung ist und das, um eine störende Amplitudenmodulation am Ausgang des Filters zu vermeiden, innerhalb seiner Bandbreite einen annähernd linearen Frequenzgang aufweist.A circuit arrangement for operating a frequency-modulated, coded track circuit is known, for example, from the journal Signal und Draht 74 (1982), 7/8, pages 151 to 160. With this circuit, a certain bit pattern is generated in the track circuit transmitter, which is fed as a frequency-modulated signal to the rail section to be monitored. For this purpose, the transmitter emits an upper or lower cut-off frequency when a bit with the logic state 1 or 0 is present. The track circuit receiver demodulates the track voltage and compares the bit pattern with a stored target bit pattern. If the target bit pattern corresponding to the bit pattern sent corresponds to a track vacancy signal. If the level of the received signal is too low or the bit patterns do not match, the track section remains reported as occupied. A disadvantage of the known circuit arrangement is that the realization of the track circuit receiver is complex because of the required, signal-technically reliable checking of the bit pattern. A bandpass filter must be used in the receiver, the bandwidth of which is greater than the frequency deviation of the track voltage and which, in order to avoid disturbing amplitude modulation at the output of the filter, has an approximately linear frequency response within its bandwidth.

Die relativ große Filterbandbreite bedingt eine gewisse Störanfälligkeit des Gleisstromkreises. Auch wenn die Störungen aufgrund der Codeprüfung keine fälschliche Freimeldung mehr verursachen, können sie doch die Verfügbarkeit des Gleisstromkreises herabsetzen.The relatively large filter bandwidth causes a certain susceptibility to faults in the track circuit. Even if the malfunctions due to the code check no longer cause false free messages, they can still reduce the availability of the track circuit.

Der Erfindung liegt die Aufgabe zugrunde, einen frequenzmodulierten Gleisstromkreis zu schaffen, der störsicher arbeitet und dabei wesentlich einfacher aufgebaut ist als der obengenannte bekannte Gleisstromkreis.The invention has for its object to provide a frequency-modulated track circuit that works interference-free and is constructed much simpler than the above-mentioned known track circuit.

Diese Aufgabe wird durch die Merkmale des Patentanspruchs 1 gelöst.This object is achieved by the features of patent claim 1.

Die Schaltungsanordnung nach der Erfindung zeichnet sich dadurch aus, daß als Gleisstromkreisempfänger einfache bekannte und bewährte Einrichtungen, wie z.B. das Röhrengleisrelais (s. z.B. DE-PS 10 98 982, insbesondere Fig. 1) benutzt werden können, die lediglich durch das eingangsseitige Bandpaßfilter ergänzt werden müssen. Als Gleisstromkreissender findet ein in der Frequenz modulierbarer Signalgenerator Verwendung, der von einem Codegenerator gesteuert wird. Die Nachführung der Mittenfrequenz des Bandpaßfilters gestattet die Verwendung eines extrem schmalbandigen Bandpaßfilters, wodurch die gesamte Anordnung kaum noch störbar ist.The circuit arrangement according to the invention is characterized in that simple known and proven devices such as e.g. the tube track relay (see e.g. DE-PS 10 98 982, in particular Fig. 1) can be used, which only need to be supplemented by the bandpass filter on the input side. A frequency generator that can be modulated in frequency and is controlled by a code generator is used as the track current circuit transmitter. The tracking of the center frequency of the bandpass filter allows the use of an extremely narrow-band bandpass filter, so that the entire arrangement can hardly be disturbed.

Vorteilhafte Ausgestaltungen der Schaltungsanordnung nach der Erfindung sind den Unteransprüchen zu entnehmen.Advantageous embodiments of the circuit arrangement according to the invention can be found in the subclaims.

Im folgenden soll ein Ausführungsbeispiel der erfindungsgemäßen Schaltungsanordnung anhand der Zeichnung beschrieben werden.An exemplary embodiment of the circuit arrangement according to the invention will be described below with reference to the drawing.

Die Zeichnung zeigt das Blockschaltbild einer Schaltungsanordnung zur Gleisfreimeldung eines zweischienig isolierten Gleisabschnittes 4 unter Verwendung eines herkömmlichen Röhrengleisrelais 8. Der Gleisstromkreissender 2 weist einen Modulationseingang ME und einen Gleisspannungsausgang GA auf. An seinem Modulationseingang ME ist ein Codegenerator 1 als Modulator angeschlossen, während sein Gleisspannungsausgang GA mit einer Einspeisestelle 3 eines Gleisabschnittes 4 verbunden ist. Das Röhrengleisrelais 8 besitzt einen Netzspannungseingang NE und einen Gleisspannungseingang GE sowie einen Ausgang GF zur Gleisfreimeldung und einen Ausgang GB zur Gleisbesetztmeldung. Die Signale der Ausgänge können z.B. in einem Stellwerk zur Anzeige gebracht werden. Der Netzspannungseingang NE des Röhrengleisrelais 8 erhält seine Spannung vom Gleisspannungsausgang GA des Gleisstromkreissenders 2 über eine Verbindung 9. Diese Spannung muß zu diesem Zweck eine Höhe aufweisen, die zum Betrieb des Röhrengleisrelais ausreicht. Die Gleisspannung an einer Ausspeisestelle 5 des Gleisabschnittes 4 gelangt über ein Tiefpaßfilter 6 zum Signaleingang SE eines Kammfilters 7 und von dessen Signalausgang SA zum Gleisspannungseingang GE des Röhrengleisrelais 8. Das Kammfilter 7 weist zusätzlich einen Referenzspannungseingang RE auf, der mit dem Gleisspannungsausgang GA des Gleisstromkreissenders 2 verbunden ist.The drawing shows the block diagram of a circuit arrangement for track vacancy detection of a double-rail insulated track section 4 using a conventional tubular track relay 8. The track current circuit transmitter 2 has a modulation input ME and a track voltage output GA. A code generator 1 is connected to its modulation input ME as a modulator, while its track voltage output GA is connected to a feed point 3 of a track section 4. The tubular track relay 8 has a mains voltage input NE and a track voltage input GE as well as an output GF for track vacancy detection and an output GB for track occupancy reporting. The signals of the outputs can e.g. be displayed in a signal box. The mains voltage input NE of the tubular track relay 8 receives its voltage from the track voltage output GA of the track current circuit transmitter 2 via a connection 9. For this purpose, this voltage must have a level sufficient for the operation of the tubular track relay. The track voltage at an exit point 5 of the track section 4 passes via a low-pass filter 6 to the signal input SE of a comb filter 7 and from its signal output SA to the track voltage input GE of the tubular track relay 8. The comb filter 7 additionally has a reference voltage input RE, which is connected to the track voltage output GA of the track circuit transmitter 2 connected is.

Als Röhrengleisrelais 8 kann das bewährte, in Anlagen der Deutschen Bundesbahn eingesetzte Röhrengleisrelais verwendet werden. Dieses gibt eine Gleisfreimeldung an seinem Ausgang GF ab, wenn die Spannung an seinem Gleisspannungseingang einen vorgegebenen Schwellwert überschreitet und in ihrer Phase nicht mehr als 15° von der am Netzeingang anliegenden Spannung abweicht. Liegt die Spannung am Gleissspannungseingang unter dem Schwellwert, so erfolgt eine Gleisbesetztmeldung am Ausgang GB. Wenn die beiden Spannungen an den Eingängen NE und GE eine Phasendifferenz von mehr als 15° aufweisen, Störspannungen auf den Eingang GE gelangen oder das Röhrengleisrelais 8 einen internen Defekt aufweist, erfolgt entweder die gleichzeitige Ausgabe einer Frei- und einer Besetztmeldung oder es wird keiner der Ausgänge aktiviert. Die zuletzt genannten beiden Zustände sind als Störung zu interpretieren. Als Kammfilter 7 läßt sich eine Schaltung, wie sie z.B. in der Zeitschrift Electronics, 22. November 1973, Seiten 118 bis 119, beschrieben ist, oder aber jedes andere getaktete Filter verwenden. Eine solche Schaltung benötigt eine externe Referenzfrequenz, die der gewünschten Mittenfrequenz f0 des Filters entspricht. Kammfilter weisen einen kammförmigen Frequenzgang auf, wobei sich jeweils bei ganzzahligen Vielfachen der Mittenfrequenz f0 Maxima befinden, ihr Frequenzgang sich also periodisch fortsetzt. Je nach Ausführung des Kammfilters muß die Referenzfrequenz zuvor noch vervielfacht werden.The proven tubular track relay used in systems of the Deutsche Bundesbahn can be used as the tubular track relay 8. This gives a track vacancy signal at its output GF when the voltage at its track voltage input is a predetermined one Threshold value is exceeded and its phase does not deviate by more than 15 ° from the voltage at the mains input. If the voltage at the track voltage input is below the threshold, a track occupancy message is issued at the GB output. If the two voltages at the inputs NE and GE have a phase difference of more than 15 °, interference voltages reach the input GE or the tubular track relay 8 has an internal defect, either the simultaneous output of a free and a busy message takes place or none of them Outputs activated. The latter two states are to be interpreted as a fault. A circuit as described in the magazine Electronics, November 22, 1973, pages 118 to 119, or any other clocked filter can be used as the comb filter 7. Such a circuit requires an external reference frequency which corresponds to the desired center frequency f0 of the filter. Comb filters have a comb-shaped frequency response, where there are maxima at integer multiples of the center frequency f0, so their frequency response continues periodically. Depending on the design of the comb filter, the reference frequency must first be multiplied.

Die Verwendung der Senderausgangsspannung oder einer in der Höhe veränderten, mit ihr frequenz- und phasengleichen Spannung zum Betrieb des Röhrengleisrelais und als Referenz für das regelbare Kammfilter ermöglicht, den Empfänger sehr schmalbandig auszulegen, denn durch die gemeinsame Modulation der Sender-Mittenfrequenz und der Referenzfrequenz des Kammfilters entfällt die Notwendigkeit, ein Frequenzband zu empfangen, das breiter ist als der Frequenzhub.The use of the transmitter output voltage or a voltage that is altered in height, with its frequency and in phase voltage, to operate the tube track relay and as a reference for the adjustable comb filter enables the receiver to be designed to be very narrow-band, because through the common modulation of the transmitter center frequency and the reference frequency of the Comb filter eliminates the need to receive a frequency band that is wider than the frequency swing.

Ein sehr schmalbandiger Empfänger, wie er durch Vorschalten eines Kammfilters verwirklicht werden kann, ist praktisch nicht mehr störbar. Die Filter-Einschwingzeit, die bei schmalbandigen Filtern bekanntlich groß ist, verhindert ein Ansprechen auf höherfrequente Störungen. Im übrigen macht sie sich kaum störend bemerkbar, da das Kammfilter ja nicht getaktet, sondern lediglich in seiner Frequenz entsprechend dem Modulationssignal verändert wird. Lediglich bei Amplitudenänderungen der Filtereingangsspannung, wie sie bei Besetzung oder Freifahren des Gleisabschnittes auftreten, kann die große Einschwingzeit verzögernd in Erscheinung treten. Es ist jedoch bei einer erlaubten Verzögerung von 0,5 s bei Besetzung oder Freifahren des Gleisabschnittes noch möglich, die Bandbreite des Kammfilters auf 1 Hz einzustellen. Störungen, die durch ganzzahlige Vielfache der Filter-Mittenfrequenz auch hier noch verursacht werden könnten, werden durch das dem Kammfilter vorgeschaltete Tiefpaß- oder Bandpaßfilter 6, das eine obere Grenzfrequenz vom 1,5-Fachen der Kammfilter-Mittenfrequenz aufweist und alle höheren Vielfachen der Kammfilter-Mittenfrequenz blockiert, ausgeschaltet. Ein zusätzlicher Gewinn an Störsicherheit kann noch dadurch erzielt werden, daß die Gleissstromkreisfrequenz nicht unabhängig vom Triebstromkreis erzeugt wird, sondern zur Triebstromfrequenz in einem festen, nicht ganzzahligen Verhältnis steht. Zufällige Übereinstimmung zwischen Gleisstromkreisfrequenz und Oberschwingungen der Triebstromfrequenz wird dadurch vermieden.A very narrow-band receiver, as can be achieved by connecting a comb filter, is practically no longer disruptive. The filter settling time, which is known to be long for narrow-band filters, prevents a response to higher-frequency interference. Otherwise, it is hardly noticeable, since the comb filter is not clocked, but only changed in frequency in accordance with the modulation signal. Only when the filter input voltage changes in amplitude, as occurs when the track section is occupied or cleared, can the large settling time appear with a delay. However, with a permitted delay of 0.5 s when the track section is occupied or cleared, it is still possible to set the bandwidth of the comb filter to 1 Hz. Interferences that could also be caused by integer multiples of the filter center frequency are caused by the low-pass or bandpass filter 6 connected upstream of the comb filter, which has an upper limit frequency of 1.5 times the comb filter center frequency and all higher multiples of the comb filter Center frequency blocked, switched off. An additional gain in interference immunity can also be achieved in that the track circuit frequency is not generated independently of the drive circuit, but is in a fixed, non-integer ratio to the drive current frequency. This prevents accidental correspondence between the track circuit frequency and harmonics of the drive current frequency.

Claims (5)

  1. A frequency-modulated track circuit comprising a track-circuit transmitter (2) which is controlled by a modulator (1) and feeds track current into the rails of a track section (4) at a feed-in point (3), and a track-circuit receiver (8) which evaluates a track voltage developed at a feed-out point (5) of the track section and indicates the track section as unoccupied (GF) only if the amplitude of the frequency-modulated track voltage exceeds a predetermined threshold value and the frequency of said track voltage corresponds to the code,
    characterized in that the track-circuit receiver (8) is preceded by a variable bandpass filter (7) whose bandwidth is less than the frequency deviation of the track-circuit transmitter and whose midfrequency is made to track the output voltage of the track-circuit transmitter (2), and that for this purpose, a reference signal corresponding to the output voltage of the track-circuit transmitter, or a reference signal derived from and in phase with said output voltage, is fed to the bandpass filter over a special connection (9).
  2. A frequency-modulated track circuit as claimed in claim 1, characterized in that the bandpass filter (7) is a comb filter whose reference frequency is identical with the frequency of the output voltage of the track-circuit transmitter (2).
  3. A frequency-modulated track circuit as claimed in claim 2, characterized in that the bandpass filter (7) is followed by a low-pass filter (6) or a bandpass filter having a bandwidth greater than the frequency deviation of the track-circuit transmitter (2).
  4. A frequency-modulated track circuit as claimed in any one of the preceding claims, characterized in that the track-circuit receiver (8) is a tube track relay preceded by a bandpass filter.
  5. A frequency-modulated track circuit as claimed in any one of the preceding claims, characterized in that the track-circuit frequency is derived from the traction-current frequency by multiplying the latter by a nonintegral factor.
EP88103941A 1987-03-18 1988-03-12 Frequency-modulated track current circuit Expired - Lifetime EP0282932B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873708788 DE3708788A1 (en) 1987-03-18 1987-03-18 FREQUENCY MODULATED TRACK CIRCUIT
DE3708788 1987-03-18

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EP0282932A2 EP0282932A2 (en) 1988-09-21
EP0282932A3 EP0282932A3 (en) 1989-12-06
EP0282932B1 true EP0282932B1 (en) 1996-07-10

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EP88103941A Expired - Lifetime EP0282932B1 (en) 1987-03-18 1988-03-12 Frequency-modulated track current circuit

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EP (1) EP0282932B1 (en)
AT (1) ATE140194T1 (en)
DE (2) DE3708788A1 (en)
ES (1) ES2091745T3 (en)
TR (1) TR24261A (en)
YU (1) YU53188A (en)

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DE19816581A1 (en) * 1998-04-08 1999-10-21 Siemens Ag Train control device
DE102007030598A1 (en) * 2007-06-28 2009-01-15 Siemens Ag Method and device for evaluating an INDUSI signal
DE102009010906A1 (en) * 2009-03-02 2010-09-16 Siemens Aktiengesellschaft Devices for detecting the occupancy or free state of a track section and method for operating such devices

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US3715669A (en) * 1970-08-13 1973-02-06 Gen Signal Corp Receiver for a frequency modulated overlay track circuit
AT311413B (en) * 1971-01-05 1973-11-12 Itt Austria Track monitoring device for railway systems
US4417229A (en) * 1980-10-15 1983-11-22 Safetran Systems Corporation Means for use on a railroad to distinguish between traction current and signal current
DE3325249A1 (en) * 1983-07-13 1985-01-31 Standard Elektrik Lorenz Ag, 7000 Stuttgart Track circuit receiver
DE3403946A1 (en) * 1984-02-04 1985-08-08 Standard Elektrik Lorenz Ag, 7000 Stuttgart Presence-of-trains indicating device with track current coding

Also Published As

Publication number Publication date
DE3708788A1 (en) 1988-09-29
DE3855407D1 (en) 1996-08-14
ATE140194T1 (en) 1996-07-15
EP0282932A2 (en) 1988-09-21
ES2091745T3 (en) 1996-11-16
YU53188A (en) 1990-12-31
TR24261A (en) 1991-07-29
EP0282932A3 (en) 1989-12-06

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