EP2100793A2 - Method and device for continuous evaluation of receipt signals in railway electricity circuits - Google Patents

Abstract

The method involves providing a section length over a section of a track which is disconnected at two ends. An alternating current voltage with two alternating frequencies is supplied at one end of the section of the track as an input signal. An output signal is picked up at the other end of the section of the track. The picked up output signal is analyzed for its characteristics with reference to the transmitted signal. An independent claim is included for a system for detecting track clearance signal of a section of a railway track.

Description

The present invention relates to a railway track circuit. A patent application for a railway track circuit was in the European patent application under the number 06 022 614.9 filed.

• a) eine Länge des Abschnitts über einen an zwei Enden unterbrochenen Schienenstrang definiert wird;
• b) an einem Ende des Schienenstranges eine Wechselspannung mit zwei alternierenden Frequenzen als Eingangssignal eingespeist wird;
• c) an dem anderen Ende des Schienenstranges ein Ausgangssignal abgegriffen wird;
• d) das abgegriffene Ausgangssignal hinsichtlich seiner Anteile in den beiden Frequenzen analysiert wird; und
• e) in Abhängigkeit von der Analyse anhand von Grenzwertvergleichen entschieden wird, welchen Zustand der Gleisabschnitt aufweist.

There, a method and system for track vacancy of a section of a track section is proposed, in which:

• a) a length of the section is defined by a broken at two ends rail track;
• b) at one end of the rail line an alternating voltage with two alternating frequencies is fed as an input signal;
• c) an output signal is tapped off at the other end of the rail track;
• d) the tapped output signal is analyzed for its components in the two frequencies; and
• e) it is decided in dependence on the analysis by means of limit value comparisons which state the track section has.

State of the art and task

The present invention relates to a method and apparatus for evaluating received signals in railway track circuits. Further, the invention relates to a method and apparatus for track vacancy using track circuits.

For the management of railways, the information about the occupancy of a track section by a vehicle is absolutely necessary. It plays an important role in setting and dissolving routes as a safety-critical variable. There are many different techniques for recognizing occupancy. The starting point of this invention is the widely used track circuit with the classical technical approach of the circuit. The functional principle is relatively simple and will be briefly introduced. A rail of the track section to be monitored is separated and insulated against the adjacent track section on a rail or both rails. The transmitter applies voltage to one end of the isolated section. The receiver at the other end of the section evaluates this voltage. When a train enters the section, its axles short the two mutually insulated rails of the track and tie the track to the same rail potential. The received signal is thereby largely suppressed. The evaluation after the receiver reports thereby the section as occupied.

Building on this basic principle, there are a large number of very different products. They differ considerably in terms of the selected transmit signal and the evaluation in the receiver. There are also so-called shockless track circuits. However, these have some overlap at the boundaries between two neighboring circles. As a result, selective assignments are not possible, for example in the area of turnouts and crossings.

One embodiment known in the art is the classic DC track circuit. This principle operates a DC circuit on the track section and in it are serially the two rails with the variable size of the ballast resistor. The axle shunt during a drive reduces the resistance in a circle. The principle works like in the FIG. 1 shown. The simplest solution is to use a relay as a receiver serially in the circuit for detecting the occupancy of the section.

Another known embodiment provides for the supply of the GSK (track circuit) by means of a three-phase network. It comes in a driving to a detuning a device of a kind of differential transformer or a kind of electric shaft or motor. At the manufacturer Siemens, such a product is referred to as a motor relay. When driving, there is a change in the circle with respect to the following parameters, namely frequency spectrum, phase, power. The mass of the motor rotor acts as an inertia filter with a pick-up delay to suppress short-term interference.

The principle of a GSK operated with a voltage over 100V AC (usually 230V) with 50 Hz or 60 Hz, in continuous operation or in pulsed mode is also known. The comparatively high voltage is used for breaking up the insulating layers, e.g. Rust on the rail rolling surfaces used in non-regular driving. Due to the high performance, the required fault clearances are created. However, such GSK also pose a potential threat to humans and animals, especially in the area of level crossings due to the voltage level.

OBJECT OF THE INVENTION Starting from this prior art, it nevertheless remains desirable to be able to improve the reliability of track circuits and their robustness.

The electromagnetic interference caused by the traction is an important part.

In general, the evaluation of the received signal is to be optimized in such a way that, as far as possible, the entire implicit information contained therein for occupying the monitored track section can be detected.

1. a) eine Länge des Abschnitts über einen an zwei Enden vorzugsweise an einem Gleis unterbrochenen Schienenstrang definiert wird;
2. b) an einem Ende des Schienenstranges eine Wechselspannung mit zwei alternierenden Frequenzen als Eingangssignal eingespeist wird;
3. c) an dem anderen Ende des Schienenstranges ein Ausgangssignal abgegriffen wird;
4. d) das abgegriffene Ausgangssignal hinsichtlich seiner Eigenschaften im Bezug auf den Aufbau des Sendesignals analysiert wird; und
5. e) in Abhängigkeit von der Analyse anhand von Grenzwertvergleichen entschieden wird, welchen Zustand der Gleisabschnitt aufweist.

In the course of the present invention, this object is achieved by a system and a method for track release of a section of a track section, in which:

1. a) defining a length of the section via a rail track interrupted at two ends, preferably on a track;
2. b) at one end of the rail line an alternating voltage with two alternating frequencies is fed as an input signal;
3. c) an output signal is tapped off at the other end of the rail track;
4. d) the tapped output signal is analyzed with respect to its characteristics with respect to the structure of the transmission signal; and
5. e) it is decided in dependence on the analysis by means of limit value comparisons which state the track section has.

The method can be further improved in one embodiment of the invention in that the very powerful signal processing based on mathematical calculation of processes is used. Processing takes place in real time with a signal-data acquisition grid suitable for the task. The digitized values of the received signal are specifically fed to the evaluation channels designed for the respective task.
A universal track circuit (UGSK) is described below. The system consists of two parts: the part "outside plant", which establishes the physical connection to the infrastructure, ie the track section, and the part "indoor plant" in the signal box with the associated electronics for the signal generation and the signal evaluation for determining the occupancy state of the associated track section on the state free resp. Occupies resp. disturbed.

The part "outdoor system" consists essentially of the galvanic separation points usually in the form of Gleistransformatoren the transmit and receive signal with the associated filter circuits at both ends of the section of the circle. They transform the transmitted high voltage on the cable to the signal box into a low voltage of a few volts permissible for track systems. They are additionally equipped with a high-pass filter. These protect the electronics of the transmitter and receiver against the high-energy interference effects of the traction currents from the 16.7 Hz resp. 50 Hz traction networks of the railways.

The part "indoor unit" consists in the supply of two variants
Variant 1: A strictly two-channel version of the power supply (in error! Reference source could not be found. ) Or one
Variant 2: A simple but strictly monitored supply to undervoltage and overvoltage and a decoupling of the consumer lying on it according to the prior art, by way of example by means of throttling.

The signal evaluation is a two-channel system with suitable control and processing units for the differentiated determination of the occupancy states and their transfer to the interlocking. A potential separation of the transmitting and receiving line is realized. Advantageously, safety relays are used for the status output. Transmitter and receiver are spatially close to each other due to disturbance influencing factors.
The detailed description of the (evaluation) method and the device is made in the following chapters according to the method "top-town".

1 Description of the system, architecture, procedure and equipment 1.1 Description of the system structure

The FIG. 1 schematically shows the system structure; the FIG. 2 according to the hardware construction.

1.2 Principles of security architecture

The architecture is designed so that it can meet the required safety features. The security architecture includes full 2-channel capability, from the secondary windings of the receiving transformer to the signaling relays. Variants are possible for the electronics supply.

The two evaluation channels are identical in the intended function of the signal evaluation. One of the channels still performs control tasks such as e.g. Clock frequency generation, control of the transmitter, control of the display, and possibly other functions. It also synchronizes the second channel for data acquisition and processing. Such an assignment is advantageous, but not mandatory.

2 The procedure 2.1 Procedures and tests to control the safe state

The correct operation of the two channels is checked cyclically by exchanging the required data for each other and comparing them in two channels. Small tolerances resulting from tolerances of the analog part are tolerated. This is operationally necessary in particular because the alarm relays of the two channels must always have the same state even in the border region of evaluation zones (eg free - disturbed).

To ensure that the fault reporting relay S1; S2, which are usually permanently attracted, are also included in a cyclic test, it should be considered to drop them at the end of an occupancy each briefly and thus to examine.

To ensure that an error in the A / D converter is detected quickly, even if the received signal is constant for a long time, the level signals of the transmitter voltage and supply are converted in the same A / D converter as the reception input signal.

The continuously changing sinusoidal signal of the transmitter voltage, as well as the constant supply voltage with small variation, which is advantageously placed in the upper half of the AD converter range (test of the MSB) thus also bring about an advantageous contribution in terms of safety.

• Zu tiefer Bettungswiderstand
• Vorschriftswidrige (zu hohe) Einstellung der Sendeleistung
• Schlechter (vorschriftswidriger) Achsnebenschluss (auch lange anhaltende Flatterachse)
• Extreme Störungen (wesentlich grössere, als die spezifizierten 4A Traktionsströme) über längere Zeit (>1s).

The following factors can worsen the risk rate independently of the GSK functional unit and are therefore not to be included in the calculation:

• To deep bedding resistance
• Irregular (too high) setting of transmission power
• Bad (improper) axle junction (also long-lasting flutter axle)
• Extreme disturbances (significantly larger than the specified 4A traction currents) over a longer period of time (> 1 s).

2.2 The transmission signals for the infeed on one side of the track section.

The signal transmitted on the track section consists of two combined operating frequencies.

The possible frequency combinations are:

- Frequency combination 1: f _a1 = f _s1 f _a2 = f _s2 f _fr = f _s3 - Frequency combination 2: f _a1 = f _s2 f _a2 = f _s3 f _fr = f _s1 - Frequency combination 3: f _a1 = f _s1 f _a2 = f _s3 f _fr = f _s2

The third frequency (foreign frequency) is not relevant for the generation of the transmission signal.

Each working frequency on its own is sent after the "send-pause" procedure. The transmission signal is schematically in FIG. 3 shown. To each other are the transmission and pause phases of the working frequencies shifted so that frequency 1 sends in the pause of frequency 2 and vice versa; Error! Reference source not found. illustrates the transmission signal.

The transmission duration of a "frequency packet" is approx. 300ms in each case. This gives the filters the opportunity to settle.
It can vary slightly, since phase jumps are to be avoided when changing the frequency (ie individual periods of the signal must be completed).

Neighbor track circuits have the third frequency f3 besides any frequency of f1 and f2. This crosstalk in the event of an insulation fault by detection can be seen.

2.3 Basic specifications

The received signal from the track section via the separation point is digitized with an AD converter and applied to the input of the filter. The separation point is equipped with a transformer / transmitter and with filter elements to eliminate unwanted traction.

In general, the entire data processing after the analog / digital conversion of the received signal to the output of the assignment state to the interlocking is purely digital. This means that the analog signals are discretized with the required resolution.

• Filterung des Eingangssignals (siehe oben Block "Filterung)
• Vorbearbeitung der gefilterten Sendefrequenzen (siehe oben Blöcke "Absolutwert" und "Signalpegel)
• Berechnung und Auswertung des gemeinsamen Signalpegels (siehe oben Blöcke "Pegeladdition", "Pegelbewertung" und "Zustandserkennung")
• Auswertung der Sendephasen und Sendepausen der Arbeitsfrequenzen (siehe oben Blöcke "Paketauswertung" und "Störungstabelle")
• Auswertung der Fremdfrequenz (siehe oben Block "Isolierstörung")
• Verknüpfung der Ergebnisse (pro Auswertungs-Pfad; Block "Pfadumschaltung)

FIG. 4 shows the most important evaluation paths and function blocks.

• Filtering of the input signal (see block "Filtering" above)
• Preprocessing of the filtered transmission frequencies (see above "Absolute value" and "Signal level" blocks)
• Calculation and evaluation of the common signal level (see above "Level addition", "Level evaluation" and "Condition detection" blocks)
• Evaluation of the transmission phases and transmission pauses of the operating frequencies (see above "Package evaluation" and "Fault table" blocks)
• Evaluation of the external frequency (see above block "Isolation fault")
• Linking the results (per evaluation path, block "Path changeover")

2.4 General functioning of the evaluation procedure 2.4.1 The Function Block Diagrams

FIG. 1 shows the system structure and the position in the interlocking as well as the track system. FIG. 2 shows the hardware architecture in general and broader the subdivision of the signal evaluation in different Evaluation paths and their function blocks. FIG. 4 shows the " Error! Reference source could not be found. Here it is obvious to the person skilled in the art how the actual signal evaluation precedes the filtering and evaluation of the received signal.

2.4.2 The two function blocks signal filtering and signal evaluation Signal filtering

In the signal filtering stage, the received signal is transferred in digital form and the further processing is conditioned. This is divided into the three operating frequencies for the process operating frequencies f1, f2 and f3. The method is designed so that the computational effort remains appropriate. The structure of the filter structure is described in section Errors! Reference source not found. described.

Signal evaluation

In the first path of the signal evaluation, the processing of the filtered transmission frequencies f1, f2, f3 takes place with the continuous calculation of the signal level for the three operating frequencies. At this point, therefore, the raw information of the track occupancy, i. free without an axle short circuit or occupied by an axle short circuit for further processing. Situationally caused by traction processes and thus the transmission signal superimposed disturbances can affect the two useful signals.

The further processing of the signal level profile takes place in a manner essential to the invention in parallel on three paths. Each of these three paths has implemented a specific signal processing method for three operating states (regular operation, faulty operation and interference disturbance by interference of adjacent circuits).

These three processing methods are described below.

In the first path, the method is designed so that in unambiguous, not or only slightly superimposed with disturbances signals of the operating frequencies based on the summed signal level for both operating frequencies used an evaluation of the received signal made and determines the condition (free, busy, fault) of the track section becomes.
This path allows rapid evaluation in case of state changes in the occupancy, because a driving event in the track section at a f1 and f2 common summed signal level has a faster effect than would be the case with a separate evaluation of the two frequency packets f1 and f2.

In the second path, the transmission phases and transmission pauses of the two operating frequencies are evaluated separately. This method is more time consuming than that of the first path.
The evaluation of the individual time sections is a method for achieving a delay of the time of entry of the operating inhibiting state "fault" when a fault-superimposed operating frequency occurs.

Finally, the third path serves to detect an insulating shock bridging of the considered track section with a neighboring section. If a signal level is detected at the third operating frequency in the unit under consideration (caused by interfering influences or one of the transmission frequencies of a neighboring section which is not transmitted by the device considered here), then the fault state is assumed.

The evaluation unit (inflow of the three paths). The current allocation results of the three evaluation paths are linked according to their states according to an appropriate logic.

In the function block "Path switching" it is decided continuously which evaluation path determines the assignment and status message to be output to the signal box by means of relays. With this decision logic, a dynamic behavior in tracking the instantaneous state of the evaluation data is possible, so that the evaluation is always optimized to the occupancy state currently contained in the received signal, taking into account the railway time scale.

3 The functional blocks in detail 3.1 Signal filtering

The fundamental frequencies transmitted on a track section for occupancy monitoring are: f1 = 208.75 Hz, f2 = 225.45 Hz or f3 = 242.15 Hz.
Other frequency triples, adjusted to intermediate values of the fundamental and the harmonics of the traction supply are arbitrarily possible.

The main goal of the evaluation is to filter out these useful frequencies and thus to suppress other interfering frequencies in the received signal.
Preliminary clarifications regarding an evaluation by means of FFT have shown that here the stopband attenuation (besides the useful frequencies) is too low.
As an alternative with better stopband attenuation, specific filter structures are available for the individual useful frequencies - (narrowband) bandpass filters.

FIG. 5 shows the structure of the digital filter system. The figure shows the digital filter system for evaluating the three useful frequencies. The input signal for the evaluation system is the output data word of the analog-to-digital converter stage (not shown in the figure).
This data word is available at the frequency f _sample on the evaluation system.

In a first step of the evaluation, the input signal is fed to an antialiasing filter (LP0). The signal is then ready for bandpass filtering. So that the computational effort in these filters is not excessive, a down-sampling (DS) must be carried out with the LP0 output signal: Thus, only every eighth data word is passed on to the next processing stage, the filtering.

In this second stage with bandpass filters (BP1, BP2 and BP3), the three useful signals are filtered out of the input signal. For filtering, the FIR filter is advantageously used, the signal processing is generally digital. The order of the filter used is expediently high and can be determined by a person skilled in the art.

In the last filter stage the up-sampling is done to the original frequency f _sample ; Suppress the low-pass filters LP1, LP2 and LP3 at the outputs Harmonics of the useful frequencies were created by oversampling.

3.2 Signal evaluation

According to the projected frequency combination of two frequencies of the track section, the transmission frequencies are guided to the respective working or foreign frequency: - Frequency combination 1: f _a1 = f _s1 f _a2 = f _s2 f _fr = fs ₃ - Frequency combination 2: f _a1 = f _s2 f _a2 = f _s3 f _fr = f _s1 - Frequency combination 3: f _a1 = f _s1 f _a2 = f _s3 f _fr = f _s2 After the working and foreign frequencies of the section have been assigned, they are rectified or the absolute value is formed from them. The input signals from 12bit / signed (-2048 to +2047) are limited to 11 bit / unsigned (0 to 2047).

• signal level

The peak values are determined from the rectified working and external frequencies; the peak values represent the signal level.

FIG. 6 shows a basic procedure for determining the signal level.

In each case, the last value of a working or foreign frequency is compared with the previous value. Depending on the current and future state with regard to the amplitude value, a peak value is present. In the FIG. 6 these are the transitions from "plateau" to "falling" and from "rising" to "falling" (dashed transitions).

Alignment of signal levels

The operating frequencies can be damped differently by the frequency dependence of the transmission path of the track circuit (transformers, track, etc.). This can lead to fluctuations in the signal level.
The equalization of the operating frequencies, or their signal level, compensates for the different attenuations; the received operating frequencies are amplified accordingly.
The degree of approximation is determined by parcel values in the free zone. Subsequently, the operating frequencies are adjusted symmetrically. For matching, a maximum capture range must be specified (cf. FIG. 7 ).

From the signal levels of the working frequencies 1 and 2, the sum is continuously formed.
By means of a number of the last total values which is suitable for the processing method, a mean value is also continuously calculated; the resulting result is referred to as a "common signal level" and further supplied to the level evaluation.

The calculated common signal level is now divided into the zones "Overdriven", "Free", "Disturbed" and "Busy".
As an example, half of the value range is used as a fault and override reserve (corresponds to 1 MSB). The remaining part - the useful range - is additionally subdivided into levels "0" to "F" (hex representation of the function indicator). The oversteer itself is passed through the stage "F." shown. Discrete values in the table below depend on the characteristics of the track layout and characteristics of the circuits and are therefore not given numerically. <b> Table 1: Zone classification for level assessment </ b> Zone from... to... Override (Ü) Fault 2 (S) Free (F) Fault 1 (S) Busy (B)

A detailed classification of the level ranges and their limits is determined by the characteristics of the amplifiers.
Note: Hysteresis boundaries between the zones are not necessary as borderline cases are taken into account by the following evaluation stages.

The function block "Condition detection" examines the time course of the common signal level and determines from this the operating state free, busy or fault.

• FMa (Freimeldung),
• STa (Störungsmeldung).

The operating state is output by means of two relay control signals:

• FMa (free message),
• STa (fault message).

Their meaning is: FMa = 0 = occupied STa = 0 = disturbed FMa = 1 = free STa = 1 = not disturbed

FIG. 8 shows the corresponding state diagram for state detection.

In addition to the evaluation of the common signal level, the two operating frequencies are also evaluated individually during the transmission phase and the transmission pause. The evaluation of the operating frequencies takes place in the transmission phase and during the transmission break differently. In the broadcast phase it is according to FIG. 8 identical to the evaluation of the common signal level.

In the transmission break, the level is quantified in three other stages:

Table 2: Classification of the value range transmission pauses Area from... to... p2 = strongly disturbed p1 = disturbed p0 = undisturbed

The discrete values are based on the real characteristics of a railway network of an operator.

• Beginn der Sendephase/-pause abwarten (Synchronisation auf Paketmitte)
• 8 Werte je Arbeitsfrequenz einlesen
• Werte mitteln und runden
• Werte bewerten (gem. Tabelle 1: Zoneneinteilung für die Pegelbewertung und Tabelle 2: Einteilung des Wertebereichs Sendepausen)

The derivation for the division of the level ranges is made based on the system data. A send phase or send pause value can be determined as an example according to the following pattern:

• Wait for start of send phase / pause (synchronization to middle of parcel)
• Read in 8 values per working frequency
• Averaging and rounding values
• Evaluate values (according to Table 1: Zone classification for the level assessment and Table 2: Classification of the value range transmission pauses)

Package evaluation at one (1) faulty working frequency

If, according to the table of disturbances 1, a faulty working frequency is determined, the condition of the track section must be determined on the basis of the second, still undisturbed working frequency.

• bei einer gestörten Arbeitsfrequenz bestimmt der Paketwert der ungestörten Arbeitsfrequenz unverzögert den Zustand Frei oder Belegt (Tabelle 1)
• bei einer gestörten Arbeitsfrequenz erfolgt aus Belegt kein Übergang nach Frei; für diesen Übergang werden 2 ungestörte Arbeitsfrequenzen vorausgesetzt
• im Falle zweier gestörter / ungestörter Arbeitsfrequenzen lauten die Relaismeldungen (FMb/STb) dieses Auswertungspfades ,0' (die endgültigen Relaismeldungen (FM/ST) werden durch die nachfolgenden Funktionsblöcke bestimmt.

The function block is described as follows:

• in the event of a faulty working frequency, the packet value of the undisturbed operating frequency determines without delay the status Free or Busy (Table 1)
• if there is a faulty working frequency, there is no transition from Busy to Free; 2 undisturbed working frequencies are required for this transition
• in the case of two faulty / undisturbed operating frequencies, the relay messages (FMb / STb) of this evaluation path are '0' (the final relay messages (FM / ST) are determined by the following function blocks.

FIG. 9 shows the packet evaluation at a faulty working frequency. In FIG. 9 It can be seen that the transitions between the states take place without delay. The function block thus generates the signals FMb and STb continuously. Subsequent function blocks then take into account any timeouts or transition patterns.

• bei einer gestörten Arbeitsfrequenz wird der Paketwert der ungestörten Frequenz nur noch in den Zuständen Frei oder Belegt unterschieden. Liegt der Paketwert im Bereich Störung oder Übersteuerung, so gilt dies gemäss Tabelle 3 als Störung beider Arbeitsfrequenzen und wird in nachfolgenden Funktionsblöcken bewertet.

Annotation:

• at a disturbed operating frequency, the packet value of the undisturbed frequency is only distinguished in the states free or busy. If the packet value is in the range of interference or overmodulation, then according to Table 3 this applies as a disturbance of both operating frequencies and is evaluated in subsequent function blocks.

Based on the determined transmission phase and pause values, the system state is now also determined in this evaluation path.
Important here are the transitions and their meaning as shown in Table 3. <b> Table 3: Fault Table </ b> f _a1
transmission phase f _a1
transmission phase f _a2
transmission phase f _a2
transmission phase Condition of the package evaluation F / S / B / E p0 F / S / B / E p0 Both operating frequencies undisturbed p1 p1 Both working frequencies disturbed p2 Both working frequencies disturbed p2 Both working frequencies disturbed p1 S / Ü Both working frequencies disturbed S / Ü p1 Both working frequencies disturbed other cases a working frequency disturbed (empty fields = X = do not care)

The third working frequency (external frequency) is used to detect interference due to insulating shock bypasses. If the signal level of the foreign frequency exceeds the value 100 (corresponds to the signal level p0), it is determined on the basis of different time criteria whether there is an insulation fault. FIG. 10 shows the corresponding state diagram for the insulation fault.

• eine gewöhnliche Isolierstörung (die Fremdfrequenz tritt paketweise auf), und
• ein dauerhafter Störer auf der Fremdfrequenz.

The evaluation of the insulation fault must take into account two cases:

• an ordinary insulation fault (the external frequency occurs in packets), and
• a permanent interferer on the foreign frequency.

If one of these faults occurs, starting from the "foreign frequency undisturbed" state, then within max. 1.5 seconds into the intermediate state "Insulation fault noted" changed. Thus, in the case of the ordinary insulation disturbance min. two consecutive packets detected before the transition occurs. The withdrawal of the marked fault occurs under the more stringent condition that no signal level ≥ 100 may occur during 1.5 seconds. Otherwise the condition "insulation fault" will be taken after 3.5 seconds at the latest. Overall, an insulation fault with a delay of max. Be detected for 5 seconds. Subdividing this delay into 'split times' 1.5 / 3.5 seconds is a choice made.

Merging of the evaluation paths

To generate the control signals of the message relays, the "intermediate signals" of the different evaluation paths are merged: Evaluation path "common signal level" FMa STa Evaluation Path "Package Evaluation" FMb ST b Evaluation Path "Isolation Disruption" FMc STc Control signals of the signaling relay FM ST

The evaluation paths "common signal level" and "packet evaluation" generate the control signals for the free and fault relays (FMa / b or STa / b).
The function block "Path switching" described below decides which evaluation path determines the effective control signals; So he switches between the two paths. FIG. 11 shows the merge of the evaluation paths.

Note: "tab" in the preceding figure indicates the condition of the packet evaluation according to Table 3.

The evaluation path "insulation fault" generates only a control signal for the fault relay (STc). This control signal dominates the "path switching" control signals; If an insulation fault is detected, the control signal causes the relay message "Busy and faulty".

Table 4 shows how to output the message "free and undisturbed" (FM = 1 and ST = 1) all evaluation paths must be undisturbed.

path switching

• sind beide Arbeitsfrequenzen ungestört¹, erfolgt die Relaismeldung entsprechend der Auswertung des gemeinsamen Signalpegels (FMa, STa),
  ¹ beide Pausenwerte im Bereich p0
• ist eine der beiden Arbeitsfrequenzen gestört, erfolgt die Relaismeldung entsprechend der noch ungestörten Arbeitsfrequenz (FMb, STb),
• sind beide Arbeitsfrequenzen gestört, oder
• ist mindestens eine Arbeitsfrequenz stark gestört, oder
• 1 Arbeitsfrequenz zu lange gestört ist, hat die Relaismeldung "Störung" zu lauten.

The function block "Path changeover" behaves according to the following criteria:

• if both operating frequencies are undisturbed ¹ , the relay message takes place according to the evaluation of the common signal level (FMa, STa),
  ¹ both pause values in the range p0
• If one of the two operating frequencies is disturbed, the relay message is issued according to the still undisturbed working frequency (FMb, STb),
• both operating frequencies are disturbed, or
• at least one working frequency is severely disturbed, or
• 1 operating frequency is disturbed for too long, the relay message "Fault" must be.

In FIG. 11 the 'switching' function is already shown as a block diagram. FIG. 12 shows the same function as a state diagram.

Hierarchy of the evaluation paths

The three evaluation paths influence each other (hierarchically).
This ensures, in particular, that the state "free" must be 'approved' after an occupancy or fault by all evaluation paths.
On the other hand, the smoothing or fault cancellation functions are thereby implemented at one point (in the "common signal level" evaluation path).

1. 1. eine Störung im Auswertungspfad "Isolierstörung" führt zum
   • . Störungszustand des Auswertungspfades "Paketauswertung"
   • . Störungszustand des Auswertungspfades "gemeinsamer Signalpegel"
2. 2. eine Störung im Auswertungspfad "Paketauswertung" führt zum
   • . Störungszustand des Auswertungspfades "gemeinsamer Signalpegel"
3. 3. die Rücknahme des Zustandes "Vorstörung" im Auswertungspfad "Paketauswertung" führt zum
   • . Vorstörungszustand des Auswertungspfades "gemeinsamer Signalpegel"

The following hierarchy applies (1 = uppermost):

1. 1. a fault in the evaluation path "insulation fault" leads to
   • , Fault condition of the evaluation path "package evaluation"
   • , Fault state of the evaluation path "common signal level"
2. 2. a fault in the evaluation path "package evaluation" leads to
   • , Fault state of the evaluation path "common signal level"
3. 3. the withdrawal of the status "Vorstörung" in the evaluation path "package evaluation" leads to
   • , Preliminary state of the evaluation signal "common signal level"

Smoothing ride and fault cancellation

According to the above description, the "common signal level" evaluation path is in the fault state as long as another evaluation path has assumed the fault state.
If no more faults are received, the evaluation path "common signal level" is the last one to enter the state Free; the smoothing and fault cancellation functions are implemented there.

Pre-fault in package evaluation

Analogous to the evaluation path "common signal level", the state pre-fault can also be taken in the evaluation path "packet evaluation".

If the packet evaluation changes back from Undelete state to Undisturbed, the "Common signal level" evaluation path must be reinitialized by also assuming the status "Vorstörung". The relay states of the packet evaluation must be taken over.

Claims (12)

Method for track release of a section of a track, in which: a) a length of the section is defined by a broken at two ends rail track; b) at one end of the rail line an alternating voltage with two alternating frequencies is fed as an input signal; c) an output signal is tapped off at the other end of the rail track; d) the tapped output signal is analyzed with respect to its characteristics with respect to the structure of the transmission signal; and e) it is decided in dependence on the analysis by means of limit value comparisons which state the track section has. The method of claim 1, wherein the section is checked for the states "FREE", "BUSY" and "FAILED". Method according to Claim 1 or 2, in which the output signal is analyzed in three channels. Method according to one of claims 1 to 3, wherein the output signal is bandpass filtered at least in two channels, wherein the pass frequencies of the bandpasses substantially correspond to the two frequencies of the input signal. Method according to claim 4, wherein in a first channel the level of the output signal is analyzed on the frequency of the input signal being transmitted, in a second channel the level of the output signal is analyzed on the frequency of the input signal not yet transmitted and in a third channel the frequency spectrum the output signal is analyzed. Method according to one of the preceding claims, in which only one frequency of the input signal coincides with the track release signal of two adjacent sections of a track section in the two sections and the respective other frequency deviates from one another, wherein the respectively just transmitted frequency in the adjacent sections is likewise set to differ from one another , System for track release of a section of a track, comprising: a) interrupted at two ends rail track whose length defines the section length; b) a transmitter which at one end of the rail line an alternating voltage with two alternating frequencies fed as input to the rail track; c) a receiver with which an output signal is tapped at the other end of the rail line; d) an analysis device which analyzes the tapped output signal with regard to its properties with regard to the structure of the transmission signal; and e) a logic device, which is decided on the basis of the analysis based on limit value comparisons, which state of the track section. A system according to claim 7, wherein the section is testable for the states "FREE", "BUSY" and "INTERFERENCE". System according to Claim 7 or 8, in which the output signal can be analyzed in three channels. A system according to any one of claims 7 to 9, wherein the output signal is bandpass filtered at least in two channels, the pass frequencies of the bandpasses substantially corresponding to the two frequencies of the input signal. A system according to claim 10, wherein in a first channel the level of the output signal is analyzable on the frequency of the input signal being transmitted, in a second channel the level of the output signal is analyzable on the frequency of the input signal not yet transmitted and in a third channel the frequency spectrum the output signal is analyzable. System according to one of the preceding claims 7 to 11, wherein for track release of two adjacent sections of a track section in the two sections only one frequency of the input signal coincides and the other frequency differs from each other, wherein each just sent frequency in the adjacent sections also from each other is deviating adjustable.

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