Railway Track Section Detection Using Frequency Division Multiplexing
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Solution Overview
Problem
Existing train detection systems on railway tracks require multiple transmitters, receivers, and dedicated wires for each section, leading to increased costs and maintenance needs, and centralized switch systems for time multiplexing are time-consuming and inefficient.
Innovation Solution
A system using selective band-pass filters near insulation joints allows a single transmitter and receiver to control multiple sections by transmitting and receiving signals with multiple carrier frequencies, enabling spectrum analysis to identify occupied sections through missing carriers, reducing the need for multiple wires and transmitters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transmitters and receivers are used for each section, then train detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
A single transmitter and receiver are designed to handle multiple track sections simultaneously by transmitting signals at multiple carrier frequencies. Each frequency corresponds to a specific section, allowing one device to perform the function of multiple dedicated devices while maintaining detection reliability across all sections
Solution Approach 2:
The system changes the frequency parameter of the transmitted signal to differentiate between multiple sections. By using multiple carrier frequencies (f1, f2, ..., fn) from a single transmitter, the system can identify which section a train occupies by detecting which frequency is blocked, replacing the need for multiple physical transmitters and receivers
2Reliability
If dedicated wires are used for each section, then signal transmission reliability is improved, but loss of substance and cost increase
Solution Approach 1:
Multiple dedicated wire connections for different sections are merged into a single shared wire infrastructure. The same physical wire carries signals for multiple sections by using frequency division multiplexing, where each section's signal is transmitted at a distinct carrier frequency, eliminating the need for separate wire pairs for each section
Solution Approach 2:
A single wire connection is designed to serve multiple track sections simultaneously by carrying multiple frequency components. The wire becomes a universal transmission medium that can convey information about the status of multiple sections through frequency-based encoding, reducing the total amount of wiring material required
3Device complexity
If centralized switch system is used for time multiplexing, then device complexity is reduced, but loss of time increases
Solution Approach 1:
The transmitter emits signals at multiple carrier frequencies in a periodic cyclic manner, with each frequency corresponding to a specific track section. By periodically alternating between different frequencies rather than using mechanical switching, the system achieves time multiplexing without the time delays and complexity of physical switches, continuously monitoring all sections through frequency division
Solution Approach 2:
The mechanical switch system is replaced with an electronic frequency multiplication approach. Instead of physically switching connections using mechanical devices that take time to operate, the system uses electronic generation of multiple carrier frequencies from a single transmitter, eliminating mechanical moving parts and associated switching delays
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution decreases the number of required cables, transmitters, and receivers, lowering costs and maintenance while ensuring reliable train detection, meeting SIL-4 safety standards with fewer components and simplified maintenance.
Implementation Method 1
a transmitter capable of emitting a main signal comprising a plurality of frequencies into a first couple of wires
Implementation Method 2
n selective coupling units with the railway track sections, such as band pass filters arranged respectively to n sections and allowing passage into the respective sections of only the portions of the main signal having the associated frequencies
Implementation Method 3
a receiver arranged to receive the main emitted signal, after its passage into the sections, through a second couple of wires
Implementation Method 4
the control unit detect therefore the presence of a train on a predetermined section if the respective frequency associated to said section is missing from the received signal
Data Source
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AI summary
A system for detecting the presence of a train on a railway track (1 b) comprising a plurality of sections (2a", 2b", ..., 2n"), the system comprising: - a transmitter (10b) arranged to emit a main signal towards the plurality of sections (2a", 2b", ..., 2n"); - a plurality of selecting devices (14a, 14b, ..., 14n) associated respectively to the plurality of sections (2a", 2b",..., 2n") along the railway track (1 b) and arranged to selectively allow passage of said main signal towards respective sections of said plurality of sections (2a", 2b", ..., 2n"); - a receiver (12b) arranged to receive the main signal after having passed through the plurality of sections (2a", 2b", ..., 2n"); - a control unit (20) associated to said receiver (12b) arranged to perform an analysis of said received signal so as to detect the presence of a train on a predetermined section (2a", 2b", ..., 2n") of said plurality of sections (2a", 2b", 2n").