1. A Study on High-Speed Recognition of Hybrid Track Circiut
17th, Dec, 2014 Changlong Li, Keyseo Lee,
Kwangwoon Univ.
Good afternoon everyone. My name is changlong li, from kwangwoon univeristy. I’m a second author of development of a Hybrid Track Circuit, sometimes we call it HTC for the abbriviation. The current railway signaling system divides tracks into several sections for the safe running of trains, and each section allows only one train to enter at a time to prevent two or more from colliding with each other, which is called a track circuit.

2. INTRODUCTION Hybrid Track Circuit Concept
RFID antenna and reader on the cab
RFID tag on the sleeper
Composed of software on the cab computer
Cab computers are a hot standby system for reliability and safety
900MHz frequency is used and ETCS specification for housing is applied.
hybrid track circuit, is proposed using RFID antenna and reader on the cab and RFID tag on the sleeper. Also HTC is composed of software on the cab computer. Cab computers are a hot standby system for reliability and safety. 900MHz frequency is used and ETCS specification for housing is applied

3. Hybrid Track Circuit System
INTRODUCTION
Hybrid Track Circuit System
Figure 1. Hybrid Track Circuit System
The hybrid track circuit has 900㎒ antennas at the front and back sides of the train, as illustrated in Figure 1, and the tag is installed in the tracks so that it can transmit the data. This is compatible with existing ATO (Automatic Train Operation) and ATP (Automatic Train Protection), and a block that is as long as the train forms the hybrid track circuit by means of software with the exact location of the train recognized.

4. OBJECTIVES This study aims to
Suggest a hybrid track circuit as a virtual track circuit
Corresponds to the length of a train by means of a train-locating hardware and software
Based on the information transmitted between RFID antennas and RFID tags at a frequency of 900MHz unlike existing track circuits.
This study aims to suggest a hybrid track circuit as a virtual track circuit that corresponds to the length of a train by means of a train-locating hardware and software based on the information transmitted between RFID antennas and RFID tags at a frequency of 900MHz unlike existing track circuits.

5. METHODS
The hybrid track circuit has 900MHz antenna at the head and tail sides of the train
The tag is installed in the tracks so that it can transmit the data.
Compatible with existing ATO and ATP
Form a block by hybrid track circuit and recognize the exact location by software
An all-in-one reader system should be used and, additionally, a transmission/ reception separating system may be needed for high-speed movement
The hybrid track circuit has 900㎒ antennas at the front and back sides of the train, as illustrated in Figure 1, and the tag is installed in the tracks so that it can transmit the data. This is compatible with existing ATO (Automatic Train Operation) and ATP (Automatic Train Protection), and a block that is as long as the train forms the hybrid track circuit by means of software with the exact location of the train recognized. An all-in-one reader system (140km/h) should be used and, additionally, a transmission/reception separating system may be needed for high-speed movement.

6. Figure 2. The Antenna for Speed Recognition Test Concept
METHODS
Figure 2. The Antenna for Speed Recognition Test Concept
The recognition speed on the moving body calculated as an RFID system is illustrated in equation 1 below:
Recognition Speed =(Distance of the Antenna Communication Passage)/(TAG Access Time) (1)
In a tunnel section, wireless communication and RFID communication may involve such problems as high frequency, induction failure, frequency interference, and scattered reflection due to tunnel structures. In addition, such environmental factors as temperature, humidity, and dust may deteriorate the performance of the RFID system. Since a train moves at various speeds, the antennas at the front and back sides may not be able to recognize the frequency of the tag as the train moves before the tag frequency is transmitted to the antennas. For the system to operate appropriately, therefore, the distance between the tag and antennas and train speed need to be measured to define the tag recognition speed corresponding to the train speed. The hybrid track circuit uses the frequency of MHz for the linear tag and MHz for the circular tag in UHF bandwidth. Such factors as train speed and distance between the tag and antennas should be checked for the system to work smoothly.
The recognition speed on the moving body calculated as an RFID system is illustrated in equation 1 below:

7. METHODS
Antenna
Antenna is indirect structure, divided into direct type and indirect type
The indirect feeding type may expand the antenna bandwidth more widely than the direct feeding type
It involves no change in antenna performance due to external temperature or foreign substances
The antenna polarization is divided into Circular Polarization and Linear Polarization.
The expression of antenna polarization is as follows:
The antennas are of an indirect structure, and they are divided into the direct feed type that approves signals in direct linkage to the radiating element and the indirect feed type that transmits signals of the radiating element through electronic coupling. The indirect feeding type may expand the antenna bandwidth more widely than the direct feeding type, and it involves no change in antenna performance due to external temperature or foreign substances. The antenna polarization is divided into Circular Polarization and Linear Polarization. Circular Polarization is advantageous in that it assures higher recognition rates in various environments. The expression of antenna polarization is as follows:

8. METHODS Figure 3. The Antenna for Speed Recognition Test
port 1
port 2
BW : 62.5˚
BW : 72.2˚
BW : 70.8˚
BW : 59.5˚
Figure 3. The Antenna for Speed Recognition Test
Table 1. Port 1 and Port 2 Specification
Figure 4. Reader’s output power
Frequency
Max Value
Average gain
Efficiency
[MHz]
θ[Deg]
Φ[Deg]
Value[dBi]
[dBi]
[%]
917 90 75
8.715
0.254
920
8.771
0.308
923
8.751
0.294
107.01
위의 식에 근거하여 그림3과 같이 제품을 만들었다. 표1은 안테나 포트의 사양서이다. 그림4는 그림3의 안테나를 사용했을때의 리더기의 출력 전압이다. 리더기에 대해서는 다음페이지에서 설명하겠다.
Frequency
Max Value
Average gain
Efficiency
[MHz]
θ[Deg]
Φ[Deg]
Value[dBi]
[dBi]
[%]
917 90
8.474
-0.112
97.451
920
8.488
-0.037
99.157
923
8.418
-0.035
99.191

9. Figure 5. The Reader block diagram for High Speed Recognition Test
METHODS
Reader
The existing combination reader into a multi-antenna type system with separate antennas for higher speed recognition.
Figure 3 transforms the existing combination reader into a multi-antenna type system with separate antennas for higher speed recognition. As illustrated in Figure 3, the radiating element (Number 1) of the multi-antennas enables the system to transmit and receive information simultaneously while recognizing speed. The radiating elements of Numbers 2, 3, and 4 antennas are dedicated to receiving information, and as the train speed increases, the antenna radiating elements of Numbers 2, 3, and then 4 are used for recognition in the order. The use of multi-antennas enables the reader to minimize high speed switch time as it promptly processes signals that are received through the detector from various resources. The treated signals are filtered through the digital filter in the RFID reader with the CLOCK TIME optimized for high speed recognition.
Figure 5. The Reader block diagram for High Speed Recognition Test

10. Figure 6. The Reader board for High Speed Recognition Test
METHODS
Reader
The use of multi-antennas enable the reader to minimize high speed switch time as it promptly processes signals that are received
The treated signals are filtered through the digital filter in the RFID reader with the CLOCK TIME optimized for high speed recognition
Tx/Rx
Tx/Rx Rx
Tx/Rx Rx
Tx/Rx Rx
Tx/Rx
Figure 6. The Reader board for High Speed Recognition Test
그림 6과 같이 리더기를 제작하였다. 네개의 안테나가 안테나가 모두 읽기 쓰기 기능을 동시에 할수도 있고 하나의 안테나에서 읽기 쓰기가 가능하고 나머지는 읽기만 가능하게 제작했다.

11. Figure 7. Tag Recognition test in the lab
METHODS
Tag Recognition Test
The gap between the tag and antenna was about 50cm
A reader with a maximum of 30dB transmission output that enables transmitting and receiving either simultaneously or separately
Figure 7. Tag Recognition test in the lab
A test was conducted to verify if the tag antenna would recognize the tag accurately with the train moving. A servo motor was utilized to simulate the train’s movement. The gap between the train and ground was about 50cm. Figure 7 shows a combination of a servo motor whose maximum speed is 5,000rpm, a reader with a maximum of 30dB transmission output that enables transmitting and receiving either simultaneously or separately, and Linear Polarization antenna and Circular Polarization antennas of 6dBi antenna gain.

12. METHODS Tag Recognition Test
Table 2. RFID Tag Specification
Table 3. RFID Antenna Specification
Item/Series
Specification
Linear
Circular
Frequency ㎒ ㎒
Data transfer rate
512kbit/s
User data
96bit
Modulation
OOK/PR-ASK
Distance
1.5m
2.5m
Size
108×108×8㎜
Weight
125g
16g
Temperature
-80℃-+120℃
IP degree
IP67
Item/Series
Specification
Linear
Circular
Frequency ㎒
Polarization
V.S.W.R
1.25:1 Typical
Gain
7.5dBi Typical
Isolation
Min 30dB Typical
2.5m
3dB Beamwidth
Min 60˚
Min 65˚
Material(Radome)
Aluminum / PC
PC / ABS
Connector
SMA-Female
Reading Range
More than 6m
Size
250×250×40㎜
Purpose
Gate Type (Logistics)
Tag Recognition Test
Linear Polarization antenna and Circular Polarization antennas of 6dBi antenna gain.
Two types of tags—linear tag and circular tag—were used
The specification of RFID tag and antenna is presented in Table 1&2
Two types of tags—linear tag and circular tag—were used, and the specification of RFID tag is presented in Table 2 below. The specification of RFID antenna is presented in Table 3 below. The recognition performance of Linear Polarization tag and Circular Polarization tag was tested with the Circular Polarization antenna as the reader antenna. As a result, it turned out that the recognition rates of Circular Polarization were high as shown in Figures 6 and 7 below:

13. Lab test about tag recognition
RESULTS
Lab test about tag recognition
The recognition performance of Linear Polarization tag and Circular Polarization tag was tested with the Circular Polarization antenna as the reader antenna. As a result, it turned out that the recognition rates of Circular Polarization were high as shown in Figures 6 and 7 below:The test environment where the tag was rotated seemed to involve less polarization loss due to a polarization discrepancy with the reader antenna of Linear Polarization. As the reader transmission output increased at a certain rotating speed, the recognition rates increased accordingly. The maximum value was observed at 25dB. With the transmission output of 25dB or higher, the signals from the reader antenna were not directly permitted to the tag but reflected to the test surroundings such as wall and structure. Such is called a scattered reflection phenomenon.
Figure 8. Linear Tag Recognition
By Means of Circular Polarization Antenna
Figure 9. Circular Tag Recognition
By Means of Circular Polarization Antenna

14. Field test about antenna recognition
RESULTS
Field test about antenna recognition
그림 11은 서울메트로 차량기지와 영업운영구간에서 진행한 테스트 사진이다. 태그는 1m의 간격으로 침목위에 부착하였고 안테나와 태그의 수직거리는 실험실과 같이 50cm를 기준으로 하였다. 현재 저속에서는 인식율이 100%에 달한다.
Figure 10. Separate Reader Recognition By Means of Circular Polarization Antenna

15. Field test about antenna recognition
RESULTS
Field test about antenna recognition
서울메트로 구간에서 시험결과 그림10과 같이 결과가 나왔다. 결과에서 녹색은 일체형 안테나를 사용했을 때이고 파랑색은 분리형 안테나를 사용했을 경우이다. 일체형 안테나의 인식효율이 분리형 안테나의 인식효율보다 훨씬 높음을 알 수 있다.

16. Field test about antenna recognition
RESULTS
Field test about antenna recognition
그림 11은 서울메트로 차량기지와 영업운영구간에서 진행한 테스트 사진이다. 태그는 1m의 간격으로 침목위에 부착하였고 안테나와 태그의 수직거리는 실험실과 같이 50cm를 기준으로 하였다. 현재 저속에서는 인식율이 100%에 달한다.

17. Field test about antenna recognition
RESULTS
Field test about antenna recognition
Power
The Number of Operation
Recognition Rate 비고
21dBm 24
100%
24 dBm %
27 dBm 41 %
30 dBm 13
87.5%
서울메트로 구간에서 시험결과 그림10과 같이 결과가 나왔다. 결과에서 녹색은 일체형 안테나를 사용했을 때이고 파랑색은 분리형 안테나를 사용했을 경우이다. 일체형 안테나의 인식효율이 분리형 안테나의 인식효율보다 훨씬 높음을 알 수 있다.

18. DISCUSSION From the lab test and field test
The test environment where the tag was installed seemed to involve less polarization loss due to a polarization discrepancy with the reader antenna of linear polarization.
As the reader transmission output increased at a certain speed, the recognition rates increased accordingly
The maximum value was observed at 25dB. With the transmission output of 25dB or higher, the signals from the reader antenna were not directly permitted to the tag
The test environment where the tag was rotated seemed to involve less polarization loss due to a polarization discrepancy with the reader antenna of Linear Polarization. As the reader transmission output increased at a certain rotating speed, the recognition rates increased accordingly. The maximum value was observed at 25dB. With the transmission output of 25dB or higher, the signals from the reader antenna were not directly permitted to the tag but reflected to the test surroundings such as wall and structure. Such is called a scattered reflection phenomenon.

19. DISCUSSION From the lab test and field test
Scattered reflection phenomenon appeared which is reflection by the test surroundings
In the field test, the recognition rate of tag from the 60km/h still need to meet 100%, it seems to improve reader’s performance
tag but reflected to the test surroundings such as wall and structure. Such is called a scattered reflection phenomenon. In the field test, the recognition rate of tag from the 60km/h still need to meet 100%, it seems to improve reader’s performance

20. CONCLUSION Plans in the future
A simulator for testing was made. The maximum speed of the simulator was 500km/h.
RFID antenna includes four antennas as one body for a level recognition as high as 500km/h.
In the tag recognition test, higher tag recognition rates were shown when the circular polarization antenna and circular polarization tag were used for RFID antenna.
A simulator for testing was made. The maximum speed of the simulator was 500km/h. The proposed HTC can detect tags correctly for 500km/h high speed and constitutes an HTC well. RFID antenna includes four antennas as one body for a level recognition as high as 500km/h. In the tag recognition test, higher tag recognition rates were shown when the Circular Polarization antenna and Circular Polarization tag were used for RFID antenna.

21. CONCLUSION Plans in the future
The field testing of HTC was carried out at the Daibul test line.
Experimental reports showed a potential for high speed. Soon a high-speed line test will be carried out at the Osong test line.
HTC combined with tachometer can be used for ATO, ATP, and ATC. Simple and low-cost HTC can be a key part of a railway signaling system.
The field testing of HTC was carried out at the Daibul test line. Experimental reports showed a potential for 200km/h. Soon a high-speed line test will be carried out at the Osong test line.
HTC combined with tachometer can be used for ATO, ATP, and ATC. Simple and low-cost HTC can be a key part of a railway signaling system.
HTC combined with tachometer can be used for ATO, ATP, and ATC. Simple and low-cost HTC can be a key part of a railway signaling system

22. Thank you!

24. safety requirement is very high compare with other countries.