역무자동화설비 안테나감도 측정기 설계 및 구현 = AFC Antenna Signal Strength Meter Design and Implementation

다국어 초록 (Multilingual Abstract)

Transportation card and a terminal at subway stations communicate by using a carrier frequency of 13.56Mhz band corresponding to the ISO-14443 specification. Old or damaged transportation cards may be deteriorate receiving performance and they can whether use normally or not depending the capability of the terminals. If the usage of a transportation card which is normally operated at some stations is impossible at other stations, the transportation card user may think that the facilities at stations are out of order even though it’s because of deterioration of the transportation card. This leads to distrust for the transportation system and make a decline of consumer satisfaction measurement.
In this paper, an antenna signal strength meter of an automatic fare collection system is designed and implemented to measure the electric field strength inducedbetween a terminal and a transportation card. The implemented meter uses an ATmega 128 microcontroller and it is used to determine the performance of a transportation card based on the measured data. Specifically, SWR (standing wave ratio) is measured between a RF-Main and the antenna of the reader, It was implemented to determine a matching state of the antenna performance and the reader.
The implemented meter has been tested to confirm the applicability at real environment. The field test was performed at all the stations of line 3 of Daegu subway and measured the antenna signal strength for different distance from the reader of a terminal. It is confirmed that as the electric field strength is the higher the recognition distance of a transportation card is the longer. Also it is found that the recognition distance is longest and shoes good performance at SWR of 1.5. The implemented meter can be helpful to get more trust from the consumer and give better objective information instead of conventional passive approach for the customer dissatisfaction.
Even though the good performance there are still several enhancement for system upgrade. Some of them include battery management capability to guarantee the continuous measurement, batter monitoring capability, and minimization of the size of the meter in order to make it portable for productive the measurement work.

국문 초록 (Abstract)

교통카드는 ISO-14443에 해당하는 13.56Mhz 대역의 반송주파수를 사용하여 교통카드와 단말기가 상호 데이터 통신을 하여 처리를 하게 된다. 사용기간이 오래된 교통카드 혹은 훼손 교통카드의 경우 정상적인 교통카드보다 성능이 저하되어 단말기의 성능에 따라 사용이 가능할 수도 있고 불가능 할 수 있다. 교통카드사용이 불가능할 경우 고객은 본인이 소유한 교통카드 불량으로 판단치 않고 교통기관의 단말기 성능편차로 느끼게 될 수 있으며 나아가 해당 교통기관에 대한 불신으로 이어져 고객만족도를 저하 시킨다.
본 논문에서는 역무자동화 설비의 안테나감도 측정기를 설계하고 구현하였다. 구현된 시스템은 Atmega128을 사용하여 교통카드에 유기되는 전계강도를 검파부와 적분기를 통하여 안정된 전압값을 측정하여 리더기의 성능을 확인할 수 있도록 하였으며, 리더기의 RF-Main과 안테나의 정재파를 측정할 수 있도록 하여 리더기의 성능과 안테나의 매칭상태를 확인할 수 있도록 구현하였다.
안테나감도측정기를 제작하여 대구도시철도 3호선에서 현장시험 진행하였고 전계강도측정값과 교통카드인식률을 비교한 결과 전계강도 값이 높을수록 교통카드의 인식거리가 길어져 인식률이 좋은 것으로 나타났으며, 정재파비와 교통카드 인식률을 비교한 결과 정재파비가 1.5에서 교통카드이 인식거리가 가장 길어 인식률이 좋은 것으로 나타났다. 안테나감도 측정기의 활용으로 기존의 수동적인 점검방법 보다 양질의 점검이 가능하여 단말장비의 신뢰성을 높일 수 있을 것으로 예상된다.
안테나감도 측정기의 문제점으로는 배터리의 남은 용량을 확인할 수 없어 측정도중 전원이 꺼지는 사례가 발생되어 배터리 용량을 계산하여 현시하는 기능이 추가되어야 하고 안테나감도 측정기의 크기를 최소화 하여 휴대용으로 사용할 수 있도록 추가 연구가 필요하다고 사료된다.

목차 (Table of Contents)

• Ⅰ. 서 론 ························································1
• 1.1배경 및 목적 ················································1
• (1) 연구배경 ····························································1
• (2) 연구목적 및 방법 ················································1
• Ⅱ. 역무자동화설비 개요 ······································3
• 2.1. 자동개집표기 ··························································5
• (1) 자동개집표기 개요·················································5
• (2) 자동개집표기 종류 및 구성 ····································5
• (3) 자동개집표기 운영모드 ··········································6
• 2.2. 통합자동발매기 ····················································7
• 2.3. 자동정산기 ··························································7
• 2.4. 휴대용정산기 ··························································7
• 2.5. 자동분류기 ··························································8
• 2.6. 관리역전산기 ··························································8
• 2.7. 운영자전산기 ··························································8
• 2.8. 중앙전산시스템 ····················································8
• 2.9. 중앙발권시스템 ····················································9
• Ⅲ. 역무자동화설비의 RFID시스템 ·····················10
• 3.1. 역무자동화설비의 RFID시스템 ·····························10
• (1) 리더기와 교통카드의 통신····································11
• 3.2. 교통카드의 전력공급··············································13
• 3.3. 변조방식에 따른 교통카드 분류 ···································14
• (1) Mifare방식 ·················································14
• (2) ISO-14443 Type A ·······································14
• (3) ISO-14443 Type B ·······································14
• Ⅳ.역무자동설비 안테나감도 측정기 설계······················16
• 4.1. 기존안테나감도 측정기 문제점·····································16
• 4.2. 안테나감도 측정기 하드웨어 설계··································17
• (1) 주제어부·················································18
• (2) 전계강도 측정부·················································19
• (3) 정재파 측정부·················································20
• (4) 선택부·················································21
• 4.3. 안테나감도 측정기 소프트웨어 설계·······························22
• (1) 전계강도 측정·················································23
• (2) 정재파 측정·················································24
• 4.4. 안테나감도측정기 제작·········································24
• 4.5. 안테나감도측정기 사용방법·········································26
• (1) 전계강도 측정방법·····································26
• (2) RF-Main 성능 측정방법·····································27
• (3) 안테나 성능 측정방법·····································28
• Ⅴ. 안테나감도측정기 현장적용시험···························29
• 5.1. 전계강도측정값과 교통카드 인식률 비교··························29
• (1) Mifare(승차권)전계강도측정값과 인식률 비교··········29
• (2) ISO-14443 Type A 전계강도측정값과 인식률 비교····30
• (3) ISO-14443 Type B 전계강도측정값과 인식률 비교····31
• (4) 변조방식별 전계강도측정값과 인식률 비교·················31
• 5.2. 정재파측정값과 교통카드 인식률 비교····························33
• Ⅵ. 결 론·······················································34
• 참고문헌······················································35
• 영문초록······················································36