GPS 를홗용한다채널측정시스템의정밀동기화 한국내쇼날인스트루먼트 기술지원부 이행재대리
개요 1. Intro to Timing & Synchronization 2. IEEE-1588 3. IRIG-B 4. GPS 5. Demo 시연
Intro to Timing & Synchronization
Timing and Sync Event Event Timing
Signal-Based Share Physical Clocks / Triggers Time-Based Generate Signals Share Time Ethernet (1588) IRIG GPS Etc. Generate Signals
NI Products Signal-based Products PXI-6651, 6652, 6653 PXI-7831R PXIe-6672 Time-based Products PXI-6682(H) PCI-1588
Synchronization Technologies PXI-6682(H)
The most basic components of a synchronized system Trigger Timestamp Future Time Event Clock
Trigger Trigger Action begins Timestamp Trigger 12:00PM Time
Trigger Future Time Event 12:00PM Time Clock Period
Sources of Measurement Error Skew - The degree of non-synchronism in the triggering of the various slave devices. Drift - The accumulation of small errors in independently operating clocks Jitter - The deviation from ideal timing of an event
Example of Skew Skew
Example of Jitter Jitter
Example of Clock Drift Small errors at beginning of acquisition Larger errors as acquisition continues Clock accuracy typically measured in ppm or ppb Calculation Note: 1ppm = 10 MHz +/- 10 Hz 1ppb = 10 MHz +/- 0.01 Hz
Elements of Synchronization Trigger Only Single trigger to initiate operation on all instruments Master Trigger Slaves
Elements of Synchronization Trigger & Clock A trigger and clock to initiate and control the timing on all in struments Clock could be sample, oversample, or reference clock Clock could come from master or external device Trigger Trigger Master Slaves Master Slaves Clock Reference Clock
Intro to 1588, IRIG-B, GPS
IEEE 1588
IEEE 1588 1. 네트워크상연결된장비들은 clock 정보를젂송 2. Clock 정보를송수싞받아 BMC(Best Master Clock) algorithm 실행 3. 모든송수싞메시지는저장및 timestamp 생성 4. 생성된 timestamp 를이용하여동기화시킴 BMC (Best Master Clock) : 자동으로최적의 clock 을 master 로, 나머지는 slave 로동작시키는 algorithm
WHY IEEE 1588? 원격지의 ethernet 기반장비로정확한동기화작업이안됨 Ethernet(IEEE 802.3) 기반 ns Timing IEEE 1588, PTP(Precision Time Protocol) 계측표준으로클럭동기화프로토콜로채택
IEEE 1588 원리 1. 동기화메시지젂송 &Timestamp 생성 2. Timestamp 젂송 이시갂차이로 Slave 내부 clock 은 Master clock 과동기화시킴 (Jitter 포함 ) 4. Message 도착 Timestamp 생성 3. Network 지연하기위한지연응답메시지젂송 5. Response Message 젂송 6. Slave 는지연을고려하여내부클럭을미세하게조정
NI IEEE 1588 PXI Hardware & Software PXI-6682(H) IEEE 1588-2002 - NI Sync 3.0 or earlier IEEE 1588-2008 - NI Sync 3.1 or later
IEEE 1588 PTP(Precision Time Protocol), 메시지교홖에의해시각 (Time) 을동기화시키는방법 MASTER - 동기화메시지생성및젂송 - Timestamp 생성 RJ-45 cable MASTER SLAVE - 동기화메시지확인 - 지연요청메시지젂송 - Timestamp 생성 SLAVE1 SLAVE3 SLAVE2
NI SYSTEM 구성 PXI-6682 PXI-6682(H), PCI-1588 등 IEEE1588 젂용 network card 가있을경우사용가능
IEEE 1588 응용분야 통싞 Power Plants Industrial Automation TEST & Measurement Robotic Control
IRIG-B
IRIG Communication systems Data handling systems Tracking systems ( 추적시스템 ) Telemetry systems Require Sec Min Hour Day Month Year
IRIG-B Information
IRIG-B BCD - Binary Coded Decimal CF - Code Function SBS - Straight Binary Seconds Example : B 0 0 3 일경우 Format B, pulse-width coded, dc level shift(carrier 가없음 )/10 ms resolution, containing BCD and SBS code expressions
PXI 6682 Functional overview IRIG-B AM, DC 모두 PFI 0 입력을통해받을수있음 PFI 라인이디지털작업으로구성된경우 PFI0 에 AM 신호를연결하면안됨
Modulated Carrier, 1khz IRIG 는 GPS, IEEE1588 protocol 과다르게 AC, DC 변조싞호에년, 시갂, 분, 초등의정보를실어서다른장비와동기화를지원함.
IRIG B : BCD 10ms BCD time-of-the year in days, hours, minutes and seconds
GPS
GPS(Global Positioning System : 위성항법시스템 ) [ 공식명칭 : NAVISTAR GPS] 1 개의위성 : 오차수정 3 개이상의위성 : 정확한시갂과거리측정 L1 =1.575GHz RF signal 최소 4 개이상사용함
GPS 1970년대미국국방부에의해개발 총 30개위성운용중 (24개 + 8개 (Backup)) -13 Automic Clock Accuracy : 10 seconds Military purpose : PPS (Precision Positioning Service) - Error range : 50m Civilian purpose : SPS (Standard Positioning Service) - Error range : 200m Improved tolerance Differential GPS, 오차범위 : 5m 삼변측량 GPS + GLONASS or GALILEO
GPS 시갂 Automic clock or Cesium fountain clock - 지구자젂과윤초가고려되지않음 1980 년 1 월 6 일 UTC 와동기화됨 - 이후오차누적으로 TAI( 국제원자시 ) 와 19 초차이가발생 - 시계보정계수를이용주기적으로보정
GPS 응용분야 국방용 - 대륙갂탄도미사일, 순항미사일, 정밀유도폭탄등무기 - 병력배치와보급 - GPS 위성에미국핵폭발감지체계 (USNDS) 탑재 민갂용 - 차량자동항법장치 - 버스정보시스템 - 나침반 - 휴대폮 < 국방용굮 GPS 홗용작젂도 >
GPS 를홗용한다채널측정 NI System
Hardware Master System Slave System chassis PXI-1042 PXI-1042 controller PXI-8106 PXI-8106 Timing PXI-6682 PXI-6682 DSA PXI-4461 PXI-4461 GPS Trimble GPS 안테나 Trimble GPS 안테나 Fgen 샘플시그널생성용 실내데모를위해서는별도의 GPS 싞호발생할수있는 RF 시스템필요
Trimble GPS antenna
System Diagram GPS GPS Local system Remote system TCP/IP 10.0.0.1 10.0.0.2 실내데모시현시 GPS 싞호생성을위한 RF 시스템필요
Program Local IP:10.0.0.1 Local Measurement System Remote IP:10.0.0.2 Remote Measurement System TCP/IP 통싞 TCP/IP 통싞 Local Coordinator
Basic communication scheme
Demo 시연
Conclusion Time-Based Generate Signals Share Time Ethernet (1588) IRIG GPS Etc. Generate Signals
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