52 research outputs found

    ์„ผํ‹ฐ๋ฏธํ„ฐ ๊ธ‰ ๊ด‘์—ญ ๋ณด๊ฐ•ํ•ญ๋ฒ• ์‹œ์Šคํ…œ์˜ ๋ฐ˜์†กํŒŒ ์œ„์ƒ ๊ธฐ๋ฐ˜ ๋ณด์ •์ •๋ณด ์ƒ์„ฑ ์•Œ๊ณ ๋ฆฌ์ฆ˜์— ๊ด€ํ•œ ์—ฐ๊ตฌ

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    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ)--์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› :๊ณต๊ณผ๋Œ€ํ•™ ๊ธฐ๊ณ„ํ•ญ๊ณต๊ณตํ•™๋ถ€,2020. 2. ๊ธฐ์ฐฝ๋ˆ.Recently, the demand for high-precision navigation systems for centimeter-level service has been growing rapidly for various Global Navigation Satellite System (GNSS) applications. The network Real-Time Kinematic (RTK) is one of the candidate solution to provide high-accuracy position to user in real-time. However, the network RTK requires a lot of reference stations for nationwide service. Furthermore, it requires high-speed data-link for broadcasting their scalar-type corrections. This dissertation proposed a new concept of satellite augmentation system called Compact Wide-Area RTK, which provides centimeter-level positioning service on national or continental scales to overcoming the limitation of the legacy network RTK methods. Using the wide-area network of multiple reference stations whose distance is 200~1,000 km, the proposed system generates three types of carrier-phase-based corrections: satellite orbit corrections, satellite code/phase clock (CPC) corrections, tropospheric corrections. Through the strategy of separating the scalar-type corrections of network RTK into vector forms of each error component, it is enable to expand network RTK coverage to continental scale using a similar number of reference stations as legacy meter-level Satellite-Based Augmentation System (SBAS). Furthermore, it is possible to broadcast their corrections over a wide-area using geosynchronous (GEO) satellite with extremely low-speed datalink of 250 bps likewise of legacy SBAS. To sum up, the proposed system can improve position accuracy by centimeter-level while maintaining the hardware infrastructure of the meter-level legacy SBAS. This study mainly discussed on the overall system architecture and core algorithms for generating satellite CPC corrections and tropospheric corrections. This study proposed a new Three-Carrier Ambiguity Resolution (TCAR) algorithm using ionosphere-free combinations to correctly solve the integer ambiguity in wide-area without any ionospheric corrections. The satellite CPC corrections are calculated based on multiple stations for superior and robust performance under communication delay and outage. The proposed algorithm dramatically reduced the latency compensation errors and message amounts with compare to conventional RTK protocols. The tropospheric corrections of the compact wide-area RTK system are computed using GPS-estimated precise tropospheric delay and weather data based model together. The proposed algorithm adopts spherical harmonics function to significantly reduce the message amounts and required number of GPS reference stations than the network RTK and Precise Point Positioning-RTK (PPP-RTK), while accurately modeling the spatial characteristic of tropospheric delay with weather data together. In order to evaluate the user domain performance of the compact wide-area RTK system, this study conducted the feasibility test on mid-west and south USA using actual GPS measurements. As a result, the 95% horizontal position error is about 1.9 cm and the 95% vertical position error is 7.0 cm after the integer ambiguity is correctly fixed using GPS-only signals. The user ambiguity resolution takes about 2 minutes, and success-fix rate is about 100 % when stable tropospheric condition. In conclusion, the compact wide-area RTK system can provide centimeter-level positioning service to wide-area coverage with extremely low-speed data link via GEO satellite. We hope that this new system will consider as candidate solution for nationwide centimeter-level service such as satellite augmentation system of the Korea Positioning System (KPS).์ตœ๊ทผ ์ž์œจ์ฃผํ–‰์ž๋™์ฐจ, ๋ฌด์ธ ๋“œ๋ก  ๋ฐฐ์†ก, ์ถฉ๋Œ ํšŒํ”ผ, ๋ฌด์ธํŠธ๋ž™ํ„ฐ๋ฅผ ์ด์šฉํ•œ ์Šค๋งˆํŠธ ๋ฌด์ธ ๊ฒฝ์ž‘ ๋“ฑ ์œ„์„ฑํ•ญ๋ฒ•์‹œ์Šคํ…œ(GNSS, Global Navigation Satellite System)์„ ์‚ฌ์šฉํ•˜๋Š” ๋‹ค์–‘ํ•œ ์‘์šฉ๋ถ„์•ผ์—์„œ ์ˆ˜ cm ์ˆ˜์ค€์˜ ์ •๋ฐ€ ์œ„์น˜ ์ •๋ณด์— ๋Œ€ํ•œ ์š”๊ตฌ๊ฐ€ ๊ธ‰๊ฒฉํžˆ ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ๋‹ค. ๋ณธ ํ•™์œ„๋…ผ๋ฌธ์—์„œ๋Š” 1 m ๊ธ‰์˜ ์ •ํ™•ํ•˜๊ณ  ์‹ ๋ขฐ์„ฑ ๋†’์€ ์œ„์น˜ ์„œ๋น„์Šค๋ฅผ ์ œ๊ณตํ•˜๋Š” ๊ธฐ์กด์˜ ์ •์ง€๊ถค๋„์œ„์„ฑ ๊ธฐ๋ฐ˜ ๊ด‘์—ญ ๋ณด๊ฐ•ํ•ญ๋ฒ• ์‹œ์Šคํ…œ(SBAS, Satellite-Based Augmentation System)์˜ ๊ธฐ์ค€๊ตญ ์ธํ”„๋ผ๋ฅผ ์œ ์ง€ํ•˜๋ฉด์„œ ํ•ญ๋ฒ• ์„ฑ๋Šฅ์„ ์ˆ˜ cm ์ˆ˜์ค€์œผ๋กœ ํ–ฅ์ƒ์‹œํ‚ค๊ธฐ ์œ„ํ•ด ๋ฐ˜์†กํŒŒ ์œ„์ƒ ๊ธฐ๋ฐ˜์˜ ์ดˆ์ •๋ฐ€ ๋ณด์ •์ •๋ณด ์ƒ์„ฑ ์•Œ๊ณ ๋ฆฌ์ฆ˜์— ๊ด€ํ•œ ์—ฐ๊ตฌ๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์‹ค์‹œ๊ฐ„ ์ •๋ฐ€ ์ธก์œ„(RTK, Real-Time Kinematic)๋Š” ๋ฐ˜์†กํŒŒ ์œ„์ƒ ์ธก์ •์น˜์— ํฌํ•จ๋œ ๋ฏธ์ง€์ •์ˆ˜๋ฅผ ์ •ํ™•ํ•˜๊ฒŒ ๊ฒฐ์ •ํ•˜์—ฌ ์ˆ˜ cm ์ˆ˜์ค€์˜ ์ •๋ฐ€ ํ•ญ๋ฒ• ์„œ๋น„์Šค๋ฅผ ๊ฐ€๋Šฅํ•˜๊ฒŒ ํ•˜๋Š” ๋Œ€ํ‘œ์ ์ธ ๊ธฐ๋ฒ•์ด๋‹ค. ๊ทธ ์ค‘์—์„œ๋„ ์•ฝ 50~70 km ๊ฐ„๊ฒฉ์œผ๋กœ ๋ถ„ํฌ๋œ ๋‹ค์ˆ˜์˜ ๊ธฐ์ค€๊ตญ ์ •๋ณด๋ฅผ ํ™œ์šฉํ•˜๋Š” Network RTK ๊ธฐ๋ฒ•์€ ๋™์  ์‚ฌ์šฉ์ž์˜ ๋น ๋ฅด๊ณ  ์ •ํ™•ํ•œ ์œ„์น˜ ๊ฒฐ์ •์ด ๊ฐ€๋Šฅํ•œ ์ธํ”„๋ผ๋กœ์„œ ์ฃผ๋ชฉ๋ฐ›๊ณ  ์žˆ๋‹ค. ํ•˜์ง€๋งŒ ์Šค์นผ๋ผ ํ˜•ํƒœ๋กœ ๊ตฌ์„ฑ๋œ Network RTK ๋ณด์ •์ •๋ณด๋Š” ๊ฐ ๊ธฐ์ค€๊ตญ ๋ณ„๋กœ ๊ด€์ธก๋œ ์œ„์„ฑ ์ˆ˜์— ๋”ฐ๋ผ ์ƒ์„ฑ์ด ๋˜๊ธฐ ๋•Œ๋ฌธ์— ๋ณด์ • ๋ฐ์ดํ„ฐ ๋Ÿ‰์ด ์ƒ๋‹นํžˆ ๋ฐฉ๋Œ€ํ•˜๋‹ค. ๋ฉ”์‹œ์ง€ ์ „์†ก์— ํ•„์š”ํ•œ ๋ฐ์ดํ„ฐ ๋Ÿ‰์ด ๋งŽ์„์ˆ˜๋ก ๊ณ ์†์˜ ํ†ต์‹  ํ™˜๊ฒฝ์„ ํ•„์š”๋กœ ํ•˜๋ฉฐ, ๋ฉ”์‹œ์ง€ ์‹œ๊ฐ„ ์ง€์—ฐ์ด๋‚˜ ํ†ต์‹  ๋‹จ์ ˆ์— ๋งค์šฐ ์ทจ์•ฝํ•œ ๋ฌธ์ œ๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๋‹ค. ๋˜ํ•œ ์Šค์นผ๋ผ ํ˜•ํƒœ์˜ ๋ณด์ •์ •๋ณด๋Š” ์‚ฌ์šฉ์ž์™€ ๊ธฐ์ค€๊ตญ ๊ฐ„์˜ ๊ฑฐ๋ฆฌ๊ฐ€ ๋ฉ€์–ด์งˆ์ˆ˜๋ก ๋ณด์ • ์˜ค์ฐจ๊ฐ€ ํฌ๊ฒŒ ๋ฐœ์ƒํ•˜๊ธฐ ๋•Œ๋ฌธ์— ๋Œ€๋ฅ™ ํ˜น์€ ๋‚˜๋ผ ๊ทœ๋ชจ์˜ ๊ด‘์—ญ์—์„œ ์„œ๋น„์Šคํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ˆ˜์‹ญ~์ˆ˜๋ฐฑ ๊ฐœ ์ด์ƒ์˜ ๊ธฐ์ค€๊ตญ ์ธํ”„๋ผ ๊ตฌ์ถ•์ด ํ•„์ˆ˜์ ์ด๋‹ค. ์˜ˆ๋ฅผ ๋“ค์–ด, SBAS๊ฐ€ ํ•œ๋ฐ˜๋„ ์ง€์—ญ ์„œ๋น„์Šค๋ฅผ ์œ„ํ•ด 5~7๊ฐœ์˜ ๊ธฐ์ค€๊ตญ์ด ํ•„์š”ํ•œ ๋ฐ˜๋ฉด Network RTK๋Š” 90~100๊ฐœ์˜ ๊ธฐ์ค€๊ตญ์ด ํ•„์š”ํ•˜๋‹ค. ์ฆ‰ Network RTK๋Š” ์‹œ์Šคํ…œ ๊ตฌ์ถ• ๋ฐ ์œ ์ง€ ๋น„์šฉ์ด SBAS ๋Œ€๋น„ ์•ฝ 15๋ฐฐ ์ •๋„ ๋งŽ์ด ๋“ค๊ฒŒ ๋œ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ๊ธฐ์กด Network RTK์˜ ๋ฌธ์ œ์ ์„ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ๋Œ€๋ฅ™ ๊ธ‰ ๊ด‘๋ฒ”์œ„ํ•œ ์˜์—ญ์—์„œ ์‹ค์‹œ๊ฐ„์œผ๋กœ cm๊ธ‰ ์ดˆ์ •๋ฐ€ ์œ„์น˜๊ฒฐ์ • ์„œ๋น„์Šค ์ œ๊ณต์ด ๊ฐ€๋Šฅํ•œ Compact Wide-Area RTK ๋ผ๋Š” ์ƒˆ๋กœ์šด ๊ฐœ๋…์˜ ๊ด‘์—ญ๋ณด๊ฐ•ํ•ญ๋ฒ•์‹œ์Šคํ…œ ์•„ํ‚คํ…์ฒ˜๋ฅผ ์ œ์•ˆํ•˜์˜€๋‹ค. Compact Wide-Area RTK๋Š” ์•ฝ 200~1,000 km ๊ฐ„๊ฒฉ์œผ๋กœ ๋„“๊ฒŒ ๋ถ„ํฌ๋œ ๊ธฐ์ค€๊ตญ ๋„คํŠธ์›Œํฌ๋ฅผ ํ™œ์šฉํ•˜์—ฌ ๋ฐ˜์†กํŒŒ ์œ„์ƒ ๊ธฐ๋ฐ˜์˜ ์ •๋ฐ€ํ•œ ์œ„์„ฑ ๊ถค๋„ ๋ณด์ •์ •๋ณด, ์œ„์„ฑ Code/Phase ์‹œ๊ณ„ ๋ณด์ •์ •๋ณด, ๋Œ€๋ฅ˜์ธต ๋ณด์ •์ •๋ณด๋ฅผ ์ƒ์„ฑํ•˜๋Š” ์‹œ์Šคํ…œ์ด๋‹ค. ๊ธฐ์กด ์Šค์นผ๋ผ ํ˜•ํƒœ์˜ Network RTK ๋ณด์ •์ •๋ณด ๋Œ€์‹  ์˜ค์ฐจ ์š”์†Œ ๋ณ„ ๋ฒกํ„ฐ ํ˜•ํƒœ์˜ ์ •๋ฐ€ ๋ณด์ •์ •๋ณด๋ฅผ ์ƒ์„ฑํ•จ์œผ๋กœ์จ ๋ฐ์ดํ„ฐ ๋Ÿ‰์„ ํš๊ธฐ์ ์œผ๋กœ ์ ˆ๊ฐํ•˜๊ณ  ์„œ๋น„์Šค ์˜์—ญ์„ ํ™•์žฅํ•  ์ˆ˜ ์žˆ๋‹ค. ์ตœ์ข…์ ์œผ๋กœ SBAS์™€ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ 250 bps์˜ ์ €์† ํ†ต์‹  ๋งํฌ๋ฅผ ๊ฐ€์ง„ ์ •์ง€๊ถค๋„์œ„์„ฑ์„ ํ†ตํ•ด ๊ด‘์—ญ์œผ๋กœ ๋ณด์ •์ •๋ณด ๋ฐฉ์†ก์ด ๊ฐ€๋Šฅํ•˜๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” 3๊ฐ€์ง€ ๋ณด์ •์ •๋ณด ์ค‘ ์œ„์„ฑ Code/Phase ์‹œ๊ณ„ ๋ณด์ •์ •๋ณด์™€ ๋Œ€๋ฅ˜์ธต ๋ณด์ •์ •๋ณด ์ƒ์„ฑ์„ ์œ„ํ•œ ํ•ต์‹ฌ ์•Œ๊ณ ๋ฆฌ์ฆ˜์— ๋Œ€ํ•ด ์ค‘์ ์ ์œผ๋กœ ์—ฐ๊ตฌํ•˜์˜€๋‹ค. ๋ฐ˜์†กํŒŒ ์œ„์ƒ ๊ธฐ๋ฐ˜์˜ ์ •๋ฐ€ ๋ณด์ •์ •๋ณด ์ƒ์„ฑ์„ ์œ„ํ•ด์„œ๋Š” ๋จผ์ € ๋ฏธ์ง€์ •์ˆ˜๋ฅผ ์ •ํ™•ํ•˜๊ฒŒ ๊ฒฐ์ •ํ•ด์•ผ ํ•œ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ์‚ผ์ค‘ ์ฃผํŒŒ์ˆ˜ ๋ฐ˜์†กํŒŒ ์œ„์ƒ ์ธก์ •์น˜์˜ ๋ฌด-์ „๋ฆฌ์ธต ์กฐํ•ฉ์„ ํ™œ์šฉํ•˜์—ฌ ์ „๋ฆฌ์ธต ๋ณด์ •์ •๋ณด ์—†์ด๋„ ์ •ํ™•ํ•˜๊ฒŒ ๋ฏธ์ง€์ •์ˆ˜ ๊ฒฐ์ • ๊ฐ€๋Šฅํ•œ ์ƒˆ๋กœ์šด ๋ฐฉ๋ฒ•์„ ์ œ์•ˆํ•˜์˜€๋‹ค. ์œ„์„ฑ Code/Phase ์‹œ๊ณ„ ๋ณด์ •์ •๋ณด๋Š” ํ†ต์‹  ์ง€์—ฐ ๋ฐ ๊ณ ์žฅ ์‹œ ์šฐ์ˆ˜ํ•˜๊ณ  ๊ฐ•๊ฑดํ•œ ์„ฑ๋Šฅ์„ ์œ„ํ•ด ๋‹ค์ค‘ ๊ธฐ์ค€๊ตญ์˜ ๋ชจ๋“  ์ธก์ •์น˜๋ฅผ ํ™œ์šฉํ•˜์—ฌ ์ถ”์ •๋œ๋‹ค. ์ด ๋•Œ ๊ฐ ๊ธฐ์ค€๊ตญ ๋ณ„ ์„œ๋กœ ๋‹ค๋ฅธ ๋ฏธ์ง€์ •์ˆ˜ ๋•Œ๋ฌธ์— ๋ฐœ์ƒํ•˜๋Š” ๋ฌธ์ œ๋Š” ์•ž์„œ ์ •ํ™•ํ•˜๊ฒŒ ๊ฒฐ์ •๋œ ๊ธฐ์ค€๊ตญ ๊ฐ„ ์ด์ค‘์ฐจ๋ถ„ ๋œ ๋ฏธ์ง€์ •์ˆ˜๋ฅผ ํ™œ์šฉํ•˜์—ฌ ์ˆ˜์ค€์„ ์กฐ์ •ํ•˜๋Š” ๊ณผ์ •์„ ํ†ตํ•ด ํ•ด๊ฒฐ์ด ๊ฐ€๋Šฅํ•˜๋‹ค. ๊ทธ ๊ฒฐ๊ณผ ์ƒ์„ฑ๋œ ์œ„์„ฑ Code/Phase ๋ณด์ •์ •๋ณด ๋ฉ”์‹œ์ง€์˜ ํฌ๊ธฐ, ๋ณ€ํ™”์œจ, ์žก์Œ ์ˆ˜์ค€์ด ํฌ๊ฒŒ ๊ฐœ์„ ๋˜์—ˆ๊ณ , ํ†ต์‹  ์ง€์—ฐ ์‹œ ์˜ค์ฐจ ๋ณด์ƒ ์„ฑ๋Šฅ์ด ๊ธฐ์กด RTK ํ”„๋กœํ† ์ฝœ ๋ณด๋‹ค 99% ํ–ฅ์ƒ ๋จ์„ ํ™•์ธํ•˜์˜€๋‹ค. ๋Œ€๋ฅ˜์ธต ๋ณด์ •์ •๋ณด๋Š” ์ ์€ ์ˆ˜์˜ ๊ธฐ์ค€๊ตญ ๋งŒ์„ ํ™œ์šฉํ•˜์—ฌ ์ •ํ™•ํ•˜๊ฒŒ ๋Œ€๋ฅ˜์ธต์„ ๋ชจ๋ธ๋งํ•˜๊ธฐ ์œ„ํ•ด ์ž๋™ ๊ธฐ์ƒ๊ด€์ธก์‹œ์Šคํ…œ์œผ๋กœ๋ถ€ํ„ฐ ์ˆ˜์ง‘ํ•œ ๊ธฐ์ƒ ์ •๋ณด๋ฅผ ์ถ”๊ฐ€๋กœ ํ™œ์šฉํ•˜์—ฌ ์ƒ์„ฑ๋œ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” GNSS ๊ธฐ์ค€๊ตญ ๋„คํŠธ์›Œํฌ๋กœ๋ถ€ํ„ฐ ์ •๋ฐ€ํ•˜๊ฒŒ ์ถ”์ •๋œ ๋ฐ˜์†กํŒŒ ์œ„์ƒ ๊ธฐ๋ฐ˜ ์ˆ˜์ง ๋Œ€๋ฅ˜์ธต ์ง€์—ฐ๊ณผ ๊ธฐ์ƒ์ •๋ณด ๊ธฐ๋ฐ˜์œผ๋กœ ๋ชจ๋ธ๋ง ๋œ ์ˆ˜์ง ๋Œ€๋ฅ˜์ธต ์ง€์—ฐ์„ ํ•จ๊ป˜ ํ™œ์šฉํ•  ์ˆ˜ ์žˆ๋Š” ์ƒˆ๋กœ์šด ์•Œ๊ณ ๋ฆฌ์ฆ˜์„ ์ œ์•ˆํ•˜์˜€๋‹ค. ๊ตฌ๋ฉด์กฐํ™”ํ•จ์ˆ˜๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ Network RTK ๋ฐ PPP-RTK ๋ณด๋‹ค ํ•„์š”ํ•œ ๋ฉ”์‹œ์ง€ ์–‘๊ณผ ๊ธฐ์ค€๊ตญ ์ˆ˜๋ฅผ ํฌ๊ฒŒ ๊ฐ์†Œ์‹œํ‚ค๋ฉด์„œ๋„ RMS 2 cm ์ˆ˜์ค€์œผ๋กœ ์ •ํ™•ํ•œ ๋ณด์ •์ •๋ณด ์ƒ์„ฑ์ด ๊ฐ€๋Šฅํ•จ์„ ํ™•์ธํ•˜์˜€๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ ์ œ์•ˆํ•œ Compact Wide-Area RTK ์‹œ์Šคํ…œ์˜ ํ•ญ๋ฒ• ์„ฑ๋Šฅ์„ ๊ฒ€์ฆํ•˜๊ธฐ ์œ„ํ•ด ๋ฏธ๊ตญ ๋™๋ถ€ ์ง€์—ญ 6๊ฐœ ๊ธฐ์ค€๊ตญ์˜ ์‹ค์ธก GPS ๋ฐ์ดํ„ฐ๋ฅผ ํ™œ์šฉํ•˜์—ฌ ํ…Œ์ŠคํŠธ๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ๊ทธ ๊ฒฐ๊ณผ ์ œ์•ˆํ•œ ์‹œ์Šคํ…œ์€ ๋ฏธ์ง€์ •์ˆ˜ ๊ฒฐ์ • ์ดํ›„ ์‚ฌ์šฉ์ž์˜ 95% ์ˆ˜ํ‰ ์œ„์น˜ ์˜ค์ฐจ 1.9 cm, 95% ์ˆ˜์ง ์œ„์น˜ ์˜ค์ฐจ 7.0 cm ๋กœ ์œ„์น˜๋ฅผ ์ •ํ™•ํ•˜๊ฒŒ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ์‚ฌ์šฉ์ž ๋ฏธ์ง€์ •์ˆ˜ ๊ฒฐ์ • ์„ฑ๋Šฅ์€ ๋Œ€๋ฅ˜์ธต ์•ˆ์ • ์ƒํƒœ์—์„œ ์•ฝ 2๋ถ„ ๋‚ด๋กœ 100% ์˜ ์„ฑ๊ณต๋ฅ ์„ ๊ฐ€์ง„๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ ์ œ์•ˆํ•œ ์‹œ์Šคํ…œ์ด ํ–ฅํ›„ ํ•œ๊ตญํ˜• ์œ„์„ฑํ•ญ๋ฒ• ์‹œ์Šคํ…œ(KPS, Korean Positioning System)์˜ ์ „๊ตญ ๋‹จ์œ„ ์„ผํ‹ฐ๋ฏธํ„ฐ ๊ธ‰ ์„œ๋น„์Šค๋ฅผ ์œ„ํ•œ ์•Œ๊ณ ๋ฆฌ์ฆ˜์œผ๋กœ ํ™œ์šฉ๋˜๊ธฐ๋ฅผ ๊ธฐ๋Œ€ํ•œ๋‹ค.CHAPTER 1. Introduction 1 1.1 Motivation and Purpose 1 1.2 Former Research 4 1.3 Outline of the Dissertation 7 1.4 Contributions 8 CHAPTER 2. Overview of GNSS Augmentation System 11 2.1 GNSS Measurements 11 2.2 GNSS Error Sources 14 2.2.1 Traditional GNSS Error Sources 14 2.2.2 Special GNSS Error Sources 21 2.2.3 Summary 28 2.3 GNSS Augmentation System 29 2.3.1 Satellite-Based Augmentation System (SBAS) 29 2.3.2 Real-Time Kinematic (RTK) 32 2.3.3 Precise Point Positioning (PPP) 36 2.3.4 Summary 40 CHAPTER 3. Compact Wide-Area RTK System Architecture 43 3.1 Compact Wide-Area RTK Architecture 43 3.1.1 WARTK Reference Station (WRS) 48 3.1.2 WARTK Processing Facility (WPF) 51 3.1.3 WARTK User 58 3.2 Ambiguity Resolution and Validation Algorithms of Compact Wide-Area RTK System 59 3.2.1 Basic Theory of Ambiguity Resolution and Validation 60 3.2.2 A New Ambiguity Resolution Algorithms for Multi-Frequency Signals 65 3.2.3 Extra-Wide-Lane (EWL) Ambiguity Resolution 69 3.2.4 Wide-Lane (WL) Ambiguity Resolution 71 3.2.5 Narrow-Lane (NL) Ambiguity Resolution 78 3.3 Compact Wide-Area RTK Corrections 83 3.3.1 Satellite Orbit Corrections 86 3.3.2 Satellite Code/Phase Clock (CPC) Corrections 88 3.3.3 Tropospheric Corrections 89 3.3.4 Message Design for GEO Broadcasting 90 CHAPTER 4. Code/Phase Clock (CPC) Correction Generation Algorithm 93 4.1 Former Research of RTK Correction Protocol 93 4.1.1 Observation Based RTK Data Protocol 93 4.1.2 Correction Based RTK Data Protocol 95 4.1.3 Compact RTK Protocol 96 4.2 Satellite CPC Correction Generation Algorithm 100 4.2.1 Temporal Decorrelation Error Reduced Methods 102 4.2.2 Ambiguity Level Adjustment 105 4.2.3 Receiver Clock Synchronization 107 4.2.4 Averaging Filter of Satellite CPC Correction 108 4.2.5 Ambiguity Re-Initialization and Message Generation 109 4.3 Correction Performance Analysis Results 111 4.3.1 Feasibility Test Environments 111 4.3.2 Comparison of RTK Correction Protocol 113 4.3.3 Latency Compensation Performance Analysis 116 4.3.4 Message Data Bandwidth Analysis 119 CHAPTER 5. Tropospheric Correction Generation Algorithm 123 5.1 Former Research of Tropospheric Correction 123 5.1.1 Tropospheric Corrections for SBAS 124 5.1.2 Tropospheric Corrections of Network RTK 126 5.1.3 Tropospheric Corrections of PPP-RTK 130 5.2 Tropospheric Correction Generation Algorithm 136 5.2.1 ZWD Estimation Using Carrier-Phase Observations 138 5.2.2 ZWD Measurements Using Weather Data 142 5.2.3 Correction Generation Using Spherical Harmonics 149 5.2.4 Correction Applying Method for User 157 5.3 Correction Performance Analysis Results 159 5.3.1 Feasibility Test Environments 159 5.3.2 Zenith Correction Domain Analysis 161 5.3.3 Message Data Bandwidth Analysis 168 CHAPTER 6. Compact Wide-Area RTK User Test Results 169 6.1 Compact Wide-Area RTK User Process 169 6.2 User Performance Test Results 173 6.2.1 Feasibility Test Environments 173 6.2.2 User Range Domain Analysis 176 6.2.3 User Ambiguity Domain Analysis 182 6.2.4 User Position Domain Analysis 184 CHAPTER 7. Conclusions 189 Bibliography 193 ์ดˆ ๋ก 207Docto

    Potential of Multi constellation Global Navigation Satellite System in Indian Missile Test Range Applications

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    In this paper, the potentials of using Global Navigation Satellite System (GNSS) techniques in the complex calibration procedure of the tracking sensors for missile test range applications have been presented. The frequently used tracking sensors in test range applications are- electro-optical tracking stations (EOTS) and tracking radars. Over the years, the EOTS are used as the reference for bias estimation of the radars. With the introduction of GPS in test range applications, especially the DGPS, the reference for bias estimation got shifted to DGPS from the EOTS. However, the achievable position solution accuracy is limited to the order of a few meters for DGPS, EOTS, and Radars. With the evolution of Multi-constellation GNSS and carrier-phase based measurement techniques in satellite navigation, achievable position solution accuracies may be improved to sub-meter level. New navigation techniques like real time kinematic (RTK) and precise point positioning have the potentials for use in the calibration procedures of the missile test ranges to the accuracies of centimeter-level. Moreover, because of the availability of a large number of navigation signals over the Indian region, multi-constellation GNSS receivers can enhance signal availability, reliability, and accuracies during the calibration of missile test ranges. Currently available compact, low-cost GNSS modules also offer the possibilities of using these for cost-effective, networked RTK for dynamic calibration of test ranges reducing cost and resource requirements

    Variability and Performance of Short to Long-Range Single Baseline RTK GNSS Positioning in Indonesia

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    As the modernized Global Navigation Satellite System (GNSS) method, Real Time Kinematic (RTK) ensures high accuracy of position (within several centimeters). This method uses Ultra High Frequency (UHF) radio to transmit the correction data, however, due to gain and power issues, Networked Transport of RTCM via Internet Protocol (RTCM) is used to transmit the correction data for a longer baseline. This Research aims to investigate the performance of short to long-range single baseline RTK GNSS (Up to 80 KM) by applying modified LAMBDA method to resolve the ambiguity in carrier phase. The RTK solution then compared with the differential GNSS network solution. The results indicate that the differences are within RTK accuracy up to 80 km are several centimeter for horizontal solution and three times higher for vertical solution

    Assessment of positioning performances in Italy from GPS, BDS and GLONASS constellations

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    The use of multiple GNSS constellations has been beneficiary to positioning performances and reliability in recent times, especially in low cost mass-market setups. Along with GPS and GLONASS, GALILEO and BDS are the other two constellations aiming for global coverage. With ample research demonstrating the benefits of GALILEO in the European region, there has been a lack of study to demonstrate the performance of BDS in Europe, especially with mass-market GNSS receivers. This study makes a comparison of the performances between the combined GPS-GLONASS and GPS-BDS constellations in Europe with such receivers. Static open sky and kinematic urban environment tests are performed with two GNSS receivers as master and rover at short baselines and the RTK and double differenced post processed solutions are analyzed. The pros and cons of both the constellation choices is demonstrated in terms of fixed solution accuracies, percentage of false fixes, time to first fix for RTK and float solution accuracies for post processed measurements. Centimeter level accuracy is achieved in both constellations for static positioning with GPS-BDS combination having a slightly better performance in comparable conditions and smaller intervals. GPS-GLONASS performed slightly better for longer intervals due to the current inconsistent availability of BDS satellites. Even if the static tests have shown a better performance of GPS-BDS combination, the kinematic results show that there are no significant differences between the two tested configurations. Keywords: GNSS, BDS, GLONASS, NRTK positioning, Accurac

    A Portuguese Case Study

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    There is a high national dependency on Position, Navigation and Timing (PNT) Systems for several individuals, services and organisations that depend on this information on a daily basis. Those who rely on precise, accurate and continuous information need to have resilient systems in order to be highly efficient and reliable. A resilient structure and constantly available systems makes it easier to predict a threat or rapidly recover in a hazardous environment. One of these organisations is the Portuguese Navy, whose main purposes are to combat and maintain maritime safety. In combat, resilient PNT systems are needed for providing robustness in case of any threat or even a simple occasional system failure. In order to guarantee maritime safety, for example in Search and Rescue Missions, the need of PNT information is constant and indispensable for positioning control. The large diversity of PNT-dependent equipment, developed over the last two decades, is a valid showcase for the high GPS dependency that is seen nowadays โ€“ which is vulnerable to various factors like interference, jamming, spoofing and ionospheric conditions. The recent interest over integrated PNT system resolutions is related to the search for redundancy, accuracy, precision, availability, low cost, coverage, reliability and continuity. This study aimed to build a current PNT Portuguese picture based on Stakeholder Analysis and Interviews; assess the vulnerability of those who depend mainly on GPS for PNT information and, find out what the next steps should be in order to create a National PNT Strategy.Existe uma elevada dependรชncia nacional em sistemas de Posiรงรฃo, Navegaรงรฃo e Tempo (PNT) por parte de diversos indivรญduos, serviรงos e organizaรงรตes que dependem desta informaรงรฃo no seu dia-a-dia. Todos os que dependem de informaรงรฃo precisa, exata e contรญnua, necessitam de ter sistemas resilientes para que sejam altamente eficientes e fiรกveis. Uma estrutura resiliente e sistemas continuamente disponรญveis facilitam a previsรฃo de possรญveis ameaรงas ou a expedita recuperaรงรฃo da funcionalidade, em ambientes hostis. Uma destas organizaรงรตes รฉ a Marinha Portuguesa cujas funรงรตes principais sรฃo o combate, a salvaguarda da vida humana no mar e a seguranรงa marรญtima e da navegaรงรฃo. Para o combate, sรฃo necessรกrios sistemas PNT, resilientes, que ofereรงam robustez em caso de uma simples ameaรงa ou falha temporรกria dos sistemas. Por forma a ser possรญvel cumprir a missรฃo, a necessidade de ter informaรงรฃo PNT, fidedigna e atualizada, รฉ constante e indispensรกvel para o controlo preciso e exato da posiรงรฃo. Uma unidade naval, por forma a permanecer continuamente no mar, manter a sua prontidรฃo, treinar a sua guarniรงรฃo ou ser empenhada num cenรกrio de guerra, necessita de saber, com confianรงa e sem erros, a sua posiรงรฃo e referรชncia de tempo. A grande diversidade de sistemas dependentes de informaรงรฃo PNT, desenvolveu-se em larga escala nas รบltimas duas dรฉcadas e sustenta cada vez mais a alta dependรชncia do GPS, que รฉ vulnerรกvel a diversas fontes de erro, tais como interferรชncia, empastelamento, mistificaรงรฃo e condiรงรตes ionosfรฉricas. Atualmente, o elevado interesse na criaรงรฃo de sistemas PNT integrados estรก associado ร  procura da redundรขncia, exatidรฃo, precisรฃo, disponibilidade, baixo custo, cobertura, fiabilidade e continuidade. Este estudo teve como objetivos construir o panorama atual, em Portugal, ao nรญvel dos Sistemas PNT, baseando-se numa anรกlise de Stakeholders e entrevistas; avaliar a vulnerabilidade de organizaรงรตes e serviรงos que dependam exclusivamente do GPS como fonte de informaรงรฃo PNT; e propor um possรญvel caminho para que seja possรญvel criar uma Estratรฉgia PNT Naciona

    Innovative Solutions for Navigation and Mission Management of Unmanned Aircraft Systems

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    The last decades have witnessed a significant increase in Unmanned Aircraft Systems (UAS) of all shapes and sizes. UAS are finding many new applications in supporting several human activities, offering solutions to many dirty, dull, and dangerous missions, carried out by military and civilian users. However, limited access to the airspace is the principal barrier to the realization of the full potential that can be derived from UAS capabilities. The aim of this thesis is to support the safe integration of UAS operations, taking into account both the user's requirements and flight regulations. The main technical and operational issues, considered among the principal inhibitors to the integration and wide-spread acceptance of UAS, are identified and two solutions for safe UAS operations are proposed: A. Improving navigation performance of UAS by exploiting low-cost sensors. To enhance the performance of the low-cost and light-weight integrated navigation system based on Global Navigation Satellite System (GNSS) and Micro Electro-Mechanical Systems (MEMS) inertial sensors, an efficient calibration method for MEMS inertial sensors is required. Two solutions are proposed: 1) The innovative Thermal Compensated Zero Velocity Update (TCZUPT) filter, which embeds the compensation of thermal effect on bias in the filter itself and uses Back-Propagation Neural Networks to build the calibration function. Experimental results show that the TCZUPT filter is faster than the traditional ZUPT filter in mapping significant bias variations and presents better performance in the overall testing period. Moreover, no calibration pre-processing stage is required to keep measurement drift under control, improving the accuracy, reliability, and maintainability of the processing software; 2) A redundant configuration of consumer grade inertial sensors to obtain a self-calibration of typical inertial sensors biases. The result is a significant reduction of uncertainty in attitude determination. In conclusion, both methods improve dead-reckoning performance for handling intermittent GNSS coverage. B. Proposing novel solutions for mission management to support the Unmanned Traffic Management (UTM) system in monitoring and coordinating the operations of a large number of UAS. Two solutions are proposed: 1) A trajectory prediction tool for small UAS, based on Learning Vector Quantization (LVQ) Neural Networks. By exploiting flight data collected when the UAS executes a pre-assigned flight path, the tool is able to predict the time taken to fly generic trajectory elements. Moreover, being self-adaptive in constructing a mathematical model, LVQ Neural Networks allow creating different models for the different UAS types in several environmental conditions; 2) A software tool aimed at supporting standardized procedures for decision-making process to identify UAS/payload configurations suitable for any type of mission that can be authorized standing flight regulations. The proposed methods improve the management and safe operation of large-scale UAS missions, speeding up the flight authorization process by the UTM system and supporting the increasing level of autonomy in UAS operations

    Accurate navigation applied to landing maneuvers on mobile platforms for unmanned aerial vehicles

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    Drones are quickly developing worldwide and in Europe in particular. They represent the future of a high percentage of operations that are currently carried out by manned aviation or satellites. Compared to fixed-wing UAVs, rotary wing UAVs have as advantages the hovering, agile maneuvering and vertical take-off and landing capabilities, so that they are currently the most used aerial robotic platforms. In operations from ships and boats, the final approach and the landing maneuver are the phases of the operation that involves a higher risk and where it is required a higher level of precision in the position and velocity estimation, along with a high level of robustness in the operation. In the framework of the EC-SAFEMOBIL and the REAL projects, this thesis is devoted to the development of a guidance and navigation system that allows completing an autonomous mission from the take-off to the landing phase of a rotary-wing UAV (RUAV). More specifically, this thesis is focused on the development of new strategies and algorithms that provide sufficiently accurate motion estimation during the autonomous landing on mobile platforms without using the GNSS constellations. In one hand, for the phases of the flights where it is not required a centimetric accuracy solution, here it is proposed a new navigation approach that extends the current estimation techniques by using the EGNOS integrity information in the sensor fusion filter. This approach allows improving the accuracy of the estimation solution and the safety of the overall system, and also helps the remote pilot to have a more complete awareness of the operation status while flying the UAV In the other hand, for those flight phases where the accuracy is a critical factor in the safety of the operation, this thesis presents a precise navigation system that allows rotary-wing UAVs to approach and land safely on moving platforms, without using GNSS at any stage of the landing maneuver, and with a centimeter-level accuracy and high level of robustness. This system implements a novel concept where the relative position and velocity between the aerial vehicle and the landing platform can be calculated from a radio-beacon system installed in both the UAV and the landing platform or through the angles of a cable that physically connects the UAV and the landing platform. The use of a cable also incorporates several extra benefits, like increasing the precision in the control of the UAV altitude. It also facilitates to center the UAV right on top of the expected landing position and increases the stability of the UAV just after contacting the landing platform. The proposed guidance and navigation systems have been implemented in an unmanned rotorcraft and a large number of tests have been carried out under different conditions for measuring the accuracy and the robustness of the proposed solution. Results showed that the developed system allows landing with centimeter accuracy by using only local sensors and that the UAV is able to follow a mobile landing platform in multiple trajectories at different velocities

    The Role of Geospatial Data in Data Economy

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    This work is a pre-study, and it is intended to produce a report under the guidance of the Ministry of Agriculture and Forestry (MAF) about the role of geospatial data in data economy, especially in a Finnish context. The aim was to review the state-of-the-art and needs regarding geospatial data and positioning in todayโ€™s data economy as well as the impact of geospatial data and positioning. Geospatial data has an important role in data economy. The report delves into the technical aspects of data, unveiling the untapped potential of its value and the cross-disciplinary role it serves in multiple industries. Furthermore, the report emphasizes the synergistic-sustainability potential geospatial data has for addressing climate impacts and facilitating more precise environmental monitoring. The subject is multidisciplinary, and therefore it was logical to include a wide variety of perspectives in the report. According to the review of literature and an illustrating case study, there is a need for many kinds of further research related to geospatial data connected to more precise Earth observation, pervasive positioning solutions, value and use of geospatial data in decision-making and resource allocation, measuring the value as well as customizing services and products related to it. The research related to competences needed to use the data, improvement of the use of data as well as the use of environmental performance indicators is needed too
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