低空無線電收訊網之轉發機開發

Development of the Transponder of the Low-altitude Radio Reception Network

陳冠任(Guan-ren Chen)

指導教授 ： 江士標 ； 葉則亮

國立中央大學/工學院/光機電工程研究所/碩士(2014年)

摘要

本論文針對微衛星、探空酬載等長距離無線電通訊需求，以雙頻轉發器為節點，建構了一低空無線電收訊轉發網路，可提升酬載對地面站通訊品質；網路中各轉發器節點單位成本低、體積小，架設及回收簡便，具地形適應力。

本無線電轉發網路，係以COTS零組件(Commercial Off-The-Shelf)構成在ISM頻段(Industrial,Science,Medical)採用MSK調變(Minimum Shift Keyying)，傳送速率2.4 ~ 250 Kbps且帶有CRC (Cyclic Redundancy Check)校驗之數位通訊系統。系統工作時以雙頻監聽，雙通道半雙工轉發，網路中各節點皆備有GPS與電池SOC，可即時監控位置與電源狀態，資料傳輸使用自行規範之通訊協定與拓樸方式，降低重複轉發造成回聲之可能性；並以C#配合GoogleMap API與Java Script，撰寫了一套PC-based的地面站網路監控軟體。

經實驗驗證本轉發網路之分散式架構能有效增加地面站收訊覆蓋面積，採用之雙通道架構於1 Hz 76.8kbps發送下PER (Packet Error Rate)為1%，相較於單頻轉發方式之PER降低0.97%，而RPR (Repeated Packet Ratio)降低38.4% 在純電池供應操作環境可待機達30小時，日照充足則可提供不中斷連續待命，於酬載資料brust下鏈時最大可提供11小時連續工作時間。

關鍵字

UHF ； 地面站 ； 轉發器 ； 探空研究 ； 微衛星

並列摘要

This thesis focuses on the micro-satellites, sounding payload and other long-distance radio communications requirements, using dual-band transponders as
nodes to construct a low-attitude radio reception network.

The radio reception network uses COTS (Commercial Off-The-Shelf) components to constitute a digital Communication systems operating in ISM band (Industrial, Science, Medical) which using MSK modulation (Minimum Shift Keying), 2.4 ~ 250 Kbps transfer rate with CRC (Cyclic Redundancy Check). System working in dual-band half-duplex transponding, each node in the network are equipped with GPS and battery SOC, ground station can real time monitor the position and power status of transponders. Transponding protocols using our special algorithms and topologies, which can reduce the possibility of echo caused by repeated transponding. Transponder network monitoring console of Ground station is programmed by C # with
GoogleMap API and Java Script.

The experimental verification of the radio reception network can effectively increase the ground station reception coverage. The PER (Packet Error Rate) of dual-band transponder architecture at 1 Hz 76.8kbps is 1% . Compared to single band transponder architecture, the PER reduced 0.97%, and the RPR (Repeated Packet Ratio) improved 38.4%. In standby state, lifespan of battery up to 30 hours, abundant sunshine can provide uninterrupted continuous standby. Maximum available continuous operation time of payload data downloading (without sunshine) up to 11
hours.

並列關鍵字

UHF ； ground station ； transponder ； sounding study ； microsatellite

參考文獻

[1] "Communication Subsystem of RASAT"

[2] "Multipath Channel Measurements and Analysis at UHF Band for LEO Satellites"

[3] "Design of a Multi-Mission Satellite Ground Station for Education and Research"

[4] "Development of a LEO Communication CubeSat"

[5] "High Gain, Linear, Low Cost Digitally Controlled VHF-UHF Analog Transponder for Nano Satellites"