Title :
Space shuttle UHF communications performance evaluation
Author :
Hwu, Shian U. ; Loh, Yin-Chung ; Tran, Tony T. ; Kroll, Quin D. ; Sham, Catherine C.
Author_Institution :
Lockheed Martin Space Oper., Houston, TX, USA
Abstract :
An extension boom is to be installed on the starboard side of the Space Shuttle orbiter (SSO) payload bay for thermal tile inspection and repairing. As a result, the Space Shuttle payload bay ultra high frequency (UHF) antenna has been under the boom. This study is to evaluate the space shuttle UHF communication performance for antenna at a suitable new location. To ensure the communication coverage performance at the proposed new locations, the link margin between the UHF payload bay antenna and extravehicular activity (EVA) astronauts (SSO-EVA) in the upper hemisphere at a range distance of 160 meters from the payload bay antenna was analyzed. The communication performance between Space Shuttle orbiter and International Space Station (SSO-ISS) during rendezvous was also investigated. The multipath effects from payload bay structures surrounding the payload bay antenna were analyzed. The computer simulation tool based on the geometrical theory of diffraction method (GTD) was used to compute the signal strengths. The total field strength was obtained by summing the direct fields from the antennas and the reflected and diffracted fields from the surrounding structures. The computed signal strengths were compared to the signal strength corresponding to the 0 dB link margin. Based on the results obtained in this study, communication coverage for SSO-EVA and SSO-ISS communication links was determined for the proposed payload bay antenna UHF locations. The radio frequency (RF) radiation to the orbiter docking system (ODS) pyros, the payload bay avionics, and the shuttle remote manipulator system (SRMS) from the new proposed UHF antenna location was also investigated to ensure the EMC/EMI compliances.
Keywords :
UHF antennas; aerospace computing; avionics; digital simulation; electromagnetic compatibility; electromagnetic interference; geometry; signal processing; space communication links; space vehicles; telecommunication computing; 160 m; EMC; EMI; International Space Station; Shuttle remote manipulator system; Space shuttle orbiter; UHF communication antenna; UHF payload bay antenna; computer simulation tool; extravehicular activity astronauts; geometrical theory of diffraction method; orbiter docking system; payload bay avionics; performance evaluation; radio frequency radiation; signal strength computing; thermal tile inspection; thermal tile repairing; ultra high frequency antenna; Computer simulation; Inspection; International Space Station; Payloads; Performance analysis; Radio frequency; Space shuttles; Tiles; UHF antennas; UHF communication;
Conference_Titel :
Digital Avionics Systems Conference, 2004. DASC 04. The 23rd
Print_ISBN :
0-7803-8539-X
DOI :
10.1109/DASC.2004.1390853