Performance Assessment of the Radio Occultation Experiment for Commercial off-the-shelf Receivers on VELOX-CI Microsatellite

• Main Authors: Li, Bing-Xuan, Han, Bo, Lim, Wee Seng, Tsai, Yung-Fu, Low, Kay-Soon
• Other Authors: School of Electrical and Electronic Engineering
• Format: Conference or Workshop Item
• Language: English
• Published: 2017
• Subjects: VELOX-CI; Radio Occultation
• Online Access: https://hdl.handle.net/10356/85796; http://hdl.handle.net/10220/44109; https://www.ion.org/gnss/abstracts.cfm?paperID=5510
• Institution: Nanyang Technological University

VELOX-CI is the second micro satellite of Satellite Research Center (SaRC) in Nanyang Technological University [1-2]. Since its launch on Dec. 16, 2015, VELOX-CI has performed a total of 136 radio occultation (RO) missions, and collected 448 hours’ GPS data with the lowest penetration altitude of 6 km. In this paper the radio occultation performance of the VELOX-CI’s COTS receiver and the space-borne receivers are compared in the upper troposphere (10~60km) in tropical region (latitude between 30°N and 30°S). VELOX-CI is designed to explore the potential of using the commercial-off-the-shelf (COTS) GPS receivers for RO mission for the first time. The satellite has a near equatorial orbit with an altitude of 550km. Three GPS antennas are located at the zenith, forward-velocity, and after-velocity directions. The tracked GPS signal phase, carrier-to-noise ratio C/N_0 are stored and sent to ground for post processing. The ionospheric profiles and preliminary tropospheric profiles are presented previously in [3]. In this paper, the VELOX-CI’s GPS RO payload is described. The RO data inversion procedures are introduced and a refractivity profile comparison study is made for refractive index obtained with VELOX-CI RO, radiosonde measurements and COSMIC data.