Performance Assessment of the Radio Occultation Experiment for Commercial off-the-shelf Receivers on VELOX-CI Microsatellite
Lim, Wee Seng
Date of Issue2017
The 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017)
School of Electrical and Electronic Engineering
Satellite Research Centre
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 . 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.
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