The CanX-7 ADS-B Mission: Signal Propagation Assessment - Positioning

POS > Vol.10 No.1, February 2019

The CanX-7 ADS-B Mission: Signal Propagation Assessment ()

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DOI: 10.4236/pos.2019.101001 873 Downloads 2,073 Views Citations

Author(s)

Ron Vincent^1*, Kelly Freitag²

Affiliation(s)

¹Department of Physics and Space Science, Royal Military College of Canada, Kingston, Canada.
²Royal Canadian Air Force W/C William G. Barker VC Aerospace College, Winnipeg, Canada.

ABSTRACT

The CanX-7 Automatic Dependent Surveillance-Broadcast (ADS-B) nanosatellite mission collected more than four million ADS-B messages between October 2016 and April 2017. An analysis of data collected over the north Atlantic Ocean from 05 to 28 Oct included 20,707 position messages in which the angle from satellite nadir to aircraft was determined. The proximity of the received signal strength to the noise floor of the sensor allowed for an analysis of optimal aircraft-satellite orientation for ADS-B transmission detection. The results showed a significant disparity between descending and ascending passes of the satellite. For descending passes, the average nadir angle was 50.1° with 90% of the contacts greater than 40°. The ascending passes had an average nadir angle of 31.6° with only 24.8% of the contacts exceeding 40°. The evidence suggests that the satellite magnetic torquer may not have been fully aligned with the north magnetic pole as the satellite moved northward, resulting in ascending pass nadir angles that were not reflective of the full range of values. Further analysis of the descending passes showed agreement with an ADS-B signal propagation model with peak reception at nadir angles of 51° ± 8°. For space-based ADS-B operations, the results support the replacement of the current aircraft upper quarter-wave monopole to an antenna that will transmit more energy directly above the airframe.

KEYWORDS

ADS-B, Space-Based ADS-B, CanX-7, Air Traffic Control

Share and Cite:

Vincent, R. and Freitag, K. (2019) The CanX-7 ADS-B Mission: Signal Propagation Assessment. Positioning, 10, 1-15. doi: 10.4236/pos.2019.101001.

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