Automatic Dependent Surveillance-Broadcast (ADS-B) Universal Access Transceiver (UAT) transmissions for Alternative Positioning, Navigation, and Timing (APNT): Concept & practice

ADS-B radio stations deployed in the conterminous United States (CONUS)

Transmissions from ADS-B radio stations and ADS-B-equipped aircraft

Leon, West Virginia, ADS-B radio station on cellular tower (L) and notional antenna layout (R)

DMEs (squares), Tactical Air Navigation (TACANs) (circles), and ADS-B radio stations (pins) deployed in CONUS

UAT frame and transmission structure based on descriptions and diagrams from (RTCA Special Committee-186, 2009)

UAT ADS-B radio station tiers based on (Federal Aviation Administration Surveillance and Broadcast Services (SBS) Program Office, 2013)

Notational layout of station tiers (L = low, M = medium, H = high, number = slot set used) figure from (Federal Aviation Administration Surveillance and Broadcast Services (SBS) Program Office, 2013)

Example of UAT coverage from low-to-medium altitude tier; L and M tier station targets providing coverage to aircraft below 3,000 and 14,000 ft above ground level (AGL), respectively. Above 3,000 ft AGL, L tier stations may interfere with each other

Histogram of pseudoranges from San Jose ADS-B radio station: All (top), Ground Segment (middle), ADS-B Segment (bottom)

Histogram of pseudoranges from Woodside ADS-B radio station: All (top), Ground Segment (middle), ADS-B Segment (bottom)

ADS-B elements of March 2015 flight test

Airborne ADS-B collection rack shelf

Test flight paths and ADS-B RS decoded (with slot numbers indicated)

Range error from March 10, 2015, p.m. flight

ADS-B radio stations in vicinity of flight test. Pin captions show station location name and UAT ground segment transmission slots assigned

Interference between two UAT FIS-B on a signal amplitude (y-axis) versus time (x-axis) plot. Nominal UAT signal has constant amplitude envelope (Photo of inflight data display)

Test flight paths and ADS-B RS decoded (with assigned slot numbers indicated); ADS-B RS sharing the same slots are circled with the same shade of color

Average number of messages decoded per second versus distance for low- (left, 100% = 2 msg/sec) and medium- (right, 100% = 3 msg/sec) altitude tier stations (March 10, 2015, p.m.). Top number indicates seconds of data available for the average

Average number of messages decoded per second versus distance for low- (left, 100% = 2 msg/sec) and medium- (right, 100% = 3 msg/sec) altitude tier stations (March 11, 2015, p.m.). Top number indicates seconds of data available for the average

Reception map of Baltimore, OH, station (numbers indicate UAT ground segment slots assigned)

Reception map of Urbana, OH, station (numbers indicate UAT ground segment slots assigned)

Minimum altitude at which an L-band signal is in radio line of sight from a 25 m tower versus distance from the tower (radio horizon model using 4/3 earth radius assumption)

Number of stations per time epoch on March 12, 2015, a.m. flight (cruise at 3,300 ft MSL)

Number of stations per time epoch on March 11, 2015, p.m. flight (cruise at 10,500 ft MSL)

Position results using GPS, UAT (iterative based on close initial guess) March 12 a.m. flight (minimum altitude of 300 m above ground level (AGL))

Position results using GPS, UAT (iterative based on close initial guess) March 11 p.m. flight (minimum altitude of 300 m above ground level (AGL))