R-Channel and T-Channel
The Inmarsat notes state that they only used the R-Channel BTO values. But, as you look through the Released Data, there and many many more data points that were ignored. If you plot all of the R-Channel BTO values, along with all of the (T-Channel BTO + 5000uSec), they line up extremely well.
With all of the data plotted on a chart you will also see the jitter, or noise, at each point in time is a spread of 60uSec to 80uSec with one especially noisy period with a spread of 120uSec (16:06-16:09UT sitting at the gate...). Keep that in mind when considering what resolution we should expect after converting signal latency to a ring, arc, or even a specific physical location.
The BTO numbers are offset (reference to the 'nominal terminal' in the notes). The key is simply to calibrate the measured time to the known location(s) at the gate (16:00-16:30 or even 16:41) and while ADS-B data is available (16:42-17:07UT). The BTO reflects the round trip time GES-satellite-AES, after subtracting the time to the nominal terminal location (GES-satellite-NomTerm).
{for those into the details, the 1st tricky part is that the earth is not round... So, converting from BTO to elevation angle and then to 'ping rings' gets complicated bu the true 'flattened' shape of the earth}
{The second tricky part is deciding where the 'real' satellite is used Vs. where the idealized fixed representation of the satellite is used... Because that affects the calculated elevation angle }
-Bill
<<edited to correct the sign in my equation above. - T-Channel BTO values are lower than R-Channel BTO by 5mS, so to align them, I should have written (T-Channel BTO + 5000uSec).>>