Burst Timing Offset
The BTO is essentially a measure of distance. It records the time delay between the satellite's interrogation signal and the aircraft's response.  

Variables involved: 

• Distance between aircraft & satellite

• Distance between satellite & ground station

• Signal propagation speed (light speed)

Burst Frequency Offset
The BFO is a measure of relative motion (the Doppler Effect). It tracks how the frequency of the signal changes based on how the aircraft and satellite are moving relative to each other. 

Variables involved: 

• Relative speed between the aircraft and the satellite,

• Relative speed between the satellite and the ground station 

• Compensation applied by the aircraft based on the aircraft's location and velocity (does not account for the aircraft's vertical speed, rate of ascend/descend)

• Satellite translation

• Further frequency compensation applied

• Errors assumed to be constant.