Re:Successfully Testing Satellite-Based ADS-B Tracking
by sandworm101 on Monday July 04, 2016 @12:43PM
(#12031698)
>> up-ward facing directional antenna?
That would only add more limitations. The sat isn't always directly overhead. Directional limitations open up the possibility of random signal loss, such as when a plane is turning away from the sat. This would appear as a dropped signal until the sat came around again, perhaps an hour or more later. If this is to be used as a black box then handshakes need to be as reliable and regular as possible.
Omnidirectional units (on the aircraft) are also cheaper and allow improvements to be made on the sat side of the equation without new hardware on the more expensive aircraft side.
Re:Successfully Testing Satellite-Based ADS-B Tracking
by mikeash on Monday July 04, 2016 @05:33PM
(#12033134)
Signal strength doesn't seem to be an issue anyway. A SPOT unit can transmit every five minutes for days on a set of AAA batteries, and that's going all the way out to geosync.
That would only add more limitations. The sat isn't always directly overhead. Directional limitations open up the possibility of random signal loss, such as when a plane is turning away from the sat. This would appear as a dropped signal until the sat came around again, perhaps an hour or more later. If this is to be used as a black box then handshakes need to be as reliable and regular as possible.
Omnidirectional units (on the aircraft) are also cheaper and allow improvements to be made on the sat side of the equation without new hardware on the more expensive aircraft side.