I appreciate your confidence but I'm not always right
Back to the "sustainable" and "lock" thingie for a moment. First we have to throw the word "Lock" away. It's simply not applicable to the situation. There's no means to lock the communications link, and neither the satellites or the H, or the ST-16 use directional antennas that can can be aligned to generate a lock between antennas. Even in that condition a "lock" is tenuous and can be broken at any time. So we don't have a "Lock" on any GPS satellite. We don't have one with our phones, or vehicular GPS systems, or the H systems. It is not possible and it's a word that has been mistakenly used to describe a GPS comm link. However, we do have what could be described as a "continuous" comm link. This is where the word "sustainable" is an effective description.
"Sustainable" is relatively easy for an automated system to define. The comm link is not a steady stream of information, but works more like a rapidly alternating exchange of information. That information is transmitted in "packets", with an ever increasing packet count being transmitted and received by both systems. In a perfect world the number of packets received would equal the number of packets sent. That is rarely the case though. Packets are lost, or "dropped" all the time. That brings us to the term "Drop Outs". Comm links keep track of packets sent and packets received and if the counts don't match the difference are called drop outs. If the drop out frequency or the count is too high the information exchange becomes unreliable and can't be used. Such a state would be one way to define an "unsustainable" signal. A number of drop outs can occur, with that number and frequency being determined by the product manufacturer, and still provide accuracy ranging from very good all the way down to a rough approximation and still be considered "sustainable". The threshold between sustainable and unsustainable in various GPS systems is something I don't know. Ultimately, parameters are established in the software that keeps track of the information exchange and uses the drop out counts and frequency over time, along with the signal to noise ratio (SNR) to define when a signal is "sustainable". How long that signal is maintained also factors into the deal, with time in view continually refining precision. The number of satellites factors in by further again refining the level of precision. There's lots of other things that make all the GPS stuff come together but I don't understand all of them.
if you have selected Angle mode the H really doesn't care how many satellites it is communicating with. It will arm without having a "sustainable" GPS solution. I know this because as mentioned in my previous post I armed the motors before the system acquired good GPS solution, having only 8 satellites at the time. Many times I have armed and flown in Angle without having 10 or more satellites. So be careful if in Angle mode and thinking you have good GPS because the motors armed. You may well not have a good GPS solution at all so pay attention to the flight mode light on the back of the H. If you do not see a white flash with the purple, the system does not yet have a good GPS solution. You could still fly without a GPS solution
, but with or without a good GPS solution you'll never have a "lock"
