I agree, and if you read the article you will see the motion alarm is not made 'louder'.
And I think you missunderstand how much motion a GPS can detect, the position from a GPS will naturaly vary by circa 1M between fixes, so a GPS is of no value in detecting vibration or tampering.
Thanks for the "louder" correction..... I have reread what was written and it is not really clear enough, but I will still take it onboard that I missread it.....
It was:-
The Blog post below describes how to modify one of the popular cycle disturb\motion alarms so you can get a warning that your bike is being nicked even if your out of earshot or have not so good hearing.
I would have written it clearer myself....
But it seems that you have either not owned a GPS Tracker, or not had a good one with variable vibration sensitivity, or did not set it to high sensivity, or did not know how, or just how many/most GPS Trackers actually work in practise!
The ones I have had, would text as soon as even a tiny vibration was sensed, BUT, it did need the user to first setup the sensitivity level to very sensitive, so maybe some owners do not know that!!!
There is no doubt in my mind, with the right GPS tracker, with a good setup, that as long as you and your bike both have cellphone reception (easily checked when parking the bike!), then you will get a text message saying that the GPS has sensed Movement/Vibration, if any movement or vibration is sensed.
Even if for any reason the cellphone signal is momentarily lost, the Tracker will store the message and send it as soon as reception returns, possible just a few seconds....
The actual movement sensor used, it is physically built into the tracker, using
different electronics to detect vibration.
It is not using GPS SAT reception as you appear to think, as that signal can vary for many, quite normal, reasons, when in use, as is simply not sensitive enough. For example buildings in cities can block it to some degree and the Satellites are constantly in motion around the globe, possible only one at a time may be received for a short time, also a passing bus/truck/lorry might also cause a change in signal level, even a thief bending over your bike can change the signal level, which is why the SAT signal is not used for vibration detecting!
I did find this picture of a car GPS, which may be of interest, showing that the
motion sensor is separate from the from the
GPS module, which detects the SAT signal, inside the unit, that receives the SAT signal, (taken from a German website).
This is as it is in the various GPS Tracker units I have been involved with! Maybe some cheapos do not have it at all, I have no idea on that point.
But what if someone only lightly clipped say your parked car/Bike, how would the tracker sense that, if it was ONLY referring to the received SAT signal, as you describe and believe?
Of course it could not!
The SAT signal, as I have mentioned, can vary for many reasons.......But the motion sensor is highly sensitive, and the firmware setup allows the user to set the level of sensitivity to vibration that he requires!!!
regards and if you have any further questions, please just ask and I will do my best to help you, or anyone else of course!
Andy