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HomeHomeDiscussionsDiscussionsiFly General Di...iFly General Di...fake GPS bars aren't always believablefake GPS bars aren't always believable
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7/17/2019 1:11 AM
 

i have been unhappy with my iFly740 lately.  it takes forever to find satellites.  i have an external antennae.  i've tried turning it on while performing my pre-flight, but then the display goes black when the engine 12V kicks in, and we start all over again.  

Today i didn't touch a single option at the beginning of the flight.  here are pics of my display, four green bars indicating gps signal good, gps altitude shows 213' no matter what altitude i fly, and zero airspeed. also the clock said 20:14 when it was only 4pm.  it took easily 5 minutes to even indicate gps green bars.  i used the gps reset twice to no avail.  i tried a hot start, nothing.  i finally hit the cold start up and 5 minutes later it seems to have corrected itself.

i need to be able to trust my GPS.  no signal while leaving an airport is no good.  that's when ADSB-IN is quite useful, near airports.  my lowrance 1000, which i still have installed grabs satellites in all of 15 seconds when powered up.  what bothers me most is that the iFly display indicates a good signal, but it is lying and actually has none, or has it but isn't processing it correctly.  my guess is that the software crashes if the gps was powered off while running on the prior flight, which has been my std procedure, it's wired to the avionics breaker.  typically i just cut power rather than shut down the application.  i feel a GPS should be more robust than that.  perhaps you designers have never been flying in deteriating conditions where the last thing you need to worry about is "are the green bars real or fake?"

 

sorry pics won't upload no matter how small i make them [256K, really?]

 
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7/17/2019 6:41 AM
 

If that behavior continues, you might try calling customer service and see if they have suggestions for your situation.  Such behavior is not common, so something is off.

That said, because of the way GPS receivers work, it is possible to have "good signal" but not have "good solution".  I don't know how the GPS bar logic works, but it's possible that that's the situation.

A GPS receiver needs information about satellite locations before it can give good solutions.  When the receiver is in operation, the satellite location information is being continuously updated by the satellites.  If the device is used "frequently", and starts up near the same position it was shut down, then the last-known information is good enough to get started quickly.

However, if the receiver has been off for a "long time" (some days), or if it has moved "significantly" from its last known location (not exactly sure how much this is, but probably a few tens of miles is not a problem), then getting an initial fix can be delayed but still be considered normal operation.

If those conditions don't fit your experience, or if the fix isn't coming even after the device has had a clear view of the sky for ~5 minutes, then there may be something else going on.

But it's also possible that there was just some transient issue that got resolved with the cold start, and it will behave properly going forward, so watch it a bit and see if it's cleared up.  If it hasn't, give the iFly folks a call:  http://www.iflygps.com/SUPPORT/GET-HELP

 
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HomeHomeDiscussionsDiscussionsiFly General Di...iFly General Di...fake GPS bars aren't always believablefake GPS bars aren't always believable