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Crazy reckless flying stunt?

Steve Carr

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#2
Anytime the ST16 and the H are connected a telemetry file is created. When the H is inside it may only pick up a few satellites and those signals will be "reflected" signals from adjoining buildings. It is, therefor, impossible for the H to determine an exact fix and the current location recorded will drift as the reflected signal drifts.
 
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#4
This is to be expected with a very low GPS accuracy. If you get a chance to check the Telemetry file the values recorded under "gps_accH" column you will find very high numbers (lower is better)

Some times I wonder how many crashes could've been caused by this kind of innacuracy but in the ST16 and taking off in Smart mode: In smart mode the H will always try to follow the ST16 GPS position, having that sort of innacuracy will cause the H to follow those ghost movements which would turn ugly very fast.

I know for sure I've seen one case of that happening here on the forum.

Greetings!
 
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#6
This is what I show for the H GPS chip. Based on the published specs it does not appear as sub standard chip and, in fact, is more expensive than many others. It appears to be used in many applications.
View attachment 10778
I meant very low accuracy as in when there's a low sat count/obstructed view of sats, not of the GPS in general :p
 
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#7
GPS used in drones indoors does not develop accurate resolution. The satellites being "seen" are delivering very degraded signals with very high drop out counts to provide position fix as they move across the horizon. That low resolution causes an appearance of "drift" as the system is trying to figure out it's position. If we want to use GPS indoors we need to install a GPS repeater station. They are not cheap.
 
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#8
All the more to make sure you get 18+ satellites locked before takeoff.
You'll never "lock" any satellites. It's not possible for the H or -16 to lock onto a satellite. What does happen is quantity present and time in view. The longer a satellite is in view the better the hdop. More satellites in view increases positional accuracy, as does the amount of time they remain in view, up to a point. After a given number no further increase in positional accuracy is possible as the system achieves the resolution limitations imposed on civilian systems by government mandate.
 
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#11
The reason to let the H sit for 15 min is to update the GPS almanac if you haven’t flown recently or changed your location significantly.

The almanac is where the data needed from the satellites is stored and it is in volatile storage. If the battery drops below a specified voltage that data is lost.
 
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#12
Got it... Now I understand better the recommended preflight check list. You know what, in case it's not been said yet, this forum is a great place to learn everything that you need to know about the H in particular, and about droning and piloting in general. Thanks to all those who shared their knowledge, often through blood, sweat and broken parts so that we too could learn.

A few hours from now would be my Hs maiden voyage, postponed multiple times coz it's hard to find an area near enough that's outside the NFz. I would really make sure to apply all I learned, foremost is to fly without the camera, in case S happens, the worst damage would be a broken prop. I flew my friend's Mavic yesterday, and he kept chiding me to look at the screen and fly fpv, but told him I'm old school hehe.
 
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#13
You'll never "lock" any satellites. It's not possible for the H or -16 to lock onto a satellite. What does happen is quantity present and time in view. The longer a satellite is in view the better the hdop. More satellites in view increases positional accuracy, as does the amount of time they remain in view, up to a point. After a given number no further increase in positional accuracy is possible as the system achieves the resolution limitations imposed on civilian systems by government mandate.
I get the feeling PatR you do not like the Gov. I can picture you living in an isolated area using Solar energy and firearms to be self sufficient?;)
 
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#17
Sorry by lock I meant fix... Anyway saw this video.... Could this be one of the reasons for the GPS problems? Or the reason behind letting the H sit for 15mins before flight so that the battery gets charged?
Nice find, @DurianFlyer
The consensus in this forum has been to let the H sit powered up but with motors off for a while to allow the H to update the GPS almanac if the aircraft hasn't flown for a while, or location from last power on is a fair distance away. The above video is interesting in that it shows that the GPS battery does charge up once the aircraft is powered up, but this charge cycle is relatively quick such that the GPS battery should be fully charged or nearly fully charged by the time the aircraft camera has connected with the ST16 and the aircraft is ready for lift off.

It is my opinion, then, that the extended wait before liftoff will not impact on the battery charge state over and above the state it is in by the time the camera has connected. So, yes, wait a while for the GPS almanac but you need not wait for the GPS battery to charge up...if you see what I mean.
 
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#19
Was not able to test it that time hehe. During my 2nd flight later at sundown, they were very bright. Here's a screen grab of the fpv showing the 'headlights' hehe. I don't have a photo or video of the H airborne because my 9 year old spotter/cameraman was busy either waving at the H, chasing after it or peering at the st16.
 

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