Lost drones....peak end 2016

[Ruud Hogenberg]

Came accross this website,

Peak lost drone - sUAS News - The Business of Drones

Never heard about GPS almanac.

Anyone can clarify


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[PatR]

It's a fact. Google is much easier than having a bunch of people explain it.


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[Rayray]

Never heard about GPS almanac.

If you search on our site for "GPS Almanac", there are good explanations.

 

[Ruud Hogenberg]

It's a fact. Google is much easier than having a bunch of people explain it.


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Its a fact you are correct in this, refresh my question to, why isnt this included in the manual. If this is the case..


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[ArnhemAnt]

Glad to see the almanac being mentioned in articles concerning UAV/sUAS.
I believe that the lack of understanding on this alone has been the cause of many issues.

 

[Ruud Hogenberg]

ArnhemAnt, indeed, what does a gps lock then does mean, i can imagine if you switch on, gps lock, fly and almanac isn't still downloaded. The reason of fly aways ??


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[ArnhemAnt]

Yes, if I am understanding you correctly, this is partly the issue with frames such as the H. I can't comment on other commercial UAV's as I don't own them.
When powering up the ST16 and the Typhoon H, you get data (on the ST16 screen) stating how many satellites you can see. This basically means that both the ST16 and the H can 'see' that many satellites and have a 'fix' on them. What it doesn't tell you is when the data from these satellites is completely updated.
Flying prior to having all data updated may cause issues with flight stability, etc because the H will not have a solid lock on your position.

Yes, the manual should state this, but there is also some ownership on the pilot to ensure that they completely understand the workings of their UAV. Unfortunately, there are some people flying the H that have never flown before or have very limited knowledge of multi rotors, particularly those with capabilities which rely on GPS.
Basically, the lack of info in the manual is a bad thing, but we can't put the blame solely on this.

Maybe there is scope in a future FW release to show a separate screen in the ST16 with this additional data?

For anyone not up to date with things like the almanac, do as Rayray has suggested and use the 'search' function on this forum. Also note that if you are regularly flying in the same location you don't need to wait up to 10-15 minutes for each flight. This is only necessary if you are flying in a new location, or if you haven't flown for over a fortnight (for example) in that location. Hope this helps.

 

[PatR]

I don't think anyone here was on the Yuneec documentation development team. Members of this site have been actively involved in the development of an "unofficial" ops document as a user group though. Perhaps directing your question to Yuneec officials would be appropriate.


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[PatR]

Very few flight controllers provide the information users need to establish a "lock". You don't really have a "lock", but instead have a number of satellites that have been established as in view and exchanging information with the receiver for "x" time, the satellite I.D., a CEP, or circular area of probability, a signal to noise ratio, and other pertinent information to assist the user establish they have enough of a data feed to provide an adequate positional fix. A positional error of only 26' is considered a "good" fix using a standard GPS system. That error can be reduced with RTK and DGPS but without additional viewable information to verify is not trustworthy.


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[Guest22]

The 15 minute 'wait time' to download the almanac has been updated to 26 seconds. There is speculation to wait longer to install the table, but that shouldn't take long since the table is downloaded/stored on the ublox chip. The link below has great information from @gwhuntoon.

Typhoon H GPS Specifications

 

[ArnhemAnt]

The 15 minute 'wait time' to download the almanac has been updated to 26 seconds.

From my understanding, there are two factors here. Yes, we may be able to get satellite acquisition within 26 seconds - and then go flying - however, the correction data is something else. Unless you are regularly flying in the same (or very similar) location, it is still necessary to wait so that the correction data is up to date. As you have stated in the link posted "Positioning accuracy decreases with the age of the correction data, with 1–3 day‑old data providing relatively high accuracy and 10–35 day‑old data progressively less accuracy. Regular updates help to ensure a high level of position accuracy."

For me, waiting a little longer for that first flight (if it's been a while) is well worth it.

 

[Guest22]

Don't get me wrong, I understand and am patient in waiting. But for how long though?? That's the million dollar question. I wouldn't think it would be too long to correct the data, but again I could be wrong.

I am thinking on when I go flying in a new area, I will start with a compass/accelerometer calibration. Reboot, and then wait 4-5 minutes.

 

[ArnhemAnt]

Don't get me wrong, I understand and am patient in waiting. But for how long though?? That's the million dollar question. I wouldn't think it would be too long to correct the data.

Valid point, and one that has too many variables - for me any way.

My rule is as follows;
#1: First time in a new location or after a FW update: wait at least 12-15 minutes before initial take-off.
#2: Subsequent visits to the same location (within a week or two): Spend an additional 5 minutes before initial take-off. Additional flights - no need to wait - just fly.
#3: Additional visits to a familiar location (more than a fortnight since last flight) see #1.

This 'may' be too long, but I'd rather err on the side of caution and have a successful (and enjoyable) flight, rather than things not going to plan.

 

[whitelaw]

Arnhem, you and I have posted about this before and I for one, got crucified on this site by a number of fairly rude members claiming the 12-15 minute wait time was BS. I do exactly as you do and wait at a new location for 12.5 minutes before take off. Have not crashed yet.

 

[PatR]

The way I figure it, if you want good video or photos you'll take a few minutes to power everything up and gauge the lighting conditions for initial camera settings prior to leaving the ground. You'll also do a visual check of intended flying area to assess people, structures, and obstructions to adjust RTH height. Not checking the area for potential safety factors is at minimum irresponsible and always high risk. You might also take a moment or two to get the days flight log and site conditions jotted down for later reference.

While all that is taking place your GPS could be updating and establishing a good fix of the home point.


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[ArnhemAnt]

^^ Dead right PatR.

It's not like you are just sitting around sipping a coffee, or beer, waiting for the time to pass. Taking time prior to (and after) each flight to do your assessments should be a standard. And, yes, that is usually enough time for the GPS to 'do it's thing'.

 

[John Dube]

And if your FAA 107 then you would/should be taking care of other tasks before flight which would allow for the time needed for the GPS to update. Also keep in mind for those worried about battery life, while your sitting on the ground waiting for the almanac to update there is very little battery loss.

 

[gwhuntoon]

I also read a lot of comparisons by users here of the drone GPS to the GPS in a car. The assumption is, its the same, it isn't, far from it. In a car GPS you have a 2D location on a map. The drone requires a 3D fix which requires a lot more satellite accuracy.