Testing a DJI Inspire 1 Raw Pro. Setting the RTH on ground with engine on. Getting RTH not registered. As soon as take off and hover above ground approximate 1.5 ft and resetting the home RTH the DJI application gives ‘green light’. Tried both home point functions then when test aircraft away from launch point and instruct RTH aircraft both times descends perpendicular from the hover position away from the launch pad to the ground. Why does it not record RTH having calibrated compass and set RTH? Also why is it not returning to the point of take off. I have learnt when RTH is set on take off with engine on, green light, one needs to hover above launch ground for ten sec to record the location as RTH. Can anyone help?
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- Thread starter Practice von stroheim
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A couple things I can think of:
1. You may already know this, but when you first power on Inspire, it can take a while to acquire enough satellites for GPS to activate or be effective. If you have a lot of cloud cover, or have a lot of buildings nearby, that may affect how many satellites you connect to. If you don't have I believe 5 or more satellites connected, GPS won't be effective and RTH probably won't work since it's GPS based. Even if you're too close to your car or other metal structure, the compass if effected which may affect RTH.
2. Are you possibly in ATTI or Manual mode? It may be that in those modes RTH doesn't work because nether of those modes use GPS?
1. You may already know this, but when you first power on Inspire, it can take a while to acquire enough satellites for GPS to activate or be effective. If you have a lot of cloud cover, or have a lot of buildings nearby, that may affect how many satellites you connect to. If you don't have I believe 5 or more satellites connected, GPS won't be effective and RTH probably won't work since it's GPS based. Even if you're too close to your car or other metal structure, the compass if effected which may affect RTH.
2. Are you possibly in ATTI or Manual mode? It may be that in those modes RTH doesn't work because nether of those modes use GPS?
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Pages 13-16 of the user manual comprehensively describes the different RTH behaviors and functions including the conditions if the aircraft is within 20m of home point.
Additionally, the manual describes the different RTH settings including return to home point, hover in position and land at current position settings.
Depending on how you have set your RTH within the Go App will determine the aircrafts behaviour
It was mentioned to me in another forum that cloud cover has no effect on satellite acquisition. I wasn’t convinced that was correct based on some other experience I’ve had in that regard. Your thoughts please.
That's one those, you can't believe everything you read on the internet.. Clearly that person that said that doesn't have Dish, or DirecTV.. 
Cloud cover ABSOLUTELY has an effect on satellite reception. It depends on how thick the cloud layer is and how WHERE the satellite is in relation to you. If a satellite is down near the horizon, there's going to be a LOT more atmospherical (if that's a word) interference than one that's directly over head. Satellite is line of site and anything in it's way will degrade the signal.
I do know this as fact, but you shouldn't take anyone's word as fact with things like this, especially in a forum. This kind of information is pretty easy to Google so you don't have to rely on someone's forum post (the other guys post or even mine here).
Cloud cover ABSOLUTELY has an effect on satellite reception. It depends on how thick the cloud layer is and how WHERE the satellite is in relation to you. If a satellite is down near the horizon, there's going to be a LOT more atmospherical (if that's a word) interference than one that's directly over head. Satellite is line of site and anything in it's way will degrade the signal.
I do know this as fact, but you shouldn't take anyone's word as fact with things like this, especially in a forum. This kind of information is pretty easy to Google so you don't have to rely on someone's forum post (the other guys post or even mine here).
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Sounds like you're not allowing the Inspire enough time to acquire satellites. There's a satellite icon at the top of the Go App. I think you have to have at least 9 satellites before acquiring a home point. Once a home point is established, you will have the ability to RTH.
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If clouds DO have affect on satellite acquisition, the difference is negligible. I have been flying my Inspire twice a month for years under clear and cloudy skies. And I can honestly say I have no noticed any difference in acquisition time.
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In answer to whether atmospheric conditions has an affect on GPS reception/accuracy the answer is yes......and no.
Yes, the ionosphere has an affect on sub millimeter GPS measurements but for non critical non accurate GPS applications like the Inspire the effect is negligible if anything.
The Inspire has a positional accuracy of a few meters ‘bubble’. It will float around within this bubble plus or minus a few centimeters (maybe even a meter).
The problem with the interface/GUI within the Go or Go4 app as I have mentioned previously is that giving a number of satellites is pretty meaningless. The reason being that four sats are required for a 3D positional fix. The more sats ‘locked’ the better the accuracy, however......the Go App gives a number of satellites it can ‘see’ but does not differentiate between if they are Navstar(GPS) or Glonass. This means that it can be very likely the Inspire can report it sees 8 satellites but they could be four from each constellation.
Unfortunately, the Inspire series chooses either/or and does not have dual computation constellation abilities. Therefore if it sees four from each constellation it will only use NAVSTAR or Glonass but not both. This can give a false sense of security since a sat count of eight ‘seems’ good but maybe only has the positional accuracy of four.
Much more use is the Dilution of Precision bar graph display next to the sat count number. If this is showing a strong level then it is safe to assume the highest sat count is coming from one constellation.
I hope that is of some help and makes sense.
Yes, the ionosphere has an affect on sub millimeter GPS measurements but for non critical non accurate GPS applications like the Inspire the effect is negligible if anything.
The Inspire has a positional accuracy of a few meters ‘bubble’. It will float around within this bubble plus or minus a few centimeters (maybe even a meter).
The problem with the interface/GUI within the Go or Go4 app as I have mentioned previously is that giving a number of satellites is pretty meaningless. The reason being that four sats are required for a 3D positional fix. The more sats ‘locked’ the better the accuracy, however......the Go App gives a number of satellites it can ‘see’ but does not differentiate between if they are Navstar(GPS) or Glonass. This means that it can be very likely the Inspire can report it sees 8 satellites but they could be four from each constellation.
Unfortunately, the Inspire series chooses either/or and does not have dual computation constellation abilities. Therefore if it sees four from each constellation it will only use NAVSTAR or Glonass but not both. This can give a false sense of security since a sat count of eight ‘seems’ good but maybe only has the positional accuracy of four.
Much more use is the Dilution of Precision bar graph display next to the sat count number. If this is showing a strong level then it is safe to assume the highest sat count is coming from one constellation.
I hope that is of some help and makes sense.
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I did not know this. This makes a ton of sense, as it explains the "floaty" nature of the Inspire 1, especially when compared to the P4P or Mavic Pro.
Do you know if the Inspire can switch from one constellation to the other?? Or she stuck on whichever constellation she initially locks onto??
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That's a very good question and...... I do not know the definitive answer .
If I had to take an educated guess I would say no, the aircraft does not switch between constellations on the fly and simply chooses a best fix at boot up.
Reasoning behind this statement is as the aircraft increases it's altitude, in theory, it will see more of the sky and thus more satellites, making the need for automatic switching kind of redundant. It would also add to the cost and complexity of both the hardware and firmware.
I do not have a cast iron certainty with the above statement but now you have piqued my curiosity I will see if I can get an answer from DJI engineering Dept.
Hold that thought.......
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That's a very good question and...... I do not know the definitive answer .
If I had to take an educated guess I would say no, the aircraft does not switch between constellations on the fly and simply chooses a best fix at boot up.
Agreed that that makes sense. If I knew more about the different constellations, I might make an argument for your arguably-logical assumption.
If I were a developer, and I knew that I had 4 of each constellation at boot, and chose to lock on Glonass, but then discovered in flight that Glonass had only 4 available satellites, but Navstar had 8 or more, I would want to provide some means of switching to the more-populated satellite system. BUT...this is predicated on the erroneous assumption that there are only limited satellites available in each system. I happen to know that there are thousands of satellites in orbit around our planet. So it seems reasonable that there would be many GPS satellites available in each system. So "switching" wouldn't be necessary. But then why bother with the option of a choice at all? And the reason for THAT might be for FASTER acquisition to the most-available-at-the-time constellation. Hmmm.... Just spit-ballin' here....
I have a friend who programs satellite telemetry for a living. Maybe I'll ask him.
That makes sense. Truth be told, my Inspire acquires satellites fairly quickly and holds onto them extremely well during flight. This seems to be true of all GPS-dependent drones. Even my old Phantom 1 (pre-Glonass daze) did a fairly good job of acquiring satellites fairly quickly.
Touche'. Better (simpler to set up) to just use both systems simultaneously instead of implementing a complex switching algorithm.
Well, well, well....you'll have to share that number/email....<;^)
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I would like to thank the editor, Steve pro, Stars, Donnie Frank for their very fast response to my problem. Very interesting was the digression about satellite process of acquisition. I flew the a/c again. I apologise for not responding faster had to keep the hearth going. Peeling through the layer of the instruction manual, I discovered that the inspire 1 pro does only return home if the a/c is beyond a radius of 20 metres. I wished that this information was in bigger print since I was more interested at the time about safety before a more extended flight test. Not that I do not trust years of technical savoir- faire but intended to give me the confidence to venture into new ground even though I have a pilot licence. And so on that beautiful afternoon the a/c did return at what I learnt from everyone’s post , “the "floaty" nature of the Inspire 1” or “It will float around within this bubble plus or minus a few centimetres (maybe even a meter)” which is what was experienced. The landings back from take-off were about 2 meters. This was experience twice at the same T/Off site with 17 satellites acquisitions, with P-GPS (GPS and Vision Positioning). So I am wrong to accept that it is the performance to expect from the the inspire 1 pro raw? Or perhaps could there be other experienced parameters to Improve accuracy?
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All flavors of the Inspire 1 are "floaty boats." My best advice is to just fly it a lot so you get used to it. I bounce back and forth between my P4P and Inspire - sometimes in the same day. And it IS amazing how "floaty" the Inspire is compared to the P4P. That's just the nature of the beast. And honestly, it makes you a better pilot. Challenge yourself to precise landings. It's a blast.
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I relieved myself of the “floaty” I1 some time ago for that reason. When you’re accustomed to what the mp’s and p4 pros do in a no stick input situation, the I1 is hard to take. After some reading, I went to the I2 and haven’t been disappointed when compared to the floaty.
Still working on some practice flying, but so far so good.
Still working on some practice flying, but so far so good.
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I keep it because I like having a vehicle with dual-operator mode, an HDMI port and the ability to shoot RAW for UNDER $10K. In fact, I own 3 of them, plus batteries, cards, cases and all the extras you can think of for under $10K. HA!.....<;^)
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