Interesting Observation after firmware update

JodyR · Jun 18, 2020

I had a new firmware update a day or so ago. I also updated to Android 1.1.5 on my phone. Went to fly it last night.. I have flown at dark before and no issue...but last night i noticed it took FOREVER to lock onto GPS Sats. I usually let it sit before its all locked on good before taking off. I could only get like 9 for longest time. Finally turned white with like 12 I think and I took off. Said home point was updated etc. I hovered about 6 foot off ground and the AC was drifting forward...not staying stationary. Never had that before. I flew and landed back manually when done but wondering why the change after firmware and updates? New to drones and flying so no expert here..lol

I DID NOT update IMU or compass after firmware as i didnt think i needed to. Wondering if it was that, or lack of light being dark? Figured GPS would hold location ?

Lastly, when you look at distances and times under your profile in the app....are they always in KM instead of Miles and heights in M not feet? My settings, with AC on and running is set to imperial... ? Just curious on that one as I thought i could change it to Imperial units for the summary somehow.

Thanks!

coneslayer · Jun 18, 2020

As the GPS and GLONASS satellites move in their orbits, a different number of them are visible from your location at different times. And the times of day with many or few satellites won't stay the same, they change over time. You can use an app like UAV Forecast to tell you how many satellites are visible now, and in the future.

From my location, I had a couple of weeks where there weren't many satellites up in the evening, when I fly. Now things have changed and there's a lot more. I flew last night with the firmware update and didn't have any problems, so I would guess that your GPS issue was just the normal variation.

bumper · Jun 18, 2020

The difference is night and day (so to speak). GPS, without dithering, or some other assistance, is only accurate to a couple of meters or so. In the daytime, downward vision, at least over surfaces with identifiable features, allows the drone to hover precisely in position. That's not so much available at night, thus the slight drift.

SkyeHigh · Jun 18, 2020

The IMU (gyro and accelerometers) allow the AC to maintain position once it is hovering with GPS/GLONASS giving it its location. The downward vision sensors only work to 30-metres.

If the IMU is out of calibration the AC can drift. Looks like it corrected on the second flight.

Antaire · Jun 18, 2020

I was told to always do a compass calibration after a update . Seen on here somewhere.

InvisibleName · Jun 18, 2020

Antaire said:
I was told to always do a compass calibration after a update . Seen on here somewhere.

Don’t believe everything you read on the internet! Here’s what DJI says in the user manual, no reference to calibration after a FW update

It is recommended that the compass is calibrated in any of the following situations when flying outdoors:

1. Flying at a location further than 31 miles (50 km) away from the location the drone was last flown.
2. The aircraft has not been flown for more than 30 days.
3. A compass interference warning appears in DJI Fly and/or the aircraft status indicator blinks red and yellow alternatively.

DO NOT calibrate the compass in locations where magnetic interference may occur, such as close to magnetite deposits or large metallic structures such as parking structures, steel reinforced basements, bridges, cars, or scaffolding.

DO NOT carry objects (such as mobile phones) that contain ferromagnetic materials near the aircraft during calibration.

It is not necessary to calibrate the compass when flying indoors.

Meta4 · Jun 18, 2020

JodyR said:
I had a new firmware update a day or so ago. I also updated to Android 1.1.5 on my phone. Went to fly it last night.. I have flown at dark before and no issue...but last night i noticed it took FOREVER to lock onto GPS Sats. I usually let it sit before its all locked on good before taking off. I could only get like 9 for longest time. Finally turned white with like 12 I think and I took off. Said home point was updated etc. I hovered about 6 foot off ground and the AC was drifting forward...not staying stationary. Never had that before. I flew and landed back manually when done but wondering why the change after firmware and updates? New to drones and flying so no expert here..lol

I DID NOT update IMU or compass after firmware as i didnt think i needed to. Wondering if it was that, or lack of light being dark? Figured GPS would hold location ?

It's unlikely that your updates had any effect at all on GPS acquisition or position stability.
The biggest factor affecting the number of satellites and time to acquire GPS is the amount of sky your drone's GPS antenna can see.
Day/night makes no difference to GPS.
If the drone was only at 6 feet, it will have tried to use VPS for position holding.
That would have had problems in the dark and can be affected by the visual pattern/texture of the ground below it.

svenmarbles · Jun 19, 2020

Here’s your answer,..

The drone merely uses the optical flow sensors while low to the ground. In the dark they don’t work well..

Now you guys can get back to over explaining more technical things [emoji23]

SkyeHigh · Jun 19, 2020

svenmarbles said:
Here’s your answer,..

The drone merely uses the optical flow sensors while low to the ground. In the dark they don’t work well..

Now you guys can get back to over explaining more technical things [emoji23]

Optical flow sensors?? Well that’s a new one.

JodyR · Jun 19, 2020

Thanks for all the replies. Makes sense, so low to ground it was using visual and not GPS per se. Learning alot on here. Much appreciated!

MARINE B · Jun 19, 2020

JodyR said:
I had a new firmware update a day or so ago. I also updated to Android 1.1.5 on my phone. Went to fly it last night.. I have flown at dark before and no issue...but last night i noticed it took FOREVER to lock onto GPS Sats. I usually let it sit before its all locked on good before taking off. I could only get like 9 for longest time. Finally turned white with like 12 I think and I took off. Said home point was updated etc. I hovered about 6 foot off ground and the AC was drifting forward...not staying stationary. Never had that before. I flew and landed back manually when done but wondering why the change after firmware and updates? New to drones and flying so no expert here..lol

I DID NOT update IMU or compass after firmware as i didnt think i needed to. Wondering if it was that, or lack of light being dark? Figured GPS would hold location ?

Lastly, when you look at distances and times under your profile in the app....are they always in KM instead of Miles and heights in M not feet? My settings, with AC on and running is set to imperial... ? Just curious on that one as I thought i could change it to Imperial units for the summary somehow.

Thanks!

Always update Imu and compass after firmware update you can change to imperial or visa versus INT the fly app

Meta4 · Jun 19, 2020

MARINE B said:
Always update Imu and compass after firmware update

I'm not sure where this idea came from.
Updates don't do anything to the compass or IMU.
Even DJI have never recommended this.

sar104 · Jun 19, 2020

JodyR said:
Thanks for all the replies. Makes sense, so low to ground it was using visual and not GPS per se. Learning alot on here. Much appreciated!

GPS is used as soon as sufficient positional accuracy is achieved, even though it may be augmented by VPS. The log files include full details on which systems are active throughout the flight.

JodyR · Jun 19, 2020

MARINE B said:
Always update Imu and compass after firmware update you can change to imperial or visa versus INT the fly app

I see where you can change imperial etc in the Fly App. That setting IS correct. I even toggled it to metric and back to Imperial. During flight it reads feet etc in distance and height. What im talking about is under PROFILE on the first screen of the app,,,It shows hours, distance (in KM) and number of flights. Is this data always in KM is what Im asking?

snapdog · Jun 19, 2020

Here's a screen shot after the latest update. Understand most everything except, not sure what happened to the little orientation icon at the bottom center of the screen? Does it disappear when your GPS is viewed in the lower left? Or maybe I missed something along the way

May need to scroll down to see the bottom. Thanks!

snapdog · Jun 19, 2020

snapdog said:
Here's a screen shot after the latest update. Understand most everything except, not sure what happened to the little orientation icon at the bottom center of the screen? Does it disappear when your GPS is viewed in the lower left? Or maybe I missed something along the way May need to scroll down to see the bottom. Thanks!View attachment 105282

Yes, it does disappear when you bring up the GPS map. I find it's much more accurate as well. Answered my own question

DavidT_ NZ · Jun 20, 2020

If you take off near or after sunset, I suggest that you add some ground lighting around your launch point and turn on the drone’s LED light at take off and during the stationary hover at 7 metres/20 feet before departure, then again at RTH and landing. And use a good “H” landing target pad, to give the drone’s visual sensors a clear image at take off (turn the gimbal down, to check) and for landing comparisons, after the GPS fixes get the drone back overhead, within a few metres/feet. When the drone gets down low enough, monitor it for self landing or flip to Tripod mode for manual control and turn the gimbal down again. With the LED on, you can land in good visibility over a bright target pad. The view is very clear and Tripod mode will let you hover and make fine adjustments, to centre over your target. Then bring it home! Setting the RC’S Fn button for gimbal up/down on one tap and LED on/off for two taps, is convenient. Safe flying. (Note: Good GPS positioning needs satellites well distributed around the drone, at various elevations. The drone likely has an elevation mask set at 15 degrees above the horizon, to avoid using satellites that will be broadcasting through more of the Earth’s atmosphere near the horizon and obstacles to their signals around your low horizon can also affect positioning. Your controller might indicate plenty of satellites whilst the drone is launched or when it is high above you, but when landing, some satellites may have moved behind obstacles and their signals could be dropped or become less accurate. Monitoring the display is especially important when light levels are reduced and hence the ground lighting can be a big help, if you need to take over manual control at the landing. And watch the battery level very closely as an emergency landing in the dark will not be your friend!)