A solution for some GPS acquisition troubles

[Derrvish]

Good day to all!
I think I found a solution to the problem "acquiring satellites".
The point is a small rechargeable battery on the unit GPS. The battery should have a voltage of 3 volts. However, after a long break in flights, I had a battery voltage of only 1.6 volts. After a long non-use of the drone, she discharges below the level at which normal operation of the unit is possible. As a result, satellites are not registered. And the constant message is "acquiring satellites".
I draw attention to two points. First, you need to solder a new battery carefully, because the board is very delicate.
Second, after re-soldering the battery, orient the board GPS correctly when installing it in the drone. There is an arrow on the board, it should look forward, towards the front of the drone.
I made a mistake during the assembly, and deployed the board 90 degrees, based on the convenience of the location of the cable from it. The result was the crash of the drone, even despite the fact that I calibrated the compass as expected. I was lucky that the drone crashed into the bush, and the damage was minimal.
All successful flights!

 

[DoomMeister]

Thanks for posting this information @Derrvish. This is something that comes up every so often and it works in many cases, but there are also cases where the flight controller board in the aircraft is the root cause. Replacing the battery is a delicate operation, but much less expensive than a new (with likely old battery) GPS unit or FC board.

 

[h-elsner]

According the datasheet of the MS series of this battery it has 'excellent' over -discharge characteristics down to 0V.
I have never changed it but sometime it was neccessary to load this battery before you can use it and this can take hours.
To do this I have a battery dummy for the Typhoon H to put it on an external power supply 15-16V. It needs only 0.3A in standby without camera. Ofcourse you can use the LiPo too, 300mA is not that much. In all cases it is good to remove the camera.


Maybe some patience may avoid replacement of the battery cell on the GPS module.

br HE

 

[Mike Irish]

Good day to all!
I think I found a solution to the problem "acquiring satellites".
The point is a small rechargeable battery on the unit GPS. The battery should have a voltage of 3 volts. However, after a long break in flights, I had a battery voltage of only 1.6 volts. After a long non-use of the drone, she discharges below the level at which normal operation of the unit is possible. As a result, satellites are not registered. And the constant message is "acquiring satellites".
I draw attention to two points. First, you need to solder a new battery carefully, because the board is very delicate.
Second, after re-soldering the battery, orient the board GPS correctly when installing it in the drone. There is an arrow on the board, it should look forward, towards the front of the drone.
I made a mistake during the assembly, and deployed the board 90 degrees, based on the convenience of the location of the cable from it. The result was the crash of the drone, even despite the fact that I calibrated the compass as expected. I was lucky that the drone crashed into the bush, and the damage was minimal.
All successful flights!

Good morning Derrvish. I am wondering if you have tried changing the position of the GPS module. I have seen that others here on the forum have mounted the GPS module on the outside on the H shell in a purpace made box to maintain the original angle. It seems to me that a better position for the module is as far as possible away from other electrical parts?
If you take a look at the 920 and some of the other large commercial drones the GPS module is raised up away from the body of the drone.
I would love to hear your thoughts on this as you seem to have a good working knowledge of electrics.
Regards.
Mike

 

[Mrgs1]

According the datasheet of the MS series of this battery it has 'excellent' over -discharge characteristics down to 0V.
I have never changed it but sometime it was neccessary to load this battery before you can use it and this can take hours.
To do this I have a battery dummy for the Typhoon H to put it on an external power supply 15-16V. It needs only 0.3A in standby without camera. Ofcourse you can use the LiPo too, 300mA is not that much. In all cases it is good to remove the camera.
View attachment 20478View attachment 20479

Maybe some patience may avoid replacement of the battery cell on the GPS module.

br HE

Yes that's what I've done before. My only problem is my spare top covers with GPS module fitted, and having to swap covers.

 

[h-elsner]

Without doubts it is better to have the GPS module outside in a higher position. Not because of the GPS but because of the compass chip.
It is more important to have a good shield below the GPS antenna. I'm not sure if the thin copper foil is enough especially because it is not connected to ground. From my point of view, shielding is more importand for the GPS. On the other hand, copper will not work for compass.
I have heard from another guy in a german forum who has also brougt the GPS module to outside but used a good grounded copper shield as. Always good experiences with that and he has had a lot of Typhoon Hs in his hands.

But let us hear what @Derrvish say...

br HE

 

[Mike Irish]

Without doubts it is better to have the GPS module outside in a higher position. Not because of the GPS but because of the compass chip.
It is more important to have a good shield below the GPS antenna. I'm not sure if the thin copper foil is enough especially because it is not connected to ground. From my point of view, shielding is more importand for the GPS. On the other hand, copper will not work for compass.
I have heard from another guy in a german forum who has also brougt the GPS module to outside but used a good grounded copper shield as. Always good experiences with that and he has had a lot of Typhoon Hs in his hands.

But let us hear what @Derrvish say...

br HE

Thank you for chiming in. It's nice to have other people's input on questions like these. The more the merrier.
I've seen others on the forum has made this modification but havent haired if it gave any benefits or not?
Cheers.
Mike

 

[Sureshot]

According the datasheet of the MS series of this battery it has 'excellent' over -discharge characteristics down to 0V.
I have never changed it but sometime it was neccessary to load this battery before you can use it and this can take hours.
To do this I have a battery dummy for the Typhoon H to put it on an external power supply 15-16V. It needs only 0.3A in standby without camera. Ofcourse you can use the LiPo too, 300mA is not that much. In all cases it is good to remove the camera.
View attachment 20478View attachment 20479

Maybe some patience may avoid replacement of the battery cell on the GPS module.

br HE

Thank you for the idea.
Now I know what to do with my old ageing battery's shell.

 

[Derrvish]

Good morning Derrvish. I am wondering if you have tried changing the position of the GPS module. I have seen that others here on the forum have mounted the GPS module on the outside on the H shell in a purpace made box to maintain the original angle. It seems to me that a better position for the module is as far as possible away from other electrical parts?
If you take a look at the 920 and some of the other large commercial drones the GPS module is raised up away from the body of the drone.
I would love to hear your thoughts on this as you seem to have a good working knowledge of electrics.
Regards.
Mike

Good afternoon!
Of course, the farther the compass and GPS module from the rest of the drone’s electronics, the better. Especially from power supply circuits of engines. However, you need to consider not only this moment. There are restrictions on the size of the body of the drone. There are aerodynamic characteristics of the drone. Streamlined body. Also weight. Of course, you can take the board of the GPS module and compass over the top cover of the drone. On the vertical leg, inside which the cable will be located. Today, making a streamlined box for the compass unit is not a problem. But this can violate the external aerodynamic performance of the aircraft body. Weight distribution.
I do not quite understand what caused this desire. I have Typhoon H Pro with RealSense. I have never had a problem with a compass or GPS module. Not a single time. In my opinion, the bigger question is the range of reliable communication with the drone, transmission of video and control signals. In this matter, Typhoon loses a lot to DJI. Also a very big question on the camera. By its characteristics and real capabilities, it is much inferior to cameras with a matrix of one inch. This is very upsetting. I was waiting for the release of a new Typhoon H - compatible camera, but it will not. Marketing. But do not buy the new drone because of this!
Personally, I’m just going to experiment and improve the range of a controlled flight of the Typhoon. I have no other serious problems with my drone.
Sorry for my insufficient English.

 

[Mike Irish]

Thank you for your informative reply.
I to don't have many problems if any with the gps my problem is with the range of the camera signal. I was hoping to find a fix for this by moving the module to the outside of the H. I would love to hear from people that tried this fix.
Any good advice is welcome.
Mike

 

[PatR]

Mike,

As an experiment, one with a high probability of working, pop the center plastic cover off the front of the camera. Once that is removed you will see a clover leaf antenna stuffed inside the camera. Carefully fish the clover leaf out of the housing and let it hang outside the camera body, oriented to the bottom of the camera. That should improve video range.

The cover can be removed by squeezing the two sides together and lifting it away from the camera. You can file a slot to fit over the exposed antenna prior to reinstalling it.

 

[Mike Irish]

Mike,

As an experiment, one with a high probability of working, pop the center plastic cover off the front of the camera. Once that is removed you will see a clover leaf antenna stuffed inside the camera. Carefully fish the clover leaf out of the housing and let it hang outside the camera body, oriented to the bottom of the camera. That should improve video range.

The cover can be removed by squeezing the two sides together and lifting it away from the camera. You can file a slot to fit over the exposed antenna prior to reinstalling it.

Thank you Pat for the info but I should have mentioned before I have the H+.
I only have lost video signal on a couple of occasions but the fact is still there I still lost the signal.
Regards.
Mike

 

[Mrgs1]

Thank you Pat for the info but I should have mentioned before I have the H+.
I only have lost video signal on a couple of occasions but the fact is still there I still lost the signal.
Regards.
Mike

Are you on EU firmware? That is weaker than US and can cause video loss more than US version.

 

[pushh]

Hey there! I have the same problem. I haven't flown my H in a good while( flown it once in december) but the last time before that was last year's august ish. I wanted to fly yesterday out on an open field, and it acquired 18 satellites almost instantly, and it would say "ready" for like 3-4 seconds, then "gps lost" (but it still said 18 satellites). After turning it off and on, I could launch it quickly when it said "ready" and it held it's position quite well despite the wind. Problems arose when I tried to land in gps mode, as it wouldn't descend farther than like 5m above the ground(lol), I didn't know what to react, so I flipped it into RTH, and it landed okay from where it took off. Then I packed, and came home. I let it sit after turning it on for like 4 hours straight, and went out to test, found 14 satellites, but it refused to say ready. Finding this, I took it apart, and my battery measured 2.3volts, tried charging it all the way to 3.1 ish volts(of course first I desoldered it from the module), then it would drop back to 2.5 in under 40seconds measuring with a multimeter. Stressing the battery with a 400ohm resistor resulted in 1.2v under load. I'll check the hobby electric store if I can find this battery, if not I'll order from ebay. Do you guys think the symptoms I'm having correspond with the battery issues? Would a new one solve the acquiring issues I'm having? Never had a problem like this before, it always locked on after like 30 seconds or so.

 

[Sureshot]

Probably the GPS battery, but just to be sure, check the log for a compass errors of 1 or more seconds when you were trying to land.

 

[h-elsner]

Let's have a look into the uBlox M8 datasheet:
"The RTC is driven by a 32 kHz oscillator, which makes use of an RTC crystal. If the main supply voltage fails and a
battery is connected to V_BCKP, parts of the receiver switch off, but the RTC still runs providing a timing
reference for the receiver. This operating mode is called Hardware Backup Mode, which enables all relevant data
to be saved in the backup RAM to allow a hot or warm start later."

This means, during normal operation (powered on) the backup-battery is inactive/not needed. It's only need to keep the RTC running and the memory alive when the power was switched off in order to perform a warmstart of the chipset later.

V-BCKP is specified min 1.4V and max 3.6V. This means from 1.4V on a warmstart is possible.
I do not belive that the backup battery is source of the problems.

The datasheet of the backup battery (MS series) says, it has an 'excellent' over-discharge characteristics down to 0V (!). We can belive that or not but the current setup chipset/backup battry is robust enough.

br HE

 

[Paul (UK)]

Excuse me for jumping in here only I too am getting the "acquiring satellites" error, is this small battery on the GPS module rechargable or does it need to be replaced? If rechargeable is it just a matter of leaving a flight battery installed with Typhoon on or off?

 

[h-elsner]

Yes, the backup battery is rechargeable. It will be charged when the drone is powered on.

br HE

 

[Paul (UK)]

Thx for that, will leave it on for a couple of hours & see what happens.

 

[Paul (UK)]

Have left Typhoon switched on for about 3 hours in total but still no lock, Typhoon detects 17 sats & ST16 10 sats but still got the "acquire" error. Status lights on back of Typhoon is 3 short flashes of green, a (blank) pause then 3 short flashes green again etc.
Removed top cover to check GPS battery, showing 2.65V disconnected, reconnect & power up showing 2.7V. Also have a red LED flashing on GPS module, error code?