The Dreaded GPS Acquire

[Jimmy5498]

Sorry to labour the point. Ive trawled the web and read countless forums from people more experienced than myself. I recently moved away completly from DJI products, An Inspire 1 V2, Phantom 3 pro, Phantom 4 V2 Pro etc to a Q500 and H pro.

I know there a different beast, the Q500 no issues at all, GPS lock and acquire in <20 secs even indoors.

The H on the other hand, even when flown almost daily, takes on average > 5 min to lock.

When I connect to the Windows GUI in the field I can see 11 sats on the graph with the colour designating in use! ST shows acquiring. The ST will find sats , > 10 in less than a minute

After this 10 min wait it will acquire then seems okay for the remainder of the flight

Happy to check and\or change the re-chargable Seiko battery on the gps board if that is the issue?

A slightly annoyed new Yuneed user !

 

[WTFDproject]

Happy to check and\or change the re-chargable Seiko battery on the gps board if that is the issue?

We can only take speculation so far. At some point, you will have to do some hands on checks of the suggested possibilities.
The current most likely suspect is the GPS battery. The picture below might help. 3.0 v is good. 1.5v is probably too low (see additional discussion below).
It recharges from the flight battery during use, so you will need to leave the main battery out long enough to reasonably mimic the discharge times between your flight days.



Additional discussion: The statement of "1.5v is probably too low" is based on other information found on the forum.
I had a TH available that has not been used much lately, and decided to use it as a benchmark for this post. I took the top off and measured the voltage. It was reading 1.5V. I reassembled the TH and took it outside. I turned on the ST16 first so I could see the GPS readings. Then I plugged in the flight battery and turned on the TH. It acquired satellites in 20 seconds. I don't really have a good, low end value to propose. I suspect the value would be somewhat different for different units.

 

[Steve Carr]

When I connect to the Windows GUI in the field I can see 11 sats on the graph with the colour designating in use! ST shows acquiring.

Needs some clarification Jimmy. Are you using the GUI check inside or outside with an open view of the sky?
The Acquiring message is displayed until BOTH the ST16 and the H have sufficient satellites for takeoff.

5 minutes seems to be excessive for Ready to appear if you have a clear view of the sky. That means no buildings or trees blocking the view. Can you provide the number of sats for both units in the open after about 2 min?

 

[PatR]

If the back up battery is down to 1.5v it will have to come up to at least 3v before the GPS system completes the power up sequence. It will take a little time for the flight battery to temporarily charge it. Shortly after the system is powered down the back up battery will drop voltage back to 1.5v and the process will have to be repeated when the next flight battery is inserted.

The GPS requires a minimum voltage to function and 3v-3.5v is a common level even with larger systems.

 

[h-elsner]

10-11 sats I have had with Blade 350QX. Its GNSS had only GPS. The Q500 and typhoon H has GPS and GLONASS. With them I have 16-20 sats visible. Which one are used and how good the GPS is (accuracy) is another question. It depends not only on the number of sats but also their postion, your position, area you are in and weather.
GPS fix will only recognized if accuracy is good enough. In you case it may be a problem with GPS antenna (low amount of sats) or a discharged backup battery (long time to get GPS fix).
If the backup battery is below 1.4V the GPS module makes a cold start. This may take a long time up to 15min.
If the backup battery has more than 1.4V the GPS is able to make a warm start because data kept and RTC is still running. In this case GPS fix should come in a time frame as you expected.

br HE

 

[WTFDproject]

@h-elsner also provided information that if the GPS battery is very low, it may take as much as 72 hours of charging to fully restore.
You're GPS battery is possibly somewhere in the marginal region, and may benefit from an extended time under power to restore normal, timely GPS acquisition.

 

[Jimmy5498]

Thanks all appreciate your input

 

[Steve Carr]

Thanks all appreciate your input

You haven't given any additional information that I asked for in post #3 nor any update on where you stand with this.
Would you be kind enough to do so. Otherwise this thread has little value for future reference.

 

[Jimmy5498]

Steve sorry for the delay. Please find the attached. The pic is not live as I had switched off the drone in anger.
Yesterday i went out and . bingo, all was well. However it seems very hit or miss whether it works or not

 

[Steve Carr]

@Jimmy5498 Please take a pic of your controller outside and pics of the area you are testing the GPS.

 

[Steve Carr]

I had switched off the drone in anger.

Frankly, that is related to your lack of knowledge of the aircraft. Your previous experience is limiting your ability to learn. Are you posting here to understand or to complain? The answer determines whether or not you are wasting our time.

 

[PatR]

Testing GPS acquisition indoors serves as much purpose as trying to put out a fire by tossing gasoline on it.

 

[DoomMeister]

This looks like the aircraft is sitting on a covered patio or near the house. It needs to be out in the open with at least 100 degrees of open sky. It sees 11 different satellites, but it does not mean it has good signal from all of them. Reflected GPS signals give false position readings.

When I have my TH in my yard in Michigan it acquires and drops acquisition a lot even with 14 or 15 satellites.There are a lot of large trees and a two story house.

 

[KEITH KUHN]

This looks like the aircraft is sitting on a covered patio or near the house. It needs to be out in the open with at least 100 degrees of open sky. It sees 11 different satellites, but it does not mean it has good signal from all of them. Reflected GPS signals give false position readings.

When I have my TH in my yard in Michigan it acquires and drops acquisition a lot even with 14 or 15 satellites.There are a lot of large trees and a two story house.

Good to know all this info.
Keith

 

[Jimmy5498]

As my knowledge is limited, i changed the battery in the GPS module for a new Seiko. After a charge of an hour all is well now. I do appreciate all the positive comments to allow me to conduct a fix