No GPS

[DCH]

Hey all, long time no post! ...I've been great, thanks for asking!

After breaking out my H Plus after 9 months of storage, there is good news and bad. The good news is the batteries are in great shape -no swelling and all cells were still well balanced, I stored them with a storage charge and they charged right up and work great.

The bad news is I have a gremlin now that makes it hard to use the setup. I have two ST16s controllers for Team Mode which I use often. My primary controller (for flight control) has an intermittent problem with the GPS. Most of the time after power up, the Sat icon shows "N/A" and is greyed out. I can power cycle it and sometimes it will start to work normally and indicate the number of sats, other times not. Most of the time (8 out of 10) it shows N/A, and I can't fly.

My secondary ST16s seems to work fine, no GPS issues, and I can swap them, but it is set up to operate the gimbal with a custom rate curve for just that purpose, it is not set up to control the aircraft like my primary ST16s, which has different custom rate curves for flight control.

Does anyone have any idea what is going on with the GPS in my ST16s and what I need to do to fix this issue? Thanks!

 

[DoomMeister]

Long time no see. Glad you are doing well!

I’ve seen this in an ST16S about 2 years ago. The problem ended up being the GPS antenna went bad. With the controller face down and the back opened it is located in the lower right portion just to the side of the main circuit board. The Ublox GPS chip is on the main PCB just left of the antenna. The antenna is secured with a fairly strong double sided tape.

I would suggest just remove, clean with contact cleaner (plastic safe), and replace the coax lead to the main PCB. If that doesn’t work, try swapping the antennas between the controllers.

Let us know how it goes. In the meantime set your RTL point to the point of takeoff and not the location of the controller. If the controller does not have a valid GPS position the aircraft may try going to 0 latitude 0 longitude in the event RTL is triggered.

 

[h-elsner]

I have a used ST16S for test purposes. It has the same problem - no GPS. I also think the antenna is bad. If I go to GPS tests there is something listed which indicates from my point of view that the GPS chip M4 is working but the input power is weak. Here is what I see:
1) Go to test tools:
Pad mode > FlightContralModeTest



GPS test results an empty page:



GPS Info test: Simple results empty page, detailed shows "something" if you let the ST16S sit a while outside:


GPS Info Count: Also shows something if you let the ST16S sit outside.



It would be nice to have those test results from a working GPS.

br HE

 

[DCH]

I'm not certain which GPS is in question. The grayed out ICON mentioned by @DCH seems to be the Drone GPS.

The ST16S GPS, as mention in the OP, of my two ST16s, one works fine the other has intermittent GPS. I'm going to try Doom's suggestion this afternoon when I get a little time. I'll post the results.

 

[WTFDproject]

The ST16S GPS, as mention in the OP, of my two ST16s, one works fine the other has intermittent GPS. I'm going to try Doom's suggestion this afternoon when I get a little time. I'll post the results.

Apologies. It took me this long to realize you are talking about an H Plus instead of an H520. H520 only has ONE Satellite ICON, and it's for the drone.
My bad.

 

[DCH]

Apologies. It took me this long to realize you are talking about an H Plus instead of an H520. H520 only has ONE Satellite ICON, and it's for the drone.
My bad.

That explains why I didn't really understand when you said the Sat icon was for the aircraft. That's okay, you get a free pass, the orange 520 body on my H Plus must have thrown you off! These old eyes couldn't see the original dark grey body against the backdrop of mountains and trees, so I swapped the body out for high vis orange. Now I can see it with my eyes closed!!

 

[WTFDproject]

It would be nice to have those test results from a working GPS.

@h-elsner,
Is this what you want?
These images are from an H Plus. The C23 and H Plus are bound to an ST16S. The ST16S is running the H Plus APP "FlightMode2.0". Build 822 Firmware.
The motors were bump started to ensure they would start with the data displayed below.

 

[DCH]

Problem solved! Judge Doom made an excellent judgment and passed down the death sentence for the Gremlin (both of them), and they have both been executed for the heinous crime of disturbing an aerial video/photo shoot at the worst possible time. It was the GPS antenna connector.

How egregious was the crime? I had four car show events to cover in two days, two Friday, two today. They were all very expensive and/or exotic cars so I lined up a photographer friend to be my Team Mode Videographer so I could concentrate on flying the aircraft and not fly over the cars or into the surrounding trees.

When I got to event one my primary (flight) controller couldn't get the GPS going despite many power cycles. I was under time pressure so I had to revert to my Camera controller for flight, but couldn't get Team mode to work with the controllers swapping roles. I had to scratch the video shoot, layoff the Videographer, and only took stills cuz I was solo now for the rest of the events.

Day two fourth event, again solo and only trying for stills, when the one working controller started having the same no GPS issue! Really?!? Fortunately, after 3 or 4 power cycles it started working again and I was able to get my shots.

When I got home this afternoon I tore into Controller 1 and Deoxed the GPS antenna connector with a shot of my favourite 'miracle magic salsa' (Deoxit D5) and it started working again right away. So I tore into Controller 2 and did the same. Happy to report they are both working great again!

 

[h-elsner]

@WTFDproject : Thank you! That's exactly what I want. Surprise to see that GPS test has also empty page. So, it's not very helpful. GPS Info test makes the difference. Signal strength says a lot:
1) The GPS chip is working and measure the signal.
2) Signal strength is bad. --> Antenna, cable, connector or signal input circuit of the GPS chip in doubt.
GPS Info count: Not a great help but shows that GPS fix is not reached. Regarding the other values - on mine st (min/max) is low whatever "st" is.

@DCH : You idenified the connector - I'm still seaching...

br HE

 

[DCH]

@DCH : You idenified the connector - I'm still seaching...

This is the one I cleaned. Lower right corner of the main board.

 

[DoomMeister]

Glad the cleaning worked for you @DCH. The one I worked on before had the antenna itself go bad or in the wiring to the antenna.

There was no difference doing an Ohms check so no shorts or breaks in the wiring that could be detected. Of course RF circuits can still have issues that don’t show with a simple Ohms test.

 

[h-elsner]

I have changed the antenna to an old one from Blade 350QX. It started with 5 sats and increased step by step up to 18 sats. But all with strength = zero. No GPS fix. After changed back no more sats are identified whatever antenna I used. Maybe I have finally killed the RF circuit or there is a invisible crack or shortcur on the PCB. However, it was not working before and it didn't work now. Because the ST16S is only for tests it's no problem. I let it as it is.

The ST16S is for my H Plus which is also only a test system.


It has a MAVlink bridge based on ESP8266 instead the camera to transmit telemetry to ST16S. I'm fine with that stuff so far.

br HE

 

[DCH]

The one I worked on before had the antenna itself go bad or in the wiring to the antenna.

Did you get a replacement antenna for it? If so where does one find this type of replacement component?

 

[Steve Carr]

Did you get a replacement antenna for it? If so where does one find this type of replacement component?

Most likely place to get parts is from an ST16s being scavenged for usable parts. I have one in that condition but I think I already sent the antenna.

 

[DoomMeister]

Most likely place to get parts is from an ST16s being scavenged for usable parts. I have one in that condition but I think I already sent the antenna.

That is the one used by me to fix the one while in FL.

 

[Vaklin]

In the AliExpress is possible to buy any size of GPS aerial. The prices are around 2-3 USD, so it's worth trying.

Use a GPS antenna as a request in the search field.

 

[DCH]

In the AliExpress is possible to buy any size of GPS aerial

Thanks, but that site didn't work out. I could not get to a search page or register a new account. Too much info lost in translation and fields that were partially obscured with no access to fill in the requested info, even when I was able to select English.

I discovered that Mouser Electronics in the US offers a large selection a GPS antennas of all types and form factors -even external antennas with a long coax that one could mount on the outside of the ST16s for better reception. However one needs to know the specs and frequency range of the OEM Yuneec antenna to know what to order.

I might need to try another antenna after all. Within 48 hours of cleaning the antenna connections, both Controllers are having intermittent GPS connection problem again. Not as bad as before, but unacceptable.
Does anyone know what Yuneec's GPS Antenna specifications are?

 

[Vaklin]

The AliExpress covers almost all languages in the world. This is a bestseller. All the rest sites are more expensive at times. Many people in the US use it, so you can do too

 

[Omnitest]

The most basic frequencies for GPS are: L1, at 1575.42 MHz, and L2, at 1227.6 MHz (newer satellites also broadcast on L5 at 1176 MHz). The svid's in the GPS test screenshots @WTFDproject provided are all GPS constellation, so an L1,L2 antenna will probably be fine.

@DoomMeister noted that it is a U-blox GPS receiver and that would make sense. Their newest (last 8-10 years) receivers could be GNSS, so a Multiband antenna might be useful. If the GPS receiver has the additional GNSS constellations, you can benefit from a multiband antenna. This adds the 1278.75 MHz band for the European Galileo constellation as well as other ranges for the Russian GLONASS and China BeiDou Constellations. Those last two have several ranges, but simply looking for multiband will do the trick.

The connector from the other photo looks like a U.FL connection, also known as IPEX. There are several sizes of IPEX connectors, but I am pretty sure the ones that are standard with the GPS antennas you can get will be the right size for this board. This is the larger IPEX connector and the smaller ones are typically found on Bluetooth and WiFi circuit board connections.

Just for fun, here is a cheap u-blox from Amazon that is GPS only (probably newer model than the one in the controller) that comes with an antenna. Maybe a reasonable way to get the antenna and have a GPS to play with as well. It is pretty typical that they have the u.fl connector like this one.

https://www.amazon.com/dp/B01D1D0F5M/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B01D1D0F5M&pd_rd_w=hICYn&content-id=amzn1.sym.f734d1a2-0bf9-4a26-ad34-2e1b969a5a75&pf_rd_p=f734d1a2-0bf9-4a26-ad34-2e1b969a5a75&pf_rd_r=ZSPKPYYKEPWQX5NZF2PV&pd_rd_wg=ljzUo&pd_rd_r=ae8b9afd-960f-4d50-800a-d24aeab8c1ad&s=gps&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

AliExpress will have similar for less. Depending upon where you are, it could be a longer ship time from China.

If you wanted to go the external route, you can get a cable that has the u.fl connector on one end and a bulkhead SMA on the other. A 1/4" hole in the case will hold the SMA connector and the world of available antennas opens up.

Here are two from Sparkfun. They would have a decent selection of GPS antenna with SMA coax connections as well.

Interface Cable U.FL to SMA - WRL-18154 - SparkFun Electronics

A U.FL to SMA (jack) bulkhead straight connector with a 1.32 mm diameter cable.

www.sparkfun.com

Interface Cable SMA to U.FL - WRL-09145 - SparkFun Electronics

This is a 4" connector cable that interfaces U.FL RF connectors to regular SMA connectors. This cable is commonly used to connect larger GPS antennas and q

www.sparkfun.com

My apologies if I have gotten too detailed about a simple question. I blame my brain.

 

[Vaklin]

ST16 remote GPS stability issue.

I have some doubts about the stability of the GPS receiver installed inside the ST16. Accuracy is relatively low. The height measurement is very poor. Can someone check in their own logs, are there the same, or I should do some troubleshooting with this controller? Probably I'll try to place a...

yuneecpilots.com