Problems with GPS

ehollis

Hi. First time poster to this forum. Let me know if I need to do something different.

I have a 13" Dudu7. Whenever I start the car and drive, the GPS system does not work. I think that I have eliminated a bad antenna: The antenna is stuck to the windshield, behind the rear view mirror. I have used the apps GPSTest and GPSReset.com. Both of these programs show that the GPS radio is seeing 7 - 14 satellites at times.

I have upgraded to the latest version of 3.6 DUDU OS. I have a 13" DUDU7 with a SIM card. I also have very good wifi access in the garage. So when I start, the unit connects to WiFi and to cellular data.

So here is what happens. I park in a garage, so when I start the car, there is no view of the sky. When the DUDU unit starts, I have Waze and Pandora start in PIP. I have Internet, because the screen icons indicate it, and because Pandora music starts. But Waze will not connect to GPS. I either get a GPS not available message, or a message that waze is connecting to GPS. It doesn't. If I leave it alone and just drive, eventually, 10 - 15 minutes later, sometimes it connects to GPS, and Waze works normally. But just as often, it doesn't connect to GPS at all. Then I switch to Carplay.

When I get to my destination (30 - 40 minutes later), I park the car outside. When I return in an hour or so, and start the car, Waze/Pandora works normally. So if the unit runs for 30/40 minutes, and is parked outside, the GPS works...almost always.

I have had the unit about 8 months. This is the third headend that I've installed in several cars, and I am very familar with installation. I am extremely dissapointed in this headend. I paid over USD 800 for it, and it is the most unreliable headend that I have ever used. I have been trying to resolve this problem for a while, but I'm really stumped.

What other information do you need to help me resolve this? I'm willing to upload logs, screenshots, whatever. Thanks for the assistance.
Eric

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DUDU-Meng

Are you saying that if the vehicle is parked indoors for an extended period of time and driven outdoors 30 minutes after being started indoors, there is a possibility that it will not be able to locate satellites for an extended period of time?
The satellite ephemeris is valid for four hours. When parked outdoors, it will automatically update, but if parked indoors for more than four hours, the satellite ephemeris will expire, resulting in a cold start. When driven outdoors, it will need to search for satellites again and will also download the network satellite ephemeris. However, the indoor Wi-Fi may fail to download or download incorrectly, among other reasons.

ehollis

Thank you very much for this information. How do I lessen the time required for a cold start? It makes the GPS essentially unuseable, as it does not update for 10 - 15 minutes minimum.
Just to recap: I park indoors. When I start the car, it connects to Internet immediately via WiFi. When I set my destination via waze, the unit tells me there is no GPS. Occasionally, it tells me that it is connecting to GPS (but it never does.) I drive for 10 - 15 minutes without GPS, then I just switch to Carplay, which always works. This does not seem normal, and it makes this very nice headend almost useless to me.
Thanks again for the quick response. What other information do you need?

DUDU-Meng

ehollis Minimize the length of time you are on indoors, you should have no problem unlocking your vehicle and driving straight outside.
Try it sometime.

Mikescotland

If the unit acts like this, it usually means that something isn't fully right with the GPS antenna. Even from cold start without valid ephemeris, 3D lock should be obtained within a minute in open space with no data connection (no assisted GPS). It may also indicate another problem with lack of assisted GPS in the Dudu libraries, as it should pull valid ephemeris from Internet sources.
To be honest, even if the car is off for 24h and outside (which is basically cold GPS start) I haven't had any problems with GPS lock within a few seconds, I'm using OEM built in roof GPS antenna.
So, I suppose either OP unit is faulty, or there is a problem with the GPS antenna.
Op should take a look at GPS test, how many satellites unit sees just after driving into open space (it should populate with at least 5 within literally 10 secs) and what is S/N ratio of the satellites.

UnagiC8

Mikescotland From what I understand, your GNSS antenna is installed upside down. Could that be the problem? In the initial setup guide, it is recommended that the antenna should be facing upwards. Install the antenna on the dashboard or underneath it.

ehollis

Thank you very much. I will try that immediately and post the results. I have used GPSTest, and I will do as Mikescotland suggested. I purchased another GPS antenna, so I'll use that one. I really appreciate the thoughtful help and careful reading of my post.

ehollis

A couple of hours ago, I had to leave home for an appointment. Before I left, I mounted a new GPS antenna in the car and stuck it temporarily on the dash. I started the car and opened GPSTest. As expected (indoors) there were no satellites detected. I drove out of the garage, and immediately saw 15 or 16 satellites. A few seconds later, GPSTest registered the longitude and latitude. I ran Waze without incident for the whole trip.

Mikescotland and UnagiC8, I cannot thank you enough for the help. You guys gave me the information that I needed to fix the problem. I've spent hours trying to figure this out, never knowing that the orientation of the antenna would make such a big difference.

Mikescotland

ehollis glad we could help. The signal from gps satellites is extremely weak hence the importance of the antenna. All good then!

KONGHY

DUDU6 사용자입니다.
구매시점에 DUDU OS 3.6로 업데이트 되어 버전 문제인지 원래 안테나 감도 문제 인지 모르겟습니다만
저도 업데이트 하고 나서 GPS 찾는 시간이 많이 소요 되어 정상적인 네비게이션 사용이 어렵습니다.

도심에 지하차도 안으로 들어가면 GPS 초기화 되고
3D FIX? GPS TEST 앱의 우측 녹색이 켜지는데 3분 정도 소요 됩니다. 경우에 따라서 1분 정도 걸리는 경우도 있지만 불편하기는 마찬가지입니다.

별도의 비용을 들여 GPS 안테나를 장착해야 할까요?

제 핸드폰과 정상시에 GPS 위치 비교를 보아도 문제가 안테나 때문인가 하는 의구 심이 듭니다.

https://drive.google.com/file/d/13TUxcKuqZ82CdTYchWYOqvt4ohOGbPRa/view?usp=sharing

DUDU-Meng

KONGHY
What kind of GPS antenna are you currently using?
After successful positioning, the number of satellites is not very high. You can try moving the antenna position and angle so that it is horizontal and facing upward. Find the position with the most satellites and the strongest signal to place the antenna.

Mikescotland

Both devices show very poor gps reception inside your car. Nothing wrong with Dudu, your phone also receives very bad signal. Possibly you have windscreen with metal to reduce heating by the sun.
Also, looks like gps antenna is either not connected to Dudu, or is inside your car, or is simply broken (plug maybe?).
Do an experiment, connect GPS antenna but open the window and stick it to your roof near window (remember to place right side up to the sky) and then measure in GPS test again.
If the results are OK, you need to have external GPS antenna.
If the results are the same but your phone outside shows much better results, it means your GPS antenna for Dudu is broken.