Gps l86 is about 1km away from real coordinate

Hi, I’m building an application that use BLE, GPS L86, moduleSim.
According to GPS L86 it can reach accuracy aproximate <5m in open sky.
But when I integrate my GPS L86 with nRF module (BLE), module sim (Sara u201)
=> GPS L86 has very bad accuracy (it’s about “1km” from the real address in “open sky”)
1km is too bad.
So I have some questions

If I have just bought GPS L86 and test it stand alone, if it can reach as datasheet <5m in open sky ? Without any configurations ? or Should I need some configurations to reach best performance ?
May radio signal from BLE and Module Sim affect to my GPS module ? I followed GPS L86 hardware design to keep a distance with these module but 1km is too bad.

Thanks for your help.

Dear Sir,
As per L86 hardware design, its static horizontal positioning accuracy is 2.5m@CEP50. No extra configuration to reach best performance.
Generally, drift on performance is about 10-200 meters. 1 km error might be caused wrong calculation of lat/long, offset in some maps or different coordinate system.
Could you provide true value point and your test log? I can help check.
BTW, you could use QGNSS to check.

Regards

Thanks for your help.
I’ll try another GPS L86 module.
No, I pretty sure about my tool. Because when I try another GPS module it showed good performance.

  1. Can you list for me some reasons that cause GPS bad accuracy ( drift on 10-200m is still bad performance compare to GPS of mobile phone). May I try A-GPS ??
  2. 10-200m bad condition like in many buildings or shelters?

Run both the good and bad modules side by side at the same time and examine the NMEA logs. There should be some differences implying why one of them has lower accuracy.

Dear Sir,
For point 1, the reasons for GPS bad accuracy might be:① indoors or the sky was covered ② antenna jamming ③ power supply ( refers to file Hardware_Design). GPS location relies on satellites signal. Different from GPS location, mobile phones rely on networks and base stations to get the location. Besides, AGPS is a method to speed up TTFF (Time To First Fix), instead of improving accuracy.
For point 2, yes.

Best regards.
Quectel_L86_Hardware_Design_V1.3.pdf (1.3 MB)

In another case, GPS L86 cannot get the coordinate when indoor. How can I handle that ?

Dear Sir,
GPS modules only supports locating outdoors, because the modules completely rely on the satellites signal. If you want to get an accurate location indoors, you may need communication modules and base stations.

Best regards.

If you have bad GPS Signal (and only 4 Sats) there could be a larg error of >1km. We tested this with a L86. The “average” over a certain period is very good.
Here: GNSS located close to window:


Best regards, Jo