Hello,
We are using the Quectel MC60 module on our custom-designed PCB, but the GNSS performance is not at the expected level.
In open-sky conditions, the module can obtain a valid position fix, but sometimes the first fix takes approximately 5–7 minutes. Under less ideal conditions, such as near a window, the performance becomes significantly worse.
We would like to understand the possible reasons for this long Time to First Fix (TTFF).
Our system includes:
-
Quectel MC60 module
-
Custom 2-layer PCB
-
Embedded GNSS antenna
-
50 Ω GNSS RF trace
-
Stable module power supply
-
GNSS antenna located inside a plastic enclosure
What could cause the GNSS fix time to take up to 7 minutes?
Could this problem be related to:
-
GNSS antenna placement or antenna efficiency
-
Incorrect antenna matching
-
PCB ground-plane design
-
Noise from the power supply or other electronic components
-
GSM interference
-
Incorrect RF trace impedance
-
Missing or unstable GNSS backup power
-
Cold-start operation or outdated assistance data
-
Module soldering or grounding problems
The same design previously obtained a fix more quickly, but the GNSS performance of recently assembled boards appears to be worse.
Which AT commands, NMEA messages or measurements should we check to determine whether the problem is caused by the antenna, RF layout, interference or GNSS configuration?
Thank you for your support.