EVK-M8xCAM - User Guide
UBX-14002462 - R07
Early Production Information
Troubleshooting
Page 21 of 24
Before shutting down the receiver externally, check the status in MON-HW in the field “Real Time Clock Status”.
Do not shut down the receiver if the RTC is not calibrated.
The EVK-M8QCAM/M8CCAM does not meet the TTFF specification
Make sure the antenna has a good sky view. An obstructed view leads to prolonged startup times. In a well-
designed system, the average of the C/No ratio of high elevation satellites should be in the range of 40 dBHz to
about 50 dBHz. With a standard off-the-shelf active antenna, 47 dBHz should easily be achieved. Low C/No
values lead to a prolonged startup time.
The EVK-M8QCAM/M8CCAM does not work properly when connected with a GNSS simulator
When using an EVK together with a GNSS simulator, pay attention to proper handling of the EVK. A GNSS
receiver is designed for real-life use, i.e. time is always moving forward. By using a GNSS simulator, the user can
change scenarios, which enables jumping backwards in time. This can have serious side effects on the
performance of GNSS receivers.
The solution is to configure GPS week rollover to 1200 (as indicated in Figure 9), which corresponds to Jan 2003.
Then, issue the cold start command before every simulator test to avoid receiver confusion due to the time
jumps.
Also ensure that the RF-signal path is switched to the RF-connector. To do this, provide an external DC-load to
the RF input, which shall be electrically decoupled from the RF signal.
Figure 9: Configuration instruction for using the EVK with a GNSS simulator
The EVK-M8QCAM/M8CCAM does not preserve the configuration when power is cut off
u-blox M8 GNSS technology uses a slightly different concept than most other GNSS receivers do. Settings are
initially stored to volatile memory. In order to save them permanently, sending a second command is required.
This allows testing the new settings and reverting to the old settings by resetting the receiver if the new settings
aren’t good. This provides safety, as it is no longer possible to accidentally program a bad configuration
(e.g. disabling the main communication port).
EVK-M8QCAM/M8CCAM receives GPS and GLONASS
Use u-center version 7.02 or newer. Message UBX-CFG-GNSS allows switching on and off the supported GNSS.
