UBX-17053592 - R03
Early Production Information
Troubleshooting
Page 30 of 33
The EVK-M8BZOE 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-M8BZOE does not work properly when connected with a GNSS simulator
There is RF-input for simulator signal (passive).
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 15), which corresponds to Jan 2003.
Then, issue the cold start command before every simulator test to avoid receiver confusion due to the time jumps.
Figure 15: Configuration instruction for using the EVK with a GNSS simulator
The EVK-M8BZOE 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).
