RCB-F9T - Integration manual
3.11.2.1 Jamming/interference monitor (ITFM) / broadband interference monitoring
The field
flags
of the UBX-MON-RF message can be used as an indicator for both broadband and
continuous wave (CW) jammers/interference. It is independent of the (CW only) jamming indicator
described in
Jamming/interference indicator
This monitor reports whether jamming has been detected or suspected by the receiver. The receiver
monitors the background noise and looks for significant changes. Normally, with no interference
detected, it will report "OK". If the receiver detects that the noise has risen above a preset threshold,
the receiver reports "Warning". If in addition, there is no current valid fix, the receiver reports
"Critical".
The monitor has four states as shown in the following table:
Value
Reported state
Description
0
Unknown
Jamming/interference monitor not enabled,
uninitialized or antenna disconnected
1
OK
no interference detected
2
Warning
position OK but interference is visible (above the
thresholds)
3
Critical
no reliable position fix and interference is visible (above
the thresholds); interference is probable reason why
there is no fix
Table 20: Jamming/interference monitor reported states
The monitor is disabled by default. The monitor is enabled by setting the CFG-ITFM-ENABLE
configuration item. In this message it is also possible to specify the thresholds at which broadband
and CW jamming are reported. These thresholds should be interpreted as the dB level above
"normal". It is also possible to specify whether the receiver expects an active or a passive antenna.
The monitoring algorithm relies on comparing the currently measured spectrum with a
reference from when a good fix was obtained. Thus the monitor will only function when the
receiver has had at least one (good) first fix, and will report "Unknown" before this time.
The monitor reports any currently detected interference over all currently configured signal bands.
3.11.3 Consolidated signal security information
The UBX-SEC-SIG
message consolidates all information related to the jamming/interferrence and
spoofing detection functions into a single message. It provides a direct method for monitoring the
current security status to alert a host to potential jamming or spoofing threats. In addition, the UBX-
SEC-SIGLOG message provides a log of past signal security events where an event is triggered by the
detection logic, thus allowing a review of up to 16 past occurances of possible jamming or spoofing
episodes. See the applicable interface description [
3.11.4 GNSS receiver integrity
3.11.4.1 Secure boot
The RCB-F9T boots only with firmware images that are signed by u-blox. This prevents the execution
of non-genuine firmware images run on the receiver.
1
TIM 2.13,TIM2.20 FW onwards
UBX-22004121 - R01
3 Receiver functionality
Page 39 of 64
C1-Public
Early production information
