Q-Flex Satellite Modem Installation and Operating Handbook
7-14
7.6 LinkGuard™ Interference Detection and Carrier Relocation
LinkGuard™
is a Paradise patented technology for detecting in-band interference
underneath satellite carriers while remaining on traffic. A visual indication of any
unwanted interference is provided through a signal-under-carrier spectrum web graph
showing the wanted carrier along with any unwanted interference. The graph includes a
‘persistence’ mode to show even intermittent interference.
In addition,
LinkGuard™
now supports the ability to optionally automatically relocate a
carrier to a new user-selected frequency when significant levels of interference are
experienced. The user can set an interference threshold and an associated time period.
When interference is experienced above the threshold for the defined time period then
the carrier frequency will be changed at both ends of the link using Paradise’s
Reversionary Control feature (which allows the distant modem’s configuration to be
changed automatically).
Figure 7-9
shows a 32APSK carrier (in blue) initially with no interference (shown in red)
and then with interference caused by another modulated carrier. Note that the
interference is sufficient to reduce the Es/No of the carrier by around 4dB but is not
obvious by looking only at the received carrier spectrum. The modem I/Q constellation
graph is also shown.
Figure 7-9 Example LinkGuard™ Web Screenshots without/with Interference