Vexilar FL-22 - Manual (Page 11)

11
Interference Rejection
The purpose of interference rejection is to reduce cross-talk interference from other nearby
depth sounders. This can be very helpful if you have another sounder mounted on your
boat running at the same frequency as your flasher. It is also helpful when other fishermen
are running sounders operating at the same frequency as your flasher nearby.
Cross-talk interference occurs when the signals sent from one depth sounder are received
by another. If the two sounder’s frequencies are the same, each unit is unable to
differentiate between it’s own signals and others. What you see as interference is actually
the reading of the other sounder displayed on your screen. The signals can circle around
the display or remain stable. Beware of the stationary interference signals. They can lead
you to believe the depth is different than it is or that there’s a fish hanging below you
which really isn’t there.
Usually, when you see interference on one sounder, the other sounder will show it too.
Therefore, when you use your Interference Rejection to reduce or eliminate the interference
on your display, the other sounder will see a similar reduction. This means you can use
your Vexilar flasher next to another sounder which does not have the I.R. feature and both
sounders can run more clearly.
If two Vexilar units are operating together, you will get the best results by leaving the IR
control set at one level on one unit, while adjusting out the interference displayed on both
units using the second unit’s IR feature.
Interference occurs when the cone angles of two different sounders
operating at the same frequency intersect. It can also occur if the
sonar signal from one sounder bounces off an underwater object and is
received by another sounder.
To reduce interference from other units, use a narrow beam transducer (see page #42)