How to Resolve Sonar Crosstalk On June 17, 2013

Why does my screen show vertical lines on it when I turn on my other sonar unit or when someone is fishing near my boat?  
When two sonar units are sending sound at the same frequency you can get crosstalk. Each transducer is sending (pinging) and receiving sound. Sometimes one sonar unit will display the other sonar units pings sonar and you will see vertical lines. Since the cone shape of the sound from a transducer gets larger as it goes deeper you get more overlap of cones in deep water. In shallow water you get less or no crosstalk. 
The arrows are pointing to the vertical lines. The sensitivity is set high to demonstrate the cross talk.

Sometimes you get crosstalk and sometimes the screen is clear even though the depth has not changed. The reason is the transducers each send sound at different times. On a Lowrance you can change the ping speed in the sonar menu. Sometimes this helps but the easy way is to turn off one unit. On a Lowrance you can select Stop Chart on the LCX/LMS/HDS units which will eliminate the crosstalk. Stopping the chart stops the transducer from pinging.

On the HDS units you can connect them with an Ethernet cable and see the same transducer readings on both displays with no crosstalk. For example; you can use the transom transducer looking for fish and switch to the trolling motor transducer when you start fishing. Your partner can see a clear screen on the console while you watch the screen on the bow. The bad news is when you see a fish and park the boat on the fish he knows what you doing since he sees the fish on the console screen!

Another choice on the HDS models is you can select 83 kHz for one unit and 200 kHz for the other and eliminate the crosstalk since the difference in frequency is enough to eliminate cross talk. This is a splitscreen of 200 on the left and 83 on the right from the same transducer showing no crosstalk.  





by Bruce Samson under lowrance lowrance sonar

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