# Sonar interference



## Derek (Jul 11, 2011)

So yesterday I figured out the problem with my rear sonar. It would usually pick up the bottom on the graph but the depth number would never read correctly. Yesterday I determined that my front sonar and rear sonar are interfering with each other. The front one does not seem to have any negative effects, but the rear goes haywire when the front is turned on. Rear sonar works fine without front turned on/in the water.

Front sonar: Humminbird 200DX, puck transducer mounted to trolling motor
Rear sonar: Lowrance X96, rear transducer mounted to transom

Is there anyway to fix this interference? If its not easy/simple Ill just deal with it for now.


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## krawler (Jul 12, 2011)

on the lowrance unit, go into the settings and turn the noise filter on or up.


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## Derek (Jul 12, 2011)

thanks
I will have to check it out next time on the water


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## shawnfish (Jul 15, 2011)

they should both have a filter, make sure the power cables for each are as far apart as possible from each other and any other wiring on your boat and away from your motor. also im pretty sure they both use different khz on their tranducers, and that may be a problem but not quite sure, somebody else might be able to verify that if its true.


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## Derek (Jul 15, 2011)

I tried turning up the noise filter yesterday. I turned it all the way up on the Lowrance and it did not make a difference. The Humminbird doesnt seem to be effected, so I didnt look for a filter on it. The problem only occurs when the front is turned on and in the water.


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## FuzzyGrub (Jul 18, 2011)

Do you get it in shallow 6' of water or less? or in deeper water where the depth is closer to the length of the boat or deeper? the latter is sonar interferance, and you could get a little more depth by angling the transom transducer so it shoots at a slight angle backward, and set the trolling motor one to shoot slightly forward. 

If the the former, then it could be electrical interferance. Try some chokes on the Lowrance power cable, isolating on seperate battery, etc.

PS: If you get noise with the trolling motor out of the water, that is a clear sign it is picking up electrical noise, either in power cord or transducer cable.


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## linehand (Jul 21, 2011)

Are both transducers mounted on the transom? If so mount the front one on the front trolling motor. I have both on the transom and have to turn off the rear finder when using the front. Especially in deeper water.


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## Derek (Jul 21, 2011)

front is on the trolling motor.
I have not been able to pick up any chokes. I will try to this weekend


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