Hi Y'all,
I just got a new boat and have been having issues with the fishfinder. It's a hummingbird Helix 9 SI GPS(Gen 1) and I have a Riptide Terrova.
The Helix's down imaging looks like picture below whenever my trolling motor runs. When not using the trolling motor, the down imaging is actually readable but there's still some(but much less) random dots on the screen.
Are these dot just interference? Are there anything else that could interfere with the fishfinger apart from the trolling motor, maybe the outboard or livewell pump? Do I need to wrap my fishfinder's cables in some anti-interference wrap or something? Or maybe I should just adjust my fishfinder's sensitivity?
I appreciate all information, thanks!

Do you have a picture of what your DI looks like with the trolling motor off? Do you use a multi bank battery charger? I was getting interference on my Garmin Echomap UHD 94SV while my Terrova was running. My interference was causing fine vertical lines shading the entire screen. I have a Minn Kota Digital 3 bank charger. I put switches on the positive and negative that charge the cranking battery. When I unplug the charger, I turn the switches off. This corrected my interference.

Where is your transducer for the DI unit? If its mounted on the TM foot it will be very difficult to eliminate interference from your TM. I tried a lot of things and finally concluded that it was just best to put the ducer on the transom, especially since I use the TM GPS lock function that makes the TM run almost all the time. The problem is that modern trolling motors use pulse width modulation to control the speed and save the battery. The frequencies of the PWM may well overlap with the frequencies of interest in your sonar.

First check to see if they put a Ferrite Ring on the transducer cable. You'll probably have to do some searching to find it. If you can't find one call Humminbird customer service and they'll send you one free of charge. If that doesn't fix it, run a dedicated power and negative wire from your cranking battery to the unit. If they wired directly to the bow panel that may be causing interference also... Dan

My transducer is at the transom and the graph is at the console. I think I'll try disconnecting multi bank charger first. Will try tomorrow.

I second the suggestion on adding a ferret core. It solved my problem easily.