Interference in a fish finder refers to unwanted signals that distort the sonar display. These can appear as random dots, lines, or clutter, making it difficult to distinguish fish or underwater structures. There are two main types of interference: Cross Talk (Sonar Interference in Water) and Electrical Interference (Rigging-Related Noise). By identifying the type of interference and applying the appropriate solution, you can significantly improve sonar clarity and performance. If issues persist, contact the manufacturer for your fish finder for advanced settings adjustments.
Cross Talk (Sonar Interference in Water)
- What it looks like:
- Duplicate sonar returns
- Ghost images
- Unusual clutter or overlapping signals on the screen
- Causes:
- Multiple transducers operating at similar frequencies
- Transducers mounted too close together
- Solutions:
- The Cannon Transducer operates at 120 kHz to reduce cross talk, but physical separation between transducers is still essential. Mount them as far apart as possible.
- The Cannon Transducer does not have adjustable settings, so if cross talk persists, contact your fish finder or chartplotter manufacturer for guidance on adjusting settings such as:
- Frequency
- Sensitivity
- Gain
- Noise rejection
- Ping speed
Electrical Interference (Rigging-Related Noise)
- What it looks like:
- Flickering screen
- Horizontal lines
- Intermittent signal loss, especially when other equipment is running
- Causes:
- Shared power sources between sonar and other electronics (e.g., downriggers)
- Poor grounding or shielding
- Pulse Width Modulation (PWM). The Downrigger Motor's speed is controlled using Pulse Width Modulation.
- Solutions:
- Use separate power sources: Ensure the depth finder is not powered by the same battery as the downriggers.
- Separate wiring: Route downrigger power wires away from the depth finder’s cables to avoid electromagnetic interference.
- Bond grounds properly: Connect the negative terminals of the depth finder and downrigger using a dedicated ground wire. Include the smallest fuse possible in this connection to protect the circuit.
- Check shielding: Make sure the transducer cable’s shielding is intact and properly grounded.
