Fishfinders use sonar to locate objects, preferably fish, underwater. Sonar is an abbreviation for "Sound, Navigation, and Ranging". The sonar consists of four parts: transmitter, transducer, receiver, and display.
Sonar Transducer basically works by sending an electric impulse from a transmitter, converting it into a sound wave by a transducer, and then sending that sound wave into the water. When a wave hits an object, it retransmits the object, which sends the resonance back to the transducer.
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The transducer then converts the echo back into an electrical signal. The receiver amplifies this signal and sends it to the display for the fisherman to see. Now the fisherman knows where to drop a line. How do I choose the appropriate fish finder for my needs? “Two aspects of a fisherman should be kept in mind while shopping.
There are two types of transducers: single frequency and dual-frequency. A single frequency is usually best for lakes and shallow coastal fishing. Dual-frequency transducers are generally better for deep-sea fishing.
Dual-beam and dual-frequency are essentially the same things. Dual-beam transducers limit the size of the beam for high-frequency beams so that for deep waters these depth searches are truly the best.
High-powered fish finders usually cost more so you have to weigh power with a cost. Remember that even in shallow water such as lakes, higher power will still help with better imaging. Most expert fishermen recommend weighting your unit's power rating the most.