When a burst of sound energy comes out of the transducer, it spreads out in a modified cone shape, hence the name cone angle. Electrical measurements based on power determine the cone angle. In general, higher-frequency units have a smaller cone angle than lower- frequency units. Freshwater units often use a cone angle of 20 degrees, so the area covered on the bottom is about one-third of the water depth. As the sensitivity setting is increased, the area of coverage is increased.
Bill Diedrich is a retired Minnetonka math teacher with a love of fishing electronics.
