Originally Posted by
CatFan
When your unit stops hearing the returns, it may increase the output power to find the bottom. That's why the ticking is more noticable when the display is messed up.
It can lose the signal because of excess signal bouncing off the bottom of the boat and then the bottom again, because of interference from other sonars, or due to transuder or transducer installation problems. The transducer will always make the sound when in operation, but it is more noticable in situations that cause the unit to increase power.