TRANSDUCER FREQUENCY QUESTIONS

[gm280]

johnny striper, not that this adds anything to your situation, but just FYI! Both SONAR and RADAR operate in similar fashions. The difference being the speed of energy in the air verses water. And Radar uses Doppler shift to determine distance and speed of the target. I'm certain Sonar does use Doppler shift as well but not in the usual fish locator system purchased for fishing. In each case the same transducer (antenna) is used for both transmitter and receiver. It is like it transmits a ping (frequency) and then turns off and waits for the return signal to be received to determine depth, or in the case of Radar, distances. The real time between the transmission and reception is calculated in depth, or distance in Radar. Inside the head unit in your fish finder, there is a precision clock and a counter counting each clock pulse and that converts to the display readout of depth, fish or any other object the ping bounces off of... If the receiver never receives a return ping in a preset time frame, it turns back on and the entire cycles starts all over once again. And that cycle time is the ping frequency of occurrence (rate). The faster the rate, the shallower the capability. The slower the rate the deeper it can display. But then power of those pings have to be able to reach their target or the return ping will be too weak to be used for calculating anything... So both transmitting power output AND a sensitive receiver are important for good operations and quality object displays. In some incidents, pinging too much power will actually return and bounce off the hull of the boat and bounce off the bottom and back more the once and then the display is over saturated to use any of the info. So you have to turn down the power until only one return is seen. That can happen real easy in shallow water, and that is why it take less power for shallower water results. Hope that isn't too technical...

 

[Texasmark]

johnny striper, not that this adds anything to your situation, but just FYI! Both SONAR and RADAR operate in similar fashions. The difference being the speed of energy in the air verses water. And Radar uses Doppler shift to determine distance and speed of the target. I'm certain Sonar does use Doppler shift as well but not in the usual fish locator system purchased for fishing. In each case the same transducer (antenna) is used for both transmitter and receiver. It is like it transmits a ping (frequency) and then turns off and waits for the return signal to be received to determine depth, or in the case of Radar, distances. The real time between the transmission and reception is calculated in depth, or distance in Radar. Inside the head unit in your fish finder, there is a precision clock and a counter counting each clock pulse and that converts to the display readout of depth, fish or any other object the ping bounces off of... If the receiver never receives a return ping in a preset time frame, it turns back on and the entire cycles starts all over once again. And that cycle time is the ping frequency of occurrence (rate). The faster the rate, the shallower the capability. The slower the rate the deeper it can display. But then power of those pings have to be able to reach their target or the return ping will be too weak to be used for calculating anything... So both transmitting power output AND a sensitive receiver are important for good operations and quality object displays. In some incidents, pinging too much power will actually return and bounce off the hull of the boat and bounce off the bottom and back more the once and then the display is over saturated to use any of the info. So you have to turn down the power until only one return is seen. That can happen real easy in shallow water, and that is why it take less power for shallower water results. Hope that isn't too technical...

Sir I can shoot holes in parts of your reply, but in the sense of getting on with the original problem I will let it be! To Mr. Striper, some of this is fact, some fiction, some misunderstanding, some lack of knowledge. So go out and have fun and possibly some of these responses have been helpful to you.

Mark