fishfinder latency & "real time"

[iam2sam]

A friend was telling me of new fishfinder models with "real time" display technology. He claimed that there was on the order of 10 seconds of latency between when a fish swims by and when it appears on the display for older tech fishfinders. I find that very difficult to believe. While I don't doubt that there is some measurable latency, it seems to me the sources are the electronic components themselves (miliseconds at most) and the transmission speed of the detection radiation through water. I'd be amazed if the total delay was more than 1 second, and fairly surpised if it was even near that value. Heck if the delay was 10 seconds, I'd think that the devices would be fundamentally useless to avoid obstacles in the water and running aground. Anyone have a pointer to actual statistics for the latency?

 

[RiverBottomOutdoors]

Sound travels something like 1500 meters per second in water and electricity moves at the speed of light.

 

[nick1169]

I believe what your friend is referring to is how the older fish finder units would scroll from one side to the other of the display with a static image of the sonar. The new units are probably displayed in real time like how the bigger boats sonar for obstacles. This was done on the older units because of cost involved to have a real time sonar display on a compact unit.


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[nick1169]

Here is a video talking about the new realtime units.

https://youtu.be/LKXSUFtRhr8


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[iam2sam]

I believe what your friend is referring to is how the older fish finder units would scroll from one side to the other of the display with a static image of the sonar. The new units are probably displayed in real time like how the bigger boats sonar for obstacles. This was done on the older units because of cost involved to have a real time sonar display on a compact unit.

Thanks! That makes a LOT more sense...