Can we make a fish finder at diy-level ?

Papabravo

Joined Feb 24, 2006
16,502
You can certainly make it. What we don't know is if it will be successful in finding fish.
Personally, I have my doubts about the efficacy of such a device.
 

Thread Starter

Motanache

Joined Mar 2, 2015
540
The ultrasonic transducer will be over the water or closed in something hermetically.
We chose this ultrasonic transducer for Arduino beyond there is a lot of documentation about it.
HC=SR04 is the name of the ultrasonic transducer
 

spinnaker

Joined Oct 29, 2009
7,835
The ultrasonic transducer will be over the water or closed in something hermetically.
We chose this ultrasonic transducer for Arduino beyond there is a lot of documentation about it.
HC=SR04 is the name of the ultrasonic transducer
Exactly how much sonic power do you think that tiny transducer is going to transmit???? You will be lucky to penetrate more than a few inches. Not to mention the water will diffuse the sound and won't be returned back to the microphone. It is designed for air not water.

Real fish finder transducers are placed in the water not over the water.
 
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GopherT

Joined Nov 23, 2012
8,012
The ultrasonic transducer will be over the water or closed in something hermetically.
We chose this ultrasonic transducer for Arduino beyond there is a lot of documentation about it.
HC=SR04 is the name of the ultrasonic transducer
Yes, but it is set up for monitoring an area about 3 meters and speed of sound of 340 m/sec. 1498 meters per second in water. The sensor is fast enough, but this difference in wave propagation speed will result in reflections of the sound rather than penetration of the energy into the water

The reflection will cause a huge attenuation and will make it difficult to sense the reflection that comes out of the water vs reflects.

Finally, how do you plan to differentiate the sound from a fish vs bulk water. From above, fish are very stealth (via angular reflection).

Lots of issues with this setup.
 

spinnaker

Joined Oct 29, 2009
7,835
Yes, but it is set up for monitoring an area about 3 meters and speed of sound of 340 m/sec. 1498 meters per second in water. The sensor is fast enough, but this difference in wave propagation speed will result in reflections of the sound rather than penetration of the energy into the water

The reflection will cause a huge attenuation and will make it difficult to sense the reflection that comes out of the water vs reflects.

Finally, how do you plan to differentiate the sound from a fish vs bulk water. From above, fish are very stealth (via angular reflection).

Lots of issues with this setup.
TS won't need to worry about differentiating the sound from a fish vs bulk water. It will be all water. Problem solved. ;)

Actually if TS got a return at all I would be surprised. The water is going to absorb the ultrasound and not reflect it,..
 

Thread Starter

Motanache

Joined Mar 2, 2015
540
If I could find a bluetooth or WiFi fish finder, it would probably be cheaper.

Staying on the shore of the lake is an incredible relaxation.
 

spinnaker

Joined Oct 29, 2009
7,835
If I could find a bluetooth or WiFi fish finder, it would probably be cheaper.

Staying on the shore of the lake is an incredible relaxation.

You do know bluetooth has a max distance of 32 feet?

Why on earth would you want your fish finder out on the water when you are on shore? How are you going to get it out on the water? Are you going to build a robot boat from your left over Aduino??
 

philba

Joined Aug 17, 2017
960
You probably can make one but you will need to start with a transducer intended for use under water. Unfortunately the only ones I could find come with a fish finder attached! I bet you couldn't build one cheaper than this: http://www.ebay.co.uk/itm/Outlife-0...374145?hash=item41cd306141:g:UWEAAOSwCdJZloyX
I had an underwater ultrasound project I wanted to do about 15 years ago but gave up when I couldn't find a source for the transducer. I thought maybe automotive US sensors would be available (though perhaps not quite water proof) but even those weren't on the open market - couldn't even find a datasheet. I could find pictures of them but nothing more. The car companies have all gone to RF or video based sensors so even that's not an option any more. I looked briefly at waterproofing existing sensors but concluded that the emitter needed to be mechanically coupled to the external surface of the sensor to work.

Here's a link to an eevblog discussion on hacking fish finders. Pretty interesting. Kind of makes we want to revive my old project plans.
 

spinnaker

Joined Oct 29, 2009
7,835
Spooky synchronicity. Just got back from kayaking. While I was paddling along the shore, someone on shore, cast his line into the water. On the end of the line, a plastic ball the size of a tennis ball. The largest bobber I have ever seen. I asked the man what it was. Turns out it was a Bluetooth fish finder! :eek:
 
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