Transducers...

[Jan]

Hi,


If fishfinder transducers are used for a sidescan it will be usefull to find a way to make their beam as narrow as possible.


Perhaps the next idea might work.


The other day I was driving at night and notice that where the light beams overlapped eachother there was, obviously, a stripe of light twice as bright as the individual beams.


This stripe of light was much narrower that the individual beams (Not a big supprise...)


It made me wonder if this could be used for the transducer.


Let 2 fishfinder transducers emit their baloon shaped soundcone overlapping eachother a bit.


Would the sound reflected from the 'double lit' part of the beam be louder then the sound reflected from the 'single lit' part ?


If so, we could filter the 'double lit' echo's and have practicaly a much narrower beam then we started off with.


Also the sound returned would be stronger.


Do you think this will work ?


Regards,


Jan

[Duke]

Re: Transducers...

Jan,


Unfortunatley, if I remember my physics right, this will only work when the two reflected sound waves are perfectly in phase. This would only happen when the target is the exact same distance from each transducer. If my figures are right (and they probably arent!) :


Approx speed sound in water = 1.5 kM/sec


assuming 200 kHz signal wavelegnth = 1500/200000


.0075 meters or 7.5 mm.


This means when the difference between the distances is a mere 3.25 mm (or a multiple of it) the waves will be 180 degrees out of phase and cancel eachother.


I hope to contribute some positive info in the future.


good luck


Duke


>Hi,


>If fishfinder transducers are used for a sidescan it will be usefull to find a way to make their beam as narrow as possible.


>Perhaps the next idea might work.


>The other day I was driving at night and notice that where the light beams overlapped eachother there was, obviously, a stripe of light twice as bright as the individual beams.


>This stripe of light was much narrower that the individual beams (Not a big supprise...)


>It made me wonder if this could be used for the transducer.


>Let 2 fishfinder transducers emit their baloon shaped soundcone overlapping eachother a bit.


>Would the sound reflected from the 'double lit' part of the beam be louder then the sound reflected from the 'single lit' part ?


>If so, we could filter the 'double lit' echo's and have practicaly a much narrower beam then we started off with.


>Also the sound returned would be stronger.


>


>Do you think this will work ?


>Regards,


> Jan


>


>

[Duke]

Re: Transducers...

Hello,


It is a good thought, but if I remember my physics class right, it wont work.


The phases of the returning signals would be different unless the transducers were exactally the same distance from the target. This would cause very unpredictable results.


How about oscillator/amplifier/receiver package in fish to maximize power with a digital link to topside electronics?


Later


Duke


>Hi,


>If fishfinder transducers are used for a sidescan it will be usefull to find a way to make their beam as narrow as possible.


>Perhaps the next idea might work.


>The other day I was driving at night and notice that where the light beams overlapped eachother there was, obviously, a stripe of light twice as bright as the individual beams.


>This stripe of light was much narrower that the individual beams (Not a big supprise...)


>It made me wonder if this could be used for the transducer.


>Let 2 fishfinder transducers emit their baloon shaped soundcone overlapping eachother a bit.


>Would the sound reflected from the 'double lit' part of the beam be louder then the sound reflected from the 'single lit' part ?


>If so, we could filter the 'double lit' echo's and have practicaly a much narrower beam then we started off with.


>Also the sound returned would be stronger.


>


>Do you think this will work ?


>Regards,


> Jan


>


>