Sensor placement

[Craig Passeno]

I was wondering if I have one sensor out on the bow of my boat and the other being towed out on a line, do they have to be equally spaced from the boat? My line of thinking is that the one on the bow will probably be closer so it might act as if it has found something. so...must they both be, say, 20feet from the boat? or doesnt it matter?
thankyou,
Craig

[C.Pruysers]

Re: Sensor placement

Ceaig . You have to look at it this way : If you put the two sensors in a homogenous field spaced a certain way from eachother , both would read the same . The signals would cancel eachother and you would read Zero . If you hit something changing the reading in one of the sensors you would get the ,,difference between the sensors as a ,, reading ,, . When you place one sensor behind the boat and the other on the boat ( in a place with the least interference ) you shall have two readings . When the signals are sent through a differential amplifier , you can have the output of the amplifier adjusted so your reading would be Zero again . Any change in the heading of your boat in the earth-field will change both sensors the same way so the reading will stay zero . Only when the towed sensor has a hit ( or the sensor on board is changed , which is in most cases unlikely ) you will get a reading . So NO you do not have to space the two sensors equally . You may tow one and have the other on board ( not close to an engine please ) and still get the proper results when you have a hit . You only measure the difference and not the reading on each individual sensor . Regards Cornelius