"Daniel North" wrote in message
...
Hi guys...

I have/need spares for a B&G Hercules 390 system.

I need to know if possible to interface Dataline/Simrad type speed
and depth transducers into the Hercules computer. Any input? The
post above might be very helpful for speed, what about depth signals??

Is the protocol similar between brands (esp of early 90's vintage)??

For depth sounders it's a lot more complicated. The transducer is a
piezoelectric element, often with a seperate temperature sensor. These are
both analog devices, at least the types I've seen. The electronics in the
display head (or possibly a central processor unit) send a high-power signal
in the high kilohertz range, then listens for the weak echo returned by the
bottom. It is possible to swap out the basic transducer if the frequency it
is designed for matches the old unit, but I don't know what the temperature
measurement interface looks like.

I've seen transducer frequencies of 50KHz and 200KHz, but I don't know what
frequency the B&G units use.