Stowe Depth NavSounder - repeater output format?

pagoda

pagoda

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This is one for the serious tinkerers.
Has anybody got any ideas about the data format used between Stowe Navsounder and the Repeater instrument for same. It involves just 2 wires, so my current suspicion is a simple serial format, maybe an early form of NMEA?
I could spend a couple of days with an oscilliscope, but should anybody else have cracked the format that would take some of the pain out. I was thinking of actively logging depth along with GPS data, using some spare instruments I have, and Arduino to process the numbers. Mixture of antique & modern YAPP :p
I know you can buy transducers which spit out DBT words ,but I don't want to spend that kind of money :D ..effort maybe , wads of cash.. no!

thanks in advance,

Graeme
 
NavSounders with serial number 4000 onwards take a repeater wired to all the terminals as shown n the manual - not just two wires.

PM me if you need the manual.

Sorry if that didn't answer your question.
 
MoodySabre said:
NavSounders with serial number 4000 onwards take a repeater wired to all the terminals as shown n the manual - not just two wires.

PM me if you need the manual.

Sorry if that didn't answer your question.
Click to expand...

Thanks,

I can't recall what the serial no is, but the "repeater" terminals on the back are marked "blue & white" - the other common connections are just power & lighting. So only 2 wires are involved in transmitting the depth value to the other display. That's the format I want to "crack". I'll maybe just pull the case off and find what chip is connected to those 2 wires. And use the scope.
It's got to be simple, even if it's 100 pulses =10.0m or something like that?
I quite like the idea of collecting bottom information of specific anchorages I use and building a library of more detailed bathymmetry over time? Boat position is not too difficult -I can log NMEA GPS data. I have a realtime clock module - so I can back out tidal differences form readings. I just want to decode the repeater output to acquire the depth values and insert them into the position stream, or in parallel at least.
I have a spare instrument and transducer, so if I can get this working -I can use it on the dinghy to grid out interesting but poorly documented approaches or anchoring spots, then generate a simple small area chart..
More systematic than doing sketches, and marking down ugly looking patches of weed/rock and scary moments of minimal clearance with a keel. I'd sketch things anyway.
I really didn't expect anybody to have tried this, but you never know!

Graeme
 
MoodySabre said:
On the East coast a lot of work is done by Tillergirl. Look at the downloads on his website Crossing the Thames Estuary.
Click to expand...

I've just had a look at that East Coast Sailing info. Very nicely presented. That's the sort of thing I fancy doing, but for various places on the Scottish West coast. I see a steep learning curve getting up to that standard :)

Graeme
 
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