depth sensor

[gumma]

HAHAHAHAH! Thans a lot mate, she is hooked now!

[Atle.norway]

Fishfinder i probably the cheapest and less complicated way.
,but do you know how many strands of wire is inside the wire itself.nice to know if im gonna buy one and cut the wire to splice on a much longer one

[njs552]

This is also another option: http://www.ebay.com/itm/261065676140

From my calculations it could go to ~303ft, and with an Arduino you could have a accuracy of up to ±6 inches.
All it would need is a analog Arduino pin. Calibration may not be easy, but the values are linear so it shouldn't be much of a problem.

Thanks,
njs552

[Atle.norway]

Checkout dive store online.search for manometer.its an analog gauge.divers use to read depth.its accurate and reliable,but,you have to keep it in reach of the camera to read it

[bigbadbob]

One idea i'm playing with is to use a car oil pressure sensor and feed it's output to a "RCD 3060 OS Mini OSD FPV" osd board,
this will work down to 100m and display your depth on screen as a voltage.
0-12v = 0-105m so you'd need to scale the voltage to read somthing sensible on the screen but it's simple and cheap.

caveat-
I havn't tried this yet so don't blame me

[janwar2009]

Hi i'm a newbie here, is this sensor sensitive enough for detecting a 6ft depth?

[Zaibach]

I already have a pressure sensor to detect depth but was wondering if anyone has any advice on a cheap (sub $100 preferably sub $30) sonar transceiver so I can check how far it is from the ROV to the bottom? I would love to be able to do some primitive imaging but that is well outside my depth of experience.

I've sorta been looking at trying to scavenge one off a cheap fish finder but I have no idea if they would survive any significant depth or what communication protocols they use. Tho the second part stymies me more than the first.

I would think some simple sonar depth sensors might well just return a voltage but something more complex would return data that would need to be parsed and I haven't been able to find any info about what standards they use or how to begin going about that. So any advice on where to find info about the commutations protocol or sensor suggestions would be greatly appreciated.

[rossrov]

Been checking out fish-finders to see how a cheap one may be "hacked into", with the view to doing USBL navigation and very simple imaging. Hummingbird (?) fish-finder around $100 which I believe is still being sold after a few years of production. In this model, I do not think there is any fancy digital signal processing (DSP), so you can tap into the analog signal where it goes into the FF microcontroller. Stick this signal into the A to D input of your own micro, and do some simple timing and level measurements on the received echoes and send whatever data you need from that to the surface. All the hard work is done in the FF analog circuitry. You could expect reflections from the water surface above, which may help or hinder.

Tried to find out how well potted or if any air was in the transducer (depth pressure issues) and could not, short of buying a transducer of the same type and cutting it open, which I did not! Would guess potted well enough with no air and just take a gamble. Alternatively, the transducer can be kept at atmospheric pressure in an oil-filled housing. This is commonly done with "shoot-thru" transducers on boats to avoid hull penetrations and things sticking out the bottom.

Sounds like what you want but usually costs more , but standard depth sounders exist which give readings in NMEA0183 serial data, basically mimicking what is on their own display. This would be the easiest. Google or whatever "NMEA0183 depth sentence"

Then there are the wireless fishing-float transducers. If I understand how these work correctly, you could get serial data from what is being sent to the transmitter inside the float, and not have to do A to D as with the Hummingbird type mentioned in the first paragraph

[rossrov]

Here's the one I recall seeing. Good article for those wanting to learn more. For depth only, maybe just a comparator on the RSSI output would work without the need for an A to D http://www.eetimes.com/document.asp?doc_id=1281283 There's also cheap handheld finders (sub $60) on ebay or the the Chinese importers like this mob http://dx.com/p/ff108-2-4-lcd-sonar-fis ... pQodLh4Akw

[Zaibach]

Awesome thank you for the link to the article
Going to be more complicated than I had anticipated but it gives me hope