[PSUBS-MAILIST] 3D dive recording, kickstarter

Mon Jan 20 02:03:24 EST 2020

Thanks James,
if you have telemetry via data modems you could transmit depth from
the submersible to the base station & then ascertain distance from the signal 
time. This would leave the sub positioned somewhere on the edge of a circular 
plane. You would only need direction. Perhaps a sonar at the base station that was mounted on a 3 axis gimbal and was then angled toward the perimeter of the circle
& rotated till it picked up the direction. Depth, distance, direction!
Then the GPS signal picked up by the base station could be transmitted to
the submersible with adjustments based on its location in relation to the base
station. This would also give the position of the base station to the submersible.
Of course a support boat could always follow the submersible to gain greater 
accuracy.
Part 2... Have a boat depth sounder / chart plotter on the submersible & hack it
so that you could send the adjusted GPS signal from the base station in to the
chart plotter. That way you could monitor your path on screen, put in way points,
do grid searches etc. A bigger problem would be recording your depth on that
chart. Although depth and location could be recorded separately.
Further thoughts are to add accelerometer, gyro & magnetometer to the base
station to adjust for wave motion. And maybe mount the submersibles transducer 
on a 3 axis gimbal so that a narrower transmission beam could be used.
I had also thought of a small surface float with 4 thrusters on it as the base station.
Have been building a hex copter & am getting ideas from it.
You could send data from the submersibles motor control stick giving the direction
& speed of the submersible so that the float could anticipate the submersibles 
movements & move accordingly.
Any thoughts on this?
Cheers Alan

> On 20/01/2020, at 8:57 AM, J. Foulkes via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
> 
> Yes, I deal with geolocation and tracking problems for work.  Mostly this is on the land or in the air, but my personal interests carry into the water.  
> 
> The problem that you face is how to provide multiple reference paths to the GPS receiver.  DSP-Comm simplifies the problem by only transmitting the range to the base station (deck unit).  If you want a better solution you would implement something similar to a LORAN-C network.  More simply you could have a modem on your deck that receives in two different frequency bands so you can perform attenuation ranging on different frequencies for improved accuracy and then triangulate the location of you underwater asset (the longer the baseline the better - a hydrophone off the bow and stern).  If you want you could still have a transmit hydrophone like DSP-Comm supplies for full duplex communications that also transmits current location to the sub.
> 
> Regards,
> James
> 
> 
>> On Thu, Jan 16, 2020 at 6:25 PM Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Thanks for the insight into their product James.
>> One of the problems is getting the GPS signal down to the sub, &
>> I have been looking at this company .....
>> https://dspcommgen2.com/aquatrans-underwater-acoustic-dunking-hydrophone-transducer/
>> for data transfer transducers & modems. 
>> They are reasonably inexpensive & are based in Bangkok.
>> BTW you seem to know your stuff, are you involved professionally in that area
>> or is it just an interest? 
>> Regards Alan 
>> 
>> 
>> 
>>> On 16/01/2020, at 8:54 PM, J. Foulkes via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>>   Hello everyone,
>>> 
>>> OEngineering was at CES this year with this product and I had several lengthy discussions with them about their system.  So, first I would like to point out that the real focus of this system is for citizen science applications (inexpensive) not for extended dive precision mapping.  If this is your application, you would be much better served using a control laptop with external IMU and GNSS devices as the IMU on this product doesn't have the best freerunning accuracy.  Secondly, it seemed that what they were really pushing as the technology you are paying for is the app interface.  It was unclear from talking with them what interface would be available (API) for downloading raw data on points of interest  and continuous tracking outside of this interface.  Also, one thing to note is that if you were using this in your sub for datalogging (it requires manual button pressing for POI logging) you would need a GNSS repeater with a bulkhead pass through.
>>> 
>>> Regards,
>>> James Foulkes
>>> 
>>>> On Wed, Jan 15, 2020 at 11:22 PM T Novak via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>> This does look interesting, Brian.
>>>> 
>>>> Worth thinking about.
>>>> 
>>>> Tim
>>>> 
>>>>  
>>>> 
>>>> From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Alan via Personal_Submersibles
>>>> Sent: Wednesday, January 15, 2020 4:38 PM
>>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>>> Subject: Re: [PSUBS-MAILIST] 3D dive recording, kickstarter
>>>> 
>>>>  
>>>> 
>>>> Looks useful Brian.
>>>> 
>>>> Some sort of mapping is definitely useful.
>>>> 
>>>> I have just been looking at GPS receivers to see how they can be water / pressure
>>>> 
>>>> proofed. I think a GPS system would be the bare minimum. 
>>>> 
>>>> If you found a treasure chest you could at least head straight to the surface
>>>> 
>>>> & get a GPS coordinate.
>>>> 
>>>> Alan
>>>> 
>>>> 
>>>> On 16/01/2020, at 11:26 AM, Brian Hughes via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>> 
>>>> OK,
>>>> 
>>>>  
>>>> 
>>>> This looks interesting:
>>>> 
>>>>  
>>>> 
>>>> https://newatlas.com/outdoors/brizo-3d-scuba-dive-maps/?fbclid=IwAR0bwSGSy8zlABzonbS9PO4M-hyca94ADtn57E7YlccucUaqQGz3WNFqYBQ
>>>> 
>>>>  
>>>> 
>>>> Brian
>>>> 
>>>>  
>>>> 
>>>> Get Outlook for Android
>>>> 
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>>>> 
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