[PSUBS-MAILIST] OTS

Sun Oct 25 00:56:42 EDT 2020

Sean, thanks that is what I was thinking as im sitting here playing with a
piece of the coax. In the mounting of the transducer and the retention
ring, am using a silicone fill around the lower portion of the retention
bracket to hold it in place so that its not connected rigid  to the hull.
As the diver unit transducer is a bit smaller diameter than the transducer
on the topside unit. I am thinking a sheild around the transducer maybe
made of acrylic to protect against impact to the transducer. It would sit
away from the transducer.  Do you have any concerns about this with it
ability to receive signal?
David

On Sat, Oct 24, 2020, 9:37 PM Sean T. Stevenson via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> David, with coax, it's better if you loosen and pull the shield braid back
> over the jacket all around on both sides, then cut the core wires a bit
> shorter. Solder the cores together and insulate, then pull the braid back
> into position with full 360° coverage, and twist it into the braid from the
> other side - cutting the cores shorter should have given you a bit of
> overlap to work with. Solder the braid all around and then heat shrink the
> works.
>
> Sean
> -------- Original Message --------
> On Oct. 24, 2020, 22:09, David Colombo via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Rick, I am cutting the ots comms wire as well to shorten its lenght for
> the yellow sub, and to get it thru the blue globe fittings. Attached are
> photos of the shield which is a braided multi strand wire and the interior
> wire which is also multi strand.  I am assuming that when i rejoin the two
> pieces there might be a small gap in which the sheilded braid may not
> completely cover the inner core.  Its kinda like a chinese finger braid
> that tightens when pulled on the ends. Does anyone have any concerns about
> the surrounding sheild braid not completely covering the inner core?
> Since the cable is 50ft long, I have lots of lenght to play with.
> David
>
>
> On Sat, Oct 24, 2020, 5:51 PM Rick Patton via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Yeah I have the surface head set system so should be fine. I had to cut
>> the wire though to pass it threw the hull penitraitor so I hope it will be
>> easy to re connect and not have any shielding leaks from any other stuff
>> running.
>>
>> On Sat, Oct 24, 2020 at 10:54 AM Sean T. Stevenson via
>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>> I think the boom mics on the surface headsets are pretty forgiving. The
>>> issue with the diver mics is that they are of a noise canceling design. In
>>> an effort to filter out regulator hiss and bubble noise, there are
>>> diaphragms on both sides of the mic, and the transmitted signal is actually
>>> the differential between the two, which is best when the mic is right in
>>> front of the diver's mouth. A lot of divers find this position a bit
>>> invasive and incorrectly push it away further into the mask cavity, so then
>>> the mic is exposed to similar signals on both sides and becomes less
>>> intelligible.
>>>
>>> Not an issue for the surface hand mics or headsets.
>>>
>>> Good idea with the transducer mounting. High and omnidirectional is
>>> ideal, so you avoid the shadowing. Actually, this is one area where OTS has
>>> a deficiency in comparison to one of its competitors, at least with the
>>> diver units. The SSB-2010 needs to be mounted on a waist belt, or on a tank
>>> cam band, and there's really no practical mounting position for that unit
>>> that leaves the transducer in an optimal position. Even the low powered
>>> Buddy Phone units that they sell for recreational divers are mounted on the
>>> side of the head, and exhibit shadowing in the cross body direction. In
>>> contrast, Divelink makes their diver worn units with transducers that sit
>>> on top of the head, attached to the upper strap of the face mask. I'm still
>>> inclined to buy OTS though. On a sub of course, you can mount your
>>> transducer anywhere you like.
>>>
>>> Sean
>>>
>>>
>>> -------- Original Message --------
>>> On Oct. 24, 2020, 14:33, Rick Patton via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>
>>> Thanks Guys
>>>
>>> In my case, the surface boat will not have the need to be underweight, I
>>> will descend from the surface boat and it will just stay put except for
>>> moving with the current. I won't have the thermoclines here in Hawaii that
>>> most of you have but there are some of course. I will be using a headset
>>> with boom mike so it will be almost touching my lips and I mounted the
>>> transducer on the top of my hatch to minimize any ghosting on my end. I
>>> agree Jon that it would be nice to have a topic on that. I would like to
>>> put a face with all the guys here so where and when will be the next
>>> convention? Oh yeah, the bloody coronavirus.Just got my trailer done enough
>>> to get it weighed and a VIN number assigned to it so am stoked!
>>> Rick
>>>
>>> On Sat, Oct 24, 2020 at 9:26 AM Jon Wallace via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>> My recollection from Lake Tahoe was that comms were good when surface
>>>> boat was somewhere in the vicinity OVER the submarine.  We didn't have to
>>>> be directly overhead, just not too far away.  When David piloted R-300 he
>>>> ended up a good 600-800 feet away from us laterally when comms became
>>>> difficult.  Water column varied 60-100 feet (I think) in that area.  Comms
>>>> ended when our propeller cut the transducer cable (whoops), ALWAYS pull up
>>>> the transducer when surface boat is underway, even at slow speeds.  I'm
>>>> just going to throw out a rule of thumb that has no emperical data to back
>>>> it up, keep within the same distance laterally as the submarine is in
>>>> depth.  If the sub is 100 feet deep, stay within a 100 foot radius of it.
>>>> If it's at 1000 feet depth, stay within 1000 foot radius of it.  I think
>>>> you could actually probably get away with a radius 4x depth and be ok, but
>>>> keeping it 1-to-1 isn't a bad plan.
>>>>
>>>> Sean is correct that water conditions matter as well as fresh vs salt.
>>>> Even so, we should spend some time at our next "meet" to do some comm
>>>> testing and publish the results on the web site just so we have some
>>>> reference.
>>>>
>>>> Notwithstanding the timber sound aesthetics Sean mentioned, comm
>>>> quality between surface and R-300 was loud and clear when within the
>>>> parameters I mentioned above.  Cliff and David may have their own
>>>> perceptions since they both manned the comms at some point during that
>>>> weekend.
>>>>
>>>> Jon
>>>>
>>>>
>>>>
>>>> On Saturday, October 24, 2020, 03:01:32 PM EDT, Sean T. Stevenson via
>>>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>
>>>>
>>>> Rick, ultrasound behaves quite a bit different than does radio as far
>>>> as the attenuation relationship to distance. Things like shadowing, (where
>>>> a diver's body / equipment or the hull or superstructure of your sub gets
>>>> in between the direct line of sight between transducers) will have a much
>>>> more profound affect on transmission effectiveness than distance alone.
>>>> Similarly, thermoclines and haloclines can act as "surfaces" that refract
>>>> or reflect the ultrasonic transmission, so it is important for the surface
>>>> crew to lower their transducer into the same operating layer as the diver /
>>>> sub. As a diver, I always report the presence and depth of any thermocline
>>>> encountered on descent to the surface support for this reason. Also, the
>>>> surface transducer needs to be suspended in the water column and not
>>>> bottomed or lost in surface sea clutter, and the transducer needs to be
>>>> weighted and boat speed limited so that it doesn't trail behind at an angle
>>>> which is ineffective for transmission.
>>>>
>>>> The rating in the published specifications for the OTS SSB-2010 (a 5
>>>> Watt unit) is greater than 1000 meters in a calm sea, and ~200 meters in
>>>> sea state 6 (Beaufort), but I presume that these are ideal scenarios
>>>> whereby the surface and dived transducers are suspended at the same depth,
>>>> in the same (vertical) orientation, with clear line of sight and no
>>>> interfering reflections, and also with no squelch applied. Real-world
>>>> conditions are obviously somewhat different, and the environment can
>>>> actually be somewhat noisy at typical channel frequencies, requiring the
>>>> application of some squelch and the consequent loss of range.
>>>>
>>>> Rated frequency response is ~300 Hz to ~3000 Hz, which covers most of
>>>> the vocal range, but will not reproduce true timbre of voice. It is fine
>>>> for intelligible speech, but not for e.g. music.
>>>>
>>>> I have used this unit as a diver only, so my impression may be also due
>>>> to the influence of the earphone / microphone assembly in my mask. Choice
>>>> of mask makes a difference (shape and size of gas cavity), as does
>>>> proximity to the mic. You need to be almost kissing those OTS diver mics to
>>>> get decent sound. That said, my experience with the SSB-2010 was decent,
>>>> but that was in the context of a dive team separated by a few meters at
>>>> most, and at relatively shallow depths (limited distance from surface unit)
>>>> where helium based breathing gas was not required.
>>>>
>>>> I can't speak to long range effectiveness, other than at Flathead last
>>>> year I was surface support for Cliff in the R-300. He was using a SSB-2010,
>>>> but the surface unit we had was something different - one of the surface
>>>> specific boxes, and I don't recall the model (Cliff?). There were times at
>>>> which we lost him and had to reposition the boat to reacquire him, and
>>>> others where we could hear him but he couldn't hear us, but I can't speak
>>>> to the exact ranges, depths or boat speeds that caused those issues. It was
>>>> never such a sustained loss of comms that the dive had to be called. Likely
>>>> the result of relative orientation or depth, or shadowing of the
>>>> transducers.
>>>>
>>>> Sean
>>>>
>>>>
>>>>
>>>> -------- Original Message --------
>>>> On Oct. 24, 2020, 12:10, Rick Patton via Personal_Submersibles <
>>>> personal_submersibles at psubs.org> wrote:
>>>>
>>>>
>>>> wanted to hear from those who have and have used the OTS comms system.
>>>> I was wondering how you liked the system and what your max clear
>>>> audible range was.
>>>> Thanks
>>>> Rick
>>>>
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