RE: [PSUBS-MAILIST] retractable buoy

["Jens Laland" <laland@artematrix.org>]

I think that the simplest voice communication system between a sub and its
emergency buoy (providing there is adequate space for a wire drum) would
be a 2-wire field-telephone line running a narrow-band audio frequency
signal (say 300 - 3000 Hz).

A more sophisticated, but still feasible method, (without any need for a
signal conducting cable) is to use the UWT communication directly between
the sub and the buoy also. However, this option would probably need about
20 feet of coax cable from the buoy and down to a stabilized the
transducer.

The emergency buoy will then have to be equipped with its own UWT
tranceiver (transmitter-receiver), plus some extra circuitry to relay the
communication further out onto the regular marine VHF network.

In addition, it would be an extra plus if the buoy also had a local
headset so any person in a small craft nearby also had the possibility to
communicate with the sub (locally from the buoy).

The UWT system would then actually serve:

- any direct communication with the emergency buoy.
- any communication with standby-diver and tender vessel.
- any direct underwater emergency calls for help (providing such a system
is using a standard frequency that your local navy can read/use.

Best regards,
Jens Laland

** Frank,
**
** Coax cable necessary to transmit and receive a radio signal through is
** subject to compression due to depth.  The insulation between the signal
** wire
** and the outer shield is usually a foam, as it collapses signal strength
** will
** fall off.  If shorted, keying the mike on a radio can cause the radio to
** be
** destroyed.  When I was looking at working with the tourist sub SubCat, one
** of the problem areas was a surface float for maintaining VHF
** communications
** with the surface.  It looks like both the hull interface and the antenna
** cable were under constant need of repair.  This sub didn't even dive very
** deep.
**
** R/Jay
**
**
**
** -----Original Message-----
** From: owner-personal_submersibles@psubs.org
** [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Jon Wallace
** Sent: Thursday, October 29, 2009 9:52 AM
** To: personal_submersibles@psubs.org
** Subject: Re: [PSUBS-MAILIST] retractable buoy
**
**
**
**
**
** Frank,
**
**> How big and what type of cable would be required to get a voice out of
**
**> a submarine.
**
** Someone with more electronics experience will hopefully respond, but any
** communication over a wire (voice or data) has distance limits determined
** by
** the type of cable and protocol used.  The issue is reflections within the
** cable over long distances and signal loss.  For example, twisted pair
** network cable has a limit of 100 meters without a switch or router to
** retransmit network packets.  USB cable has a recommended limit of 5 meters
** without a powered hub to retransmit data.  Antenna cable (TV, CB,
**
** Marine) is usually recommended to be as short as feasible.  Get to 50 feet
** or so and in-line amplifiers are going to be required for a better signal.
**
**
**
**





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