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Jay, This is a very good point! I think of a large amount of background noise in the case of a broadband system would be like trying talk ten rows back in a crouded stadium during a football game...It can be done, but it would not be easy at all! I am aware that much better systems do exist that filter out most outside "extras" by using a very small bandwidth thru electronics majic. These systems I'm sure are awesome and have incredible range. I am trying to help include those (such as myself) that will delve into mainly shallower water (less than 200'), and are working on a budget that won't budge. As I stated earlier, my goal is a modest one...To clearly and reliably talk sub to sub while both are submerged at 150' and both 150' apart...farther would be icing on the cake. I think this system will work very well as both the transmit electronics and listen electronics are exactly identical. (these input and outputs can also be switched in case of emergencies also!) As best as I can tell, actual cb communications are limited to a mere ten feet when done underwater! I am sure if we all work together, we could do better than this. The testing on this most simplest of voice communications as I said is slated for Spring. We will share all that we find both good and bad with the group at that time (If nothing else, it gives us a topic to talk about) Thanks early for all the support you Guys! David Bartsch From: bottomgun@mindspring.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] sound transducers Date: Sat, 15 Nov 2008 09:45:14 -0500 David, In open water (salt) you are going to have varying irreproducible results due to background noise (biologics + man-made), back scatter, reverberation, temperature, and salinity issues. Most of these will degrade a given signal and reduce dependability. Some days it might work and others it might not. Freshwater is a more reasonable environment for your endeavor. It is a complicated process to determine the maximum range which will vary from place to place.
You need to be careful with casual underwater comms as you may be happy with relatively poor capability while chit-chatting but in an emergency, clear dependable communications is mandatory to increase the probability of a successful emergency resolution. R/Jay
Jay K. Jeffries Andros Is., Bahamas
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of David Bartsch
Jay,
Joe, For efficient transmission, the signal is translated in frequency (still audible but unintelligible) to maximize range and single side-band is used to conserve energy. Anything else will have difficulties of one form or another. Opening a basic sonar acoustic text will document this, you can’t get around basic physics. R/Jay
Jay K. Jeffries Andros Is., Bahamas
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Joseph Perkel
David,
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