Re: [PSUBS-MAILIST] Sonar/Telephones was Propulsion

["Paul Suds" <paul_suds@hotmail.com>]

Gary, thanks for the info. there was some useful information there. 
Understand that what I was trying to accomplish was to transmit data through 
water using modems. I was just using the ultrasonic waves as a signal 
carrier through the water medium.  I used  a ~200KHz frequency generator, 
and 2 old military surplus transducers that I bought about 20 years ago for 
experimentation. I finally got around to using them. Luckily I have a 
variable output generator and was able to determine the optimum frequency in 
the fish tank. Here's the concept that I used though: Since the modems are 
set up for analog signals (I did not want to use digitals for various 
reasons), I had to vary the signal from a high (1) to a low (0) state. To do 
this,I had to use a pulser to develop a set time rate that could easily be 
interpreted by the software that I designed at either high (1) or low (0) 
for the modem "sending data", (SD) and "receiving data" (RD). The receiving 
computer software essentially read the data in the buffer every 50 milli 
seconds. If the buffer had a value, it was considered a 1. If during that 
time it had no input, it was considered a zero. I could have used ASCII 
characters, but I really wanted to try this first. The biggest problem I had 
was initial handshaking between the modems. This turned into a real mess. I 
eventually realized that since I didn't have to dial up over a telephone 
line, that I could treat the water like a leased line and establish the 
handshaking up front by the software and eliminate all other error 
correction protocols and file transfer protocols since I did not need them.
Any way as a result of my experiment, I think that I can make some 
significant improvements in data transmission.  Again, thanks for your 
input.
Suds
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