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[PSUBS-MAILIST] Passive sonar research



To all:
 
   I will of course continue to assist those that wish to obtain broadband underwater communications capabilities however...
 
   I will be attempting to restart my research into directional passive sonar which is and has been my first true passion.
 
   I am at the present researching what if anything I could use to detect 200k for use as an collision avoidance tool. The reason this frequency is of such importance is that most shallow water depth sounders and fish finders transmit at this distinct frequency.
   I was able to locate a kids toy that could detect and allow the listening to bats. Perhaps if I took this simple device apart, I could modify it to detect slightly higher frequencies I so desire.
 
   Here is some interesting points of interest...
 
   This is the range by scientific study to these various animals by Ramsey William L. (1986):
 
   Human                                                     20hz   to   20Khz
   Cats                                                        100hz to   32Khz
   Dogs                                                        40hz  to   46Khz
   Horses                                                      31hz  to   40Khz
   Elephants                                                  16hz  to   12Khz
   Cattle                                                       16hz  to   40Khz
   Bats                                                          1Khz  to  150Khz
   Mice or rodents                                           1Khz  to   100Khz
   Whales and Dolphins                                     70hz  to   150Khz
   Seals and Sea Lions                                      200hz to  55Khz
 
   Has anyone a suggestion as to what if anything I could use or obtain to detect and draw this very high frequency down to what we as humans can hear? Any schematic sources known of? Perhaps the return electronics within a fish finder itself could be used in some way?
 
                                                                                                                                                         David Bartsch


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