--0__=85256A85004D76978f9e8a93df938690918c85256A85004D7697 Content-type: text/plain; charset=us-ascii My experience with magnetic waves has been at the opposite end of the spectrum, and perhaps you are right in that it is proportional to wavelength. During my days at IFCO we would contain a swimming dog.... we could get several hundred feet of usable signal at 10Khz. Basically saw no effect of the water (received field strength obeyed Biot Savart law). This is a fun and timely topic... I just started building a model sub that will operate at 75mhz. I would greatly appreciate any far out ideas to improve range without changing the xmtr... this will undoubtably be a challenge! Scott Scott Stephens cc: Sent by: pic Subject: Re: [EE]: Underwater RF microcontrolle r discussion list 07/10/01 09:50 PM Please respond to pic microcontrolle r discussion list From: Scott F. Touchton >In college I built a sub using depth finder transducers to communicate >acoustically... we never found the limit of the range (pond was too >little). We at least had 500'. Will this approach work for you? I would definitely choose acoustics for underwater communication. Just watch for the multi-path interference in small, complex places. >Also, magnetic fields are uneffected by water... you may have better luck >(less attenuation) dealing with the magnetic field component instead of >primarily the electric field component. Rapidly changing magnetic fields will induce electric fields, and the signal will not propagate as a wave (at 2 meters) for long. I'll SWAG using a loop or ferrite antenna would increase the reception depth another foot. Scott **************************************************************** Freedom is pursuing your carrot, not running from a stick. The mob only rules what its members are allowed to achieve. Physics - the manifold ways the odds always get even... **************************************************************** -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu --0__=85256A85004D76978f9e8a93df938690918c85256A85004D7697 Content-type: application/octet-stream; name="$RFC822.eml" Content-Disposition: attachment; filename="$RFC822.eml" Content-transfer-encoding: base64 UmVjZWl2ZWQ6IGZyb20gc2pzbXRwMDEudW5pcGhhc2UuY29tIChbMTAuMTAuNDkuMjM5XSkNCiAg ICAgICAgICBieSBzanNtdHAwMS51bmlwaGFzZS5jb20gKExvdHVzIERvbWlubyBSZWxlYXNlIDUu MDdhKQ0KICAgICAgICAgIHdpdGggU01UUCBpZCAyMDAxMDcxMDA2NTAyNTIwOjY4MjA1IDsNCiAg ICAgICAgICBUdWUsIDEwIEp1bCAyMDAxIDA2OjUwOjI1IC0wNzAwIA0KUmVjZWl2ZWQ6IEZST00g Y2hlcnJ5LmVhc2UubHNvZnQuY29tIEJZIHNqc210cDAxLnVuaXBoYXNlLmNvbSA7IFR1ZSBKdWwg MTAgMDY6NTA6MjQgMjAwMSAtMDcwMA0KUmVjZWl2ZWQ6IGZyb20gUEVBUi5FQVNFLkxTT0ZULkNP TSAoMjA5LjExOS4wLjE5KSBieSBjaGVycnkuZWFzZS5sc29mdC5jb20gKExTTVRQIGZvciBEaWdp 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