Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site oliveb.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!ihnp4!zehntel!hplabs!oliveb!jerry From: jerry@oliveb.UUCP (Jerry Aguirre) Newsgroups: net.physics Subject: Re: passingwater Message-ID: <170@oliveb.UUCP> Date: Fri, 14-Sep-84 20:35:07 EDT Article-I.D.: oliveb.170 Posted: Fri Sep 14 20:35:07 1984 Date-Received: Tue, 25-Sep-84 02:28:56 EDT References: <13195@sri-arpa.UUCP> Organization: Olivetti ATC, Cupertino, Ca Lines: 55 I don't remember all the details but I did one read an article about a way of transmitting signals thru water. The diagram was something like this: ------ | | | XMTR | ----------------------| |-------------------------- | ------ | | | ////////|////////////////////////////////////////////////////////|//// | | ------- ------- | | | | | Metal | Water | Metal | | Plate | | Plate | | | | | ------- ------- ---- ---- | | ---- | | | |-|RCVR|-| | | | ---- | | ---- ---- Transmission range is restricted to the general area between the two plates. Go to deep or to far off to the side and you lose the signal. Still, plates on either end of a lake or section of river would give you total coverage of the area. The transmission should be low frequency, probably in the 1 to 500 Khz. range. I don't think the effect can properly be considered radio. I think that it depends on the conductivity of the water to transmit the signal. The receiver just intercepts the current flowing thru the water. This results in the signal only being available between the tranmission plates. For your application this would still require long wires to reach both ends of the lake but does result in a "free" probe. It does not address the problem of how to get pictures back from the probe. I think that if it was possible to have a wireless underwater probe then someone would have done it. As other netr's have pointed out there is a lot of effort going into communicating with underwater subs and drone probes of the type you suggest. Every one I have heard of either used a tether (fiber optic is the latest) or took photographs for later recovery. It is probably possible to sent pictures via sonar but not very quickly. Ham radio operators send slow-scan pictures but at 14 seconds a frame you might have trouble dodging the cliffs. Ah, if someone would only invent a nutrino transmitter and receiver. Jerry Aguirre {hplabs|fortune|idi|ihnp4|ios|tolerant|allegra|tymix}!oliveb!jerry