ultrasonics with a lot of averaging... If a measure goes way apart from the average just discard it. -----Original Message----- From: "Michael Rigby-Jones" Sent: 2/17/2006 10:07:05 AM To: "Microcontroller discussion list - Public." Cc: Subject: RE: [EE] Distance Measurement >-----Original Message----- >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] >Sent: 17 February 2006 15:57 >To: Microcontroller discussion list - Public. >Subject: Re: [EE] Distance Measurement > > >Tim N9PUZ wrote: > >>I'm researching options for measuring distances in a wet, outdoor >>environment. The task is to measure the distance between two drive >>units on a boat. The drives both propel and steer the boat. >> >>Ideally I will end up with an indicator for the crew that sits at "0" >>when the drives are a certain distance apart and will go positive or >>negative from center if the drives are misaligned. The boat has >>provisions for trimming the positions of each drive from the cockpit. >> >>I'm looking for options to consider to do the actual distance sensing. >>Water will occasionally splash around the sensor locations and since >>the drives will be running there will be vibration. I do not know the >>exact target distance right now but it is approximately 7.5 feet. The >>drives have places where sensors, etc. could be mounted >starting about >>a foot behind the transom and out to about 5 feet or so on to the >>drive assemblies. >> >>Tim >> >> >That should be easy with ultrasonic sound. The pulse is sent, and the >echo tells distance. >The sender/receiver modules are available commercially. I'm wondering if high frequency vibrations from the engines could play havoc with ultrasonics, and water splashing up will certainly cause problems with reflections, though those can probably be filtered out. The only viable alternative I can think of would be a laser based system, which would also have problems with water splashes, but at least should be more immune to vibration. Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist