---- START NEW MESSAGE --- Received: from cherry.ease.lsoft.com [209.119.0.109] by dpmail10.doteasy.com with ESMTP (SMTPD32-8.05) id A08A773E009A; Fri, 30 Jan 2004 14:54:02 -0800 Received: from PEAR.EASE.LSOFT.COM (209.119.0.19) by cherry.ease.lsoft.com (LSMTP for Digital Unix v1.1b) with SMTP id <23.00CC58B5@cherry.ease.lsoft.com>; Fri, 30 Jan 2004 17:53:47 -0500 Received: from MITVMA.MIT.EDU by MITVMA.MIT.EDU (LISTSERV-TCP/IP release 1.8e) with spool id 7539 for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 17:52:03 -0500 Received: from MITVMA (NJE origin SMTP@MITVMA) by MITVMA.MIT.EDU (LMail V1.2d/1.8d) with BSMTP id 3191; Fri, 30 Jan 2004 17:51:47 -0500 Received: from smtp2.globo.com [200.208.9.169] by mitvma.mit.edu (IBM VM SMTP Level 430) via TCP with ESMTP ; Fri, 30 Jan 2004 17:51:47 EST X-Warning: mitvma.mit.edu: Host smtp2.globo.com claimed to be mail.globo.com Received: from user88l53zxzyb (200.158.164.61) by mail.globo.com (6.0.053) id 40076DB000171696 for PICLIST@MITVMA.MIT.EDU; Fri, 30 Jan 2004 20:51:48 -0200 References: <401A9A93.20071.28A7C0C@localhost> <006201c3e75d$14b7f200$0301a8c0@user88l53zxzyb> <008101c3e767$6673d1e0$0301a8c0@user88l53zxzyb> <401AB450.90D8D861@UALBERTA.ca> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Message-ID: <006301c3e78c$020f4a20$0301a8c0@user88l53zxzyb> Date: Fri, 30 Jan 2004 20:51:23 -0300 Reply-To: pic microcontroller discussion list Sender: pic microcontroller discussion list From: Pedro Drummond Subject: Re: [EE]: Challenge for keen minds To: PICLIST@MITVMA.MIT.EDU Precedence: list X-RCPT-TO: Status: U X-UIDL: 371856595 Although I like the idea of having 2 sensors, this will be known by everyone. There is no way I will have something installed in theses boxes that people working with it 24/7 will not know and understand. What happens today is that people that know these boxes are opening it, stealing from it, and closing it again ! Inside job, definitely, but not with a key. They rebuild the box seal (I don't exactly know how this seal is, so far). My device will definitely be welded in the box, and I am not sure this is enough protection for it. Items in the box are double-checked at the beginning, and will be checked at the end of every trip. When something is missing, the question is WHEN did it happen, so they can point out the responsibles. I like the idea of a button out of the reach (jamb near the hinge, flange protecting it). Maybe even a PIR detector, if well-protected. Taking a picture would be perfect, but I am skeptical about how to implement it (type of camera, protection, etc). ----- Original Message ----- From: "Robert Rolf" To: Sent: Friday, January 30, 2004 4:45 PM Subject: Re: [EE]: Challenge for keen minds > Properly arranged, there should be NO glitches in a reed switch > caused by truck movement. > > Have two sensors. One obvious, to be disabled/bypassed. One hidden, > that logs the 'real' activity. > > If the box is normally dark, a light sensor (CdS cell) > hooked to one of the self contained Dallas data logger > chips should work with minimal effort. The crooks are going > to need light to see what they're stealing. And if they think > they've disabled the detector, they're more likely to turn on > the lights. > > And you could always put a floor switch at the entrance, hidden under > under a mat. > > And why not put a disposable camera in a box over the door or shooting > through a hole in the side wall. > Easy enough to have it snap an image when the door opens (with a 1 sec delay), > which presumably happens only at the final destination. > > Autowinding is fairly easy too. Rubber hobby tire and small gear head motor > timed to wind many minutes AFTER the door closes. > > R > > Pedro Drummond wrote: > > > > Yes, but the problem here is someone that, when opening the gate, > > immediately recomposes the sensor (for example, puting a second magnet close > > to the reed switch). If he takes, say, 2-3 secs to do it, it will be > > analyzed afterwards as a glitch, probably caused by truck movement. The > > ideal would be some kind of sensor not easily or quickly "recomposed" when > > opening the gate. > > > > ----- Original Message ----- > > From: "James Nick Sears" > > To: > > Sent: Friday, January 30, 2004 2:50 PM > > Subject: Re: [EE]: Challenge for keen minds > > > > > In this case couldn't you just use a switch mounted inside the door > > > somewhere where it can't be feasibly reached from the outside until the > > door > > > has already opened and the time of intrusion has already been logged? > > > > > > > > > ----- Original Message ----- > > > From: "Pedro Drummond" > > > To: > > > Sent: Friday, January 30, 2004 12:12 PM > > > Subject: Re: [PICLIST] [EE]: Challenge for keen minds > > > > > > > > > > Thank you all for the help and interest. > > > > > > > > Ok, time for more data: > > > > > > > > The space being protected is a metallic box, the size of an elevator, > > that > > > > will be towed by small trucks. Its metallic "door" (actually a double > > > door) > > > > is the gate I mentioned. During long trips, these boxes are commonly > > moved > > > > from truck to truck, with long periods waiting for the next one, with no > > > > guards nearby. Although there is a very strong lock, theft was detected > > at > > > > final destination in locked boxes (i.e., someone opened it, took some > > > goods, > > > > and somehow relocked it). A redesign of the metal box is being made, but > > > it > > > > will be a long time until all of them are replaced. It is enough for now > > > to > > > > help the insurance company in detecting WHEN and for HOW LONG it was > > > opened, > > > > so the responsible will be known. > > > > I do not mind reading its information only when the gate is open, and I > > > > cannot modify the gate, only add some small device close to the door. > > > > > > > > > > > > To comment some of the group ideas: > > > > > > > > Using a contact method for data transfer - I am afraid of dust, grease, > > > etc. > > > > But maybe. > > > > RFID - cheap tag, but expensive sensor (I guess). > > > > Gyro/acceleration sensors - can't do, since it will be towed by a truck. > > > > Hinge sensored - can't alter the hinge. > > > > > > > > > > > > BTW, special thanks to Russel ! > > > > > > > > -- > > > > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > > > > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > > > > > > > > > -- > > > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > > > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > > > > > > -- > > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body .