RFID Setup Advice

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   Ok all,
Let me start by saying that for security reasons, I have to be careful what I say on here, but here is the deal...
We have a situation where we have decided that we would like to implement RFID Access to a mobile facility.  Here are the facts that I feel are relevent and I hope will be enough for you to assist me with. if not let me know and I will try to get any info needed.
We have a facility that is mobile which (when in use) uses a generator to power its internal devices that require power.  When not in use it has 2 standard 12v car batteries that provide power to the FEW devices that need power 24/hrs. We would like to implement RFID access to each door, but keep it controlled from a single unit. (so no matter which entrance an authorized tag was added at, it would work at both) 
Due to its mobility I would like a stand-alone solution that is completely autonomous (adding/deleting authorized tags, etc.) and have it unlock the appropriate entrance based on which door recieved the authorized tag. 
I feel that passive is probably better then active due to the 12v batteries during "closed" times. And we were leaning towards the parallax or M1.
In short I thought that the Ch. 3 (Car door) project would translate fairly well except it would need a way to monitor 2 antenaes and only unlock which ever entrance was associated with that "antanea".
Any and all constructive input is appreciated thanks ;)

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Xyvius Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21 April 2007 Status: Offline Points: 3	Post Options Post Reply Quote Xyvius Report Post Thanks(0) Quote Reply Topic: RFID Setup Advice Posted: 09 May 2007 at 4:08am
	Ok all, Let me start by saying that for security reasons, I have to be careful what I say on here, but here is the deal... We have a situation where we have decided that we would like to implement RFID Access to a mobile facility. Here are the facts that I feel are relevent and I hope will be enough for you to assist me with. if not let me know and I will try to get any info needed. We have a facility that is mobile which (when in use) uses a generator to power its internal devices that require power. When not in use it has 2 standard 12v car batteries that provide power to the FEW devices that need power 24/hrs. We would like to implement RFID access to each door, but keep it controlled from a single unit. (so no matter which entrance an authorized tag was added at, it would work at both) Due to its mobility I would like a stand-alone solution that is completely autonomous (adding/deleting authorized tags, etc.) and have it unlock the appropriate entrance based on which door recieved the authorized tag. I feel that passive is probably better then active due to the 12v batteries during "closed" times. And we were leaning towards the parallax or M1. In short I thought that the Ch. 3 (Car door) project would translate fairly well except it would need a way to monitor 2 antenaes and only unlock which ever entrance was associated with that "antanea". Any and all constructive input is appreciated thanks ;)

amal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Group Joined: 22 November 2005 Location: United States Status: Offline Points: 2060	Post Options Post Reply Quote amal Report Post Thanks(0) Quote Reply Posted: 09 May 2007 at 10:57am
	Hmm, yeah that sounds like a pretty fun project. If security is a top concern here, then I would suggest you look into using an RFID tag that supports at least some kind of security. It's rather trivial to sneak up on someone, read the tag in their wallet by bumping into them, and "cloning" that tag to enter the facility. For more info on this, google for "clone verichip" and check www.rfidanalysis.org Ok, so, that being said, you can't use the chapter 3 readers, they are closed units. You will also have a very difficult, if not impossible time using multiple antennas with a passive RFID system. On the other hand, you could multiple readers and use a basic stamp microcontroller or PIC controller to accomplish this, but you might have to use more than one, and/or get a RAM/Memory expansion board to hold all the code and store a small log of entries. To conserve power, you'd probably have a button by the reader that would wake up the processors and power up the readers for 5-10 seconds... long enough for the person to present a tag to the reader. Because the basic stamp has plenty of I/O pins, you could easily support two readers, operate two entrance latches, and support a "wake up" button and power-up signal for the readers. Edited by amal - 09 May 2007 at 10:59am
	Amal ;) www.amal.net

Xyvius Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 21 April 2007 Status: Offline Points: 3	Post Options Post Reply Quote Xyvius Report Post Thanks(0) Quote Reply Posted: 09 May 2007 at 11:40am
	Thanks Amal for taking the time to give input. Well I don't know that I would call security a TOP concern lol.. I can say this is not like a Goverment Lab or anything, just proprietary company info we want to keep out of public knowledge ;) We hoped to avoid an "active" system so that we could mantain an "invisible" entrance.. there is a small glass window near each door and we had thought that maybe we could avoid having to have an external "button" by placing the "readers" behind that glass thereby avoiding any "breeches" of the "shell". What about those "sensors" that you can attach to glass, and they can sense touch through glass? could that be integrated? That would allow for a "button" and at the same time keep the shell intact with no holes needing to be made. If so, how difficult are those to work with? how precise can you make the "sensitive" area, etc. Only heard of them, never dealt with em... thanks, Xy Edited by Xyvius - 09 May 2007 at 11:44am

amal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Group Joined: 22 November 2005 Location: United States Status: Offline Points: 2060	Post Options Post Reply Quote amal Report Post Thanks(0) Quote Reply Posted: 09 May 2007 at 4:40pm
	Hmm, depending on your power consumption during the night, you could probably get away with keeping multiple passive readers and a microcontroller like the STAMP powered up during the night. By just keeping each reader powered up and searching for RFID tags, you could do away with the button entirely. You could also extend your power consumption by putting the readers and microcontroller to sleep for 5-10 seconds between reads. By powering up, looking for tags, and going into low power mode for 5-10 seconds, you could cut your power use dramatically. Of course, this means you'd have to hold your tag up to the window for anywhere from 5-10 seconds while waiting for the system to power up and look for tags ;) I've also heard about those glass proximity sensors as well. I'm not sure what kind of power consumption they have. I'm also unsure if you would still need a microcontroller powered up in order to read and process the value from the proximity sensors. I say estimate your power consumption for this project and do some calculations to figure out if the two car batteries will work for you or not. If your system is 12v, you might also consider using two 6v batteries in series rather than two 12v batteries in parallel. Often, 6v batteries have much higher power densities and can provide more amp hours than 12v batteries. Of course, you'll have to check to see if two 6v batteries in series can provide more amp hours than two 12v batteries in parallel, but it's worth looking into.
	Amal ;) www.amal.net