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dear all, it's first time i need help for a work matter:
I need to implement bidirectional access control at long distance (5 meters)
I understood i can use 900MHz tags and readers to achieve 5-15 meters distance
But i have one more problem: i wish to reveal if the person is going inside or outside of the building.
Actually the building has no turnstile and we don't want to install turnstile.
Do such systems exists? is it just a fantasy? I suppose that with directional antennas and more than 1 reader it is possible to understand if the person is going inside or outside the building. And may be such system still exists on the market.
I Hope you can point me to a ready to use solution.
I manage a website that shall use control access data from this future rfid system, and i just need the rfid data on my mysql database. I wish i don't need to develop anything, but I'm open to any solution.
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Hi my friend. Why don't you connect the rfid with a movement sensor ?
For example you put the sensor only outside so if it activates the user is going out, if not is going in (you can have problems if more than 1 person is coming in-out at the same time). Those sensors are really cheap and you can easily connect them if the reader is near the door.
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i'm not aware of that specific use case, but it wouldn't be hard with either as asper says or more accurately you could use 2 antennas one for outside one inside, read the tag twice and see which read last - tells you incoming or outgoing.
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with only one antenna it would be difficult to be accurate but it may not be impossible. ( you would likely have to rely on # of reads per second... to detect distance from the antenna)
Last edited by marshmellow (2015-04-06 04:50:18)
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Another thing you can implement can be a "in" / "out" procedure to enter or exit so it will be user-side to tell if he is going inside or outside (for example swiping the card from left to right or vice versa).
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I have 3 new details:
1)the opening is 2,5 meters width.
2)users continuously pass through the gate in both directions.
3) the opening is in a place where it can rain, so the device shall be weather protected.
So The use of presence sensors Is not good.
I can use 2 rfid reader with 2 directional antennas. But which reader to use? Which antennas? Which tags?
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Are you telling me that no one sells this kind of system for automatic bidirectional control?
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Readers can be embedded inside walls or poles (so they become waterproof); for this kind of distance 800-900MHz tags are preferred. Tags are all almost waterproof if embedded in a plastic case such as smar cards.
I have another possible solution: if all will be software-controlled and there only 1 controlled exit only without other uncontrolled exits you can imagine that a person will enter at a certain time (rx.in the morning at 8:00) and then leave to re-enter so the 1st "encounter" will surely be "in" while the second encounter with the same tag will be to go "out" (it will be impossible to enter again if the person is already inside).
I saw those kind of "gates" without turnstles during congresses: they were using 1.0-1.5 meters antennas (dunno the antenna real size) and hid cards (gates similar to the ones found in boutiques shops):
Last edited by asper (2015-04-06 11:35:04)
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Gaucho, I think you may be better suited talking with a company or two that develops such uhf solutions. I know there are many, I do not know the best, only one I've worked with is zebracard.
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I can't rely on pass time cause users goes in and out continuously.
I wrote to some companies but i couldn't read about this specific kind of system
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the cheapest product i've found is this one: http://www.ebay.it/itm/270677996155?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
you shall add 4 cables, 4 antennas, tags and power supply
anyway it seems that all the solution that i found requests to develop a custom code in order to obtain the human direction by means of comparison between antennas (2 antennas are located outside and 2 inside of the building)
moreover i need to add a modem to convert the ethernet to hdspa (gsm).
the posted box is linux based, so i suppose something cna be added on the device.
it seems that the tag, in order to be correctly read, shall be placed on the jacket of the humans and the badge support (tag holding) shall have spacer on the back side in order to create a distance of at least 5-10mm between the tag and the human body.
Last edited by gaucho (2015-04-09 07:16:32)
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