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Proximity Door Locks

You just get close to your vehicle (or house) and the doors unlock. No button pushing. However, there's still a battery powered thingy to carry around in a pocket.

I spotted the proximity door lock feature as part of fancy car alarm system I found on eb*y.

Anybody here using a proximity door system on their car? I think the doors also relock after some away distance. Any goofiness like the doors unlocking/locking while mowing the lawn near the car or taking out the trash. :) click...click....click.....click..

I'll guess how the system works...

The car sends out some periodic RF blip. Once the keyfob is in range it'll process the blip and then transmit a unlock code to the car.

This way the keyfob is most often listening which I suspect uses less power than periodically broadcasting like a beacon. The car gets the burden of being a beacon. It's got a bigger battery.

D from BC British Columbia Canada

Reply to
D from BC
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If you only need to go a few feet, the keyfob can be entirely passive, obtaining all of its energy from the car's transmitted RF. E.g., it's just like a passive RFID tag.

Reply to
Joel Koltner

The fob is an RFID tag... probably has some of my designs in it ;-)

...Jim Thompson

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Reply to
Jim Thompson

Forgot to say, the new Infiniti (and Lexus) high-end vehicles only require the fob in your pocket... no ignition key is needed, just press a start button on the dash.

...Jim Thompson

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| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
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Reply to
Jim Thompson

mmmmm...a few feet?? Hope it's fast enough. I'd like to be able to run up to my car and have the locks unlock before I reach the door handle.

D from BC British Columbia Canada

Reply to
D from BC

Dirt? ;-)

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Reply to
Michael A. Terrell

There are some passive tag readers that can go considerably further (e.g., tens of feet -- someone posted a link to one of these long-range systems some months back), although as you'd expect they require a higher-power transmitter as well... and you don't want to kill the car battery too fast.

I suspect you probably could "beat" the system without trying too hard; I wouldn't be surprised if the "ping" interval were in the ballpark of a second.

---Joel

Reply to
Joel Koltner

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

This feature has been on the prius since 2001. It requires you to touch the handle, which I'm guessing has some kind of sensor, and triggers the RFID query.

I want one for my front door... I hate pulling my keys out of my pocket while holding my groceries :)

Regards, Bob Monsen

Reply to
Bob Monsen

Power would be needed at the door lock. If the house AC is routed that could be a $$$ install and a possible ugly wire running to the lock. However, no visible wires if the system is built into the door frame. But..In case of power failure, a key has to open the door.

Perhaps a rechargeable battery in the door lock. I've seen something similar but the home door lock had a key pad.

D from BC British Columbia Canada

Reply to
D from BC

They have fingerprint scanners in door lock sets. I'm sure RFID would be simple to incorporate.

These typically operate off replaceable batteries for quite some time. But I'm sure someone could arrange to install a couple of contacts in the door jamb to tie a low voltage charging source to the locust. It would charge only when the door was closed and eliminate the need for a flexible wire to the door.

Most of the electronic locks designed for residential use appear to have all of their smarts on the door. Probably to make a replacement of a key lock simple. Commercial installations typically have an electric latch built into the frame. This makes it trivial to run wiring to whatever type and size of control system easier.

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Paul Hovnanian P.E.

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