secure wireless remote control - long range relay

[marc22]

Hello,

I got myself involved in project of gate opening using actuator.

I use arduino nano (for timing control, emergency sensors etc)  and wireless remote like this ->

http://www.ebay.com/itm/4-CH-Wireless-Transmitter-Receiver-Remote-Control-Switch-Relay-DC-12V-10A-315MHz-/181446904368?hash=item2a3f140a30:g:7m4AAOSwVupTqUBz

Everything was working perfect, but range was not enough (while driving car, gate was not able to get opened so i was blocking a one way street and people need to wait) so i mounted external receiving antenna. Got myself a great range but stuck in other problem...

Other people are opening gate

Bigger antenna, bigger gain, bigger range, more people in range = troubles.

First of all i change couple times "id" programmed in transmitter and not i got gate opened  once a week (earlier couple times a day).
Probably i can find "free one" but at night when propagation of radio waves is better still someone could hit my key and don't know it...

I found that impossible to treat as good job.

Could anyone recommend me a remote like this one
"http://www.ebay.com/itm/4-CH-Wireless-Transmitter-Receiver-Remote-Control-Switch-Relay-DC-12V-10A-315MHz-/181446904368?hash=item2a3f140a30:g:7m4AAOSwVupTqUBz"

what will have some kind of encryption to be sure that only I can open gate and remotes programmed by me?

I was thinking about wifi module, but still will be problem with range...

Is there any out of box solution?
 
I was thinking about doing it myself but i'm unable to create form factor that could be fit on pocket (i need one for car, couple for people to wear in pocket).
I was thinking about arduino nano and digital transmission.
1) Set up a encryption key shared between keychain   for example 123456789
2) When i want open gate, i send message to gate arduino (gate arudino respond with random numbers 987654321)
3) I recevie random number and multiple by secret key and send to gate.
4) gate is know secret key and key that he send so calculate and match if equal if yes then open gate (if 123456789 * 987654321 = answer then yes open  .

So it's "impossible" to tamper that transmission if numbers are long enough.

Can anyone share out of box idea like this?
I need 4 chanel NO relays, go to close when key-press.


Regards
Any ideas are welcome:)

[marc22]

Just get an XBEE module or use 802.11 WLAN or something.
ZigBee, 802.11 WLAN and BlueTooth Low Energy (which has a new longer range option in some of the new bluetooth 4.2 compatible modules out there) all have bonding / pairing / link encryption as standard parts of their protocols.
Just "pair" or otherwise authenticate / join the transmitter unit with the receiver unit and you're done.

Most BlueTooth Low Energy units are only intended for 10m ranges so you'd need to pick a long range oriented pair for using it.

But 802.11 WLAN or ZigBee units typically are intended to have something like 100m more or less ranges depending on whether you are having obstructions and indoor uses or not.  Several units have km ranges, I think Digi XBEE has many such solutions with several having arduino shields.

Microchip, Atmel, NXP, and Energy Micro have their own RF link evaluation boards several of which have arduino compatible shield evaluation boards as well.

With many of these I doubt you'd even need the aruino board since they almost always have a microcontroller which you can program that has several GPIO lines that you can control using commands sent over the air.

Thank You for answer but i'm not sure about this.

Im looking for about 700m range (most open space, and some woods) - on this chines at 315 mhz i got no problem in range.


The problem with all of this devices there are designed to create a link between devices. disconnected device, make discovery,  find  then connect and that take time.
I was thinking about bluetooth and wifi - but it's to small range and need to establish connection(i can put a outdoor antenna, but still phone inside car will have limited range, while driving) - don't looks good and safe.

Transmiter is operated from battery so it should start working at key-press.


What about:
HC-12 433Mhz SI4463
and external antenna ?
at lowest baud rate?

Maybe this is what i'm looking for?
 

[Ian.M]

How about a range of anywhere on the planet with a mobile signal?
There are off the shelf GSM relay control modules available, some even in IP68 enclosures. 
However you would then have the ongoing expense of a SIM only contract for the module.

They invariably use some sort of security code, and can typically be activated by text message, smartphone app or normal call with a PIN. You'd want one that supports multiple codes or caller ID so you can revoke/blacklist lost/stolen phones.

[tautech]

You can mix and match equipment from these guys:
http://www.rfremotech.com/Others.html
http://stores.ebay.com/RFRemotech?_trksid=p2047675.l2563

To get good current ratings it's easy to cascade relays to suit your requirements.

[LabSpokane]

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https://store.particle.io/collections/electron