Long Distance Remote Button

I am trying to build a button that can control an Arduino from about 350m distance. Either with radio signals through the air or with acoustic signals that can be send through a lake. (Sound can travel very far in water). Either solution should be able to incorporate some sort of encryption or signature to be sure that no random signal triggers the Arduino. A simple "Button Press" signal would be enough.

Anyone got ideas?

A pair of these with the antenna http://yourduino.com/sunshop2/index.php?l=product_detail&p=190 http://yourduino.com/sunshop2/index.php?l=product_detail&p=191

A garage door opener will do it. Usually they operate on 433MHz. There's a lot of modules out there that can be adapted to do this for only a few bucks. You may need to pay attention to the antenna design to get this range working reliably.

https://www.youtube.com/watch?v=y1FCKpARWY8

APC220 will also do the job. Rated to 1000mtr.

I am playing with them for a simple farm gate project using a vehicle sensor to tell a basic MCU to send a simple message that can be checked by the receiving end.

There is plenty of information on them and a program can be downloaded to set up the device.

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