Raspberry pi hardware watchdog

We run outdoor-devices based on raspberry pi platforms. Those devices are remotely controlled via a web-application that generates the control-commands and sends them via openvpn to the respective Raspberry Pi device. Due to poor infrastructure, some of the devices must work under 3G/umts conditions. In this case a mobile USB-Surfstick (3G/UMTS) provides the Internet connection. Unfortunately this solution does not work sufficiently enough for our purposes. For unknown reason the device looses connection and does not come up again - even not with a software reboot. In such cases we must travel to the devices location and plug-off plug-on the power cable to re-initiate the internet connection. This is too nasty and costly. The scope of this project is to develop an appropriate software running on the ArchLinux RaspberryPi which initiates a reset by interrupting the units power as soon the internet-connection is lost for a given period of time. We have foreseen to use Yocto-Watchdog's as hardware unit (please see [login to view URL] for details.