I bought one of these units since I can't see our driveway from the house, and it worked beautifully, so much so that I decided to buy one for the back of the house, but discovered that they are on the same frequency. Now when something sets off the front driveway, the back receiver goes off too, and vice versa, so I have no idea which side of the house someone is approaching. I checked,(by taking the unit apart) and there is no way to change frequencies on the the units.Anybody know a work around for this situation?