Apparatus for generating an indicator on a remote monitor screen representative of the orientation of the monitoring camera. A sensor on the camera produces a signal proportional to the camera orientation. An encoder, including a sawtooth generator, a comparator, and time delay single-shot multivibrators,...http://www.google.com/patents/US4490742?utm_source=gb-gplus-sharePatent US4490742 - Encoding apparatus for a closed circuit television system
