Most satellite dish actuators send a series of pulses to indicate their position. By counting pulses the positioner knows where the dish is pointing. It is possible to use a serial port and Linux with RTAI patches in order to count these pulses, thus minimising the external hardware required for a positioner. The zip contains instructions, circuit diagrams and example code.-Most satellite dish actuators send a series of pulses to indicate their position.　By counting pulses the positioner knows where the dish is pointing.　It is possible to use a serial port and Linux with RTAI patches in order to count these pulses, thus minimising the external hardware required for a positioner.　The zip contains instructions, circuit diagrams and example code.