An inertial navigation system utilizing a servo-controlled twodegree of freedom pendulum to obtain specific force components in the locally level coordinate system. The pendulum includes a leveling gyroscope and an azimuth gyroscope supported on a two-gimbal system. The specific force components in the locally level coordinate system are converted to components in the geographical coordinate system by means of a single Euler transformation. The standard navigation equations are solved to determine longitudinal and lateral velocities. Finally, vehicle position is determined by a further integration.

The relative azimuth bearing between first and second space terrestrial points (which may be obscured from each other by intervening terrain) is measured by placing at one of the points a laser source for projecting a collimated beam upward in the vertical plane. The collimated laser beam is detected at the second point by positioning the optical axis of a receiving instrument for the laser beam in such a manner that the beam intercepts the optical axis. In response to the optical axis intercepting the beam, the beam is deflected into two different ray paths by a beam splitter having an apex located on the optical axis. The energy in the ray paths is detected by separate photoresponsive elements that drive logic networks.

A METHOD AND APPARATUS FOR OPERATING ON
COMPANDED PCM VOICE DATA

A method and apparatus for digitizing audio signals being generated from a plurality of parties in order to provide audio communication between the parties with a minimum of interference. Each of the parties has an audio transmitter and receiver provided for transmitting and receiving audio signals. The audio signals are converted to a PCM companded signal for transmitting to a remote location and then converting each of the companded signals to a first eight parallel signal. A pre-programmed ROM is located at the remote location and has a plurality of inputs and outputs. Each of the eight-bit parallel signals from the individual parties are fed to the ROM causing the ROM to produce an eight-bit signal on the output representing the instantaneous sum of the eight-bit parallel signals being supplied to the inputs thereof. The eightbit parallel signal appearing on the output of the ROM is converted to a serialdigital signal by a parallel-to-serial converter for transmitting over a single line to another serial-to parallel converter prior to being fed through a digitalto-analog converter to the receiver for producing the audio signal at the receiver.

This invention describes a method and apparatus applicable to jet engines for improving operating efficiency over broad ranges of flight conditions and for reducing engine noise output in take-off and landing by controlling the airflow entering and exiting the engines. A turbojet engine apparatus is described which operates efficiently at both subsonic and supersonic speeds and a method is described which enables a turbofan with an associated satellite turbojet or turbofan to operate more efficiently at both subsonic and supersonic speeds. In both cases, take-off and landing noise is reduced substantially. The apparatus consists essentially of arranging for two separate portions of an engine to act upon one airstream or, alternately, to operate on independent airstreams.