APPENDIX I GLOSSARY

AI-1 APPENDIX I GLOSSARY ACTIVE SATELLITE—A satellite that amplifies the received signal and retransmits it back to earth. AFDS—An abbreviation for the amphibious flagship data system. ANGLE OF INCLINATION—The angular difference between the equatorial plane of the earth and the plane of orbit of the satellite. ANTENNA COUPLER—A device used for impedance matching between an antenna and a transmitter or receiver. APOGEE—The point in the orbit of a satellite the greatest distance from the earth. ASSEMBLY—A number of parts or subassemblies, or any combination thereof, joined together to perform a specific function. ASWTDS—An abbreviation for the antisubmarine warfare tactical data system. ASYNCHRONOUS ORBIT—One where the satellite does not rotate or move at the same speed as the earth. ATDS—An abbreviation for the airborne tactical data system. AUDIO FREQUENCY TONE SHIFT—A system that uses amplitude modulation to change dc mark and space impulses into audio impulses. AUTOMATIC TRACKING—Tracking done by the equipment comparing the direction of the antenna axis and the direction of the received signal. AUTOMATIC VOLUME/GAIN CONTROL—A circuit used to limit variations in the output signal strength of a receiver. BALANCED PHASE DETECTOR—A circuit that controls the oscillator frequency (afc). BAUD—A measurement of speed based on the number of code elements or units per second. BEAT-FREQUENCY OSCILLATOR—An additional oscillator used in a receiver when receiving a cw signal. It provides an audible tone. BITS-PER-SECOND—Bit is an acronym of the words binary digit. One bit is equal to one signal unit or element. BLACK—The reference color of equipment that passes unclassified information. It normally refers to patch panels. CODE—In teletypewriter operation, code is a combination of mark and space conditions representing symbols, figures, or letters. COHERENT—Radiation on one frequency.