tailieunhanh - THE GLOSSARY

ACCEPTABLE DEGRADATION - The allowable reduction in system performance. For a fire control radar, the acceptable degradation is usually expressed as a reduction in range; for example, the maximum lock-on range might be degraded by 25 percent without loss of essential defense capability. | GLOSSARY ACCEPTABLE DEGRADATION - The allowable reduction in system performance. For a fire control radar the acceptable degradation is usually expressed as a reduction in range for example the maximum lock-on range might be degraded by 25 percent without loss of essential defense capability. ACQUISITION - A procedure by which a fire control tracking radar attains initial lock-on. Usually the approximate target coordinates are supplied to the tracking radar and it searches a predetermined volume of space to locate the target. AEROSOLS - Solid particles dispersed in the atmosphere having resonant size particles with a high index of refraction. The particles both scatter and absorb visual and laser directed energy so as to cut down on weapon systems directed by these techniques. AFC AUTOMATIC FREQUENCY CONTROL - An arrangement whereby the frequency of an oscillator or the tuning of a circuit is automatically maintained within specified limits with respect to a reference frequency. A magnetron drifts in frequency over a period of time. The AFC of a radar makes the local oscillator shift by an equal amount so the IF frequency will remain constant. AGC AUTOMATIC GAIN CONTROL - A method for automatically obtaining an essentially constant receiver output amplitude. The amplitude of the received signal in the range gate determines the AGC bias a DC voltage which controls the receiver gain so as to maintain a nearly constant output even though the amplitude of the input signal changes. AMPLIFIER - An electronic device used to increase signal magnitude or power. See also GaAs FET Amplifier Klystron Amplifier Traveling-Wave Tube Amplifier. AMPLITUDE MODULATION AM - A method of impressing a message upon a carrier signal by causing the carrier amplitude to vary proportionally to the message waveform. AMPLITUDE SHIFT KEYING ASK - A method of impressing a digital signal upon a carrier signal by causing the carrier amplitude to take different values corresponding to the different