signal that creates torque for two antenna positioning motors. One motor moves the antenna left/right. The other motor drives the antenna up/down. The result is to move the antenna position so that the center of the antenna beam remains aimed directly at the aircraft even when the aircraft is moving perpendicular to the antenna beam. For a track while scan radar, position and velocity is maintained for multiple aircraft. The last position of the aircraft is coasted using the velocity, and that information is used to direct a beam of energy toward the aircraft. The monopulse angle error information that is received is used to adjust the position and velocity data for the aircraft. This is a common mode with phased array radar systems. Amplitude-Comparison Monopulse provides an explanation of the antenna signals involved in this process. Doppler Doppler effect can be used to separate different objects based on speed. Pulse Doppler RADAR signal processing uses this technique. This is combined with conical scanning or monopulse to improve track reliability. It is necessary to separate the object signal from the interference to avoid being pulled off the object. This avoids problems where the system is fooled by aircraft flying too close to the surface of the earth or aircraft flying through clouds. Conical scan and monopulse antennas are susceptible to interference from weather phenomenon and stationary objects. The resulting interference can produce feedback signals that move the antenna beam away from the aircraft. This can produce an unreliable antenna position when the antenna is aimed too near the ground or too near to heavy weather. Systems with no Pulse Doppler tracking mode may remain aimed at irrelevant objects like trees or clouds. Constant operator attention is required when there is no Doppler signal processing. History Monopulse radar was extremely "high tech" when it was first introduced by Robert M. Page in 1943 in a Naval Research Laboratory experiment. As a result, it was very expensive, labor-intensive due to complexity, and less reliable. It was only used when extreme accuracy was needed that justified the cost. Early uses included the Nike Ajax missile, which demanded very high accuracy, or for tracking radars used for measuring various rocket launches. The world's first airborne monopulse radar system was the British Ferranti-designed AIRPASS system which went into service in 1960 on the RAF's English Electric Lightning interceptor aircraft. An early monopulse radar development, in