417 - Radar Principles

Pulse Doppler is a modification of pulse modulation that utilizes the Doppler effect. It is commonly used in radar systems to detect the velocity of moving objects. However, it cannot detect stationary effects because it relies on the Doppler effect, which is the change in frequency of a wave due to the motion of the source or observer. Since stationary objects do not produce any motion-related frequency shifts, they cannot be detected by a Pulse Doppler system.

Surface search is used extensively as a navigation aid in coastal waters and in poor weather conditions. It is able to detect and determine accurate range and bearing of surface objects and low flying aircraft. This type of search is specifically designed to locate and track objects on or near the surface of the water, making it ideal for navigation purposes in coastal areas and during adverse weather conditions.

The three methods of transmission mentioned in the question are Pulse Modulation (PM), Frequency Modulation (FM), and Continuous Wave (CW). These are all different techniques used for transmitting signals in various communication systems. Pulse Modulation involves encoding the message signal into a series of pulses, while Frequency Modulation varies the frequency of the carrier signal according to the message signal. Continuous Wave, on the other hand, uses a continuous carrier signal without any modulation. These methods are commonly used in telecommunications and broadcasting to transmit information over long distances.

Frequency modulation (FM) is a type of RF transmission that radiates RF energy with a continuously changing frequency. In FM, the frequency of the carrier wave is modulated by the input signal, causing the frequency to increase and decrease from a fixed reference. This modulation technique is commonly used in broadcasting and communication systems to transmit audio signals with high fidelity.

The question asks for a phase of tracking that is not included in the given options. The options include Designation, Height, Acquisition, and Tracking. Out of these options, Height is not a phase of tracking. Designation refers to the process of identifying and selecting a target, Acquisition refers to the process of acquiring and locking onto the target, and Tracking refers to the process of continuously monitoring and following the target's movement. Height, on the other hand, does not represent a specific phase in the tracking process.

Continuous Wave RF transmission operates on the principle of the Doppler effect and is the best means of detecting fast moving targets when range and resolution are not required. Continuous wave transmission involves the continuous emission of a single frequency signal, which allows for the detection of moving targets by measuring the frequency shift caused by the Doppler effect. This method is particularly effective for detecting fast-moving targets as it provides a constant signal for tracking their movement. Pulse modulation and frequency modulation, on the other hand, are not specifically designed for detecting fast-moving targets and may not provide the same level of accuracy in such scenarios.

Tracking provides continuous positional data on a target and is used as a fire control radar.

Missile guidance is the system or technology that directs a missile towards its intended target. It involves various methods such as radar, GPS, inertial navigation systems, and target tracking systems. These systems provide information about the target's location and the missile's position, allowing the missile to adjust its trajectory and make necessary corrections to hit the target accurately. By combining these guidance techniques, missiles can be guided to their targets with high precision and effectiveness.

Approach radar is used to help an aircraft land even in bad weather conditions. It provides guidance and information to the pilot during the final stages of landing, ensuring a safe and accurate approach. This radar system assists in detecting obstacles, monitoring the aircraft's position, and guiding it towards the runway, even in low visibility situations. By utilizing approach radar, pilots can navigate and land the aircraft safely, regardless of the weather conditions.

The transmitter pulse, pulse width, and the recovery time of the duplexer and receiver determine the minimum range. This means that these factors play a crucial role in determining the shortest distance at which the transmitter can effectively communicate with the receiver. The pulse characteristics and recovery time directly impact the ability of the system to detect and receive signals accurately, thus defining the minimum range at which communication is possible.