机载雷达常用工作模式，你都知道吗？
Unlike ground system, that can afford to have different radars for different roles, airborne radars often have strict limitations in size and weight. Thus, for a fighter, her radar have to take on various jobs.
小划子As a result, software were developed to allow radars to operate in very different modes, each with unique PRF, scan ctor and pul duration so as to be best optimid to the specific job that they have to do at that moment. Here are some common radar modes.
Velocity Search（VS）
The PRF are t at maximum, higher PRF results in more power on target, more power mean more reflection, this mode is specifically for detecting medium and high closure targets, with the cost of not detecting low and no-closure targets at all.
Velocity arch mode displays targets on the radar screen by azimuth and velocity instead
of by azimuth and range. In velocity arch, many new puls are nt before original pul coming back.
Thus, radar cannot determine the distance, as a result it can only be ud for detection rather than tracking. Main advantage of velocity arch mode is very long detection range, could be double of track while scan mode.
Range While Scan（RWS）
会议安排The system is t up so as to get quick target information at the expen of accuracy. The RWS mode provides all-aspect (no-on, tail-on) and all-altitude (look-up, look-down) target detection.
This is the most commonly ud mode upon nearing a hostile environment. It is a good balance of wide volume and fairly rapid scan. This mode is ud to resolve multiple targets parated by less than the antenna beam width, at long range.
形影不离There are three RWS modes, depending on what PRF is ud for emitting radar energy. I
n RWSH mode high PRF is ud, while in RWSM mode medium PRF is ud.
High PRF’s are better to detect distant contacts with high closure rates with the risk of low or no-closure contact not showing up on the radar screen.
Medium PRF’s are not very good at long ranges since they are subject to clutter when receiving returns from long ranges, but they are uful for detecting medium-range low closure targets or targets which are below the radar water line.
A good mixture of high and medium PRF’s is realid in RWSI mode (interleaved RWS) when the radar emits energy alternating between high and medium PRF’s as it scans through bars.
RWS mode cannot be ud to effectively to attack targets, but to get quick information about where the potential targets are. RWS is the most common mode.
电脑怎么看wifi密码Track While Scan（TWS）
With the aid of sophisticated computer systems, multi-function radars are capable of simultaneously tracking many targets. In this ca, each target is sampled once (mainly range and angular position) during a dwell interval (scan).
Then, by using smoothing and prediction techniques future samples can be estimated. The mode that allow radar to perform multi-tasking and multi-target tracking are known as Track-WhileScan (TWS) radars.
黄忠技能Once a radar in TWS mode detects a new target it initiates a parate track file for that detection; this ensures that quential detections from that target are procesd together to estimate the target’s future parameters.
Position, velocity, and acceleration compri the main components of the track file. Typically, at least one other confirmation detection (verify detection) is required before the track file is established.
Unlike single target tracking systems, TWS radars must decide whether each detection belongs to a new target or belongs to a target that has been detected in earlier scans. 雪作文400字
And in order to accomplish this task, TWS radar systems utilize correlation and association algorithms. In the correlation process, each new detection is correlated with all previous detections in order to avoid establishing redundant tracks.
Generally, in TWS mode the radar system places a gate around the target position and attempts to track the signal within this gate. The gate dimensions are normally azimuth, elevation, and range.
Becau of the uncertainty associated with the exact target position during the initial detections, a gate has to be large enough so that targets do not move appreciably from scan to scan;
more precily, targets must stay within the gate boundary during successive scans. After the target has been obrved for veral scans the size of the gate is reduced considerably.
