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--- radar:doppler [2018/06/05 21:26] – masrour
+++ radar:doppler [2026/04/28 15:13] (current) – external edit 127.0.0.1
@@ Line 247: / Line 247: @@
 <figure label>
 {{ :media:new_cw.png?400x400 }}
-<caption> (upper . Fig) Simple CW radar block diagram ; (lower. Fig) response characteristic of beat-frequency amplifier [(cite:Image8>> title: http://nptel.ac.in/courses/101108056/module2/lecture4.pdf, section:Cw Radar:Doppler frequency shift,publisher:nptel
+<caption> (upper . Fig) Simple CW radar block diagram ; (lower. Fig) response characteristic of beat-frequency amplifier [(cite:Image8>> title: http://nptel.ac.in/courses/101108056/module2/lecture4.pdf ,section:Cw-Radar,Doppler frequency shift,publisher:nptel)] </caption>
-)] </caption>
 </figure>
@@ Line 1261: / Line 1260: @@
 When the MTI improvement factor is not great enough to reduce the clutter sufficiently..the clutter residue will appear on the display and prevent the detection of aircraft targets whose cross sections are larger than the clutter residue.
-Whereby setting the limit level $L$, relative to the noise $N$, equal to the MTI improvement factor $I$ or $L/N = 1$. If the limit level relative to noise is set higher than the improvement factor. clutter residue obscures part of the display and If it is set too low there may be a " black hole " effect on the display. The limiter provides a **C**onstant **F**alse **A**larm **R**ate (**CFAR**) and is essential to usable MTI performance.
+Whereby setting the limit level $L$, relative to the noise $N$, equal to the MTI improvement factor $I$ or $L/N = 1$. If the limit level relative to noise is set higher than the improvement factor. clutter residue obscures part of the display and If it is set too low there may be a " black hole " effect on the display. The limiter provides a **C**onstant **F**alse **A**larm **R**ate (**CFAR**)[(A **false alarm** is “an erroneous radar target detection decision caused by noise or other interfering signals exceeding the detection threshold”. In general, it is an indication of the presence of a radar target when there is no valid aim. The False Alarm Rate (FAR) is calculated using the following formula: $FAR=\frac{false targets per PRT}{Number of rangecells}$)] and is essential to usable MTI performance.
 Unfortunately, nonlinear devices such as limiters have side-effects that can degrade performance.
@@ Line 1280: / Line 1279: @@
-The **M**oving **T**arget **D**etector, as we discussed earlier ,is able to optimize mobile targets in the presence of white addictive and clutter or improves target resolution.by use of the $Neyman$-$Pearson$ optimum filter theory according to the $SNR_{max}$, the optimum FIR filter ($h_k$) will be
+The **M**oving **T**arget **D**etector, as we discussed earlier ,is able to optimize mobile targets in the presence of white addictive and clutter or improves target resolution.
+The output of the receiver is a signal, which contains the required target plus various forms of noise and clutter. In the case of the MTI output, this clutter residue is the result of imperfect cancellation due to various factors such as equipment instability, antenna modulation, lack of dynamic range or Doppler content within the clutter itself. The detection process separates the required target from the noise and clutter. Detectors are normally designed to carry out this process with a constant false alarm rate (CFAR).
-\begin{equation}
+The diagram shows the location of the detector in the chain of signal processing. This device forms the information on a point like target as a digital report. The up to this point existing information about the analog value (or digital description of) of the received power in a particular binary cell will be transformed to information about the coordinates of a target. The value of the power is included in this report mostly.
- h_k=s^{\ast }_{k}= exp^{(-2j\pi k f_{D}{T})}
-\end{equation}
-Where, $W = M^{-1}s^{\ast }$ and $M = I$ ,
+The important procedure is, that up to this point all binary cells (containing the received power) must be processed. After the detector exist only reports about selected binary cells. However, there may exist several reports about a single target, generated by adjacent binary cells. This will processed in the next device.
-\begin{equation}
+<figure label>
- h_{fD}(f)= \sum_{k=1}^{N}h_kz^{-k}|_{z=exp(j2\pi fT)}
+{{ :media:termination_of_mti_mtd.png?500 }}
-\end{equation}
+<caption> Part of block diagram(information flow)[(cite:Image3)]</caption>
+ </figure>
-therefore
-\begin{equation}
- h_{fD}(f)= exp\left ( -j\frac{2\pi (N-1)}{2}(f+f_{D})T \right )\frac{sen(\pi(f+f_D)TN )}{sen[\pi(f+f_D)T]}
-\end{equation}
-If the Doppler frequency associated with the target is known it is possible to calculate  $h_{fD}(f)$ and FIR filter in otherwise instead of making a single optimum processor its possible to realize as many of expected doppler ranges for a category of targets ( i.e. using N-optimum filter for N- given frequency ).
-\begin{equation}
- f_{Di}=-\frac{iPRF}{N}
-\end{equation}
-Where $N$ is number of pulses in the beam and is equal to (N = 0,1,2,..,N-1).
+Until now its simply discused about MTI performance limitiation ,MTD device operation and using different filters or transformation.deeper discussion on the Doppler frequency and adaptive thresholds on the different filters ,etc. __is presented in__
-More information is presented in **Modern Radar System Analysis** by **David K.Barton** chapter $6$.
+    *  **Modern Radar System Analysis**, Author: David K.Barton ,chapter $6$ .
+    *  **Advanced radar techniques and systems**, Author: Gaspare Galati ,chapter $12$ .