Radar itself is an abbreviation for RAdio Detection and Ranging. Radar systems send out modulated waveforms using antennas in order to transmit electromagnetic energy into a specific volume of space to search for targets. Objects (i.e. targets) within a certain volume will reflect part of the energy (radar returns or echoes) back to the radar. From these radar returns, the radar reciever then extracts information such as velocity and range, angular position, and other identifying characteristics.
Assumptions made in poject for radar
In our project, we decided to keep the level of complexity of how rader is utilized down to a manageable level for a group size of two. As a result we made the following assumptions in our approach to modeling radar inside of Matlab.
The target is in direct line with our transmitted wave (i.e. not at an angle)
For velocity processing, the target has a constant velocity
For range processing, the target is not moving
We will now examine the concept of one of the most commonly used signals to do radar processing, the Linear Frequency Modulated Chirp (LFM Chirp) and its characteristics. Following that, the important concept of match filtering is discussed since it is implemented for calculating the range of a target.
Linear frequency modulated chirp (lfm chirp)
Basic definition (in continuous time)
A linear frequency modulated chirp signal for radar is defined by the equation (1)
Lfm continuous-time chirp
t = time on the range of [-T/2,T/2],
T =time duration in seconds of LFM signal pulse,
W = swept bandwitdth over the life of the pulse in Hz
Characteristics
The changing frequency of the chirp signal sweeps from (-1/2)W to +(1/2)W Hz. It is interesting to note that the phase of s(t) varies quadratically versus t while the frequency changes linearly versus time. The deriviative of phase determines the instantaneous frequency of the signal. The signal is complex valued in this case because it is the baseband form of the linear frequency modulation.
See Figure(1.1 ) below for example.
Characteristics of spectrum
Thus, it would seem like the frequency spectrum S(f) would have most of its energy in the range of | f |<(W/2). However, this is in fact only true if the frequency sweeps slowly enough or if T is large enough.
Modeling chirp with matlab
In Matlab however, the chirp signal has to be represented as a discrete time signal. A solution to this problem is to just oversample s(t) enough so that we can effectively simulate the continuous time version. Otherwise, if we just wanted to have a discrete time signal, the sampling frequency would be kept approximately equal to the swept bandwidth W. But, we will need to oversample by at least a factor of 5 at least in order to properly simulate the continous time signal.
Figure(1.1) continuous-time lfm chirp radar signal
Continuous-time LFM chirp radar signal
Since the chirp signal is compex valued and will be processed through a complex valued matched filter, all plots must be made of either the real part of equations (1), (2), or of the magnitude of the Fourier transform below. Figure 1.1 is a plot of the real part of the LFM chirp.
Questions & Answers
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
