# 0.2 A police gun radar and how it works

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This describes the basics of how a police gun works and what happens to the sent/received signals.

## Police simulation

The police simulation simulates the function of the radar gun translating the received spectrum into a speed estimate. The police program takes in the sent frequency and the spectrum from the car or the jammed signal. With this, the police program can reconstruct the unshifted, attenuated reflection of the pulse from the background and reflected signal to obtain a spectrum. Using a matched filter, the simulation shifts through the frequency spectrum and compares to the Gaussian pulse to the received spectrum using the inner product to produce a vector of comparison values. The maximum index of the vector can be interpreted as the shifted freqnecy, and using this value, the speed of the car can be computed. The final output of the police gun is the estimated velocity of the car, which is the original frequency over the recieved frequency, multiplied by the speed of light.

For the program simulations, this velocity can be compared to the original input to the car simulation to check the accuracy of the police program, as well as the relative effectiveness of the various jamming methods.

## Example

Let's suppose that the frequency of the pulse was 1GHz. Figure 1 shows what the spectrum of the police gun is. The pulse is centered around 0.

Figure 2 shows a doppler effect of the signal reflected back. The first spike is the reflected, non-shifted surroundings portion, and the second, smaller spike is the Doppler shifted portion, which is reflected off of the car. We have a certain amount of background noise that is added to the signal. The radar gun does recognize the non-shifted part, and strips it off, leaving only the shifted part, shown in figure 3:

#### Questions & Answers

where we get a research paper on Nano chemistry....?
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
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da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
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Alexandre
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Rafiq
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Damian
How we are making nano material?
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What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
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