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Approach

Flow chart for approach of range

Range analysis block diagram

Range Analysis Block Diagram

Chirp and chirp train design

First, we design a Linear Frequency Modulated (LFM) chirp for the desired time-bandwidth product amount (TW), oversampling amount p, and sampling frequency (fs) . The MATLAB program" dchirp2 "will build up a single pulse while" ctbuild4 "will design a burst waveform consisting of L chirps, repeated over a period M.

Example of"Dchirp2"Matlab function call

[s,h,y,T,W,Ts] = dchirp2(TW,p,sampfreq) with outputs:
  • s = single LFM chirp set to specified input paramters
  • h = match filter impulse response
  • y = (used for testing of original code) passing s through match filter
  • T = time duration of LFM chirp (units: sec)
  • W= swept bandwidth of LFM chirp (units: Hz)
  • Ts= sampling period (1/fs)

Example of"Ctbuild4"Matlab function call

[s,ssent,h,y,T,W,Ts] = ctbuild4(TW,p,sampfreq,M,L) with outputs:
  • s = single chirp defined by TW,p
  • ssent = noise-free burst waveform of L lfm chirps of the same TW, p
  • h = match filter impulse response
  • y = (used for testing of original code) passing s through match filter
  • T = time duration of LFM chirp (units: sec)
  • W= swept bandwidth of LFM chirp (units: Hz)
  • Ts= sampling period (1/fs)

Simulate radar returns

In order to simulate proper radar returns, we first simulate the noise of a channel. Thus, we add complex white Gaussian nosie, using the"crandn"command in MATLAB, to our complex train of chirps. We perform this opertion in our main MATLAB function called" burst4 ."Next, we then apply a time delay to our signal. The program accomplishes that by shifting a vector x of length N to the right by amount TD.
For the project we worked only with an assumed value of SNR = -10 dB (i.e. the std. deviation is the square root of 10 multiplied against the chirp's average amplitude). We did a visual comparison of these two values to make sure our value of n was correct. See MATLAB function" burst4 "for detailed commentary.
The TD value inputted by the user is in terms of how many elements the user wants to physically shift the transmitted wave form by and do not correspond to actual units of time.

Defining max range of radar processing

The Maximum Range of our radar system is determiend by two things. First, how large the resting time is between consecutive falling and rising edges of chirps. Secondly, how long our signal is. The reason why these are important is that since this model for range processing is in discrete time, we can not simulate an infinite range for our targets. That would correspond to having to time delay our transmitted signal by a extremely large amount. If shifted by an amount greater than the signal's length, the simulated return would just be a flat line of value zero for the length of the signal. Basically, the signal can be time delayed only up until the first LFM chirp's falling edge. This location corresponds to the last value of the recieved signal to ensure getting a big enough spike in the match filter's output to use in calculating range. Thus, since we define the value for time period (Ts) of our chirp pulse train and the number of pulses, we can define the max range by finding the maximum amount we can shift our signal. Then by plugging in this max Td value into the discrete-time range equation below, the max range value is found.

Equation for max time delay

MaxTD M L M N

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Damian Reply
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s. Reply
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are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
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what is the actual application of fullerenes nowadays?
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That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
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Mostly, they use nano carbon for electronics and for materials to be strengthened.
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is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
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SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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what's the easiest and fastest way to the synthesize AgNP?
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Cied
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I start with an easy one. carbon nanotubes woven into a long filament like a string
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Source:  OpenStax, Ece 301 projects fall 2003. OpenStax CNX. Jan 22, 2004 Download for free at http://cnx.org/content/col10223/1.5
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