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This program performs spectral analyses on five separate time series, each 400 samples in length.

Each time series contains a pulse and the pulses are different lengths. (The lengths of the individual pulses match that shown in Figure 1 .) Each pulse consists of a truncated sinusoid. The frequency of the sinusoid for each pulseis the same.

All frequency values are specified as type double as a fraction of the sampling frequency. The frequency of all five sinusoids is 0.0625 times thesampling frequency.

The lengths of the pulses are:

  • 25 samples
  • 50 samples
  • 100 samples
  • 200 samples
  • 400 samples

If this sounds familiar, it is because the pulses are identical to those displayed in Figure 1 and discussed under Dsp031a above.

Uses a DFT algorithm

The spectral analysis process uses a DFT algorithm and computes the amplitude of the spectral energy at 400 equally spaced frequencies between zero and thefolding frequency.

(Recall from the module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm that the folding frequency is one-half the sampling frequency.)

This program computes and displays the amplitude spectrum at frequency intervals that are one-half of the frequency intervals for a typical FFTalgorithm.

Normalize the results

The results of the spectral analysis are multiplied by the reciprocal of the lengths of the individual pulses to normalize all five plots to the same peakvalue. Otherwise, the results for the short pulses would be too small to see on the plots.

Will discuss in fragments

Once again, this program is very similar to programs explained in the previous module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm . Therefore, this discussion will be very brief.

Beginning of the class named Dsp031

The code in Listing 3 declares and initializes some variables and creates the array objects that will contain the sinusoidal pulses.

In addition, the code in Listing 3 declares reference variables that will be used to refer to array objects containing results of the spectral analysisprocess that are not used in this program.

Finally, Listing 3 declares reference variables that will be used to refer to array objects containing the results plotted in Figure 2 and Figure 3 .

Given the names of the variables, the comments, and what you learned in the earlier modules, the code in Listing 3 should be self explanatory.

Listing 3. Beginning of the class named Dsp031.
class Dsp031 implements GraphIntfc01{ final double pi = Math.PI;int len = 400;//data length //Sample that represents zero time.int zeroTime = 0; //Low and high frequency limits for the// spectral analysis. double lowF = 0.0;double highF = 0.5; int numberSpectra = 5;//Frequency of the sinusoids double freq = 0.0625;//Amplitude of the sinusoids double amp = 160;//Following arrays will contain data that is // input to the spectral analysis process.double[] data1 = new double[len]; double[]data2 = new double[len];double[] data3 = new double[len]; double[]data4 = new double[len];double[] data5 = new double[len];//Following arrays receive information back // from the spectral analysis that is not used// in this program. double[]real; double[]imag; double[]angle;//Following arrays receive the magnitude // spectral information back from the spectral// analysis process. double[]mag1; double[]mag2; double[]mag3; double[]mag4; double[]mag5;

Questions & Answers

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
what is the coefficient of -4×
Mehri Reply
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
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lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
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12, 17, 22.... 25th term
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12, 17, 22.... 25th term
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I'm 13 and I understand it great
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
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find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
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If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
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I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
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Commplementary angles
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A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
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how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
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