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This figure was generated using the following code:

n=50000;                           % number of steps in simulation r=randn(n,1);                      % generate raw random inputsenv=0.75+abs(sin(2*pi*[1:n]'/n));  % the fading profiler=r.*env;                          % apply profile to raw input r[k] ds=0.5;                            % desired power of output = d^2a=zeros(1,n); a(1)=1;              % initialize AGC parameter s=zeros(1,n);                      % initialize outputsmu=0.01;                           % algorithm stepsize for k=1:n-1  s(k)=a(k)*r(k);                  % normalize by a(k) to get s[k]   a(k+1)=a(k)-mu*(s(k)^2-ds);      % adaptive update of a(k)end
agcvsfading.m compensating for fading with an AGC (download file)

The “fading profile” defined by the vector env is slow compared with the rate at which the adaptive gain moves, which allows the gain to track the changes. Also, the

When the signal fades (top), the adaptive parameter compensates (middle), allowing the output to maintain nearly constant power (bottom).
When the signal fades (top), the adaptive parameter compensates (middle),allowing the output to maintain nearly constant power (bottom).

power of the input never dies away completely. The problemsthat follow ask you to investigate what happens in more extreme situations.

Mimic the code in agcvsfading.m to investigate what happens when the input signal diesaway. (Try removing the abs command from the fading profile variable.) Can you explain what you see?

Mimic the code in agcvsfading.m to investigate what happens when the power of the input signalvaries rapidly. What happens if the sign of the gain estimate is incorrect?

Would the answers to the previous two problems change if usingalgorithm [link] instead of [link] ?


Sampling transforms a continuous-time analog signal into a discrete-time digital signal. In the time domain, thiscan be viewed as a multiplication by a train of pulses. In the frequency domain this corresponds to a replication ofthe spectrum. As long as the sampling rate is fast enough that the replicated spectra do not overlap, the samplingprocess is reversible; that is, the original analog signal can be reconstructed from the samples.

An AGC can be used to make sure that the power of the analog signal remains in the region where the sampling deviceoperates effectively. The same AGC, when adaptive, can also provide a protection against signal fades. The AGC can be designedusing a steepest descent (optimization) algorithm that updates the adaptive parameter by moving in thedirection of the negative of the derivative. This steepest descent approach to the solutionof optimization problems will be used throughout Software Receiver Design .

For further reading

Details about resampling procedures are available in the published works of

  • Smith, J. O. “Bandlimited interpolation—interpretation and algorithm,” 1993,

which is available at his website at http://ccrma-www.stanford.edu/ ˜ jos/resample/.

A general introduction to adaptive algorithms centered around the steepest descent approach can be found in

  • B. Widrow and S. D. Stearns, Adaptive Signal Processing, Prentice-Hall, 1985.

One of our favorite discussions of adaptive methods is

  • C. R. Johnson Jr., Lectures on Adaptive Parameter Estimation, Prentice-Hall, 1988.

This whole book can be found in .pdf form on the website accompanying this book.

Questions & Answers

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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how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
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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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what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
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a perfect square v²+2v+_
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algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
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rolling four fair dice and getting an even number an all four dice
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Kristine 2*2*2=8
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Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
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Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
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. 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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I start with an easy one. carbon nanotubes woven into a long filament like a string
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preparation of nanomaterial
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
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how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
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I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Software receiver design. OpenStax CNX. Aug 13, 2013 Download for free at http://cnx.org/content/col11510/1.3
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