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-jps-



Joined: 03 Jan 2008
Posts: 23
Post23 Sep 2008 14:04   Help
Someone answers this questions pls.... Crying or Very sadCrying or Very sad

1. Why are signals soft keyed?


2. How does the spectrum of an unipolar and a bipolar PAM differ?

3. At what frequency spacing do the spectral lines follow one another when only the sampling pulse is analyzed?

4. In what cases can the information signal no longer be filtered out of the PAM signal by a low pass filter Fg=3.4 kHz?

5. How can a PSK modulator be assembled with the product modulator?
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m_pourfathi



Joined: 07 Feb 2008
Posts: 200
Helped: 13
Post24 Sep 2008 7:20   Re: Help
I didn't fully understand your questions but only the second one.
The difference between a same-rated unipolar and bipolar pulse is that it contains a dc component so it will have an dirac impulse function with the mean value of the unipular pulse in the zero frequency which bipolar doesn't have.
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