100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Exam (elaborations) TEST BANK FOR Principles of Communication Systems, $5.80
Add to cart

Exam (elaborations)

Exam (elaborations) TEST BANK FOR Principles of Communication Systems,

 4 views  0 purchase
  • Course
  • Institution

Exam (elaborations) TEST BANK FOR Principles of Communication Systems, For the single-sided spectra, write the signal in terms of cosines: x(t) = 10 cos(4πt + π/8) + 6 sin(8πt + 3π/4) = 10 cos(4πt + π/8) + 6 cos(8πt + 3π/4 − π/2) = 10 cos(4πt + π/8) + 6 cos(8πt + π/4) For the d...

[Show more]

Preview 4 out of 330  pages

  • February 13, 2022
  • 330
  • 2021/2022
  • Exam (elaborations)
  • Questions & answers
avatar-seller
,Chapter 2

Signal and Linear System Theory

2.1 Problem Solutions
Problem 2.1
For the single-sided spectra, write the signal in terms of cosines:

x(t) = 10 cos(4πt + π/8) + 6 sin(8πt + 3π/4)
= 10 cos(4πt + π/8) + 6 cos(8πt + 3π/4 − π/2)
= 10 cos(4πt + π/8) + 6 cos(8πt + π/4)

For the double-sided spectra, write the signal in terms of complex exponentials using Euler’s
theorem:

x(t) = 5 exp[(4πt + π/8)] + 5 exp[−j(4πt + π/8)]
+3 exp[j(8πt + 3π/4)] + 3 exp[−j(8πt + 3π/4)]

The two sets of spectra are plotted in Figures 2.1 and 2.2.

Problem 2.2
The result is

x(t) = 4ej(8πt+π/2) + 4e−j(8πt+π/2) + 2ej(4πt−π/4) + 2e−j(4πt−π/4)
= 8 cos (8πt + π/2) + 4 cos (4πt − π/4)
= −8 sin (8πt) + 4 cos (4πt − π/4)




1

,2 CHAPTER 2. SIGNAL AND LINEAR SYSTEM THEORY


Single-sided amplitude Single-sided phase, rad.
10 π/4


5 π/8

f, Hz f, Hz
0 2 4 6 0 2 4 6



Figure 2.1:

Problem 2.3
(a) Not periodic.
(b) Periodic. To find the period, note that
6π 20π
= n1 f0 and = n2 f0
2π 2π
Therefore
10 n2
=
3 n1
Hence, take n1 = 3, n2 = 10, and f0 = 1 Hz.
(c) Periodic. Using a similar procedure as used in (b), we find that n1 = 2, n2 = 7, and
f0 = 1 Hz.
(d) Periodic. Using a similar procedure as used in (b), we find that n1 = 2, n2 = 3, n3 = 11,
and f0 = 1 Hz.

Problem 2.4
(a) The single-sided amplitude spectrum consists of a single line of height 5 at frequency 6
Hz, and the phase spectrum consists of a single line of height -π/6 radians at frequency 6
Hz. The double-sided amplitude spectrum consists of lines of height 2.5 at frequencies of
6 and -6 Hz, and the double-sided phase spectrum consists of a line of height -π/6 radians
at frequency 6 Hz and a line of height π/6 at frequency -6 radians Hz.
(b) Write the signal as
xb (t) = 3 cos(12πt − π/2) + 4 cos(16πt)
From this it is seen that the single-sided amplitude spectrum consists of lines of height 3
and 4 at frequencies 6 and 8 Hz, respectively, and the single-sided phase spectrum consists

, 2.1. PROBLEM SOLUTIONS 3




Double-sided amplitude
5


f, Hz

-6 -4 -2 0 2 4 6


Double-sided phase, rad.
π/4

π/8
-6 -4 -2
f, Hz
0 2 4 6
-π/8

-π/4



Figure 2.2:

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller COURSEHERO2. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $5.80. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

51056 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 15 years now

Start selling
$5.80
  • (0)
Add to cart
Added