LESSON 1
INTRODUCTION TO TELEPHONE SYSTEMS
SCOPE ............................. Survey of terms and definitions used to
describe
characteristics
of
telephone
communication
systems;
effect
of
these
characteristics on transmission losses.
CREDIT HOURS ...................... 2
TEXT ASSIGNMENT ................... Attached Memorandum, para
1-1
thru
1-3;
Appendix A, para 1 thru 31;
Appendix B, para 1 thru 9
MATERIALS REQUIRED................ None
SUGGESTIONS ....................... Study Appendix A and Appendix B first, and
then the Attached Memorandum.
LESSON OBJECTIVES
When you have completed this lesson, you should:
1.
Know that the interfering effect of noise depends upon its amplitude and
frequency.
2.
Know that loading of a telephone line reduces its attenuation over the
voice-frequency range.
3.
Know that leakage in a telephone line reduces the amount of received
signal power.
4.
Know that a telephone line has characteristics resembling those of a low-
pass filter.
5.
Know that the passband of a telephone network need be no greater than the
bandwidth of the signal.
6.
Know that careless
use
of
telephones
by
system
users
can
introduce
disturbing noise.
7.
Be able to compare weighting characteristics.
8.
Be able to determine resistance of a wire in a pair from the knowledge of
its resistance per loop mile.
9.
Be able to
determine
cutoff
of
a
line
from
its
loss
characteristic.
1
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