Page 194 - Computer_Science_F5

Transmission waves Properties
Communication (i) In satellite communication, signal transferring between
satellite or light the sender and receiver is done with the help of a satellite. Chapter Three: Advanced Computer Networks
waves (ii) The signal, which is a beam of modulated microwaves,
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is sent toward the satellite. Then the satellite amplifies
the signal and sends it back to the receiver’s antenna
present on the earth’s surface. So, all the signal
transferring is happening in space. Thus, this type of
communication is known as space communication.

Cable testing tools
Every cable run must receive a minimum level of testing. The most important test
is simply determining whether the cable pairs are connected properly or not. To
achieve testing, you can use cable testers which are included in Table 3.10.
Table 3.10: Cable testers
No Tool Description

(a) Tone generators and amplifier probes A wire-map tester that examines wire
pairs to ensure they are correctly
connected and checks the continuity
of each wire. Figure 3.38 shows a
simple tester that performs both wire-
map and continuity testing.

Figure 3.38: Tone generator

(b) Continuity testers This tool tests if the signal reaches the
far end of the cable. Simple continuity
testers confirm signal reception as
shown in Figure 3.39 but do not test
for attenuation or crosstalk.

Figure 3.39: Signal testing tool
(c) Wire-map testers A wire-map tester checks if wire pairs
are correctly connected and verifies
wire continuity. Figure 3.40 shows
a tester that performs both wire-map
and continuity testing.

Figure 3.40: A simple cable testing tool

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