CISSE Advanced Level
Networking and Telecommunications glossary
Every term this guide defines, A to Z, each with the chapter that teaches it. Open it when a word in a question is unfamiliar, and test yourself on it in the last week: cover the definition and say it in one sentence.
14 terms from the free first chapter
A
- Attenuation
The weakening of a signal's strength as it travels along a medium, which is why long transmission runs need amplification or regeneration.
Taught in Introduction to network and telecommunication systems
B
- Bandwidth
The range of frequencies a medium can carry (analogue), or the maximum data rate it can support (digital), commonly measured in Hz or bits per second respectively.
Taught in Introduction to network and telecommunication systems
C
- Communication system
The complete arrangement of hardware, software and protocols that gets a message from a source to a destination, of which a data network is the transport layer.
Taught in Introduction to network and telecommunication systems
- Crosstalk
Unwanted coupling between adjacent transmission paths, a signal on one cable or channel bleeding into another running alongside it.
Taught in Introduction to network and telecommunication systems
F
- Full-duplex
Data flows in both directions simultaneously, e.g. an ordinary telephone call.
Taught in Introduction to network and telecommunication systems
H
- Half-duplex
Data flows in both directions, but only one direction at a time, e.g. a walkie-talkie.
Taught in Introduction to network and telecommunication systems
I
- Impulse noise
Irregular, high-amplitude spikes from external sources (lightning, electrical switching), brief but capable of corrupting a burst of data outright.
Taught in Introduction to network and telecommunication systems
- Intermodulation noise
Produced when signals of different frequencies share the same medium and interact, generating spurious signals at sum and difference frequencies.
Taught in Introduction to network and telecommunication systems
J
- Jitter
The variation in latency from one packet to the next, particularly damaging to real-time voice and video, which expects a steady, predictable arrival rate.
Taught in Introduction to network and telecommunication systems
L
- Latency
The time delay between a signal being sent and being received.
Taught in Introduction to network and telecommunication systems
N
- Network
An interconnected set of devices able to exchange data, ranging from two directly connected computers to the global internet.
Taught in Introduction to network and telecommunication systems
S
- Simplex
Data flows in one direction only, sender to receiver, never the reverse, e.g. a broadcast radio signal.
Taught in Introduction to network and telecommunication systems
T
- Thermal noise
Random noise from the thermal agitation of electrons in a conductor, present in every electronic system and unavoidable in principle, only reducible.
Taught in Introduction to network and telecommunication systems
- Throughput
The actual achieved data rate in practice, which is always less than or equal to the theoretical bandwidth once overhead and contention are accounted for.
Taught in Introduction to network and telecommunication systems
The full glossary adds every term from the other 13 chapters, A to Z, each with the chapter that teaches it.