Chapter 4 Questions 16 to 30

	16. What grounding device allows the data to be save safely if there is a power cut
		Uninterruptable Power Supply
		Surge Suppressor
		Power Distribution Panel
		Transformer

	17. A continuously waving voltage is given the name
		Direct current
		Alternating current
		Analog signal
		Digital signal

	18. The number of cycles an alternating current completes in one second is known as
		Amplitude
		Period
		Time
		Frequency

	19. What does propagation mean
		Power signal loss
		White noise
		Travel
		Collision

	20. If propagation time is too short, what is the solution to the problem
		Use of buffer memory
		Speed up the transmission of digital data
		Slow down the transmission of digital data
		There is only a problem in network communication when propagation time is too long

	21. Attenuation problem with digital communication can be solve by
		Repeater
		Switch
		Router
		NIC

	22. Loss of signal strength is described by
		Propagation
		Attenuation
		Collision
		Reflection

	23. A reflection with a signal can be cause by
		Mismatch in impedance in the networking media
		Crack in the fibre optic cable
		Broken Wire
		All of the above

	24. Which is not a recognised form of noise
		Cross talk
		Thermal noise
		EMI
		RFI
		Ground noise
		Jitter

	25. If two computers are not synchronised then this is known as what to the digital signal
		Latency
		Jitter
		Dispersion
		White noise

	26. In a collision
		the digital signal is said to lengthen in time
		the digital signal is said to loss strength
		the digital signal is said to be destroyed bit by bit
		the digital signal is said to reflect back down the cable

	27. Bits at the destination computer are
		Decoded into a Data PDU
		Encoded into a Data PDU
		Decrypted into a Data PDU
		Encrypted into a Data PDU

	28. Which of the following are Binary encoding Systems
		TTL
		Manchester
		NRZ-L
		All of the above

	29. Which analogue encoding system increases and decreases the energy of the signal
		FM
		AM
		PM
		FPM

	30. AM stands for
		Amplitude Modulation
		Alternating Modulation
		Amplitude Modulus
		Alternating Modulus