Use of power lines for transmission of messages (PLC, BPL)

1. The abbreviation PLC encompasses:

		a)	systems for telecommunication over cables
		b)	specifically, narrowband telecommunication systems using power lines
		c)	specifically, broadband telecommunication systems using power lines
		d)	broadband as well as narrowband telecommunication systems using power lines

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2. Ripple control systems in power distribution network use the band:

		a)	10 kHz – 100 kHz
		b)	up to 100 Hz
		c)	217 Hz – 1050 Hz
		d)	30 kHz – 150 kHz

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3. Ripple control transmitters can not be connected to the power distribution network at the secondary side of transformers:

		a)	very high voltage / high voltage
		b)	high voltage / high voltage
		c)	high voltage / low voltage
		d)	very high voltage / low voltage

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4. The structure of ripple control code sequence with serial double-commands is as follows:

		a)	starting impulse – security space – command part
		b)	starting impulse – security space – address part – command part
		c)	starting impulse – security space – command part – address part
		d)	starting impulse – address part – command part

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5. The operating frequencies commonly used in ripple control systems do correspond to:

		a)	the band 200 Hz – 300 Hz
		b)	the frequencies corresponding to odd harmonics of the technological frequency 50 Hz
		c)	the band 1000 Hz – 3000 Hz
		d)	the band 150 Hz – 500 Hz

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6. Duration of the command code most commonly used in the Czech Republic is:

		a)	64 s
		b)	33 s
		c)	120 s
		d)	125 s

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7. Parameters of high-frequency PLC systems in the Czech Republic are the following:

		a)	HF band 10 kHz – 150 kHz, LF bandwidth 4 kHz
		b)	HF band 30 kHz – 150 kHz, LF bandwidth 2.5 kHz
		c)	HF band 30 kHz – 750 kHz, LF bandwidth 2.5 kHz or 4 kHz
		d)	HF band 150 kHz – 1000 kHz, LF bandwidth 4 kHz

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8. Narrowband PLC systems use (according to the EN 50065-1 standard) the band:

		a)	0.25 MHz – 0.75 MHz
		b)	3 kHz – 148.5 kHz
		c)	from tens up to hundreds of kHz, with transmission speeds from units up to hundreds of Mbit/s
		d)	from units up to hundreds of MHz, with transmission speeds from tens up to hundreds of kbit/s

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9. Broadband PLC systems (BPL) operate most usually with the following parameters:

		a)	bandwith from units up to hundreds of MHz, transmission speed from units up to hundreds of Mbit/s
		b)	bandwith from units up to hundreds of MHz, transmission speed from units up to tens of Mbit/s
		c)	bandwith from tens up to hundreds of kHz, transmission speed from units up to hundreds of Mbit/s
		d)	bandwith from units up to hundreds of MHz, transmission speed from units up to hundreds of kbit/s

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10. BPL systems in public power distribution network (outdoor part) most commonly use the frequecies:

		a)	148.5 kHz – 1 MHz
		b)	1MHz – 18 MHz
		c)	10 MHz – 52 MHz
		d)	1 MHz – 30 MHz

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11. BPL systems in private section of the power distribution network (indoor part – i.e. in buildings) commonly use the frequencies:

		a)	148.5 kHz – 1 MHz
		b)	1MHz – 18 MHz
		c)	10 MHz – 52 MHz
		d)	18 MHz – 30 MHz

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12. BPL systems most commonly use the following modulation methods:

		a)	amplitude modulation with suppressed carrier
		b)	frequency modulation
		c)	spread-spectrum modulation – DSSM, modulation with transmission in separate subbands – OFDM
		d)	combination of amplitude modulation and pulse-code modulation

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13. Which modulation allows selective disabling of a disturbed frequency band at the expense of lower transmission speed?

		a)	DSSM
		b)	PCM
		c)	OFDM
		d)	FM

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14. Which PLC systems suffer from the most serious EMC problems?

		a)	HDO
		b)	HF power plants telephony
		c)	Narrowband systems for local telematics
		d)	Broadband (BPL) systems

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15. Contemporary overhead very-high voltage power lines use for communication purposes optical cable

		a)	that is led in parallel with power wires
		b)	that is woven into a pair of phase wires
		c)	that is woven into the ground protective wire
		d)	that is woven into one phase wire

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16. Ripple control systems in power distribution network are used to transmit signals

		a)	in both directions over a branched network
		b)	in one direction over a branched network
		c)	in both directions over a non-branched network
		d)	in one direction over a non-branched network

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17. Static frequency converters in ripple control transmitters on the secondary side of a 110 kV / 22 kV transformer commonly operate with the output power

		a)	1 kVA
		b)	10 kVA
		c)	100 kVA
		d)	800 VA

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18. The ripple control receivers using the principle of serialized double-commands can recognize

		a)	up to ten double-commands
		b)	tens of double-commands
		c)	hundreds of double-commands
		d)	thousands of double-commands

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19. Which applications cannot be implemented with the help of ripple control?

		a)	switching of rates in electricity meters
		b)	distribution systems coupled with remote control
		c)	distribution systems of warning signals
		d)	remote control of public lighting

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20. Narrowband telematic PLC systems can commonly reach the distance of

		a)	tens of meters
		b)	tens of kilometers
		c)	hundreds of meters, up to approx. 5 km
		d)	up to approx. 50 km

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