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1 What do the following abbreviations stand for?

1 FM 6 PAM 11 AFSK

2 PM 7 ASK 12 CPM

3 RF 8. QAM 13 SSB-AM

4 FDM 9 VSM 14 VSB-AM

5 PSK 10 OFDM 15 SSB-SC

2 Translate the following sentences into English:

1 Энергетическая эффективность определяет минимальную мощность передатчика, необходимую для приемлемой работы.

2 Спектральная эффективность – отношение скорости передачи данных к необходимой полосе пропускания радиоканала.

3 На сигнал могут воздействовать такие специфичные искажения как замирание вследствие многолучевого распространения, ограничение полосы, сосредоточенные по частоте и времени помехи и др.

4 Вероятность ошибки идеального демодулятора зависит от отношения сигнал/шум.

5 Для усиления сигналов с некоторыми видами модуляции могут быть использованы нелинейные усилители класса С.

3 Choose from part II the appropriate continuation of the sentences.

1 Digital baseband modulation or line codes are methods to transfer a digital bit stream over an analog low pass channel ………..

2 Each of these phases, frequencies or amplitudes …………..

3 Usually, each phase, frequency or amplitude…………

4 PSK and ASK, and sometimes also FSK, are often generated and detected……

5 The QAM principle can generate…………

6 Any possible band-limited signal can be decomposed………….

7 The I and Q signals can be combined into a complex valued signal………….

8 This number of bits comprises the symbol that is…………..

9 The resulting signal is a combination of PSK and ASK,…………

II 1 ….using QAM into the baseband I and Q signals necessary to generate it.

2 …. called the equivalent low pass signal or equivalent baseband signal.

3 … using the principle of QAM.

4 …. represented by the particular phase.

5 ….encodes an equal number of bits.

6 ….are assigned a unique pattern of binary bits.

7 …. with a finite number of at least two phases, and a finite number of at least two amplitudes.

8 ….any possible band-limited signal.

9.….using a discrete number of signal levels, by directly modulating the voltage or current on a cable.

4 Read the following paragraph. Fill in each blank with a suitable word given below.

Channel, scheme, allowing, data, medium, into, on, different, transfers, sub-carrier, share, modulation, than, over, considered, extended, summarized.

OFDM is based ______the idea of Frequency Division Multiplex (FDM), but is utilized as a digital _______scheme. The bit stream is split ______several parallel _______streams, each transferred over its own _______using some conventional digital modulation______. The sub-carriers are ______into an OFDM symbol. OFDM is _______as a modulation technique rather ______a multiplex technique, since it ______one bit stream ______one communication______using one sequence of so-called OFDM symbols. OFDM can be ______to multi-user channel access method in the Orthogonal Frequency Division Multiple Access (OFDMA) and MC-OFDM schemes, ______several users to ______the same physical ______by giving ______sub-carriers to different users.