Digital Communications Final Exam

Both amplitude and phase of the carrier frequency are varied proportional to the binary input signal

• Amplitude Shift Keying

• Frequency Shift Keying

• Phase Shift Keying

• Quadrature Amplitude Modulation

BPSK transmitter and receiver consists of the following circuits except

• balanced modulator

• clock recovery

• level converter

• carrier recovery

• low pass filter

In higher-level encoding systems such as 8-PSK, 16-PSK, 16-QAM, and 32-QAM, the bit rate is always _______ the baud.

• lesser than

• greater than

• equal

Digital modulation is also known as digital radio because digitally modulated signals can be propagated through Earth’s atmosphere and used in wireless communications systems.

• TRUE

• FALSE

8-QAM and 16-QAM transmitters both have two (2) ___________________ and ____________ as inputs to the two (2) product modulators.

• level converters

• 2-to-4 level converters

• reference oscillators

• bandpass filters

Another name for a constellation diagram is a signal state-space diagram.

• TRUE

• FALSE

QPSK modulator that consists of two BPSK modulators combined in parallel.

• TRUE

• FALSE

Digital communication transport information in digital form (digital pulses) and therefore, require a physical facility between the transmitter and receiver, such as a metallic wire pair, a coaxial cable, or an optical fiber cable.

• TRUE

• FALSE

The FSK modulated signal in a noncoherent FSK detection is simultaneously applied to the bandpass filters while for a coherent FSK receiver, the FSK modulated signal is multiplied by a recovered carrier signal.

• TRUE

• FALSE

Baud and minimum bandwidth are always equal in all forms of digital modulation except to _____.

• Amplitude Shift Keying

• Frequency Shift Keying

• Phase Shift Keying

• Quadrature Amplitude Modulation