What is Quadrature Amplitude Modulation or QAM?

1. A A technique for digital data compression used in digital television which removes redundancy in the data by comparing bit amplitudes
2. B Transmission of data by modulating the amplitude of two carriers of the same frequency but 90 degrees out of phase
3. C A method of performing single sideband modulation by shifting the phase of the carrier and modulation components of the signal
4. D A technique for analog modulation of television video signals using phase modulation and compression

What is the definition of symbol rate in a digital transmission?

1. A The number of control characters in a message packet
2. B The maximum rate at which the forward error correction code can make corrections
3. C The rate at which the waveform changes to convey information
4. D The number of characters carried per second by the station-to-station link

Why should the phase of a PSK signal be changed at the zero crossing of the RF signal?

1. A To minimize bandwidth
2. B To simplify modulation
3. C To improve carrier suppression
4. D All these choices are correct

What technique minimizes the bandwidth of a PSK31 signal?

1. A Zero-sum character encoding
2. B Reed-Solomon character encoding
3. C Use of sinusoidal data pulses
4. D Use of linear data pulses

What is the approximate bandwidth of a 13-WPM International Morse Code transmission?

1. A 13 Hz
2. B 26 Hz
3. C 52 Hz
4. D 104 Hz

What is the bandwidth of an FT8 signal?

1. A 10 Hz
2. B 50 Hz
3. C 600 Hz
4. D 2.4 kHz

What is the bandwidth of a 4,800-Hz frequency shift, 9,600-baud ASCII FM transmission?

1. A 15.36 kHz
2. B 9.6 kHz
3. C 4.8 kHz
4. D 5.76 kHz

How does ARQ accomplish error correction?

1. A Special binary codes provide automatic correction
2. B Special polynomial codes provide automatic correction
3. C If errors are detected, redundant data is substituted
4. D If errors are detected, a retransmission is requested

Which digital code allows only one bit to change between sequential code values?

1. A Binary Coded Decimal Code
2. B Extended Binary Coded Decimal Interchange Code
3. C Extended ASCII
4. D Gray code

How can data rate be increased without increasing bandwidth?

1. A It is impossible
2. B Increasing analog-to-digital conversion resolution
3. C Using a more efficient digital code
4. D Using forward error correction

What is the relationship between symbol rate and baud?

1. A They are the same
2. B Baud is twice the symbol rate
3. C Baud rate is half the symbol rate
4. D The relationship depends on the specific code used

What factors affect the bandwidth of a transmitted CW signal?

1. A IF bandwidth and Q
2. B Modulation index and output power
3. C Keying speed and shape factor (rise and fall time)
4. D All these choices are correct

What is described by the constellation diagram of a QAM or QPSK signal?

1. A How many carriers may be present at the same time
2. B The possible phase and amplitude states for each symbol
3. C Frequency response of the signal stream
4. D The number of bits used for error correction in the protocol

What type of addresses do nodes have in a mesh network?

1. A Email
2. B Trust server
3. C Internet Protocol (IP)
4. D Talk group

What technique do individual nodes use to form a mesh network?

1. A Forward error correction and Viterbi codes
2. B Acting as store-and-forward digipeaters
3. C Discovery and link establishment protocols
4. D Custom code plugs for the local trunking systems