87 lines
4.6 KiB
Markdown
87 lines
4.6 KiB
Markdown
E7F Software defined radio fundamentals: digital signal processing (DSP) filtering, modulation, and demodulation; analog-digital conversion; digital filters
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- [[E7F01]] (C)
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What is meant by “direct sampling” in software defined radios? #card
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- [[A.]] Software is converted from source code to object code during operation of the receiver
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- [[B.]] I and Q signals are generated by digital processing without the use of RF amplification
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- [[C.]] Incoming RF is digitized by an analog-to-digital converter without being mixed with a local oscillator signal
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- [[D.]] A switching mixer is used to generate I and Q signals directly from the RF input
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- [[E7F02]] (A)
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What kind of digital signal processing audio filter is used to remove unwanted noise from a received SSB signal? #card
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- [[A.]] An adaptive filter
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- [[B.]] A crystal-lattice filter
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- [[C.]] A Hilbert-transform filter
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- [[D.]] A phase-inverting filter
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- [[E7F03]] (C)
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What type of digital signal processing filter is used to generate an SSB signal? #card
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- [[A.]] An adaptive filter
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- [[B.]] A notch filter
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- [[C.]] A Hilbert-transform filter
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- [[D.]] An elliptical filter
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- [[E7F04]] (D)
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Which method generates an SSB signal using digital signal processing? #card
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- [[A.]] Mixing products are converted to voltages and subtracted by adder circuits
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- [[B.]] A frequency synthesizer removes unwanted sidebands
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- [[C.]] Varying quartz crystal characteristics are emulated in digital form
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- [[D.]] Signals are combined in quadrature phase relationship
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- [[E7F05]] (B)
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How frequently must an analog signal be sampled to be accurately reproduced? #card
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- [[A.]] At least half the rate of the highest frequency component of the signal
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- [[B.]] At least twice the rate of the highest frequency component of the signal
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- [[C.]] At the same rate as the highest frequency component of the signal
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- [[D.]] At four times the rate of the highest frequency component of the signal
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- [[E7F06]] (D)
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What is the minimum number of bits required to sample a signal with a range of 1 volt at a resolution of 1 millivolt? #card
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- [[A.]] 4 bits
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- [[B.]] 6 bits
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- [[C.]] 8 bits
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- [[D.]] 10 bits
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- [[E7F07]] (C)
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What function is performed by a Fast Fourier Transform? #card
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- [[A.]] Converting analog signals to digital form
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- [[B.]] Converting digital signals to analog form
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- [[C.]] Converting signals from the time domain to the frequency domain
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- [[D.]] Converting signals from the frequency domain to the time domain
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- [[E7F08]] (B)
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What is the function of decimation? #card
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- [[A.]] Converting data to binary-coded decimal form
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- [[B.]] Reducing the effective sample rate by removing samples
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- [[C.]] Attenuating the signal
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- [[D.]] Removing unnecessary significant digits
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- [[E7F09]] (A)
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Why is an anti-aliasing filter required in a decimator? #card
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- [[A.]] It removes high-frequency signal components that would otherwise be reproduced as lower frequency components
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- [[B.]] It peaks the response of the decimator, improving bandwidth
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- [[C.]] It removes low-frequency signal components to eliminate the need for DC restoration
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- [[D.]] It notches out the sampling frequency to avoid sampling errors
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- [[E7F10]] (A)
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What aspect of receiver analog-to-digital conversion determines the maximum receive bandwidth of a direct-sampling software defined radio (SDR)? #card
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- [[A.]] Sample rate
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- [[B.]] Sample width in bits
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- [[C.]] Integral non-linearity
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- [[D.]] Differential non-linearity
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- [[E7F11]] (B)
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What sets the minimum detectable signal level for a direct-sampling software defined receiver in the absence of atmospheric or thermal noise? #card
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- [[A.]] Sample clock phase noise
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- [[B.]] Reference voltage level and sample width in bits
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- [[C.]] Data storage transfer rate
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- [[D.]] Missing codes and jitter
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- [[E7F12]] (A)
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Which of the following is generally true of Finite Impulse Response (FIR) filters? #card
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- [[A.]] FIR filters can delay all frequency components of the signal by the same amount
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- [[B.]] FIR filters are easier to implement for a given set of passband rolloff requirements
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- [[C.]] FIR filters can respond faster to impulses
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- [[D.]] All these choices are correct
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- [[E7F13]] (D)
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What is the function of taps in a digital signal processing filter? #card
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- [[A.]] To reduce excess signal pressure levels
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- [[B.]] Provide access for debugging software
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- [[C.]] Select the point at which baseband signals are generated
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- [[D.]] Provide incremental signal delays for filter algorithms
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- [[E7F14]] (B)
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Which of the following would allow a digital signal processing filter to create a sharper filter response? #card
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- [[A.]] Higher data rate
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- [[B.]] More taps
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- [[C.]] Lower Q
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- [[D.]] Double-precision math routines
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