Extra-Study/pages/E7F.md

E7F Software defined radio fundamentals: digital signal processing (DSP) filtering, modulation, and demodulation; analog-digital conversion; digital filters

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