Quiz 7: Digital Communications Techniques

What is the chief disadvantage of analog communication? A.Simplicity B.Bandwidth requirements C.Susceptibility to noise D.Cost

What concept is represented by noise corrupted signals being periodically restored to their original values recreating an ideal,perfect representation of data at regular intervals and enabling transmissions over long distances? A.Regeneration B.Coding C.Pulse modulation D.DSP processing

In _______________,the pulse amplitude is made proportional to the amplitude of the modulating signal. A.pulse-width modulation (PWM) B.pulse-amplitude modulation (PAM) C.pulse-position modulation (PPM) D.pulse-code modulation (PCM)

Which of the following forms the basis for class D power amplification? A.PCM B.PPM C.PAM D.PWM

The process of ____________ is one of reproducing the original analog signal. A.coding B.modulation C.demodulation D.aliasing

Which of the following allows complex,periodic waveforms to be broken down into a series of sine and cosine terms? A.Flat-top sampling B.Quantization C.Reconstruction D.Fourier analysis

_________ is assigning one of a fixed number of numerical values to each pulse. A.Coding B.Sampling C.Quantizing D.Decoding

Which of the following did Harry Nyquist in 1928 first demonstrate mathematically? A.An analog signal can be reconstructed from periodic samples. B.Pulses can be time-division multiplexed over a single communication channel. C.The sample rate must be at least twice the highest frequency of the intelligence or information signal to be sampled. D.Analog signals are quantized to the closest binary value provided in the digitizing system.

What function does the sample-and-hold circuit perform in a PCM system? A.Encoder B.Modulator C.Filter D.Decoder

Why do high-quality capacitors have polyethylene,polycarbonate,or Teflon dielectrics? A.They minimize voltage variations resulting from capacitor characteristics. B.They limit the maximum input frequency that the S/H circuit can accurately process. C.They convert quantized waveforms into stepped analog signals. D.They isolate the input signal from the S/H circuit and provide proper impedance matching.

Analog signals are quantized to the closest _________ value provided in the digitizing system. A.waveform B.bit C.binary D.pulse

What is required to increase the resolution of a digitizing system? A.The number of quantization levels to be increased. B.The aperture and acquisition times must limit the maximum input frequency. C.The maximum input or output voltage level to the smallest voltage level be quantized and/or reproduced by the converters. D.The input amplitude must be increased with reference to the quantizing error.

In what terms is dynamic range typically expressed? A.Decibels B.Bits C.Ohms D.Farads

What is the primary advantage of the flash ADC? A.It uses little power. B.It's simplicity. C.It is inexpensive. D.It is very fast.

What is the most common method of error detection? A.Block check character B.CRC dividing circuit C.Parity D.Cyclic redundancy check

With codes and data,error detection is accomplished through some form of ___________. A.redundancy B.modulation C.coding D.quantization

Techniques that allow correction at the receiver are called forward error-correcting codes.Which of the following is an example of an FEC? A.Nyquist B.Hamming C.Schmitt D.Fourier

What technique do Reed-Solomon (RS)codes employ to enable the system to correct multiple data-bit errors? A.Aliasing B.Amplitude companding C.Natural sampling D.Interleaving

Conversion of the digital word to analog form consists of three steps: regeneration,decoding,and _______________. A.modulation B.reconstruction C.distortion D.substitution

PCM is a building block in many digital communication applications and consists of three steps: sampling,quantizing,and __________. A.decoding B.coding C.error-detection D.retransmission

What does error detection and correction techniques rely heavily on? A.Digital signal processing B.Baseband transmission C.Pulse modulation D.Capacitance

__________ involves the use of mathematical functions such as addition and multiplication to control the characteristics of a digitized signal. A.Flat-top sampling B.Interleaving C.Reed-Solomon coding D.Digital signal processing

The undesired byproduct of mixing is known as a(n)___________. A.sine-wave B.alias C.pulse train D.Nyquist rate

Which of the following is the conversion of quantized waveform into a stepped analog signal? A.Regeneration B.Digitizing C.Modulation D.Reconstruction