Deck 12: Signal Conversion and Processing

Question 1

Digital Signal Processing is the processing of analog signals by conversion to digital form.

Answer 1

True

Question 2

After DSP, a digital signal can be converted back to a much- improved version of the original analog signal.

Answer 2

True

Question 3

Usually an analog signal does not require filtering before DSP occurs.

Answer 3

False

Question 4

The process preformed by an ADC is called quantization.

Question 5

A digital- to- analog (D/A) converter changes data like temperature variations into digital quantities.

Question 6

An operational amplifier can be used as a comparator.

Question 7

An eight- bit D/A converter has a resolution of 0.125.

Question 8

The primary disadvantage of the flash A/D converter is the large number of comparators required.

Question 9

When the analog input to a tracking A/D converter is at a constant level, the digital output will oscillate.

Question 10

DSPs are typically programmed in either assembly language or in C.

Question 11

The DSP, unlike the general- purpose microprocessor, must typically process data in real time; that is, as it happens.

Question 12

The typical DSP does not have a CPU like a general- purpose microprocessor does.

Question 13

What operation can a DSP perform on incoming data?

A) increase the amplitude of selected frequencies
B) remove unwanted interference
C) detect errors
D) all the above

Question 14

What operation can a DSP perform on incoming data?

A) reduce the amplitude of selected frequencies
B) correct errors
C) encode the data
D) all the above

Question 15

The highest frequency component of the analog signal in an ADC is known as theD) packets.

A) Shannon frequency
B) Nyquest frequency
C) Aliasing frequency
D) Sampling frequency

Question 16

Quantization is performed by a(n) D) packets.

A) DAC
B) DSP
C) ADC
D) Filter

Question 17

An analog- to- digital converter (ADC) has a four- bit output. How many analog values can it represent?

A) 4
B) 0.0625
C) 1/4
D) 16

Question 18

An analog quantity varies from 0- 7 V and is input to a 6- bit A/D converter. What analog value is represented by each step on the digital output?

A) 0.109 V
B) 0.111 V
C) 0.857 V
D) 1.17 V

Question 19

What function is performed by the block labeled 'X' in the figure below?

A) Power supply for the audio amplifier
B) Analog- to- digital conversion
C) Audio ON/OFF control
D) Digital- to- analog conversion

Question 20

Which of the equations below expresses the voltage gain relationship for an operational amplifier?

A) Vout/Vin = - Rf/Rin
B) Vin/Vout = Rout/Rin
C) Vout = Vin/Av
D) Vout/Vin = Rout/Rin

Question 21

What type of op- amp circuit does not typically have a feedback path connected between its output and either of its input pins?

A) A current multiplier
B) An open- loop amplifier
C) An inverter
D) A comparator

Question 22

?

-The circuit shown in Figure 12- 1 is a(n) ________.

A) R/2R ladder D/A converter
B) binary- weighted- input DAC
C) four- bit decoder
D) four- bit A/D converter

Question 23

?

-What is the output from the circuit in Figure 12- 1 at the time marked 'X'?

A) 2.75 V
B) 1.011 V
C) - 1.011 V
D) - 2.75 V

Question 24

The circuit shown below is a(n) _________.

A) four- bit A/D converter
B) R/2R ladder D/A converter
C) binary- weighted- input DAC
D) four- bit decoder

Question 25

What advantage does the R/2R ladder DAC have over a binary- weighted- input DAC?

A) The virtual ground is eliminated and the circuit is therefore easier to understand and troubleshoot.
B) It uses only two different resistor values.
C) It is much easier to analyze its operation.
D) It has fewer parts for the same number of inputs.

Question 26

What is the resolution of a D/A converter?

A) It is the deviation between the ideal straight- line output and the actual output of the converter.
B) It is the reciprocal of the number of discrete steps in the D/A output.
C) It is the comparison between the actual output of the converter and its expected output.
D) The ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.

Question 27

What is the linearity of a D/A converter?

A) It is the deviation between the ideal straight- line output and the actual output of the converter.
B) It is the ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.
C) It is the reciprocal of the number of discrete steps in the D/A output.
D) It is the comparison between the actual output of the converter and its expected output.

Question 28

What is the accuracy of a D/A converter?

A) It is the ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.
B) It is the deviation between the ideal straight- line output and the actual output of the converter.
C) It is the reciprocal of the number of discrete steps in the D/A output.
D) It is the comparison between the actual output of the converter and its expected output.

Question 29

What is the resolution, in percent, of a 12- bit DAC?

A) 0.024
B) 0.000488
C) 0.083
D) 8.33

Question 30

A simultaneous A/D converter is also known as a/an ________A/D converter.

A) asynchronous
B) flash
C) synchronous
D) comparator

Question 31

The primary disadvantage of the simultaneous A/D converter is _________.

A) the long conversion time required
B) the large number of output lines required to simultaneously decode the input voltage
C) the large number of comparators required to represent a reasonable- sized binary number
D) that it requires the input voltage to be applied to the inputs simultaneously

Question 32

What is the main disadvantage of the stairstep- ramp A/D converter?

A) It requires a precision clock in order for the conversion to be reliable.
B) It requires a counter.
C) The counter must count up from zero at the beginning of each conversion sequence, so the conversion time varies with the input voltage.
D) All of the above are correct.

Question 33

The figure below represents a _________.

A) tracking A/D converter
B) successive- approximation A/D converter
C) dual- approximation D/A comparator
D) dual- slope A/D converter

Question 34

The main advantage that a tracking A/D converter has over a stairstep- ramp A/D converter is that it ________.

A) uses an up/down counter to allow it to measure both positive and negative voltages
B) is faster
C) does not require a counter
D) uses an up/down counter to indicate the polarity of the input voltage

Question 35

One disadvantage of the tracking A/D converter is ________.

A) the need for an accurate clock reference for the counter
B) the binary output will oscillate between two binary states when the analog input is constant
C) the need for a latch and its associated control circuit
D) it requires two counters: one for up and one for down

Question 36

Which of the following describes the basic operation of a single- slope A/D converter?

A) A ramp generator is used to enable a counter through a comparator. When the ramp voltage equals the input voltage the counter is latched and then reset. The counter reading is proportional to the input voltage since the ramp is changing at a constant V/second rate.
B) A ramp voltage and analog input voltage are applied to a comparator. As the input voltage causes the integrating capacitor to charge, it will at some point equal the ramp voltage. The ramp voltage is measured and displayed on the digital panel meter.
C) The input voltage is used to set the frequency of a voltage- controlled oscillator (VCO). The VCO quits changing frequency when the input voltage stabilizes. The frequency of the VCO, which is proportional to the analog input voltage, is measured and is displayed on the digital display as a voltage reading.
D) Any of the above could be correct, depending on the specific type of A/D converter involved.

Question 37

Which of the statements below best describes the basic operation of a dual- slope A/D converter?

A) The input voltage is used to set the frequency of a voltage- controlled oscillator (VCO). The VCO quits changing frequency when the input voltage stabilizes. The frequency of the VCO, which is proportional to the analog input voltage, is measured and is displayed on the digital display as a voltage reading.
B) A ramp voltage and analog input voltage are applied to a comparator. As the input voltage causes the integrating capacitor to charge, it will at some point equal the ramp voltage. The ramp voltage is measured and displayed on the digital panel meter.
C) A ramp generator is used to enable a counter through a comparator. When the ramp voltage equals the input voltage the counter is latched and then reset. The counter reading is proportional to the input voltage since the ramp is changing at a constant V/second rate.
D) Two ramps are generated: one by the input voltage and the other by a reference voltage. The input voltage ramp charges the integrating capacitor, while the reference voltage discharges the capacitor and enables the counter until the capacitor is discharged, at which time the counter value is loaded into the output latches.

Question 38

The basic approach to testing D/A converters is to ________.

A) apply a sequence of binary codes covering the full range of the input to the input while observing the output on an oscilloscope. The output should consist of a linear stairstep ramp
B) single- step the device through its full input range while checking the output with a DMM
C) apply the correct input to the analog terminal and then check to see if the proper binary code exists on the digital inputs
D) check the output with zero input and then full input. The output of the converter should extend from zero to its maximum value. If so, then everything in between can be assumed to be operating properly

Question 39

Refer to the figure below. What, if anything, appears to be wrong with the output of the D/A converter?

A) It appears that certain input codes are incorrect; double- check the input coding.
B) There appears to be some nonlinearity in the scope display.
C) The converter has a nonmonotonic output error.
D) The input signal is probably noisy.

Question 40

?

-Refer to Figure 12- 2. What, if anything, appears to be wrong with the D/A converter?

A) There is an offset error.
B) There is nothing wrong with the converter.
C) The power supply voltage appears to be too high.
D) There is a nonlinearity error.

Question 41

Refer to the figure below. What should the display on the scope look like if the A/D converter is working properly?

A) The pattern should be a straight line across the screen due to the equal but opposite voltages being applied to the scope inputs.
B) The scope should display a sequential binary count with the LSB being on the left and the MSB on the right side of the display.
C) A uniform stairstep pattern should be displayed.
D) It should be a circular Lissajous pattern resulting from the simultaneous application of ramps to the vertical and horizontal inputs of the oscilloscope.

Question 42

Sigma- Delta ADC utilizes ________.

A) a one- bit quantization method
B) quantized difference between two samples
C) delta modulation
D) all of the above

Question 43

DSPs are programmed in ________.

A) assembly language
B) ABEL
C) visual basic
D) none of the above

Question 44

DSP applications include ________.

A) telecommunications
B) radar
C) speech generation
D) all of the above

Question 45

DSP applications include ________.

A) image processing
B) music processing
C) filtering
D) all of the above

Question 46

The CPU of the DSP is also known as ________.

A) the general- purpose registers
B) the ALU
C) the DSP core
D) the MIPS