Data-Acquisition Challenges: Answers and Winners

Data-Acquisition Challenge: December 2008

Question
To what type of measurement can a Hall-effect sensor be applied (choose the best answer)?

a) Rotational speed 
b) Fluid flow 
c) Current 
d) Pressure 
e) All of the above 
f) A and B only 
g) B and C only 
h) A and C only

Answer: The correct answer is e.

Winner: The winners of the two $100 Best Buy gift cards (courtesy of Test & Measurement World) are Neal Naumann, Stafford, TX; and John Shea, Pittsburgh, PA.

Data-Acquisition Challenge: November 2008

Question
Many data-acquisition and control systems use a high-value (1 mega-ohm or greater) pull-up resistor connected between a thermocouple and a fixed voltage. Why?

a) The pull-up resistor eliminates a ground loop that can cause measurement errors. 
b) If the thermocouple breaks, an open circuit will occur. The resistor will pull up to the fixed voltage and trick the system into shutting down heaters, preventing a runaway heating condition. 
c) A thermocouple needs bias voltage to operate over its full temperature range. 
d) The resistor prevents external interference from reaching the measuring circuits. 
e) The measurement circuits get their power through the pull-up resistor. 

Answer: The correct answer is b.

Winner: The winners of the two $100 Best Buy gift cards (courtesy of Test & Measurement World) are Darrell Wagner, Austell, GA; and Arnold Spring, Springfield, MA. 

Data-Acquisition Challenge: October 2008

Question
What is the potential role of LXI in data-acquisition applications?

a) To provide signal conditioning for low-level sensor outputs in noisy industrial applications.
b) To facilitate time-stamping in multichannel data-acquisition applications.
c) To provide a convenient way of providing power to remote sensors.
d) LXI is an instrument standard and has no role in data acquisition.

Answer: The correct answer is b.

Winner: The winners of the three $100 American Express gift cards (courtesy of contest sponsor Data Translation) are Glen Chenier, Allen, TX; Yao Ding, San Carlos, CA; and James Migliaccio, Greensboro, NC.

Data-Acquisition Challenge: September 2008

Question
Which of the following sensors needs no excitation voltage or current, thus no external power source?

a) Strain gage 
b) RTD 
c) Thermistor 
d) Accelerometer 
e) Thermocouple 
f) None of the above 

Answer: The correct answer is e.

Winner: The winners of the three $100 American Express gift cards (courtesy of contest sponsor Data Translation) are Mark Timmer, Grand Rapids, MI; Gary Mierzwa, Pensacola, FL; and David Perez, West Mifflin, PA.

Data-Acquisition Challenge: August 2008

Question
Which kind of sensor typically uses six wires?

a) strain gage
b) RTD
c) thermistor
d) accelerometer
e) thermocouple
f) none of the above

Answer: The correct answer is a.

Winner: The winner of the $300 American Express gift card (courtesy of contest sponsor Data Translation) is Adam Tarpine, Thorofare, NJ.

Data-Acquisition Challenge: July 2008

Question
Assume a signal measured with a voltmeter reads 1 VRMS. Which statement is true regarding the peak voltage?

a) The peak voltage is always 1.414 V.
b) The peak voltage is 1.414 V if the signal is purely sinusoidal.
c) The peak voltage is always greater than 1 V.
d) The peak voltage is always less than 1 V.

Answer: The correct answer is b.

Winner: The winner of the TomTom ONE navigational system (courtesy of contest sponsor Data Translation) is Alice Young, Huntington Beach, CA.

Data-Acquisition Challenge #13: December 2007

Question
Which of the following statements about thermocouples, RTDs, and thermistors is true?

a) Thermistors’ resistance always increases with temperature.
b) RTDs’ resistance always decreases with temperature.
c) Thermocouples are typically more accurate than either RTDs or thermistors.
d) All of these statements are true.
e) None of these statements is true.

Answer: The correct answer is e.

Winner: The winner of the $100 American Express gift certificate courtesy of Test & Measurement World is John Paschkewitz, St Louis, MO.

Data-Acquisition Challenge #12: November 2007

Question
To what does the term "gauge factor" apply?

a) Change in resistance with respect to strain.
b) Change in voltage with respect to strain.
c) Change in resistance with respect to pressure.
d) Change in voltage with respect to pressure.
e) None of the above.

Answer: The correct answer is a.

Winner: The winner of the $100 American Express gift certificate courtesy of Test & Measurement World is James McDonald, Sterling, VA.

Data-Acquisition Challenge #11: October 2007

Question
To what does the term "gauge factor" apply?

a) Change in resistance with respect to strain.
b) Change in voltage with respect to strain.
c) Change in resistance with respect to pressure.
d) Change in voltage with respect to pressure.
e) None of the above.

Answer: The correct answer is a.

Winner: The winner of the $100 American Express Gift Card courtesy of Test & Measurement World is Shawn Quinn, Redmond, WA.

Data-Acquisition Challenge #10: September 2007

Question
To what type of data-acquisition system do considerations relating to Poisson’s Ratio apply?

a) One that measures temperature.
b) One that measures strain.
c) One that measures pressure.
d) One that measures flow.
e) None of the above.

Answer: The correct answer is b.

Winner: The winner of the $100 American Express gift certificate courtesy of Test & Measurement World is Daniel T. Schellenbach, Vernon Hills, IL.

Data-Acquisition Challenge #9: August 2007

Question
Thermocouples are often described by a letter (K, E, G, N, for example). Which option below best describes to what this letter refers?

a) input temperature range
b) alloys from which the thermocouples are fabricated
c) output voltage as a nonlinear function of input temperature
d) accuracy
e) resolution

Answer: The correct answer is b.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsorYokogawa) is Vadryn Pierre, New York, NY.

Data-Acquisition Challenge #8: July 2007

Question
Which statement best defines an intelligent sensor?

a) An intelligent sensor must have a sensing element and computational capability.
b) An intelligent sensor must have a sensing element, computational capability, and a communications interface.
c) An intelligent sensor must have a sensing element, computational capability, a communications interface, and an actuator that responds intelligently to sensed parameters.

Answer: The correct answer is b.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor IOtech) is Tommy Harris, Kingsport, TN.

Data-Acquisition Challenge #7: June 2007

Question
The Hall effect can be applied to measure which of these parameters?

a) Current
b) Position
c) Acceleration
d) Magnetic flux density
e) Both a and b
f) Both a and d
g) All of the above

Answer: The correct answer is g.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor National Instruments) is Charles Trottman, Plano, TX.

Data-Acquisition Challenge #6: May 2007

Question
What is the purpose of the Steinhart-Hart equation?

a) It describes the nonlinear response of an LVDT.
b) It describes the nonlinear response of a thermistor.
c) It determines the sampling rate necessary to make time-varying temperature measurements.
d) It defines a data-acquisition system’s accuracy in terms of resolution and sampling rate.

Answer: The correct answer is b.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor National Instruments) is Michael Johnston, Camarillo, CA.

Data-Acquisition Challenge #5: April 2007

Question
Which of the following statements about pressure sensors is true?

a) A common way to measure pressure is to convert it to some intermediate form, such as displacement.
b) A thermocouple-based technique can be used to measure pressure.
c) A Pirani gauge employs a diaphragm or bellows to measure pressure.
d) Statements a and b are true.
e) Statements b and c are true.
f) Statements a, b, and c are all true.
g) None of the above statements is true.

Answer: The correct answer is d.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor National Instruments) is Qutaiba Khasawneh, Dallas, TX.

Data-Acquisition Challenge #4: March 2007

Question
Which statement accurately describes data-acquisition-system triggering? (You can find the answer in the Test & Measurement World archives.)

a) In a post-triggered acquisition, such as a crash test, a trigger event occurs and then the system collects the data you want.
b) A pretriggered acquisition can collect data before and after a trigger event occurs.
c) Statements a and b are both true.
d) Neither statement a nor statement b is true.

Answer: The correct answer is c.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor National Instruments) is David Perez, Bethel Park, PA.

Data-Acquisition Challenge #3: February 2007

Question
Which of the following statements regarding data-acquisition-system inputs is true?

a) Differential inputs compensate for common-mode noise.
b) Isolated inputs eliminate ground loops.
c) An integrating ADC can help compensate for power-line noise.
d) Statements a and b are true.
e) Statements b and c are true.
f) Statements a and c are true.
g) All these statements are true.

Answer: The correct answer is g.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor National Instruments) is Dennis Weller, Colorado Springs, CO.

Data-Acquisition Challenge #2: January 2007

Question
Regarding sensors used in data-acquisition systems, which of the following statements are true?

a) LVDTs are used to measure displacement
b) The IEEE 1451.4 standard describes transducer electronic data sheets (TEDS) for smart sensors.
c) All TEDS sensors require at least four wires: two to carry the digital TEDS information and two or more to carry analog sense and excitation signals.
d) a and b are true.
e) b and c are true.
f) a and c are true.
g) a, b, and c are all true.

Answer: The correct answer is d.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor National Instruments) is Duane Cousino, Canton, MI.

Data-Acquisition Challenge #1: December 2006

Question
Strain-gage data-acquisition applications typically employ Wheatstone-bridge circuit topologies. Which of the following statements are true?

a) Full-bridge configurations provide better sensitivity than do half- and quarter-bridge configurations.
b) The primary advantage of half- and quarter-bridge configurations is that they consume less power than full-bridge configurations and therefore are more suitable for use in battery-powered data-acquisition applications.
c) Kelvin-bridge configurations employ six wires: two excitation wires, two output wires, and two sense wires.
d) All of the above statements are true.
e) Statements (a) and (b) are true.
f) Statements (b) and (c) are true.
g) Statements (a) and (c) are true.
h) None of these statements is true.

Answer: The correct answer is g.

Winner: The winner of the Bose Noise-Canceling headphones (courtesy of contest sponsor IOtech) is Joe Plummer, Moscow, ID.

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