Data Acquisition Flashcards
What are the four standard elements of a DAQ device? (A single answer is correct)
a. Analogue I/O, Digital I/O, Counters, Pulse Width Modulation.
b. Analogue I/O, Digital I/O, Counters, Frequency.
c. Analogue Output, Analogue Input, Digital I/O, Frequency.
d. Analogue Output, Analogue Input, Digital I/O, Counters.
d. Analogue Output, Analogue Input, Digital I/O, Counters.
Analogue and Digital I/O’s, and Counters (iterations).
From that you can then measure freq, pwm, period etc
Which of the Figures Q illustrate LabVIEW code to implement a Functional Global Variable? (A single answer is correct).
A, B, C, D
A
The general form of a function global variable includes an unitalicized shift register with a single iteration for or while loop.
So the only one with a perpetual loop with a stop button is A.
Which of the following statements about an optical quadrature encoder with 200 counts per revolution are correct? (More than one answer may be correct).
a. The resolution will be 0.45 deg.
b. The resolution will be 1.8 deg.
c. Differentiating the signal encoder output will produce a noiseless angular velocity signal.
d. The output of the encoder will be a digital signal
a. The resolution will be 0.45 deg.
c. Differentiating the signal encoder output will produce a noiseless angular velocity signal.
d. The output of the encoder will be a digital signal
a. 360 deg / 200cpr = 1.8 / 4 = 0.45 deg …divide by 4 as quadrature!
c. Will essentially smoothen it, think TV
d. Encoder can only output digital
Which of the following statements regarding optical encoders is correct? (A single answer is correct)
a. Optical encoders output a digital signal.
b. Optical encoders output an analogue signal.
c. Optical encoders utilise small magnets inside them to sense position.
d. Optical encoders always have a high resolution.
a. Optical encoders output a digital signal.
Which of the following statements about race conditions is correct? (A single answer is correct).
a. Race conditions are easy to identify and debug.
b. Most race conditions only occur when a resource has multiple writers.
c. You can avoid race conditions by using variables.
d. Code with race conditions behaves differently every time it is executed.
b. Most race conditions only occur when a resource has multiple writers.
Race conditions are difficult to identify and fix, only occur when multiple writers, they can be avoided by reducing variables and controlling shared resources.
What is the code width (resolution) of a 12-bit ADC with a voltage signal range of -5V to +5V. (A single answer is correct)
a. 1.2μV
b. 1.2mV
c. 0.42V
d. 2.4mV
d. 2.4mV
10V / 2^12 = 0.00244V = 2.4mV
Which of the following statements are correct regarding arrays. (More than one answer may be correct)
a. You can create an array of arrays.
b. You can have an array with more than 3 dimensions.
c. It is possible to have a 2D array of ‘string’ data type.
d. The first element in an array is indexed at 0.
b. You can have an array with more than 3 dimensions.
c. It is possible to have a 2D array of ‘string’ data type.
d. The first element in an array is indexed at 0.
No you can’t create an array of arrays, no shit 8x8 etc, yes string=words, indexed at 0.
Which of the following statements regarding variables are correct? (More than a single answer may be correct)
a. Variables can be the following types: Local, Global, Functional Global and Shared.
b. Variables allow you to circumvent normal dataflow by passing data from one place to another without connecting the two places with a wire.
c. Variables should only be used when absolutely necessary.
d. You should use a global variable or a single process shared variable to share data between multiple VI’s.
a. Variables can be the following types: Local, Global, Functional Global and Shared.
b. Variables allow you to circumvent normal dataflow by passing data from one place to another without connecting the two places with a wire.
c. Variables should only be used when absolutely necessary.
d. You should use a global variable or a single process shared variable to share data between multiple VI’s.
All are correct
Which of the following statements are correct? (More than one answer may be correct).
a. The speed which a While loop executes can be changed.
b. A For loop can have an iteration terminal.
c. You cannot have a While loop within a While loop.
d. A While loop can execute zero times.
a. The speed which a While loop executes can be changed.
b. A For loop can have an iteration terminal.
Inspect the LabVIEW code and identify which of the statements a) – d) are correct. (More than a single answer may be correct)
a. The top loop will execute 3 times
b. The loops will not execute in parallel
c. The output of ‘Numeric’ will be 2
d. Neither of the loops will execute
a. The top loop will execute 3 times
b. The loops will not execute in parallel
c. The output of ‘Numeric’ will be 2
Top executes 3 times yes. Not parallel, think electricity, this would be series not parallel. And numeric will be 2 as iterations is 0 based.
Which of the following statements are correct? (More than one answer may be correct)
a. The 4 bit binary number 0101 represents the number 5.
b. The 4 bit binary number 0111 represents the number 10.
c. The highest numeric value that can be represented by a 12-bit number is 4095?
d. The highest numeric value that can be represented by a 12-bit number is 4096?
a. The 4 bit binary number 0101 represents the number 5.
c. The highest numeric value that can be represented by a 12-bit number is 4095
0x2^3 + 12^2 +02^1 + 1*2^0
= 4 + 1 = 5
b^n -1
= 2^12 -1 = 4095
Which of the following statements are correct? (More than one answer may be correct)
a. To reduce problems associated with aliasing you should apply a low pass filter at half the sampling frequency.
b. Aliasing can always be solved by increasing the sampling frequency.
c. Aliasing means frequencies above half of the sampling frequency appear at frequencies below half the sampling frequency.
d. To avoid problems with aliasing your sampling frequency should be twice that of the highest frequency contained in your signal.
a. To reduce problems associated with aliasing you should apply a low pass filter at half the sampling frequency.
c. Aliasing means frequencies above half of the sampling frequency appear at frequencies below half the sampling frequency.
d. To avoid problems with aliasing your sampling frequency, the frequency should be twice that of the highest frequency contained in your signal.
For b. It doesn’t solve anything. Frequencies above half will still appear below. Aliasing doesn’t disappear.
Which of the following statements is correct about buffered Data Acquisition? (A single answer is correct)
a. Buffered Data Acquisition does not require a fixed sample rate.
b. Buffered Data Acquisition is not suitable for control applications.
c. Buffered Data Acquisition utilises less memory overhead than single sample Data Acquisition.
d. Buffered Data Acquisition should always be used for acquiring Digital Signals.
b. Buffered Data Acquisition is not suitable for control applications.
Buffered does require a fixed sample rate, isn’t suitable for control applications, uses more memory (think RAM), just not true.
Which of the statements below is correct regarding the LabVIEW code illustrated in the figure? (More than one answer may be correct)
a. The Case structure only has the Cases ‘Startup’, ’Shutdown’, and ’Idle’.
b. The error cluster has data types of Boolean, Numeric, and String contained within it.
c. This is an example of a state machine architecture.
d. The code within the “Startup” Case will execute as fast as possible.
b. The error cluster has data types of Boolean, Numeric, and String contained within it.
c. This is an example of a state machine architecture.
d. The code within the “Startup” Case will execute as fast as possible.
a. No as we don’t know for sure that its only startup, shutdown and idle. Could be more.
b. Yes as all error clusters contain status (boolean), code that identifies the error numerically, and source (string).
c. Yes state machine as we have T/F, numbers (iterations, wait timer) and text.
d. Yes as no timer.
The equation below illustrates the relationship between the Gain in decibels and the gain of an amplifier. Which of the following answers (a-d) correctly represents the gain in dB if a voltage of 400μV is the input to the amplifier and a voltage of 5mV is measured as the output. The answers are displayed in 2 significant figures format. (A single answer is correct). GdB = 20 Log(G) a. 61.6 dB b. -61.6 dB c. 21.9 dB d. -21.9 dB
Input = 400 x 10-6V. Output = 5 x 10-3V
G = 5 x 10-3 / 400 x 10-6 G = 0.005 / 0.0004 G = 12.5
Gdb = 20Log10G Gdb = 20Log10 12.5 Gdb = 20 x 1.0969 Gdb = 21.9
Which of the following statements about ultrasonic sensors are correct? (More than one answer may be correct)
a. Ultrasonic sensors use ultrasound at a frequency of 2KHz.
b. Two ultrasonic sensors can interfere with each other.
c. The bearing of the ultrasonic sensor will have a finite uncertainty.
d. Environmental noise cannot affect an ultrasonic sensor.
b. Two ultrasonic sensors can interfere with each other.
c. The bearing of the ultrasonic sensor will have a finite uncertainty.
50KHz not 2KHz, ofc they can interfere, won’t be infinitely uncertain, environmental noise can affect ultrasonic…imagine a dolphin and a container ship
The LabVIEW code illustrates a For Loop and Shift Register. What will be the number displayed in the numeric indicator ‘Output’ when the code has finished executing? (A single answer is correct).
a. 4
b. 24
c. 8
d. 2
a. 4
Top shift register: 2x1 = 2 2x2 = 4 2x3 = 6 2x4 = 8
Bottom shift registers means previously value. So, 2 initial 2 initial from above 2 = 2x1 4 = 2x2
Whilst top does, 2x1, 2x2, 4x3, 12x4
The LabVIEW code illustrates a For loop. What will be the output of ‘Indicator’ when the loop finishes? (A single answer is correct)
a. 27
b. 19
c. 0
d. 6
c. 0
Value will always be 0
A Data Acquisition system has been developed to monitor the deflection of an aircraft wing for a dynamic test. Sensors are placed on the wing and 10m of cabling is used to pass the sensor signals to a central Data Acquisition (DAQ) system. The signals of interest are under 30Hz and there is a problem with high frequency noise in the measurements. Which of the following solutions could solve the problem? (More than a single answer may be correct)
a. Applying a high pass filter to the sensor signals before they reach the DAQ system.
b. Applying a low pass filter to the sensor signals before they reach the DAQ system.
c. Applying an amplifier to the sensor signal before sending through the cabling.
d. Applying a second order Butterworth filter with a cut off frequency of 40Hz.
b. Applying a low pass filter to the sensor signals before they reach the DAQ system.
c. Applying an amplifier to the sensor signal before sending through the cabling.
d. Applying a second order Butterworth filter with a cut off frequency of 40Hz.
Everything but high-pass. For Butterworth just read it. It cuts off anything above 40Hz (45Hz is half above sample). Hence, does the same job as a low pass filter.
Inspect the LabVIEW code in the figure and identify which of the following statements is correct? (A single answer is correct).
a. The number of loop iterations will be 7.
b. The number of loop iterations will be 3.
c. The code will not execute.
d. The indicator “Iterations” will display a value of 3 after code has finished.
b. The number of loop iterations will be 3.
Loop will iterate 3 times as the 3 element array is auto indexed (brackets not block). And hence, can only have 3 elements and not a 4th so will stop.
Which of the following statements are correct? (More than one answer may be correct)
a. To reduce problems associated with aliasing you should apply a low pass filter at two times the sampling frequency.
b. Aliasing means that frequencies at greater than half the sampling frequency will appear as frequencies below half the sampling frequency.
c. The passband ripple for a filter is undesirable as this will result in changes in the magnitude of frequencies in the retained frequency domain.
d. The stopband ripple for a filter is undesirable as this will result in frequencies outside the frequency range of interest retaining some finite magnitude.
b. Aliasing means that frequencies at greater than half the sampling frequency will appear as frequencies below half the sampling frequency.
c. The passband ripple for a filter is undesirable as this will result in changes in the magnitude of frequencies in the retained frequency domain.
d. The stopband ripple for a filter is undesirable as this will result in frequencies outside the frequency range of interest retaining some finite magnitude.
Yes low-pass filter but not a 2x the sample frequency, b is the definition, we know all other filters are undesirable bar the low-pass filter.
Which of the following statements about arrays and clusters are correct? (More than one answer may be correct)
a. Arrays do not have to be a fixed size
b. You can not have an array of arrays
c. A cluster cannot contain boolean data
d. Clusters can contain more than one data type
a. Arrays do not have to be a fixed size
b. You can not have an array of arrays
d. Clusters can contain more than one data type
Arrays can be whatever size, correct you can’t have arrays of arrays, a cluster can contain boolean, clusters can contain 3 types of data
Note: A cluster is basically an array bundled with criteria. I.e. a list of students who graduated with their age. 3 criteria, string, boolean, numeric
The musical note middle c is an oscillation at 262Hz. To accurately represent the waveform in the time domain, which sampling frequency would be most suitable? (A single answer is correct)
a. 131 Hz
b. 262 Hz
c. 524 Hz
d. 2620 Hz
d. 2620 Hz
262 Hz in 0.1s, hence 262/0.1 = 2620Hz
Inspect the LabVIEW code. Which of the statements a) – d) are correct? (More than a single answer may be correct)
a. The Indicator will display a value of 4.5 when the loop finishes executing.
b. The Indicator will display a value of 1.5 when the loop finishes executing.
c. If the DBL precision conversion block was not utilised and the integer number was connected to the divide block, there would be an error and code would not execute.
d. The loop will execute two times.
a. The Indicator will display a value of 4.5 when the loop finishes executing.
d. The loop will execute two times.
9/1 = 9
9/2 = 4.5
Stop as 2 iterations
The equation illustrates the relationship between the Gain in decibels and the gain of an amplifier. Which of the following answers (a-d) correctly represents the gain in dB if a voltage of 100μV is the input to the amplifier and a voltage of 5V is measured as the output. The answers are displayed in 2 decimal places format. (A single answer is correct). GdB = 20 Log(G) a. -93.98 dB b. 93.98 dB c. 33.98 dB d. -33.98 dB
b. 93.98 dB
100μV = 0.1mV = 0.0001V 20 log(5/0.0001) = 93.98dB
The LabVIEW code illustrates a While loop. What frequency will the loop operate at? (A single answer is correct)
a. 100Hz
b. 10Hz
c. 1000Hz
d. 50Hz
a. 100Hz
Loop executes every 10ms. 10ms occurs 100x in 1s. Hence, 100Hz.
What is the code width (resolution) of a 16-bit ADC with a voltage signal range of 0V to +10V. (A single answer is correct)
a. 0.625mV
b. 15mV
c. 0.625V
d. 0.15mV
d. 0.15mV
10 / 2^16 = 0.15mV
Inspect the LabVIEW code which illustrates a calculator with two functions ‘add’ and ‘subtract’. Identify which of the statements a) – d) are correct. (More than one answer may be correct)
a. The structure inside the while loop is a case structure.
b. The value displayed in indicator will depend on the value selected in the control.
c. The loop will continue to complete calculations so long as the stop button has a value of false selected.
d. This .vi architecture is easy to adjust to include multiply and divide functions.
All are correct. Says only a and d, but b and c are defo right also.
Buffered I/O should be used when? (More than a single answer may be correct)
a. Many samples are acquired at a faster rate than can be displayed
b. The sampling rate must be precise
c. The sample rate needs to be variable
d. Trying to control an external system
a. Many samples are acquired at a faster rate than can be displayed
b. The sampling rate must be precise
Use buffered I/O when:
- Many samples are acquired at a rate faster than is practical to display, store, or analyze in real-time
- Data is acquired/displayed continuously on the fly
- The sampling period must be precise and uniform throughout the data samples
Which of the following statements are true? (More than a single answer may be correct)
a. The accuracy of a system is always equal to its resolution
b. The accuracy of the sensor is the maximum difference that will exist between the actual value and the indicated value at the output of the sensor.
c. The resolution of a system is the smallest increment it can measure
d. The resolution of a system can never be more than 3 times its accuracy
b. The accuracy of the sensor is the maximum difference that will exist between the actual value and the indicated value at the output of the sensor.
c. The resolution of a system is the smallest increment it can measure
Resolution = x dp Accuracy = +- x
Which of the following statements describes the concept of race conditions in LabVIEW programming? (A single answer is correct).
a. A situation in which two sub .vi’s are trying to execute a task quicker than each other.
b. A situation where the timing of events or the scheduling of tasks may unintentionally affect an output or data value.
c. A situation in which a cluster has to move data between two locations in the fastest possible time.
d. A situation in which you are trying to save data to an array before a timed loop begins its next iteration.
b. A situation where the timing of events or the scheduling of tasks may unintentionally affect an output or data value.
The definition^
Inspect the LabVIEW code in Figure Q3. If this program is run multiple times, what will the value on ‘Indicator 1’ be? (A single answer is correct)
a. 2
b. 3
c. 6
d. Cannot say
d. Cannot say
We don’t know as there is no initial value at the shift register
Which of the following statements are correct regarding sequence structures, as illustrated. (More than one answer may be correct)
a. Sequence structures are not an efficient way to program if we may need to change the order in which the sequences are to execute.
b. The sequence frames will execute Left to Right.
c. You can stop a sequence structure part way through its execution.
d. You cannot pass data between frames in the sequence structure.
a. Sequence structures are not an efficient way to program if we may need to change the order in which the sequences are to execute.
b. The sequence frames will execute Left to Right.
You cannot stop part way through and you can pass data between frames
Inspect the LabVIEW code. Which of the statements a) – d) are correct? (More than a single answer may be correct)
a. The top loop will execute at 10 times the rate of the bottom loop
b. Indicator 1 will count upwards in increments of 0.1 starting at 0.
c. Indicator 2 will count upwards in increments of 1 starting at 0.
d. This code illustrates how you can program in parallel with LabVIEW.
b. Indicator 1 will count upwards in increments of 0.1 starting at 0.
d. This code illustrates how you can program in parallel with LabVIEW.
a. Is obviously wrong.
c. Is wrong because CONTINUE IF TRUE SYMBOL. Hence false constant means that the bottom loop will run only once and output 0.
What are the four standard elements of a DAQ device? (A single answer is correct)
a. Analogue I/O, Digital I/O, Counters, Pulse Width Modulation
b. Analogue Output, Analogue Input, Digital I/O, Counters
c. Analogue I/O, Digital I/O, Counters, Frequency
d. Analogue Output, Analogue Input, Digital I/O, Frequency
b. Analogue Output, Analogue Input, Digital I/O, Counters
Duplicate with card 1.
Which of the following statements about sensors are correct? (More than one answer may be correct)
a. Fibre optic strain gauges are a good choice when there are high levels of background electro-magnetic interference.
b. Three important factors when choosing a sensor are environmental factors, economic factors and sensor characteristics.
c. A single channel optical encoder with 200 gratings will have a resolution of 1.8deg.
d. The output of an optical encoder is an analogue signal.
a. Fibre optic strain gauges are a good choice when there are high levels of background electro-magnetic interference.
b. Three important factors when choosing a sensor are environmental factors, economic factors and sensor characteristics.
c. A single channel optical encoder with 200 gratings will have a resolution of 1.8deg.
Fibre optic gauges are immune to EM, yes, 360deg/200 = 1.8deg, encoder always outputs digital.
Inspect the LabVIEW code and identify which of the statements a) – d) are correct. (More than one answer may be correct)
a. The top loop will execute 2 times.
b. The loops will execute in parallel.
c. Both loops will stop at the same time
d. Indicator and Indicator 2 will display the same value when the programme finishes executing.
a. The top loop will execute 2 times.
d. Indicator and Indicator 2 will display the same value when the programme finishes executing.
Not parallel as they’re connected, hence it flows. Also the 1st loop will stop before the 2nd as not parallel. Imagine it was electrical, it would be series as wire connecting.
Inspect the LabVIEW code. Identify which of the statements a) – d) are correct. (A single answer is correct)
a. The loop will execute 5 times.
b. The values inserted into ‘Output Array’ will be the iteration terminal value multiplied by 2.
c. The size of the ‘Output Array’ can be increased by increasing the numeric value wired to N.
d. Any values in ‘3 element Array’ (outside the For loop) will be overwritten by the code.
a. The loop will execute 5 times.
So essentially every value gets inserted but then deleted as NO shift register. So every value gets overwritten outside the loop and the output array will be identical to the input array.
Technically, the 5th/last value would have been inserted into the array but its 5th element in a 3 element array hence ignored.
a. Yes iterates 5 times.
b. Wrong because no shift register
c. No its a 3 element array.
d. No. The code won’t write any values as explained above.
Which of the following statements are correct? (More than one answer may be correct)
a. The 6 bit binary number 000011 represents the decimal number 3.
b. The highest number that can be represented using a 6-bit representation is 64.
c. Sensors which utilize digital signals as outputs are less susceptible to low voltage noise induced in the transmission wiring.
d. Multiplexers can be utilized in DAQ systems to reduce the cost.
a. The 6 bit binary number 000011 represents the decimal number 3.
c. Sensors which utilize digital signals as outputs are less susceptible to low voltage noise induced in the transmission wiring.
d. Multiplexers can be utilized in DAQ systems to reduce the cost.
a. 0… + 12^1 + 12^0 = 2+1 = 3
b. 2^6 -1 = 63 not 64
c. 1’s and 0’s vs physical analogue? So digital signals are far more immune to interference.
d. Multiplexing involves routing a number of signals into a single digitizer. This is a much more cost effective way of expanding the signal count of the system. Multiplexing is necessary for any high channel count application.
Inspect the LabVIEW code. Which of the answers a) – d) correctly states the value displayed by the indicator when the code has finished executing? (A single answer is correct).
a. 8
b. 9
c. 4
d. 7
b. 9
1+2+1+1=5
5+2+1+1=9
Key is that the shift registers are baso trickle down. So top gets 5, mid[1], bottom[2]. Hence, mid and bottom both stay on the initial value of 1.
The LabVIEW code illustrates a While loop. Which of the following statement are correct? (More than one answer may be correct).
a. The For Loop will execute 3 times.
b. When the loop has completed the iteration terminal will have a value of 2 associated with it.
c. Given the input to the or gate, it serves little function and could be removed without effecting the codes functionality.
d. The For Loop will execute 2 times.
b. When the loop has completed the iteration terminal will have a value of 2 associated with it.
c. Given the input to the or gate, it serves little function and could be removed without effecting the codes functionality.
This is a while loop. not a for loop. A for loop is like a pad of paper with a corner folded over.
0>1 false, 1>1 false, 2>1 true so stop. 3 iterations so value shows 2 (indexed). And yes the or gate is pointless and makes no sense.
Which of the following statements are correct? (More than one answer may be correct).
a. A While Loop must execute at least once
b. Unlike a While Loop a For Loop cannot have a conditional terminal
c. You can have a While Loop within a While Loop.
d. A While Loop iteration terminal is zero indexed
a. A While Loop must execute at least once
c. You can have a While Loop within a While Loop.
d. A While Loop iteration terminal is zero indexed
Both can have stop buttons, i.e. conditional terminals.
Which of the following statements are correct regarding arrays and clusters? (More than one answer may be correct)
a. You can create an array of arrays.
b. You can have an array with more than 5 dimensions.
c. You can have a cluster with multiple data types within it
d. You can have an array with multiple data types within it
b. You can have an array with more than 5 dimensions.
c. You can have a cluster with multiple data types within it
Bool, string, numerical in clusters…but not arrays. Think a cluster of data types.
What is the resolution (code width) of a 24-bit ADC with a voltage signal range of 0V to +10V? (A single answer is correct)
a. 0.732mV
b. 0.596μV
c. 6.0V
d. 0.852nV
b. 0.596μV
10V / 2^24 = 0.596μV