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Questions and Answers
Ice detection on an aircraft can be done with an oscillating. Upon accretion of ice, its natural frequency:
Ice detection on an aircraft can be done with an oscillating. Upon accretion of ice, its natural frequency:
- Is not of importance
- Slightly decreases (correct)
- Slightly increases
- Stays the same
In a Fiber Optic Gyroscope, what is the phase difference between laser beams proportional to?
In a Fiber Optic Gyroscope, what is the phase difference between laser beams proportional to?
- Linear acceleration
- Linear velocity
- Angular velocity (correct)
- Angular acceleration
Optical fiber technology makes use of total internal reflection. This means that the laser beam:
Optical fiber technology makes use of total internal reflection. This means that the laser beam:
- Mostly travels inside the cladding of the fiber.
- Totally reflects from the protecting buffer of the fiber.
- Totally reflects from the air surrounding the fiber.
- Mostly travels inside the core of the fiber. (correct)
An AC current I = 5.0 cos(300t) mA is sent through a resistor of 2kohm. The voltage across the resistor is measured with a digital voltmeter (AC position). The reading is:
An AC current I = 5.0 cos(300t) mA is sent through a resistor of 2kohm. The voltage across the resistor is measured with a digital voltmeter (AC position). The reading is:
In ARINC 429 twisted wires are used between sender and receiver. The reason is to minimize EMC related problems by:
In ARINC 429 twisted wires are used between sender and receiver. The reason is to minimize EMC related problems by:
An AC signal V = 100cos(1000t)mV is digitized with an 8 bits ADC. The resolution of the digitized signal is approximately:
An AC signal V = 100cos(1000t)mV is digitized with an 8 bits ADC. The resolution of the digitized signal is approximately:
Thermocouples determine temperature. The principle is based on:
Thermocouples determine temperature. The principle is based on:
In a computer-based instrumentation system, the order of processing a signal is:
In a computer-based instrumentation system, the order of processing a signal is:
A 100 MHz signal and a 1 GHz signal are both transported by a copper cable. The attenuation of the 100 MHz signal compare to that of the 1 GHz signal?
A 100 MHz signal and a 1 GHz signal are both transported by a copper cable. The attenuation of the 100 MHz signal compare to that of the 1 GHz signal?
An AC potential V = 150 cos(3000t) mV is measured with a digital voltmeter set to AC position. The reading is:
An AC potential V = 150 cos(3000t) mV is measured with a digital voltmeter set to AC position. The reading is:
Optical fibers have a large bandwidth. This means that:
Optical fibers have a large bandwidth. This means that:
When a coax cable is terminated by its characteristic impedance, at the end of the cable the signal:
When a coax cable is terminated by its characteristic impedance, at the end of the cable the signal:
An analog signal with a voltage range between -1V and +1V is digitized using a 10 bits ADC. The resolution of the digitized signal is approximately:
An analog signal with a voltage range between -1V and +1V is digitized using a 10 bits ADC. The resolution of the digitized signal is approximately:
Considering EMC, which of the following statements is correct?
Considering EMC, which of the following statements is correct?
The potential across a resistor of 100 ohm is measured by an oscilloscope. The calibrated Volts/Div. switch reads 2 Volts/Div. What is the calibrated current scale?
The potential across a resistor of 100 ohm is measured by an oscilloscope. The calibrated Volts/Div. switch reads 2 Volts/Div. What is the calibrated current scale?
Transportation of a 1 Ghz signal by a copper cable and by an optical fiber is compared. The attenuation of the signal:
Transportation of a 1 Ghz signal by a copper cable and by an optical fiber is compared. The attenuation of the signal:
Ring Laser Gyroscopes and Fiber Optic Gyroscopes make use of:
Ring Laser Gyroscopes and Fiber Optic Gyroscopes make use of:
In a piezoelectric sensor, a force leads to:
In a piezoelectric sensor, a force leads to:
A thermistor is used to determine:
A thermistor is used to determine:
On a Boeing 747-400, ice detection is done with a probe that is oscillated at a
frequency close to its natural frequency because this frequency is very sensitive to:
On a Boeing 747-400, ice detection is done with a probe that is oscillated at a frequency close to its natural frequency because this frequency is very sensitive to:
When aliasing occurs, this means that:
When aliasing occurs, this means that:
An analog signal with a voltage between 0 V and 1 V is digitized with 8 bits ADC. The
resolution of the digitized signal is approximately:
An analog signal with a voltage between 0 V and 1 V is digitized with 8 bits ADC. The resolution of the digitized signal is approximately:
Considering EMC is important, since electric components:
Considering EMC is important, since electric components:
What does it mean when a coax cable is terminated by its characteristic impedance?
What does it mean when a coax cable is terminated by its characteristic impedance?
In relation to EMC, what does emission mean?
In relation to EMC, what does emission mean?
Optical fibers have a large bandwidth. This means that:
Optical fibers have a large bandwidth. This means that:
Which temperature sensors have a negative resistance–temperature relationship?
Which temperature sensors have a negative resistance–temperature relationship?
Why is the other end of the thermocouple placed far away from the engine? (Reference temperature is 18 °C)
Why is the other end of the thermocouple placed far away from the engine? (Reference temperature is 18 °C)
In an optical fiber, electromagnetic radiation—and thus information—is transmitted. The electromagnetic radiation is:
In an optical fiber, electromagnetic radiation—and thus information—is transmitted. The electromagnetic radiation is:
Which of the following correctly lists the three basic criteria for EMC (Electromagnetic Compatibility)?
Which of the following correctly lists the three basic criteria for EMC (Electromagnetic Compatibility)?
Which of the following are the three key aspects of EMC (Electromagnetic Compatibility)?
Which of the following are the three key aspects of EMC (Electromagnetic Compatibility)?
What does emission mean in the context of EMC (Electromagnetic Compatibility)?
What does emission mean in the context of EMC (Electromagnetic Compatibility)?
What does noise mean in the context of EMC (Electromagnetic Compatibility)?
What does noise mean in the context of EMC (Electromagnetic Compatibility)?
Based on EMC requirements, in which order would you rank the following cables from best to worst in terms of electromagnetic compatibility?
Based on EMC requirements, in which order would you rank the following cables from best to worst in terms of electromagnetic compatibility?
The principle of light traveling in an optical fiber is based on:
The principle of light traveling in an optical fiber is based on:
In an accelerometer based on a mass-spring system, the acceleration is determined by:
In an accelerometer based on a mass-spring system, the acceleration is determined by:
To digitize an analog signal, it is sampled with a frequency of 500 kHz. What is the maximum frequency of the signal that can be sampled?
To digitize an analog signal, it is sampled with a frequency of 500 kHz. What is the maximum frequency of the signal that can be sampled?
What does the Sample and Hold (S/H) step in a data acquisition system do? It converts:
What does the Sample and Hold (S/H) step in a data acquisition system do? It converts:
An inductive proximity sensor is used to measure whether an aircraft door is open or closed. Whether the door is open or not ix measured via:
An inductive proximity sensor is used to measure whether an aircraft door is open or closed. Whether the door is open or not ix measured via:
A thermocouple consists of 2 metal wires and is used to determine temperature via:
A thermocouple consists of 2 metal wires and is used to determine temperature via:
In a Ring Laser Gyroscope 2 laser beams travel in opposite directions. The angular velocity is determined from:
In a Ring Laser Gyroscope 2 laser beams travel in opposite directions. The angular velocity is determined from:
In a computer based instrumentation system, 'Sample and Hold' takes place:
In a computer based instrumentation system, 'Sample and Hold' takes place:
In an aircraft it is advantageous to use optical fibres as compared to copper cables because they are lighter. Other properties of optical fibres as compared to copper cables are:
In an aircraft it is advantageous to use optical fibres as compared to copper cables because they are lighter. Other properties of optical fibres as compared to copper cables are:
A new avionics system is mounted in an aircraft. There is no cable connection with the other systems of the aircraft. Considering EMC for this new system is:
A new avionics system is mounted in an aircraft. There is no cable connection with the other systems of the aircraft. Considering EMC for this new system is:
To digitize an analog signal, it is sampled with a frequency of 10 kHz. What is the maximum frequency of the signal that can be sampled properly?
To digitize an analog signal, it is sampled with a frequency of 10 kHz. What is the maximum frequency of the signal that can be sampled properly?
Flashcards
Ice accretion effect on oscillating probe's natural frequency?
Ice accretion effect on oscillating probe's natural frequency?
The natural frequency of the probe slightly decreases upon ice accretion.
Fiber Optic Gyroscope phase difference proportionality?
Fiber Optic Gyroscope phase difference proportionality?
In a Fiber Optic Gyroscope, the phase difference is directly proportional to angular velocity.
Path of the laser beam in optical fiber?
Path of the laser beam in optical fiber?
The laser beam mainly travels inside the core of the fiber.
Purpose of twisted wires(ARINC 429)?
Purpose of twisted wires(ARINC 429)?
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Thermocouple temperature sensing principle?
Thermocouple temperature sensing principle?
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Attenuation comparison between copper and optical?
Attenuation comparison between copper and optical?
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Signal reflection when terminating a coax cable?
Signal reflection when terminating a coax cable?
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What does a piezoelectric sensor do?
What does a piezoelectric sensor do?
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Wires vs. Coax cables in EMC
Wires vs. Coax cables in EMC
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Analog signal voltage?
Analog signal voltage?
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Study Notes
Ice Detection
- Ice detection on aircraft uses an oscillating probe
- Accretion of ice slightly decreases the natural frequency of the probe
Fiber Optic Gyroscope
- In a Fiber Optic Gyroscope the phase difference between laser beams is proportional to angular velocity.
Optical Fiber Technology
- Optical fiber technology relies on total internal reflection
- The laser beam mostly travels inside the core of the fiber
AC Current Through Resistor
- An AC current of 5.0 cos(300t) mA through a 2 kΩ resistor yields a voltage that can be measured with a digital voltmeter in AC position
- The reading is 7.1V
ARINC 429 Twisted Wires
- ARINC 429 twisted wires minimize EMC related problems
- This is acheived by reducing radiative coupling
AC Signal Digitization
- An AC signal V = 100 cos(1000t) mV digitized with an 8-bit ADC has a resolution of approximately 0.4 mV
K-Type Thermocouple
- For a K-type thermocouple, the relationship between potential (V) and temperature (T)is V = a(T - Tref)
- The thermocouple is calibrated using a small oven, heated up to 500 °C
- One end is in the oven, the other is connected to a voltmeter at a large distance
- The voltmeter's temperature is 20 °C
- A single Temperature/Voltage combination is determined: (500 °C, 28.8 mV)
- Measure the potential difference between the points of the materials that make up the thermocouple
- Place voltmeter at a large distance from the oven to avoid heat affecting the voltmeter
- Determine a (alpha)
- Determine the temperature of the oven when a potential of 18 mV is measured. alpha = 6.16E-05 V/degreeC, Tout = 311.4 degreesC
Passive Filter
- A passive filter contains two capacitors (C) and two resistors (R)
- The values are R = 1 kΩ and C = 1 µF
- The input voltage applied is Vin = (1 + cos(200t) + cos(2000t)) V
- Calculate the break frequency fb of this filter
- Determine the transfer function H(f) = Vout/Vin of this filter
- Determine what kind of filter this is
- Calculate the output voltage Vout
Ideal Operational Amplifier Circuit
- An ideal operational amplifier is used to amplify a potential vI
- Resistances are R1 = 500 Ω, RF = 5 kΩ
- Capacitance is CF = 2 µF
- The gain is given by A(ω) = -ZF / ZI
- Calculate the impedances ZI and ZF
- Show that the gain is given by A(ω) = -10 / (1 + jω/100)
- For vI = 500 mV, calculate the output potential vo
- For vI = cos(100t) V, calculate the output potential vo
Number System Conversions
- Convert the hexadecimal number A9A to decimal number
- Convert the binary number 0.10101010 to decimal form
Boolean Algebra Simplification
- Use Boolean algebra to simplify (A ∧ B) ∨ (¬B ∧ (A + C)) and give the shortest logic expression
- Set up the truth table for (A ∧ B) ∨ (¬B ∧ (A + C)) and derive the shortest logic expression
Logic Circuit with Flip Flops
- A logic circuit consists of two D flip flops and a T flip flop
- D flip flop outputs connect to their inputs
- The T flip flop's input is 1
- The first D flip flop is clocked by the CLK waveform
- The first D flip-flop's output clocks the second D flip-flop
- The second flip-flop's output clocks the third flip flop
- Initial outputs Qo, Q1, Q2 of the flip flops are 0.
Coax Cable Signal Transmission
- Two analog AC signals at 100 MHz and 1 GHz are transported by a 100 m coax cable
- The attenuation is 4 dB/100 m at 100 MHz and 14 dB/100 m at 1 GHz
- The signals are digitized at the end of the cable
Ice Detection with Oscillating Probe
- The natural frequency of an oscillating probe used for ice detection on an aircraft slightly decreases upon ice accretion
Fiber Optic Gyroscope Phase Difference
- The phase difference between laser beams in a Fiber Optic Gyroscope is proportional to angular velocity
Optical Fiber Laser Beam
- The laser beam mostly travels inside the core of the fiber in optical fibre
AC Current Through Resistor Voltage Measurement
- Measuring the voltage across a 2k resistor with a 5.0 cos(300t) mA AC current using a digital voltmeter (AC position) results in a reading of 7.1V
Minimizing EMC Problems with ARINC 429 Twisted Wires
- ARINC 429 twisted wires minimize EMC related problems, primarily by reducing radiative coupling
Resolution of Digitized AC Signal
- An AC signal V = 100 cos(1000t) mV digitized with an 8-bit ADC has an approximate resolution of 0.4 mV
Pitot Tubes for Pressure Measurement
- Pitot tubes measure static pressure (Ps) and total pressure (Pt)
- Dynamic pressure (Q) is calculated via Q = Pt - Ps
- Dynamic pressure is directly related to the aircraft indicated airspeed vI
- The relation is Q = Ps * [(1 + 0.2 * (vI / As)^2)^(7/2.5) - 1]
- Ps at sea level = 10^5 Pa
- As (speed of sound) = 340 m/s
- Calculate the dynamic pressure for an indicated airspeed of 68 m/s
- With Pitot tubes, Ps = 7*10^4 Pa, Pt = 10^5 Pa, the indicated airspeed can be calculated
- Plot vI/As as a function of Q/Ps on the interval of Q/Ps = 0 to 1
Passive Filter with Inductors and Resistors
- A passive filter uses two inductors (L and 3L) and two resistors R
- Values are R = 1 kΩ and L = 200 mH
- Input voltage is Vin = (1 + cos(200Ï€t) + cos(2000Ï€t)) V
- Derive the transfer function in the form H(f) = 1 / (1 + j * f / (1000/(2*pi)))^-1
- What is the break frequency (fb) of this filter?
- What kind of filter (low-pass, etc)?
- Calculate the output voltage
Ideal Operational Amplifier
- An ideal operational amplifier uses two resistors (R1, R2) and two inputs (V1, V2)
- Output is Vo
- Resistor values are R1 = 1 kΩ, R2 = 2 kΩ
- Input voltages are V1 = 5V, V2 = 1V
- Find the potential VA at the negative input of the operational amplifier
- Calculate the currents I1 and I2
- Calculate the output potential Vo
- Calculate the output potential Vo again when V2 is increased to 5V
Number System Conversions
- Covert the hexadecimal ABBA to a decimal
- Covert the decimal form 1250.125 to binary, use MAX 16 bits
Boolean Algebra and Truth Tables
- Draw the truth table for F = ¬A ∧ B + A ∧ ¬C + ¬B ∧ C
- Simplify with boolean algebra A ∧ (A ∧ ¬B + (A + ¬B)) with shortest logic expression
Logic Circuit with NOR Gate and T Flip Flop
- A logic circuit contains a NOR gate and a T flip flop
- Signals A and B connect to the NOR gate inputs, and its output connects to the T flip flop's input (T).
- The T flip flop is clocked at a positive edge
- Logic circuit, input waveforms, and the clock signal are given
- Draw the output of the NOR Gate
- Draw the output of the T flip flop
- Draw the output of ¬ the T flip flop
Analog Signal Attenuation in Coax Cable
- An analog AC signal at 500 MHz is transported via a 200 m coax cable
- The cable attenuation is 7 dB/100 m at 500 MHz
- Find the fraction of power for the signal halfway through the cable (after 100 m)
- Find the fraction of power when the signal reaches the end of the cable
Temperature Measurement with Thermocouples
- Thermocouples are based on difference in potential between 2 wires.
Order of Signal Processing in Computer-Based Instrumentation
- The order of processing a signal is: Sensor -> Sample and Hold -> A/D Conversion
Signal Attenuation Comparison of 100 MHz and 1 GHz in a Copper Cable
- A 100 MHz and a 1 GHz signal are both transported by a copper cable, the attenuation of the 100 MHz signal will be smaller since the cable acts as a low-pass filter
Digital Voltmeter Measurement of AC potential
- The reading is 106 mV, given AC potential V = 150 cos(3000t) mV measured with a digital voltmeter (AC position).
Impact of Large Bandwidth in Optical Fibers
- Large bandwidth in optical fibres means the frequency range of signals transported without attenuation is large
Effect of Coax Cable Termination on Signal Reflection
- When a coax cable is terminated by its characteristic impedance, at the end of the cable the signal is not reflected at all
Strain Gauge Resistance Determination
- A Wheatstone bridge determines the resistance of a strain gauge
- Three bridge resistances are equal: R = 200 Ω
- Strain gauge resistance is equal to the other three resistances: R_s = R, no strain
- Given: (ΔL/L = 1/2 * (ΔR_s/R_s)). Input potential is Vin = 5 V
- Show the relation between output and input potential: Vo = (Rs / (R + Rs)) * Vin
- Determine the output potential Vo when the strain gauge is fully relaxed
- At a certain moment the strain gauge is stretched The output potential Vo of the Wheatstone bridge becomes 25 mV
- Calculate the resistance Rs of the strain gauge
- Calculate the strain: ΔL/L
Passive Filter for Vo Calculation
- A passive filter consisting of 2 inductors (L) and 2 resisters (R)
- R = 100 Ohms and L = 200mH
- Input voltage is Vin = (10 + 0.5cos(200pit) + 0.25cos(2000pit))V
- Show that the transfer function can be written as H(f) = jpi10^-3f/(1+jpi10^-3f)
- Calculate the break frequency fb of this filter
- What kind of filter this is (low-pass, band-pass, high-pass, etc.)?
- Calculate the output voltage Vo
Using an Ideal Operational Amplifier
- An ideal operational amplifier is used to amplify potential VI = 750mV
- The resistors are R1 = 500 Ω, R2 =1 kΩ, and R3 = 6 kΩ
- Determine the potential VA and the negative input of the operational amplifier
- Determine the current flow through the circuit (/1 and /2)
- Determine the potential at V2, a point between resistors R1 and R2
- Give the gain Av and determine the output potential Vo given all known values
Conversions
- Converts binary number "10101010.0101" to a decimal number
Circuit
- Draw the circuit for the function F=A ⊕ B + A C + ¬B ¬C. Do not simplify the formula yet and only use NOT, AND, and OR gates (if needed, gates with more than 2 inputs can be used)
- Use Boolean algebra to simplify the formula, then derive the shortest logic expression
Logic Circuit with D and T Flip Flops Timing Diagrams
- Composed of a D flip flop and a T flip flop
- Circuit is clocked at the positive edge and T flip flop is clocked at the negative edge
- Show the wave forms of the input
- Show clocking signal
- Draw the output of the D flip flop
- Draw the output of the T flip flop
- Draw the outputs ⊕D and ⊕T.
Signal Digitization
- Signal contained 500 cos (2000 * Pi *t) mV
- Sampling and digitising can determine the minimum frequency using 12 bit ADC
Sensor
- Force in sensors leads to Charge separation which is converted to a potential in a capacitor.
Usage of ring laser and fiber optic gyroscopes
- 2 laser beams traveling in opposite directions yielding the angular velocity
Transport of 1 GHZ signal of copper cable and optic fibre is compared
- Copper cable will be larger, more attenuation than compared to fiber
Potential of 100 measured of oscilloscope
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