Week 4

Doppler effect

The Doppler effect, also known as Doppler shift, is a phenomenon that occurs when there is a change in frequency or wavelength of a wave in relation to an observer moving relative to the source of the wave. This effect is commonly observed in sound waves, light waves, and other types of waves.

The most familiar example of the Doppler effect is related to sound waves, such as the change in pitch of a siren as it approaches and then moves away from an observer.

Free space path lost

The term you are referring to is likely “Free Space Path Loss” (FSPL), not “Free space path lost.” Free Space Path Loss is a concept in telecommunications and radio frequency engineering, describing the attenuation or reduction in signal strength that occurs as electromagnetic waves propagate through free space (a vacuum or air) without any obstacles or reflecting surfaces.

d is the distance between the transmitter and receiver (in meters),

f is the frequency of the signal (in hertz),

c is the speed of light in a vacuum (approximately 3×10^8 per second)

Phase noise

Phase noise is a phenomenon in signal processing and communications that refers to the short-term, random fluctuations in the phase of a signal. In simpler terms, it’s the instability or jitter in the timing of a signal. This phenomenon can affect the accuracy and precision of various systems, particularly in high-frequency communication systems, oscillators, and other applications where precise timing is crucial. Phase noise originates from imperfections and random variations in the components of electronic devices, such as oscillators and amplifiers.  Variations can lead to fluctuations In phase of the signal causing instability. In summary, phase noise is a critical consideration in systems where precise timing and stable frequency are essential. Engineers work to minimize phase noise to ensure the reliable performance of communication systems, especially those operating at higher frequencies or requiring high precision.


Fault Detection, Isolation, and Recovery (FDIR) is a systematic approach employed in intricate systems, especially in sectors like aerospace, automotive, and other safety-critical domains. The primary goal of FDIR is to ensure the resilience and dependability of a system by promptly identifying faults, pinpointing their origins, isolating the affected components or subsystems, and executing corrective measures or recovery strategies to sustain or restore the system’s functionality.

Breaking down the essential components of FDIR:

  1. Fault Detection (FD):
    • Objective: Recognizing abnormal conditions or faults within the system.
    • Methods: Monitoring diverse parameters, sensors, and system states to identify deviations from expected behavior.
    • Techniques: Employing redundancy, statistical approaches, or model-based methods to detect anomalies by comparing actual system outputs with anticipated values.
  2. Fault Isolation (FI):
    • Objective: Identifying the root cause and isolating the faulty component or subsystem linked to the detected fault.
    • Methods: Analysing system behaviour and utilizing diagnostic algorithms to narrow down potential fault locations.
    • Techniques: Deploying redundancy, analysing sensor data, or utilizing model-based reasoning to ascertain the source of the fault.
  3. Fault Recovery (FR):
    • Objective: Applying corrective measures to alleviate the effects of the fault or restore the system to regular operation.
    • Methods: Implementing predefined recovery strategies or reconfiguring the system to bypass or substitute the faulty components.
    • Techniques: Leveraging backup systems, switching to redundant components, adjusting control parameters, or restarting subsystems to recover from the fault.

The FDIR process operates continuously and iteratively, as faults can manifest at any point during system operation. The successful execution of FDIR necessitates a comprehensive comprehension of the system’s behaviour, potential fault scenarios, and the development of robust algorithms for fault detection, isolation, and recovery.


Full Authority Digital Engine Control (FADEC) stands as a cutting-edge electronic system employed in contemporary aircraft to govern and manage the functioning of gas turbine engines. This technology supersedes traditional mechanical and hydromechanical control systems, introducing a fully digital and computerized interface that ensures precise and optimal control of the engine’s performance. Let’s delve into the key facets of FADEC:

  1. Objective:
    • Enhanced Control: FADEC is designed to provide meticulous and optimal control of the aircraft’s engines throughout all flight phases, from ignition to descent.
    • Efficiency: By continuously monitoring and adjusting engine parameters, FADEC aids in optimizing fuel efficiency, overall performance, and emission levels.
  2. Components:
    • Electronic Control Unit (ECU): Serving as the central component of the FADEC system, the ECU is a computer responsible for processing data from various sensors and issuing commands to engine actuators accordingly.
    • Sensors: FADEC relies on an array of sensors to gather data on factors like engine temperature, pressure, airflow, and RPM (Revolution Per Minute).
    • Actuators: These components, such as fuel injectors, variable stator vanes, and variable nozzle systems, respond to commands from the ECU to adjust engine parameters.
  3. Modes of Operation:
    • Normal Mode: In standard operation, FADEC continuously fine-tunes engine parameters to maintain optimal performance and efficiency.
    • Alternate Mode: In the event of a FADEC system malfunction, an alternate mode may be available, enabling the pilot to manually control the engine using traditional backup systems.
  4. Advantages of FADEC:
    • Precision and Optimization: FADEC ensures precise control over the engine, optimizing both performance and fuel efficiency.
    • Reduced Pilot Workload: With automated control, pilots can focus on other aspects of flying, as FADEC manages the engine parameters.
    • Improved Reliability: FADEC systems are engineered for high reliability, featuring self-monitoring capabilities that can detect and respond to faults.
  5. Applications:
    • Aerospace: FADEC is widely utilized in commercial and military aircraft, helicopters, and unmanned aerial vehicles (UAVs).
    • Marine: FADEC technology has also found applications in marine propulsion systems for ships.
  6. Safety Features:
    • Redundancy: FADEC systems often incorporate redundancy measures to ensure continuous operation even in the face of component failures.
    • Built-in Diagnostics: FADEC continuously monitors its own performance and can provide real-time diagnostics to the flight crew.

In summary, Full Authority Digital Engine Control (FADEC) signifies a substantial advancement in engine control technology, introducing improved efficiency, reliability, and safety to aviation and other related fields. It exemplifies the integration of digital electronics to elevate the performance and control of intricate systems

The benefits of implementing these two techniques increases efficiency massively, due to an internal system being integrated will help reduce time having to find the problem manually.

In both cases, the integration of hardware and software is crucial for the effective functioning of these systems. The hardware collects data, processes information, and executes commands, while the software provides the intelligence and decision-making capabilities to achieve the desired control, fault detection, isolation, and recovery functionalities.

It’s important to note that the specific implementation details can vary depending on the application and the type of system. Aircraft engines commonly utilize FADEC for precise control, while FDIR systems are prevalent in safety-critical applications where fault detection and recovery are paramount, such as aerospace, automotive, and industrial control systems.

Week 3

Unlike ground systems, when working with avionics there are certain parameters that are considered more important than what would be on the ground. This is obvious within weight for several factors, minimum weight for a couple of reason, optimise space and weight for other things, optimise fuel.

Be able to work in several different operating environments when working with things such as operating temp range, acceleration, shocks, vibration, humidity range and electro-magnetic interference, a lot of these thigs wouldn’t need to be considered to this extent. When working with avionics there is little room for error, unlike a car if there is an issue there is a good chance of coming to a gradual stop, unfortunately planes do not have this luxury in most situations, meaning there must be a high level of reliability, safety checks and integration.

Also, if a part does fail, there is normally a back up copy of that part that can be integrated into the system without failure of the plane, resulting in safer travel and a back up plan to help mitigate the problem.

Week 2

A Machmeter is a instrument that uses the ratio of true air speed and the local speed of sound , some aircrafts use a constant mach number rather than a constant speed for cruising operations.

The term “Barber Pole” refers to different areas of the airspeed indicator showing at different stages what is the operating range for several parameters as can be seen below.

Flight Management System (FMS)
The flight management system was introduced in the 1980s, it helps predefined  flight plan to calculate and display the aircrafts lateral and vertical trajectory providing guidance.
Safety in avionics
Regulatory bodies, such as the Federal Aviation Administration (FAA) in the United States and the European Union Aviation Safety Agency (EASA) in Europe, play a crucial role in overseeing and enforcing safety regulations. They conduct thorough reviews and audits to ensure compliance with safety standards.

What Is DO-254?
DO-254: Design Assurance Guidance for Airborne Electronic Hardware

DO-254 is the equivalent standard in the United States, developed by RTCA (Radio Technical Commission for Aeronautics) in collaboration with EUROCAE. It is titled “Design Assurance Guidance for Airborne Electronic Hardware” and provides guidance on the development and certification of airborne electronic hardware. DO-254 is recognized by aviation authorities such as the Federal Aviation Administration (FAA) and is widely used in the aerospace industry.

What is ED-80?

ED-80: Guidelines for the Certification of Airborne Electronic Hardware
ED-80 is a document published by EUROCAE (European Organization for Civil Aviation Equipment) that provides guidelines for the certification of airborne electronic hardware. It covers aspects related to design assurance and the development process of electronic hardware used in the aviation industry. The document outlines the processes and considerations for ensuring the reliability and safety of electronic hardware in airborne systems.
What is DO-178C
DO-178C is a comprehensive standard that plays a crucial role in ensuring the safety and airworthiness of software in airborne systems. Adherence to DO-178C is typically a requirement for obtaining certification from aviation authorities such as the Federal Aviation Administration (FAA) in the United States and the European Union Aviation Safety Agency (EASA) in Europe.
In summary, DO-178C, DO-254, and ED-80 are standards and guidelines that address different aspects of avionics development. DO-178C is specific to software, DO-254 is specific to electronic hardware, and ED-80 provides guidelines for both hardware and software in the context of airborne electronic systems. Compliance with these standards is essential for obtaining certification for avionics systems (link)

Analysing the opportunities and challenges for mitigating the climate impact of aviation: A narrative review

The paper above highlighted talks about technical, ethical, environmental and societal impact considerations of avionics systems, when writing report, refer back to this.

Aircraft failures examples and what went wrong (link)

Electronical flight instrument

Display Units

  • Primary flight display (PFD)
  • Multi-function display (MFD) / Navigation display (ND)
  • Engine indications and crew alerting system (EICAS) / electronic centralized aircraft monitoring(ECAM)


  1. link
  2. link


Week 1 Tasks True Airspeed from Indicated Airspeed Calculation


(Airspeed formulas)

(link 1)

Using this code below to open up the True airspeed indicator calculations on simulink

  • open_system(‘aeroblk_calibrated’);
  • snapshotModel(‘aeroblk_calibrated’);
True airspeed (TAS) is the airspeed that we would read ideally (and the airspeed value easily calculated within a simulation). However there are errors introduced through the pitot-static airspeed indicators used to determine airspeed. These measurement errors are density error, compressibility error and calibration error. Removing these errors from indicated airspeed (IAS) will result in true airspeed

For errors referring to, Correcting Calibrated Airspeed for Compressibility and Density Errors, Compressibility Error, Density Error and Simulate Model to Display Airspeeds.

Mach to knots

the temperature and density of air decreases with altitude, which means so does the speed of sound, hence given a true velocity results in a higher Mach number at higher altitude.
airspeed is a very generic term and and is instead broken down into 6 different airspeeds-
  1. Indicated airspeed (IAS)- The reading obtained from the Airspeed indicator is incorrect if there is a variation in atmospheric density, installation error, or instrument error. “The Airspeed Indicator (ASI) measures the difference between the static pressure from the aircraft’s static ports, and the ram pressure (dynamic + static) from the pitot tube. This difference is the dynamic pressure, which translates into a reading.”  normal use as a basis for aircraft performance.
  2. Calibrated Airspeed (CAS)- This is used to correct installation error and instrument error. Has to be calibrated for each plane due to variations in parameters.
  3. True Airspeed (TAS)-  “True Airspeed is Calibrated Airspeed (CAS) corrected for altitude and nonstandard temperature. Because air density decreases with an increase in altitude, an aircraft has to be flown faster at higher altitudes to cause the same pressure difference between pitot impact pressure and static pressure.”
  4. Ground speed (GS)- Ground speed is the speed of the airplane over the ground which is the true air speed adjusted for wind.
  5. Equivalent Airspeed (EAS)- “Equivalent Airspeed is Calibrated Airspeed (CAS) corrected for the compressibility of air at a non-trivial Mach number. It is also the airspeed at sea level in the International Standard Atmosphere at which the dynamic pressure is the same as the dynamic pressure at the True Airspeed (TAS) and altitude at which the aircraft is flying. It’s mainly used for structural calculations and testing.”
  6. Mach Number (M)- “The Mach Number is the ratio of the True Airspeed (TAS) of the aircraft to Local Speed of Sound (LSS) displayed on the Machmeter. M varies depending on atmospheric conditions, air temperature, and density.”


Development and evaluation of a new airspeed information system utilizing airborne Doppler LIDAR

(link 2)

Interesting points

  • The former shows the predicted airspeed typically ten seconds ahead based largely on the aircraft’s acceleration or deceleration, while the latter displays a target speed computed by the flight management system or set by the pilot. During the approach and landing phase, the pilot sets the target approach speed taking into account airport wind information provided by air traffic control and/or ATIS (Automatic Terminal Information Service) broadcasts. Although the autothrottle system controls airspeed using the target speed and acceleration information, satisfactory speed control performance might not be achieved when wind is changing rapidly because the control system assumes steady or slowly changing winds. Sudden changes in wind speed and direction (windshear) can force pilots to execute a go-around maneuver.

Avionics hardware and software-based systems and their architecture

  • Hardware“Every physical component of a device is hardware. You can reach out and touch hardware, you cannot touch software. Hardware includes all of the physical devices in a computer, like a motherboard, RAM, or processors. For devices like computers, hardware has a heavy influence on performance. Higher performance hardware tends to cost more and requires more resources. Powerful video cards or a CPU, for example, may require a lot of electricity and more cooling than weaker internal components. Most computer components perform better at cooler temperatures Hardware is limited in what it can do on its own. Hardware enables the technology to run, software is what is actually running. A good analogy is with a book. Hardware is the paper, binding, and ink. The primary purpose of hardware for most use cases is to allow the device to run software. Most users won’t have to worry much about computer hardware. Businesses often buy prebuilt desktop computers or laptops. This lets them leave most hardware considerations to professionals, from power supply to output devices. In hardware-related product categories like rack servers, vendors provide hardware and software so that users have a nearly out-of-the-box solution.”
  • Software“Software is all of the programs and code that runs on top of hardware for additional functionality. Software programs range from application software like MS Word or Photoshop to operating system software like Windows. Simple programs make computers able to be used by normal consumers. Unlike hardware, software is a nonphysical component of devices. Software, to continue the book analogy, is the illustrations and other content. Still, hardware is necessary for using software. More complex software may require more powerful hardware. Activities like rapid, complex calculations or highly detailed image rendering can have stringent hardware requirements to run correctly.  Weaker hardware can run less demanding software like PowerPoint or basic Excel functions.”

How do these interlink- Hardware and software both are interdependent on each other. Each of them should work along to form computer produce a helpful output. The software can not be used if there is no support of any hardware device. When there is no proper instructions given, the hardware cannot be used and is useless.

Research the overarching framework associated with avionics design for certification.

(link 3)

The Overarching Properties are intended to define a sufficient set of properties for making approval decisions.

This document is written in a conversational style, unlike the more formal styles usually employed in standards and guidance documents. Two reasons motivate the choice. One, a conversational style is more likely to facilitate understanding by actively engaging the reader than is a formal style. Two, using a different writing style helps emphasize the fact that the Overarching Properties approach is substantially different in at least some respects from current approaches.

ED-79 and ARP-4754 are standards in the aviation industry that offer guidance for certifying and developing aircraft systems, with a specific emphasis on safety and integration. ED-79, published by EUROCAE, is titled “Guidelines for the Certification of Aircraft Systems.” It serves as a reference document, providing recommendations on the certification processes for aircraft systems. The focus is on ensuring safety and reliability, with an emphasis on systematic hazard identification and mitigation.

ARP-4754, an Aerospace Recommended Practice by SAE International, is titled “Guidelines for Development of Civil Aircraft and Systems.” This document offers guidelines for the development of civil aircraft, emphasizing a systems engineering approach. ARP-4754 outlines processes for system-level requirements, architecture, design, verification, and validation. The primary goal is to ensure that civil aircraft and their integrated systems meet stringent safety and performance requirements throughout the entire development life cycle. Adhering to these guidelines is critical for maintaining the safety and airworthiness of aviation systems.