Elias's Best Notes on Mod 5 PDF

5.3 Data conversion Digital bus digital devices usually needs to communicate with each other. one device sends information to another, processing this data and possibly sending it to another device. These are called data buses.   FMC(flight management computer) can make flight routes. IRS (Iner...

5.3 Data conversion Digital bus digital devices usually needs to communicate with each other. one device sends information to another, processing this data and possibly sending it to another device. These are called data buses.   FMC(flight management computer) can make flight routes. IRS (Inertial reference system) often used for navigation/speed   Controlling computers. Used to help pilots control the plane. one example FSEU(flap/slat electronic unit)   Informational computers. Gives information, (oil temperature, engine temperature and more)   Analog to digital converter   Sample rate/ frequency  is measured with samples per second or SPS or S/s Sample rate= 1:T or 1/T Where T = Period of the sample or the time it takes before sampling again.   Nyquist Theorem According to the theorem, the sampling rate/ frequency needs to be atleast twice as much as the highest frequency in the analogue signal to recreate the original analogue signal without aliasing.  FNyquist = "fmax    ADC 2Bit Har 4 muligheter 00,01,10,11 Deler opp mulig Volt i 4 deler.   Jo flere bit jo nærmere det analoge signalet. Bit size 8 er 256 levels Bit size 10 er 1024.   Flash ADC Also called a parallel converter, because the conversion takes place in a single cycle.  For this reason it is also the fastest type of ADC, but it does have the most complicated architecture. 2n-1 comperators.    Pipeline ADC Uses multiple steps to convert from analog to digital until there is no rest.   Ramp generation ADC counts upwards from 0 to whatever you choose.      Digital to analogue converters (DAC's)     5.4 Databuses A bus is a collection of wires used to transmit data from one part of a computer to another.  Busen fikser hvor det skal og databussen er innholdet. Serie og parallell busser, Serie går 1 og 0 etter hverandre, mens på parallell så går de parallelt på rekke Klokker som timer signalene. Mange forskjellige måter å kombinere det på.   Labels på forskjellige type signaler f.eks til flyets høyde. A data bus that can transmit in just one direction is called a simplex. It is called a half duplex if it can transmit in both directions but not simultaneously.  A data bus that can transmit in both direction simultaneously is called a full duplex or just (duplex)   The size of a buss known as its width, is crucial because it determines how much data can be transmitted at one time. f.eks 16 bits or 32 bits.   Aircraft network topology The configuration or topology of a network is key to determining its performance.  The following topologies are the main types used for any networked system.   Star Topology The most common one, is laid out so every node is directly connected to one central hub via coaxial, twisted-pair, or fibre-optic cable.  Advantages. Are common since they conveniently allow you to manage your entire network from a single location. Disadvantages if the central hub goes down, the rest of the network cannot function.   Bus Topology A bus topology orients all the devices on a network along one single cabel running in a single direction from one end of the network to the other.  Advantage Good cost effective choice for smaller networks because the layout is simple.  Disadvantage Because it uses a single cabel it can be vulnerable, if the cabel experiences a failure the whole network goes down.   Ring Topology Goes in a ring, if there is a failure in the cable it will still send signals all the way.   Tree Topology Easy addition of nodes and network expansion. Mesh Topology point to point connection. every LRU can speak to eachother because everything is connected. Uses a lot more cable but are reliable and stable.    ARINC (Aeronautical Radio, Incorporated)  ARINC is a major company that develops and operates systems and services to ensure that aviation and travel industries efficiency, operation, and performance. They make a standarisation for different equipment.    Parity Checking Adding a parity bit to make the number odd or even with 0 or 1 7+1 bit Even.  0101010+1 partall med enere.  1101010+1 mottakeren ser at tallet er feil og sender tilbake.  Tar mye feil, men ikke alt. Hvis tallet fortsatt er partall vil det gå igjennom.    ARINC Standard 429 (Arinc 429 is the most commonly used data bus for commercial and transport aircraft) Unidirectional transmission Uses bipolar return to zero encoding (BRPZ) Simplex 32-bit Words Two Wire (twisted pairs) Bipolar RZ format Low speed 12,5kbps (kilo bit per second) High speed 100kbps One transmitter Up to 20 receivers Odd parity (normally) Self-clocking: the receiver senses the NULL between the bits to generate its internal clock. Self-synchronising: the receiver senses the four-bit NULL between words to generate word synchronisation.     ARINC 629 A faster half duplex Up to 120 terminals can be connected to the bus. Un-shielded twisted pair of wires that can be up to 100m long.   5.5 Logic circuits Positive and Negative Logic. Fan-in and fan-out. Fan-in the maximum amount of digital inputs. Fan-out the maximum amount of digital outputs. AND gate. A logic 1 state: and     B logic 0 state.    5.8 Intergrated Circuits Half adder A half adder combines two binary digits and produces a carry. An and gate is added in parallel It cannot receive a carry input. Full adder is able to receive a carry input. Almost like half adder.   Klokker/Clocks Kan bli påvirket av temperatur. Krystaller blir ofte brukt i klokker pga at de er så presise og ikke blir påvirket. Blir ofte oppgitt i 1,xxxxxxx MHz.   Counter/Tellere Blir brukt til å telle, kan også brukes til å dele opp frekvenser. Er en serie med Flip-Flops som er satt sammen.    Ripple Counters Asynchronous counter.  Halveres for  hver klokke.   Synchronous counter Får klokke pulsen inn på hver enkelt flip flop for å slippe delayen.  Er en Up counter/increment counter   Decade counter. En Nand gate som gir et 0 signal som aktiverer clear på JK flip flops.   Ring counter En loop of bistable devices(flip flops) Bare en er høy om gangen.   Down Counters/decrement counter Starter på 1 og teller ned til 0   Registere - Brukes til å lagre data mellom inn og ut.   - Parallel Register Parallel registers are designed to receive or transfer bits of data or information simultaneously.    - Serial and Parallel transfers and conversion Used to conver from serial too parallel or the other way   - Shift registers  used to shift numbers one place to the left or right.  Can be used to double or split a number in half.   Integrated circuits-5.8 BCD-decimal and decimal-BCD decoder and encoder Graycode Scale integration   5.9 Multiplexing, to typer (fdm, frequency division multiplexing and tdm, time-division multiplexing)   Multiplexing (MUX) fdm, kombinerer to frekvenser. tdm, gir informasjon i tidsluker og separer det før det leveres. tdm må synkroniseres sånn at riktig innputt går til riktig output.   De-multiplexer (DEMUX) Motsatte av multiplex, fordeler signalene.   5.10 Fiber Blir sendt som lys, ikke elektrisk signal. Tre hoved handlinger for å fungere Convert electrical input signal to an optic signal. to send the optical signal over an optic fibre, And to convert the optical signal back to an electrical signal.   Different fibres Single mode is the smallest one and is used for long distances and it is faster. Wavelengths 1310-1550 nm. Multimode is the largest one, used for shorter distances and is slower. Multimode og singlemode step-index fibres (reagerer kun ved treff av cladding.) Multimode og singlemode graded-index fibres (reagerer ved de forskjellige lagene i kjernen og lager en rundere lys bølge.)   Fibre buffers Coatings and buffers protect the optical cable from breakage and loss caused by microbends.  Three different types, Tight buffer( solid), Loose tube (filled with air) Loose tube ( filled with gel)   Type-A connector  Is for production breaks that are not regularly connected and disconnected.  Has three or five fibre optic cables.  Threaded coupling mechanism. Butt-type connector with ceramic terminuses.    Type-B connector Often used on LRU. The type-b connector is suitable for use where the connector is more frequently connected and disconnected.  Ball lens connector, not possible to over torque.   Type-C connector  Push-pull coupling mechanism. An expanded beam connector Also ball lens.    Couplers Type mux eller demux for fibre.   Optical sources and fibre optic transmitters 1st optical window 800-900nm       Light emitting diodes  By using elements such as gallium, arsenic and phosphorus an led can be designed to radiate colors such as red, green, yellow, blue and infrared light.   Laser diode   5.12    Electro-Static Discharge (ESD) Electrostatic Sensitive Device (ESD) Electrostatic discharge sensitive (ESDS)   Positivt ladet stoff må avgi elektroner.  Negativt ladet stoff vill ha elektroner.    Human Body Model (HBM) etterligner et menneske som tar på komponenten. Charged Device Model (CDM) etterligner et samlebånd/produksjonsbånd. Machine Model (MM) er veldig røff og blir nesten ikke brukt lenger.   Hard failure: Komponenten slutter å fungere med en gang.  Soft failure: Feil som kan oppstå under visse forhold og er vanskelig å oppdage.    - 5.13 Software management control Three types: Firmware, operational software and databases.    - Firmware Lowest level. Non volatile.   - Operational software Typ windows. Avhengig av firmware.    - Databases Collection of data that a computer can look through to get specific information. Flight management navigation (NAV) database is a good example. Updates every 28 days.    Easa part 21: Regulates production, design and more related to parts and software. Easa part M: Focuses on the continuing airworthiness of aircrafts.  D0-178B: Hvordan skal software lages. Klasser ut ifra konsekvensen av feil i software.  Klasser A-E     - 5.14 Electromagnetic environment    -(EM) electromagnetic, Electric and magnetic field.   -(RFI) Radio Frequency Interference   -(HIRF) High Intensity Radiated Field Non-ionising electromagnetic energy external to the aircraft that may cause adverse effects upon the electrical and electronic systems of the aircraft that affect the continued safe flight and landing of that aircraft. Between 10kHz and 18GHz   -(EMI) Electromagnetic Interference Radiative, får signaler den ikke skal ha. Inductive Conductive Capacitive   -(EMC) Electromagnetic Compatibility   Backround From about 1984, British Airways experienced system faults in the bermuda triangle. Main concern was the INS would not countdown sufficiently to enter the present position.  The memory had been scrambled but could not explain why.  They concluded that it was a HIRF because of some radio transmitters in the area.    Methods for minimising interference. Bonding: connects parts of the aircraft together to secure good ground.  Screening: Multiple layers of insulation and mesh to secure the main conductor.  Static discharges: Rather than allow any static build up, these discharges randomly.  Twisted pair wires can be used as a solution for EMI. Shielding Filtering: filtrere ut uønsket signaler   Separation: f.eks ikke legge strøm og signal kabler sammen.  Proper circuit design.   EMC Gaskets/ Electromagnetic conductive gaskets.    - 5.15 Typical electronic/ digital aircraft system   - Acars (aircraft communication addressing and reporting system) Brukes på sivile fly. Communications between aircraft and ground stations. OOOI ( out of the gate, off the ground, on the ground and in the gate) Acars management unit (hjernen) Bruker Satcom eller VHF til å sende ut eller motta meldinger. SITA-AIRCOM er den mest brukte typen i verden. -ACARS messages may be of three broad types Air Traffic Control (ATC) messages are used to request or provide clearances. Aeronautical operational control. Airline administrative control.   The contents can be OOOI events, flight plans, weather information, equipment health or status of connecting flights.    -  Flight management system (FMS)  Interfaces with ACARS.  Syr sammen de forskjellige systemene i flyet. Kan bli sett på som hjernen til navigasjonssystemene. Performance: Kalkulerer kortest flytid med lavest drivstofforbruk.  Guidance gir tips f.eks hvis man ligger bak skjema.    - Fly by wire Gjør om fysiske bevegelser til elektroniske signaler istedenfor å bruke metallvaier. Computeren kan overskrive signaler, om det er nødvendig.   Inertial navigation system (NMS) bruker gyro. Inertial reference system (IRS) bruker ring laser gyros.   (ECAM) electronic centralised aircraft monitor.  Warning and cautions (Airbus)  Four display modes, flight phase related, advisory, failure related modes, permits the selection diagrams related to 12 aircraft systems for routine checking.  4 levels, information, level 1, level 2 and level 3. Information lowest level to level 3 being the highest. Level 1 and 2 have amber visual warning, and level 3 is red.    (EICAS) Engine indication and crew alerting system. (Boeing) Uses different colors with different meanings, white and green normal, yellow meaning something wrong and red warning. Three displays: (i) Operational, (ii) Status and (iii) maintenance. Three warning levels: A meaning warning and immediate action, B meaning cautions requiring immediate crew awareness and possible action and C meaning to be aware of and crew awareness.      - EFIS, Electronic flight instrument system PFD, primary flight displays. EADI, electronic attitude direction indicator. ND, navigation display.  EHSI, electronic horizontal situation indicator.   (GPS) Global positioning system, (GNSS) Global navigation satellite systems. Gps amerikank, gnss resten av verden.  Russland sitt system GLONASS. Basic principle: uses the same principle as DME. Measures the time and calculates the distance.  GPS receivers uses trilateration for a accurate pinpoint.  Three segments: Space segment (satelite), user segment (GPS receiver) and control segment (Ground station).    - Traffic collision avoidance systems (TCAS) Bruker en transponder (transmitter og receiver), gir varsel ved fare for kollisjon.  To forskjellige varsler, (TA) trafick advisory and (RA) Resolution advisory To handlinger, climb or descend.  Begrensninger i forhold til høyde på flyet.   - Integrated modular avionics (IMA)  Began in the late 1980's. First fully integrated plane ca 2007. Reduce weight, increased reliability and easier upgrades. CPIOM= core processing input/ output module. AFDX= Avionics full-duplex switched ethernet. ADN=Aircraft data network. GPM= General processing module   LRM= line replaceable module Nyere versjon av LRU, men samme modul kan brukes til flere ting. Bruker bare forskjellige software.    - Cabin core system Cabin intercommunication data system (CIDS) Airbus Cabin service system controller (CSSC) Boeing.  Operates, controls monitors and transmits data from different cabin systems related to the passengers and cabin crew.  Flight attendant panel (FAP)  Exit signs are not controlled by this but by the emergency power supply unit.    - Information systems  The information systems aim to improve flight, cabin and maintenance operations.   Gives the maintenance personnel a lot of information.   - Health management systems  Two types: Aeroplane health management (AHM) Boeing. Airman from Airbus.  Sends information to the pilots and the ground crew about faults or part needing replacing.    - Electronic flight bag (EFB) Is an electronic information management device that helps flight crews perform flight management tasks more quickly and efficiently with less paper.    Divided into three classes.  Class 1- COTS. Equipment such as laptops or ipads, used as loose equipment.  Class 2- Also portable devices but can be modified to the flight.  Class 3- A part of the plane and needs to certified.    Maintenance Information System