Data and Signal Notes PDF

# Data and Signal ## DATA N SIGNAL (definition n diff) - Data - entities that convey meaning, it is the information - Signal - electric / electromagnetic impulse used to encode and transmit data, it is the medium for data transfer and retrieval ## DATA TO SIGNAL CONVERSION - include - Modulation...

# Data and Signal ## DATA N SIGNAL (definition n diff) - Data - entities that convey meaning, it is the information - Signal - electric / electromagnetic impulse used to encode and transmit data, it is the medium for data transfer and retrieval ## DATA TO SIGNAL CONVERSION - include - Modulation Models, Shift Keyings how to read and draw ## A2A (Analog data to analog signal) - Amplitude and Frequency Modulation - Modulate data onto a set of analog signals, used to allow multiple channels to coexist and be transmitted simultaneously at different frequencies - Improve signal and audio quality - Components: analog data, carrier signal, composite signal ## D2D - NRZL-L NRZ MANCH DIFF.MANCH BIPOLARAMI ## D2 discrete analog - Amplitude shift keying - To carry diff amplitudes of data - Formula of bits = log2(n of amplitude/freq changes / phase changes / bauds) - Frequency shift keying - Same as Amp but frequency - Phase shift keying - Quadrature phase shift keying - BLJR HOW TO DRAW PHASE KEYING ## A2D - Pulse code modulation - Analog wave sampled at multiple diff intervals (snapshots) to create a binary pattern - Nyquist theory = n of snapshots => 2*highest frequency - Delta modulation - Snapshots taken based on signal changes (1 = rise in volt, 0 = drop in volt) ## EBCDIC ASCII UNIVODE - 8 bit, 7 bit, 16 bit. BLJR CARA BACA ## DATA TRANSMISSION DIRECTION (simplex-half duplex duplex) - ez ## NETWORK (LAN-WAN SWITCH ROUTER-MICROWAVE RADIOWAVE SATELLITR) - LAN - comm network interconnecting data comm devices within a small geographical area - ADV 1. Can share hard / software resources easily. 2. Can connect to other wan and lan. 3. Secure data transfer with high bandwidth and low error rate. - DISADV 1. Some hardwares can not interoperate. 2. Expensive equipments and installation cist. 3. Growing level of maintenance. - LAN topologies 1. Bus / Tree topology - original topology of LAN. Workstations have NIC which attaches via a tap onto the bus network. Uses baseband data transfer. 2. Star-wired Bus - shaped like star (devices connected in star format with hubs in the middle) but hubs connected like bus topology. ## Adv = low cost installation compared to normal bus; Disadv = device connected on network can hear when a device speaks so eavesdropping risks - WAN - comm network interconnecting data comm devices in large area / interconnects lan and or man or other wans - SWITCH - device which maintains an internal port table, keeping track of frames arriving on which ports. It is capable of frame filtering, commonly used to interconnect LAN to LAN. - Primary goal = isolate a pattern of traffic from other pattern of traffic. - ^^ full-duplex switches eliminate collision of data therefore allowing simul transmission and reception of data - ^^ workstations connected to switch uses its own dedicated segment so no eavesdropping risk and lower traffic congestion - Router - accepts input packet then check destination before forwarding it to its respective telecomm. line - Conditions: - Optimal cost - Fair - Robust so can reroute traffic if network fails ## Types: - **Flooding:** When packet is recieved, node will forward a copy of packet to every neighbouring node. - **Centralized:** Have a central node which keeps routing table and calculates optimal route for data transfer. - **Dedicated:** Each node has its own routing table and will send routing table to everyone else (might consist inaccurate info so inefficient routing) - **Adaptive:** Routing tables can change depending on network changes such as traffic/failure - **Static:** Routing table stays the same at all times, must be configured individually. ## Dynamic Routing -> primarily for adaptive routing - **RIP (routing information protocol):** Distance-vector routing; only know distance and direction of data transmission. - **OSPF (open shortest path first):** Link-state routing; calculate shortest path using Dijkstra's algorithm. - **BGP** ## Microwave - Satellite - used for wireless high speed long distance data transmission. Requires repeaters to ensure that signal is transferred in the proper direction and amplify signal, preventing it from attenuation due to long distance and interference ## HUB VS SWITCH VS ROUTER ## VPN VLAN - configure using tunneling technique - VLAN - logical subgroup within LAN created via switches and software - IEEE 802.1Q, allows multiple device to intercommunicate and work tgt to creat VLAN - VPN - uses encryption methods to create a secure private internal network whilst connecting to public network (tunnelling for secure data transmission) ## ADV DISADV VPN VLAN - VLAN - improve network security, simplify network administration, reduce network traffic by dividing it into subgroups, devices can be easily added or removed in VLAN and they dont need to be individually physically configured; complex so might require expertise to configure - VPN - enhance security, maintain private browsing; costly and time consuming ## COAXIAL CABLES, ADV DISADV - Large frequency spectrum, can create multiple channels so they can coexist - ADV: Broadcast system, large bandwidth supporting high data transmission rate and multimedia, less distortion so low error rates - DISADV: Bus topology, high installation cost, highly susceptible to interference ## FIBRE OPTIC, ADV DISADV - Thin glass cable - ADV: Not susceptible to electromag interference, low error, large bandwidth - DISADV: Susceptible to reflection and refraction, fragile, high installation cost ## TWISTED PAIR CAT 1-6 ## MULTIPLEXING (diff between multin demulti, examples, harys bisa explain each multiplex/along w the subgrps kyk statistical/synchronous time div multi) - ^^ Multiplexer = combines multiple input signals into 1 continuous output signal. Data flow = many to one - Demultiplexer = single input then distribute to multiple output lines. Data flow = one to many - Frequency division multiplexing: Transmits multiple signals simultaneously over a communication channel by allocating non-overlapping ranges of frequency to its users connected on the medium. - Time div multi: Transmits multiple signal by identifying order of transmission through dividing time into fixed length time slots whereby lengthy data transmission will nantj balik sana lagj kl blm selesai - Synchronous - every device connected will be included in multiplexed stream even if it is idle - ^^ Accepts input in round-robin fashion then transmits data in never-ending pattern. All device transmission will end at the same time. - Statistical - only active devices included in stream. More efficient as it prevents storage wastage. - Code div multi - divides channel by code whereby each user has their own dedicated binary pattern - REFRESH INGETIN HOW TO BACA ## CIRCUIT VS PACKET VS VIRTUAL SWITCH + EXAMPLES N WHEN TO USE + PROS N CONS - Circuit - have dedicated route for direct data transmission between sender and receiver. Used in telephone lines, or for large important transactions. - Packet - data is converted into fixed small size packets (datagram) and data transmission tereerah bisa go own route move sendiri. No need direct connection between sender and receiver and this method most effective for data sharing as other sources can share the same medium. - Used in emails/sending texts kyk watsapp, used in UDP and IP - Virtual - creates path for data transmission through subnets (data transmission antar subnets) whereby all data transmitted will have the same path (dedicated subnet path) - Used in WANs and VPNs ## NOISE definition types n preventions - Impulse - White - Crosstalk - Evho - Jitter - Delay distortion - Attenuation ## ERROR DETECTION + CONTROL - Parity - Arithmetic Checksum - CRC (Cyclic redundancy Chevksum) ## IP DEFINITION N FUNCTION - IP is a set of rules encompassing the format of data sent via internet or local network. - IPv4 - Purpose and function: / chars - Does datagram fragmentation using fragment offset - Each device connected will have 32-bit IP address and router - Detect and delete datagram which exceeds time to live - IP address is displayed in dotted-decimal notation - Datagram fragmentation -> Done to ensure full data is transmitted as each packet has an MTU, reduces network traffic as data is sent in small packets. - Offset is in multiples of 8 - IP address format: - Fragment Offset (13 bits) >> TTL >> Protocol >> Header checksum >> IP address (32 bits) - Classful Address (Class A - E) -> A itu 1000 B itu 1100 C itu 1110 .. and A ke bawah itu network size decreases - Not used no more since this leads to inefficient IP address allocations - Classless Address -> Using subnetting - Subnetting = allows network to be segmented into smaller portions using part of Host address space to create hierarchy - First IP after subnetting always for router, last IP for broadcast device so available IP for devices itu yg ditengah - Cara baca IP address after subneyting -> .._ - Yg after / itu the n of subnet mask, Host ID = 32- - IPv6 - Purpose/Chars - Simpler header than ipv4 - Establishes priority level and QoS - 128 bit IP address - No fragmentation - Classless address - Binary form displayed in short-hand hexadevimals ## TOPOLOGY - Mesh - all devices on network are interconnected to one another, therefore each device is capable of direct data transmission/communication - ADV: Robust network, secure and maintains privacy. - DISADV: High installation cost soalny banyak cables used, hard to maintain. - Star – has a central unit in the middle which is a hub. Every device will connect to the hub and data transmission from device A to B is done with hub being the intermediate. - ADV: Robust network, cheaper than mesh - DISADV: If hub broken then entire network collapse - Bus – 1 long backbone cable connected to multiple workstations through a drop-line with a Tap attaching it to the NIC of a workstation - ADV: Easy to install and modify, cheaper, if 1 dropline fails then only transmission from the ws it connects to will be stopped - DISADV: If failure is in bus backbone cable, then transmission of data will be stopped fully - Ring - dual and single ring - ADV: Fault isolation (for dual ring), easy to install and configure, 1 directional data flow (single ring) - DISADV: Number of ws increase, data transmission decreases since distance will increase and if want to transmit data from A to C then data must br sent through B first to reach C - LAN TOPOLOGIES ADA DIATAS ## TCP ARP DHCP - TCP - ARP - DHCP ## WIRELESS NETWORK ADV DISADV - ADV 1. Mobility 2. Easy and low cost installation 3. Increased reliability 4. Disaster recovery - DISADV 1. Susceptible to radio signal interferance 2. Security / privacy 3. Health risks ## WLAN SECURITIES (IEEE 802.11 Security) - Authentication - Verify client device permission to data. - Privacy - Carries data encryption and ensures data transmission not accessible by unauthorized devices. - WEP (Wireless Equivalent Privacy) - It is a data encryption specification - Ada 2 types of encryption: 64 bits and 138 bits tp 128 easy to decrypt - Uses simple RC4 implementation so used only in home networks - WPA (Wi-Fi Protected Access) - Network authentication and encryption - 128 bit pre-shared key (PSK) - 48 bit TKIP (temporal key integrity protocol) which does MIC (message integrity check) - Compatible with 802.11i - 802.11i and 802.11x -> robust security network association. It carries out: 1. Mutual authentication 2. Access control 3. Security keys establishment and management - Must be authenticated by external auth server -> RADIUS (Remote Authentication Dial-In User Services) -> EAP (Extensible Authentication Protocol) - Push-button wireless security - Automatically configures security settings for wireless devices. - VPN (Virtual Private Network) - Uses encrypted connection to create a private secure tunnel using strong encryption algorithm - ADDITIONAL WLAN SECURITY STRATS 1. Reduce WLAN transmission power 2. Change default security setting on AP 3. Antivirus + antispyware 4. Seperate WLAN transmissions from wired network traffic by placing a firewall in between ## PHISHING VS OHARMING ## SDLC