Telecommunication and Teleinformatics Notes
Telecommunication and Teleinformatics
Historical View and Basic Definitions
Teleinformatics: A field covering computer science (hardware and software) used for information creation, processing, uploading, presentation, and securing. Also includes telecommunication tools and related technologies.
Telecommunication (Legal Definition): According to Polish law (2004), it's a set of cooperating IT devices and software that ensures sending, receiving, storing, and processing data through telecommunication networks using terminal equipment appropriate for the network type.
Telecommunication (Process): Transmission of information involving:
A thought model in the sender's mind.
Description of the model using contractual symbols (auditory, visual, numerical).
Coding for transmission.
Transmission.
Decoding and reproduction of information.
Reconstruction of the model to be close to the original, or processing, saving, or analysis.
Historical Timeline
450 BCE: Greeks of Alexandria devised optical coding of alphabet letters using torches as a telegraph.
1794: Claude Chappe demonstrated a semaphore telegraph with moving arms.
The first route was 220 km from Paris to Lille, divided into 20 substations.
Within 50 years, the system expanded to ~5,000km across major French cities, with an average transmission time of a few minutes.
1800: Alessandro Volta discovered the battery, marking the beginning of electrical engineering and the development of telecommunication, electronics, and IT.
Telecommunication involves transmitting multimedia data in analog or digital signals via the electromagnetic field.
1837: Samuel Morse invented the telegraph, using a combination of dots and dashes to send specific alphabet letters or numbers.
May 24, 1844: The first telegraph line connected Washington and Baltimore (60 km). Morse sent the message "What hath God wrought?", marking the beginning of telegraphy and telecommunication.
1876: Graham Bell patented the first phone using an electromagnetic microphone. On March 10, 1876, he sent the historic sentence, "Watson, please come here."
1864: Maxwell developed the electromagnetic theory of light, predicting the existence of radio waves.
1887: H. Hertz experimentally discovered radio waves.
1895: The first radio transmission of information (Morse Code).
1906: Spoken text and music were broadcasted, marking the beginning of electronics and radio. Quantitative and qualitative development was then limited by circuit switching and wired network infrastructure.
Commutation
Commutation (switching) is the technique of connecting subscribers in telecommunication, involving variable and periodic connections for information transmission.
Manual Commutation Process:
Subscriber sends a call signal to the control panel (using an inductor or by picking up the handset).
The telephone operator receives the call signal and accepts the connection with the desired subscriber.
The operator verifies the subscriber's availability and sends a call signal by activating the telephone bell.
The operator connects the calling subscriber with the desired subscriber using a connecting cord.
After the conversation, one subscriber signals the end of the call.
The operator disconnects the subscribers, registering the call and its duration for billing.
Modern subscriber connection is similar but done automatically.
1897: A.B. Strowger (an undertaker) invented a rotary selector (automatic switch) to prevent unfair telephone operators from giving information to competitors, leading to automatic telephone exchanges.
Further Developments
1913: Automatic cross-processing using cross selectors in control panels (channel switching).
1924: The first television picture (cross mark from 3 m), by John Baird.
1935: The first public television broadcasts (England).
1927: Cable undersea Europe-America's first intercontinental conversation.
1935: The first working radar (GB).
1936: Konrad Zuse patented a mechanical computer working in zero-one arithmetic, including the idea of floating-point operations.
1938: Digital technique a/c. Digital PCM (Pulse Code Modulation) link for digitizing analog signals.
1941: K. Zuse finishes work on the first programmable computer built on electric relays.
1943: England. Alan Turing, a tube decrypting computer - Colossus with 19,000 electron tubes, was not programmable
1944: America, Harward Mark I computer, consisting of 800,000 electromechanical elements
1944: America. Johann von Neuman proposes to store a computer program in his memory - program memory
Definitions of Telecommunication
Derived from Greek terms "tele" (distant) and "communicare" (sharing with someone).
Definitions:
The field of knowledge, scientific, technical and economic activities related to the transmission of information at a distance, using signals - usually electrical.
The process of sending information between two or more system users (human or machine, or both), one- or two-way.
Signals in Telecommunication
Information is provided in the form of signals, most commonly electrical signals.
Sounds (e.g., human voice) are composed of elementary harmonics, representable as mathematical functions (sine or cosine).
Human speech ranges from several dozen Hz to several kHz; human hearing ranges from about 16 Hz to about 20 kHz.
Microphones convert sound waves to electrical signals, representing the sound.
Loudspeakers and headphones convert electrical signals into speech sounds.
Image Information
Images (static and moving) are more complex forms of information.
The eye's limited ability to distinguish small details allows images to be divided into points with sub-distinction dimensions.
Image sensors analyze images into components, and data about brightness and color is provided for each point.
Devices like kinescopes, LCDs, or plasma matrices reproduce images.
Moving images (cinema) are created by rapidly changing subsequent images (above 16 times per second), leveraging the eye's inertia.
Television combines the analysis of single images with rapid repetition to transmit moving images remotely.
High speed of analysis and synthesis is required where approximately 13,015,625 points need to be generated within 1 second using 625 lines and 833 points per line with an aspect ratio of 3: 4.
Transmitting TV signals (multimedia) requires better transmission path parameters than voice signals.
Digital Data
Digital data (measurement, control, computer) can be simplified using a base-2 counting system.
Binary digits "0" and "1" can be represented by two states of an electrical signal parameter (current, voltage, etc.).
Signal Classification
Basic classifications include:
Analog (continuous).
Discrete (impulse).
Digital.
Deterministic.
Random.
Sampling theory states that signals with finite spectrums can be represented by collecting and transmitting samples periodically with appropriate frequency.
Signal Description
Signals are described by:
Duration (time interval ).
Instantaneous value (in appropriate units).
Waveform function (of one or more variables).
Specific properties (amplitude, frequency, periodicity, energy, power, etc.).
Model of a Telecommunication System
Key components:
Transmitter (terminal device).
Transmission channel (transmission medium).
Receiver (terminal device).
Sometimes, humans are excluded, and machines communicate directly.
Telecommunication focuses on the layout of characters transformed into waveforms and electrical signals, not the information content itself.
Telecommunication Types
Based on transmission type:
Communication (two-way between points).
Broadcasting (one-way from one point to many).
Aggregate (unidirectional transfer from many points to one).
Based on message type:
Telephony (voice).
Broadcasting (sound, speech, music).
Telegraphy (handwriting characters).
Symilography (static images).
Television (moving pictures).
Telemetry (measurement data).
Signaling (contractual signs).
Telemechanics (control pulses).
Teledication (digital data).
Based on operations performed:
Message processing techniques (electrical or optical signal).
Teletransmission (signal transmission).
Telecommuting (connection setup and removal).
Telecommunication Environments
Based on the environment in which signals carry information:
Track communication (Torowa): uses concentrated signals within wires, waveguides, or directional antennas.
Non-track communication (Beztorową): uses electromagnetic waves propagating with low energy concentrations (radio waves).
Telecommunications Tracks
Telecommunications tracks are passive systems that allow electromagnetic wave propagation in a defined space, with energy concentrated in a cylinder.
Wired tracks (symmetrical and coaxial).
Waveguide tracks.
Fiber optic tracks.
Radio tracks.
Information Capacity
Telecommunication paths often have transmission capabilities exceeding single-signal needs, considering:
Signal frequency band.
Signal duration.
Signal-to-interference power ratio.
Information capacity refers to the transmission capabilities of a telecommunications track.
Multiplication Techniques
Multi-frequency multiplication: Divides the frequency band to allow simultaneous transmission of multiple signals.
Time multiplication: Allocates time slots for various signals in the communication path after converting a continuous information signal into a discrete one, per sampling theorem.
Time multiplication is commonly used in digital teletransmission systems.
Power gradation: Divides signal dynamics to allow multiple signals, used only in special cases due to technical issues.
Telecommunication Channel and Connection
Telecommunication channel: Technical means enabling the transmission of telecommunications signals from point A to point B, potentially running through different telecommunications tracks.
Telecommunication connection: Technical means enabling the two-way transmission of telecommunications signals between points A and B.
Telecommunication Systems
Formally divided based on signal form:
Analog.
Digital.
Analog systems: Use continuous signals (usually sinusoidal) where amplitude, frequency, or phase changes with the information signal.
Discrete signals: (telegraph, data transmission). Continuous signals can be converted into discrete pulse signal without any loss of information using sampling theorem.
Impulse signals use pulse modulation like PAM, PDM, PPM, or PFM.
PAM(Pulse Amplitude Modulation)
PDM(Pulse Duration Modulation)
PPM(Pulse Phase Modulation)
PFM(Pulse Frequency Modulation)
Digital systems: Convert discrete signals into digital form (binary numbers), integrating messages and telecommunication systems with switching systems. A/C and C/A conversions are made once at the sender and receiver.
OSI Model and ISDN
OSI (Open Systems Interconnection) model: A seven-layer hierarchical architecture that standardizes telecommunication network architecture by defining input-output parameters at each interface.
ISDN (Integrated Services Digital Network): Fully implements the idea of integrating telecommunication systems through digitization and standardization.
ISDN Concepts:
Application of digital teletransmission systems
Implementation of functional control-based digital, commutative systems
Connection of independent telecommunications of various telecommunication services into one integrated network
Unification of user's physical access to the network and standardization of connection control procedures
Standardization and orderly development of intelligent telecommunications services.
Benefits of ISDN
Eliminates disadvantages of separate telecommunications networks, by:
Reducing construction costs through standardization.
Increasing network efficiency by better use of common elements.
Increasing user availability.
Increasing production efficiency and sales of terminal equipment.
Intelligent Network (IN)
Digital switching and teletransmission enable new services beyond "classic" services.
Intelligent Network (IN) : Modern network architecture characterized by susceptibility to new services.
Key Feature of IN
Additional services implemented in one place in the network using INAP (Intelligent Network Application Protocol), standardized by ETSI in 1990.
Convergence in Telecommunications
Convergence of telecommunications, IT, and audiovisual sectors.
Telecommunications dominated by fiber optics and digital commutation.
IT controlled by computers and networks.
Audiovisual media (multimedia broadcast).
This convergence results in the field of ICT (Information and Communication Technology).
Areas of Convergence
Convergence of the network, including the merger and penetration of technologies and services in computer- based networks, in which data transmission and public networks of telecommunications origin predominated .
Convergence of services, including the provision of similar or the same electronic subscriber services in various telecommunications systems, built using different types of networks and technologies .
External resources
Historyczne podstawy teorii informacji 6/9 - Historia telegrafów optycznych https://www.youtube.com/watch?v=qoz2R9cHaZE
Historyczne podstawy teorii informacji 8/9 - Bateria i elektromagnetyzm https://www.youtube.com/watch?v=npPgtf1QIw8
Historyczne podstawy teorii informacji 9/9 - Alfabet Morse'a https://www.youtube.com/watch?v=sifm5X9ILQE