Communicated information: a piece of information communicated by an action Means of communication: an action, gesture or sign as a mean of communication Incitement: something that incited somebody to action Electronics transmitted information: information transmitted by means of modulated current or an electromagnetic wave and received by telephone, telegraph, radio or radar

Spectra Signal spectra (plural of spectrum) describe the frequency content of the signal Spectrum is a condition or value that is not limited to a specific set of values but can vary infinitely within a continuum Evolved from old english “Spectre” meaning ghost or apparition but the modern meaning now comes from it’s use within science` First scientific use of word spectrum is within the field of optics. it is used to describe the rainbow of colors in visible light when separated using prism (prismatic diffraction)

Analog signal Any variable signal continuous in both time and amplitude. Any information can be conveyed by an analog signal, often such a signal is measured response to changes in physical phenomena, such as sound, light, temperature, position or pressure, and is achieved using a transducer. This signal uses some property of medium to convey the information. Electrically, the properties commonly used are Voltage followed closely by frequency, current and charge

Digital Signal Is a digital representation of discrete-time signal which is often derived from analog signal. An analog signal is a datum that changes over time Discrete-time signal is a sampled version of an analog signal: the value of the datum is noted at fixed intervals rather than continuously. If individual time values of the discrete-time signal, instead of being measured precisely (which would require an infinite number of digits) and are approximated to a certain precision – which therefore, only requires a specific number of digits - then the resultant data stream is Digital Signal

Digital Signal Quantization – the process of approximating the precise value within a fixed number of digits

SIGNAL PROCESSING

Signal Processing Refers to extracting information from a signal, conditioning a signal for subsequent use, signal transformation or altering a signal structure

Analog signal Processing Any signal processing conducted on analog signals by analog means. Specifically the mathematical algorithm that processes the the signal is implemented with analog electronics in which the mathematical values are represented as a continuous physical quantity, an analog, usually as voltage, electric current or electric charge around some components in the electronic devices. A small error or noise affecting such physical quantities will result in a corresponding error in the signals represented by such physical quantities

Digital Signal Processing (DSP) Is the study of signals in a digital representation and the processing methods of signals. Four major subfields of DSP are: a.Audio signal processing b.Control engineering c.Digital image processing d.Speech processing Four major subfields of DSP are: a.Audio signal processing b.Control engineering c.Digital image processing d.Speech processing

Transmitter It is the device that generates high frequency power, which, by means of a suitable antenna, is radiated or transmitted through space, or through conductors or through obstructive media, such as walls and glass It may be modulated with information, (noise, voice, pictures). This modulation or information may be received and demodulated in a receiver, where the combination of transmitter and receiver is known as radio system.

AM Transmitter Low-level modulation approach AM Transmitter Low-level modulation approach

AM Transmitter High level modulation approach AM Transmitter High level modulation approach

Radio Receiver Is understood to mean any device which is intended to receive a radio signal and extract the information or intelligence (modulating signal) from the rf signal (carrier signal)

Tuned Radio Frequency (TRF) Composed of several tuned-radio frequency amplifiers followed by circuits to detect and amplify the audio signal

Superheterodyne Invented by Edwin Armstrong in 1918

Characteristic of Good Receiver Selectivity – ability of the receiver to receive the desired signal and reject all others Sensitivity – ability of the receiver to amplify weak signals Fidelity – it is the ability of the receiver to faithfully reproduce the information

End na talaga