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Beat frequency oscillator. In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy (CW) transmissions to make them audible. The signal from the BFO is mixed with the received signal to create a heterodyne or beat frequency which is heard as a tone ...
The SN76489[1] Digital Complex Sound Generator (DCSG) is a TTL -compatible programmable sound generator chip from Texas Instruments. [2] Its main application was the generation of music and sound effects in game consoles, arcade video games, and home computers (TI-99/4A, BBC Micro, ColecoVision, IBM PCjr, Tomy Tutor, Master System, Game Gear ...
This Morse key was originally used by Gotthard railway, later by a shortwave radio amateur [2] Morse code is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. [3][4] Morse code is named after Samuel Morse, one of the early developers ...
An 1860s-era siren. [ 2 ] A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. There are two general types: mechanical and electronic.
Underwater acoustic communication is a technique of sending and receiving messages in water. [1] There are several ways of employing such communication but the most common is by using hydrophones. Underwater communication is difficult due to factors such as multi-path propagation, time variations of the channel, small available bandwidth and ...
t. e. A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. [1] It may refer to e.g. a laser or particle accelerator having a continuous output, as opposed to a pulsed output.
American Morse code. American Morse Code — also known as Railroad Morse—is the latter-day name for the original version of the Morse Code developed in the mid-1840s, by Samuel Morse and Alfred Vail for their electric telegraph. The "American" qualifier was added because, after most of the rest of the world adopted " International Morse Code ...
CW Morse code signals are not amplitude modulated, but rather consist of bursts of sinusoidal carrier frequency. When CW signals are received by an AM receiver, the operator does not hear a sound. The direct-conversion (heterodyne) detector was invented to make continuous wave radio-frequency signals audible. [10]