Continuous wave
Continuous wave or continuous waveform abbreviated (CW), comes as a physical concept from English and is equivalent to an undamped or permanent, constant wave and the word CW. In calculus, it is the mathematical term for infinite duration.
In the physical sense, a particular state is described with CW, reach the waves of any kind, when their amplitude and frequency are constant. The initial use of the term initially referred only to electromagnetic waves. However, waves, such as sound or water waves can reach a particular steady state.
By pressing a telegraph key in the radio being can be generated either by a short press of the short sound, the point or prolonged pressure of the long sound of the Morse alphabet. From this Morse - line of the continuous wave was derived because a permanent constant transmission energy leaves through the longer pressure at this moment the antenna. If a shaft is graphically depicted in this steady state frequency and amplitude for example, on a monitor, a continuous wave may occur. But even with the actuator such as a laser pointer, which does not generate pulsating laser, created almost a " continuous wave " when it would be made visible by reflection in smoke or fog. This created for a specific type of radar sensors, the term continuous wave radar ( a radiated unmodulated signal in the microwave range is reflected and absorbed back into shares ) as well as for a type of equipment with non-pulsating lasers: continuous wave or CW laser.
However, CW is just a mode ( amateur radio ) of amateur radio. On the basis of these examples is to see how the meaning of the term during the evolution of technology over the original sense of the word - has changed - like a Polysem.
Historical Usage
At the beginning of radio and radio technology in the end of the 19th century emitted CWs had yet another meaning. They were in signal transmission as a constant undamped waves, the effective counterpart of those which. , In the form of attenuated, interrupted stepped shafts The first functional transmitter for wireless transmission of Morse letters were still electric radio stations such as Pop, impact and quenched spark transmitter.
However, this could only transmit when they
- Between charging of the capacitor is located in the transmitting apparatus,
- The subsequent appearance of a letter by discharge this capacitor through the coil as Funke and
- Re- charging ( with a high voltage supply )
- To issue the next letter or character
Alternated back and forth. And with this ever- repeating process, as well as these technical limitations regular pauses between the signals only subdued, broken waves were generated. Therefore, and because of their considerably large bandwidth and frequently possible interference by one too poor frequency tuning and the loud bang when any discontinuation of the transmit sparks, these apparatuses were as dirty - dirty transmitter. Shortly after the beginning of the twentieth century Reginald Fessenden invented Valdemar Poulsen and with each arc and machine modern station transmitter types. With their use of a new era of wireless transmission could begin not only in telegraphy, but also for the first time in the broadcast of speech and music. By the existing radio transmitters operating with interruption of a usable transmission of tones was not possible. But even for Morse there was an improvement: The now possible " smoother " Send. With the replacement of the radio station by Poulsen and Fessendes equipment, the linguistic juxtaposition of damped and undamped had done as a bearer of waves.
Definition of presence
Continuous wave in addition to the historical uses of the conventional designation of the condition of a constant wave frequency and amplitude, an early type of wireless transmission, in which an unmodulated carrier signal on and off. Contrary to other modulation techniques includes a CW signal no information ( news in the technical sense ); in fact, the information is transmitted through the rhythm and breaks the signal.
Continuous wave was designated a long time as RT, as well as the telegraph it works by switching on and off a key in Morse code. Instead of a current pulse in an overland telegraph line (wire) in this case the power of a transmitter is controlled. This mode is due to its simplicity and reliability even today at radio amateurs around the world.
CW typically uses a narrow-band signal, so that the total energy is concentrated in a narrow range. To have CW transmissions even at low transmit power, a tremendous reach, since the signal can be even in strong noise or decoded by the use of narrow-band filter - the filter bandwidth can be up to 250 Hz or less. In QRP contest ( QRP = low transmitted power ) can be realized with a few milliwatts (<500 mW) CW compounds ( QSOs ) around the world.
In order to prevent a failure of the international radio communications, amateur radio users CW may not use, because its long range precludes the license-free locality character of the CB radio and its possibly untrained participants.
In amateur radio CW and Morse code are often used interchangeably, although there is a difference: while CW exclusively based on electromagnetic waves, the Morse code can also be other carriers, such as light or knock characters are transmitted.