en:modes
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+ | ====== Reception or Operation modes ====== | ||
+ | There are very different ways, information can be superimposed to a RF carrier signal. In the early years of wireless signal transmission, | ||
+ | In modern transmitters, | ||
+ | |||
+ | ==== A1 ==== | ||
+ | {{: | ||
+ | **Continuous Wave** or **CW** or **telegraphy unmodulated** is an operation mode, in which an unmodulated carrier signal is transmitted in the rhythm of the morse code. | ||
+ | |||
+ | On the transmitter side, this " | ||
+ | |||
+ | For reception of these signals, the signal of a "beat frequency oscilator" | ||
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+ | So only receivers which have a switch for " | ||
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+ | Also TRF receivers with regeneration (" | ||
+ | |||
+ | ==== A2 ==== | ||
+ | **Telegraphy modulated** or **modulated tone telegraphy** is an operation mode in which the RF carrier is modulated with a tone frequency in the rhythm of morse code (in the very early years of wireless telegraphy, often the frequency of the power generator has been used for this). | ||
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+ | In contrast to the unmodulated carrier of A1-transmissions, | ||
+ | |||
+ | ==== A3 ==== | ||
+ | {{: | ||
+ | For broadcast reception on mediumwaves and longwaves and also for telephony on early military and commercial wireless equipment, " | ||
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+ | {{: | ||
+ | In [[wpen> | ||
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+ | A simple crystal detector or a valve or semiconductor diode is sufficient to demodulate such signals. | ||
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+ | {{: | ||
+ | The requirements conncerning energy and bandwidth is quite high, when amplitude modulation is used. A relevant fraction of the transmitter output is used for the carrier and not carrying any information, | ||
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+ | Signals using amplitude modulation are subjected to propagation disturbances (" | ||
+ | |||
+ | ==== A3J ==== | ||
+ | {{: | ||
+ | The current designation of **Single Sideband** or **SSB** is **J3E**. | ||
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+ | For a more efficient use of the transmitter output and bandwidth, **single sideband modulation** is used: Only one sideband containing the audio or voice information ist transmitted, | ||
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+ | In the shortwave transceiver [[SE-222]] introduced in the year 1959 by [[Zellweger]], | ||
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+ | In a **single sideband** transmission, | ||
+ | For military and commercial communication, | ||
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+ | For correct demodulation, | ||
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+ | A special transmission mode is ISB (" | ||
+ | |||
+ | ==== F3 ==== | ||
+ | {{: | ||
+ | **Frequency modulation**, | ||
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+ | On higher frequencies above 30 MHz, signal bandwidth or channel spacing is less important. FM signals have much better audio quality and are easier to understand and a " | ||
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+ | In a transmitter using frequency modulation, the transmitting frequency is altered according to the audio information transmitted. In the receiver, demodulation is far more demanding as a limiter (to eliminate unwanted residual amplitude modulation) and a discriminator (for the demodulation) stage is necessary. | ||
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+ | In contrast to FM broadcasting, | ||
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+ | ==== FSK ==== | ||
+ | For radioteletype, | ||
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+ | As an alternative, | ||
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+ | Quite similar is mode to transmit image data in a signal with frequency modulation, the designation for this " | ||
+ | |||
+ | ==== Hell === | ||
+ | A completely different approach is the HELL radioteletype mode. This has taken it's name from the German engineer Rudolf Hell, the developer of the **[[wpen> | ||
+ | |||
+ | In the side of the receiving station, the Hell -signals are fed to the Hell - printing machine, a spiral writing head is electromechanically moved on a colour ribbon and the text is printed on paper tape which can be glued on the telegram form. | ||
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+ | In Switzerland, |
en/modes.txt · Zuletzt geändert: 2019/04/21 17:07 von 127.0.0.1