en:frequency_range
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+ | ====== Frequency Range ====== | ||
+ | Wireless transmitting und reception devices work on specific frequencies. The higher the quality of the receiving or transmitting device, the better is the correlation between the dial markings and the real operation frequency. | ||
+ | Very high accuracy of the frequency of a receiver or transmitter can be reached, when crystals are used. Because these crystals used in receivers or transmitters are expensive, engineers developed ways to safe the cost of many different crystals and ensure a high frequency stability anyway. | ||
+ | **Frequencies** are measured in Hz (cycles / second), or in multiples, for example kHz (Kilohertz = 1000 Hz), MHz (Megahertz = 1000' | ||
+ | In the very early time of wireless telegraphy, frequencies have been indicated inthe form of a **wavelength in meters** angegeben, you can use the formula **300' | ||
+ | In older British sets, you might encounter the dial marked in **cps** (cycles per second) instead of Hertz. | ||
+ | |||
+ | The frequency spectrum has been divided in different bands which were allocated for certain use: | ||
+ | * VLF (Very Low Frequency): 3 - 30 kHz; used for the communication with submarines while under water, not in use by the Swiss Army. | ||
+ | * **Longwaves**: | ||
+ | * **Mediumwaves**: | ||
+ | * **Shortwaves**: | ||
+ | * **VHF / FM - Band**: 30 - 300 MHz; mainly used for military communications in the 30 - 88 MHz range, for FM broadcasting in the 87,5 - 108 MHz range, for **aeronautical communications** in the "Air Band" 108 - 132 MHz (here, [[AM]] is used on contrast to the rest of communications in the VHF band), for aamteur radio (2m - band), for public services and for television (old VHF channels 5 - 12, today in Europe used for DAB / DAB+). | ||
+ | * **UHF**: 300 MHz - 3 GHz; used for military aeronautical communication in the 225 - 400 MHz range, for amateur radio (70 cm band) and television (old UHF channels 22 - 70), mobile telephony and WLAN, bluetooth. | ||
+ | * **SHF**: 3 - 30 GHz; used for military and civilian microwave communications, | ||
+ | |||
+ | In historic german sets, frequencies above 30 MHz have been addressed as " |
en/frequency_range.txt · Zuletzt geändert: 2018/10/29 19:14 von 127.0.0.1