General Theory

The General Theory wiki currently has 2 pages. The last time a page was edited in this wiki was July 1, 2020 at 10:18. To link to pages in this wiki from other wikis use the wiki reference [theory:page_name]. The full reference for any page can be found at the top of that page. This wiki can be sent to you as a wiki book.

All General Theory related pages

List all categories

Get wiki book

Did you know about...

HF

Also from: High Frequency

HF radio frequencies are between 3 and 30 MHz, although transceivers are usually from 2 to 30 MHz.

HF radio waves are propagated simultaneously by ground, direct and sky waves. Ground waves can travel about 100 km over land, and about 300 km over sea. Direct waves are line of sight. Sky waves are transmitted by skywave propagation. This is where the electromagnetic waves at HF frequencies are refracted back to the earth's surface by the ionosphere.

Due to properties of the ionosphere, the general rule on the use of frequencies is the higher the sun, the higher the frequency. This also applies to the distance the signal needs to travel: the greater the distance, the higher the frequency.

SSB and AM

SSB (or single sideband) is used to compress the transmitted information (voice) into a more compact signal. This is done to reduce the power required to transmit the signal over a given distance, and reduces the bandwidth of the signal (compared to AM). SSB also allows for more channels due to the use of only one sideband.

AM signals are double sideband.

Categories: General Theory | Avionics

Does this page need editing? Maybe the contents or references need updating, there might be spelling or grammatical errors, or you might be able to improve the formatting or add your own expertise.
If so, please update HF!