Given some discussions I've had recently with people, I figured it may be best to write a layman's guide to DXing, especially given the likely percieved 'elitism' around some discourse online. In part one, I will cover the basics, provide a short explanation of the skywave, and cover a rough "state of the portable radio," as the design and components may have changed beyond similarity since some people last dealt with portable radios.
To put it in the simplest terms, I'll paraphrase from DXing.info: DXing is the act of recieving and listening to distant radio stations. For example, if you live in Chicago, Illinois, and you recieve a radio station from Detroit, Michigan, you are DXing. For readers in North America, you will most likely be recieving stations on the AM band (also called Medium Wave [MW] in Europe and parts of Asia, apparently), due to skywave propagation (more on this later) from dusk until dawn and the relative (supposed) popularity of AM radio in North America compared to the popularity in Europe. Skywave propagation, when combined with North American power regulations makes it exceedingly possible to recieve distant signals during the nighttime hours.
Information retrieved from: https://www.fcc.gov/media/radio/am-clear-regional-local-channels
North American AM stations are licensed for the following classes; stations in the U.S., Canada, and Mexico are licensed in this fashion:
There are three frequency types designated by the FCC: clear, regional, and local. Frequencies designated as 'clear' may only have class A, B, and D stations operating on them, and for class B and D stations, only those which will not cause interference with the class A/clear channel station during the overnight hours; the fact that B and D stations shall not cause overnight interference makes it possible to, for example, recieve KSL-AM (which broadcasts from Salt Lake City, Utah) from a location such as St. Louis, Missouri. Frequencies designated as 'regional' may have class B and D stations operating on them. Frequencies designated as 'local' may only have class C stations operating on them.
The only exception to the prior frequency rules is that 530 kHz is reserved for Travelers' Information Stations (or TIS), which exist to deliver information to people traveling on highways, and may only broadcast at up-to 10 watts.
In layman's terms, skywave propagation is when radio-waves are reflected back from the ionosphere, making radio communications possible well beyond "line-of-sight" (otherwise known as "groundwave propagation," where reception is only possible within a smaller radius, since the signal cannot radiate much beyond ~100 KM [PDF explaining groundwave propagation] possible.
The skywave is most functional at night because the E-layer of Earth's atmosphere virtually disappears.
Many people still call portable radios (which, in this case, also refers to pocket radios) "transistor radios," which is technically incorrect, seeing that most, if not all radios built today use digital signal processors (DSPs for short). DSPs allow for more precise tuning, as well as for the filtering of interference. It may be anectodal, but in my experience, DSP-tuned radios tend to draw less power than transistor radios. DSP-tuned radios, however, may have one major fault: being locked into the 9 kHz channel spacing used in Europe and parts of Asia, while North America uses 10 kHz spacing.
DSP-tuned radios may also have tuning that sounds "choppy" (where the sound may cut out when tuning the radio) compared to the tuning on analog/transistor radios. Some lower-quality DSP chips may also output a sound which sounds "lossy," or indicative of digital aliasing. Unfortunately, there is no way to fix the latter of which, short of replacing the radio with a different model, likely from a different manufacturer.
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