Talk:Shortwave radio

Note

This is a good summary on Shortwave and how it's used.

An annual conference dedicated to shortwave listening is the Winter SWL Fest, located outside of Philadelphia in the USA. Its URL is http://www.swlfest.com

Number of receivers

"The Asia-Pacific Telecommunity estimates that there are approximately 600,000,000 shortwave radio receivers in use in 2002."

I know there are a lot about but the figure seems extremely high, especially if we're talking about receivers actually in use as opposed to the total number ever produced or something. This works out at about one shortwave radio for every ten people in the world. Can anyone confirm it? — Trilobite (Talk) 04:24, 26 Nov 2004 (UTC)

• I can confirm that I personally own 11 shortwave radios.  :) bneely 19:27, 26 February 2006 (UTC)

Add Section on PC-Controlled Receivers and Software?

Suggestion: Anyone think it's a good idea to include a section on PC-controlled shortwave receivers (and software)? (I am not the prospective author, as no experience with this setup.) I didn't find any reference to it in Wikipedia.--Kibbitzer 07:11, 14 July 2005 (UTC)

• Only in conjunction with a general discussion of shortwave and amateur radio hardware, and a mention of Digital Radio Mondiale (which pretty much requires a computer anyway). Not a bad idea though, just needs a fair amount of background to go with it. Haikupoet 06:00, 15 July 2005 (UTC)

Yes. Perhaps zealot will contribute. Also, this is the first I heard of DRM. Perhaps the Wikipedia article on that could be appropriately linked? Again, I am not qualified to know where to work it into the existing shortwave article.--Kibbitzer 06:22, 15 July 2005 (UTC)

Better band descriptions?

This page needs better descriptions of the meter bands. For starters, I dispute the "not in the americas" label for the 41 meter band. I have other descriptions for these bands but I believe it is under copyright (from radio manuals). bneely 19:29, 26 February 2006 (UTC)

Ionosphere refraction?

I was reading the article and this part was unclear to me:

Shortwave frequencies are capable of reaching the other side of the planet because they can be refracted by the ionosphere. Are radio waves refracted (bent) or reflected? . User:Rjairam

They are actually refracted since the waves enter the ionosphere and their direction of propagation is gradually changed by interaction with the free electrons therein. However, for practical purposes, the interaction can be characterized as a reflection from a thin, conductive surface at a single virtual height above the earth. Jim, K7JEB 02:27, 13 April 2006 (UTC)

It is actually a dual process of refraction and reflection. As the ray enters the layer it bends - refraction and it eventually reaches a part of the ionosphere where the angle of incidence equals the angle of reflection and reflection back or out of the layer occurs and at his point refraction again follows until the ray exits the layer. If you were to plot the path of the ray through the layer it makes a curve. If pure refraction were to occur the actual location of reception is not at the predicted location but can be several hundreds of kilometres away. Proof that reflection plays an important role is that only then can the predicted zone of reception actually in over 90% of the time be reached. Other factors also play a major part but without reflection the ray would not be received where expected. I also happen to be a retired radio engineer responsible for long range (HF) communication and in the context that I refer to a "ray" it means radio wave. — Preceding unsigned comment added by 90.244.55.57 (talk) 12:39, 3 August 2013 (UTC)

Merger with High Frequency?

The shortwave and high frequency articles seem to be about the same subject:

• Shortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly in use at that time. An alternate name is HF, or high frequency.
• High frequency (HF) radio frequencies are between 3 and 30 MHz. This range is often called shortwave.

Shouldn't these be merged? If so, which title should be the "main" article title? — Johan the Ghost _seance 14:12, 23 April 2006 (UTC)

I'm making this a formal proposal. Please comment at Talk:high frequency. — Johan the Ghost _seance 10:35, 11 May 2006 (UTC)

Needs Improvement

This article fails. Lacks date when shortwave was invented and/or came into practical use. --68.190.117.179 00:15, 18 June 2006 (UTC)

• You're absolutely right; although there is an article called History of radio, and there is another called Shortwave listening, this would be a GOOD place to start a history of shortwave broadcasting ... although that's a very large subject in it's own right. Twang 02:18, 11 July 2006 (UTC)

Note on HF

The term "HF" is not misapplied; it's historical and has been in use for many, many decades -- particularly before VHF and UHF (which are no longer VERY or ULTRA) transmitting became commonplace. In fact the HF amateur radio bands were allocated to amateurs (like reservations were allocated to indians) precisely because it was once thought they would be of little use to broadcasting. Twang 02:03, 11 July 2006 (UTC)

Disambig

There needs to be a disambigulation page to differentiate between radio waves and other uses of "short wave" and "long wave" (such as those terms in Meteorology).

Globalize tag

I've added a globalize/USA tag to this article, since it is a particularly bad example of US-centric writing, especially in the first section. 86.31.35.135 (talk) 23:24, 11 January 2008 (UTC)

Can you support this with some basic elaboration? 71.228.184.188 (talk) —Preceding comment was added at 19:04, 4 February 2008 (UTC)

A good deal of the development of shortwave radio came from the United States first, especially in the 1920s. U.S. hams were the first to discover the ability of shortwave to reach long distances. GABaker (talk) 19:35, 4 February 2008 (UTC)GABaker 19:34 4 February 2008

I think that you will find the FIRST across the pond or trans-Atlantic transmissions were from Europe to the Americas and the first almost trans-global or almost 180 degree path was again from Europe actually the United Kingdom to Australia and New Zealand. Like most technology advances in the early part of the 20th Century these occurred strangely in Europe with the US copying and in some cases blatantly stealing the ideas and claiming them as being designed in the US - computers come to mind!

File:Modern_Short_Wave_Radio.jpg may be deleted

I have tagged File:Modern_Short_Wave_Radio.jpg, which is in use in this article for deletion because it does not have a copyright tag. If a copyright tag is not added within seven days the image will be deleted. --Chris 10:23, 28 April 2009 (UTC)

Narrow-band FM

Because of the larger bandwidth required, NBFM is much more commonly used for VHF communication.

I thought that NBFM had the same bandwidth as AM. 72.75.98.88 (talk) 22:04, 4 June 2009 (UTC)

"Sliver band" (slang term) FM is a form of NBFM that can have the same bandwidth as AM. It requires that the deviation not exceed one radian at any modulating frequency greater than half of the highest input frequency. This does not provide as much S/N ratio as what is usually referred to as NBFM.

Typical NBFM uses about 16kHz of bandwidth with a 3000 Hz limit on the audio (versus 6 kHz BW of an AM signal with 3 kHz limit on the audio).

I do have in issue with the statement that "phasic distortions" limit the distance of NBFM. If anything, NBFM reception is better than AM reception under skip conditions, provided the signal strength is adequate. Wideband FM broadcasts can be heard with superb quality when Sporadic-E propagation is present on the FM broadcast band.

The user cited a book reference, but without access to the text of the book, one cannot find where Sinclair (the author) received the information in the book. As the title of the book would imply that the purpose of the book is to aid in the obtaining the highest quality audio reproduction, it may be possible that the implications of ionospheric propagation were given limited attention.

NBFM has not been used for shortwave broadcasting because of the bandwidth issues and because of the lack of FM detection capability in virtually all consumer grade shortwave receivers, and has not been used in shortwave voice communication (note that the preferred term in that field is "HF communication) because SSB uses less bandwidth and delivers superior signal-to-noise for a given consumption of power. FM signals will propagate to the same distance of AM, CW, data or SSB signals on the same frequency. — Preceding unsigned comment added by 313 TUxedo (talk • contribs) 17:21, 12 April 2014 (UTC)

Power over Wireless

Some mention of this new technology would possibly fit here? 87.74.77.209 (talk) 21:14, 23 July 2009 (UTC)

Wavelength

Frustratingly, the first citation just doesn't support what is in the introductory paragraph of the article. What is the range of shortwave frequencies? Anyone know? —Preceding unsigned comment added by 173.2.230.224 (talk) 03:29, 1 July 2010 (UTC)

According to all contemporary information - 3 to 30 MHz. — Preceding unsigned comment added by 90.244.55.57 (talk) 12:45, 3 August 2013 (UTC)

Reflection? Refraction? I'm confused

I'm driving along a highway. Ahead of me I see a car, and just below that in my visual field, there's a wavery sort of "reflection" of the car. I know that neither asphalt nor air has any reflective properties, but clearly this is "reflection by refraction" and analogous to the way shortwave radio gets bounced around the ionosphere. Is it really that clear-cut? --Wtshymanski (talk) 15:08, 2 September 2011 (UTC)

Yes. Light and shortwave are both electromagnetic radiation, and either can be reflected or refracted. My recollections at the atomic level are fuzzy, but at a gross level, they are very different phenomena, as different as a reflector telescope and a refractor telescope. One difference is that the angle through which a refractive media bends electromagnetic waves depends on frequency, while the angle of reflection for a mirror is independent of frequency. Jc3s5h (talk) 17:25, 2 September 2011 (UTC)

There's an awful lot of literature out there that has radio waves "bouncing" off the ionosphere like a puck off the boards. Are we really sure that using the esoteric, possibly correct form "refracting" is more accurate than the equally descriptive, familiar "reflecting" ? Surely the dependancy of refraction on frequency only holds true in a dispersive medium...(even if just about every thing *is* a dispersive medium). Why doesn't the car reflected in the pavement change color, then? Why does HCJB come in on the same frequency that they announce? Why does my face look funny in a red or green mirror? Maybe we should just say something like "the path of the waves is bending", which is clearly happening. --Wtshymanski (talk) 19:22, 2 September 2011 (UTC)

Reflection and refraction are not the same process, even though under certain circumstances they may produce simular results. Stating "reflection by refraction" is somewhat simular to stating "driving by bicycling" (I realize this is not a perfect comparison). Both driving and bicycling involve the movement of an operator via a vehicle, but they are otherwise very different processes. Like-wise reflection does not occur by refraction, or vice-versa. The following except is from: "Chapter 22: Radio Frequencies and Propagation". The ARRL Handbook for Radio Amateurs 1994 (71 ed.). The American Radio Relay League. 1993. pp. 22-1–22-2. ISBN 0-87259-171-9.

"Reflection and refraction are two words that often seem to be used interchangeably, even though they describe quite different phenomena. Reflection occurs at any boundary between materials with different dielectric constants. ... Refraction is the bending of a wave as it passes from one medium into another. ... Most amateur communication on the HF bands depends on this bending of radio waves, so it is a very important concept. ... On frequencies below 30 MHz, long distance communication is the result of refraction (bending) of the wave in the ionosphere."

Even further reading of techinical literature supports that reflection is not the process by which most long distance shortwave communications occurs. –Sparkgap (talk) 20:05, 2 September 2011 (UTC)

Since there is a more technical article available for those who want to read more, I don't object to using less technical language like "bending" rather than "refraction". But we should avoid incorrect language such as "reflection" so as not to point our readers in the wrong direction.

Also, in answer to "Why does HCJB come in on the same frequency that they announce?", the frequency is the same at the transmitter and receiver, so long as the transmitter, receiver, and intervening ionized regions are all stationary with respect to each other. But if the speed of propagation of the electromagnetic radiation is different at the transmitter and receiver (say, the receiver is on a high-altitude balloon), the wavelength will be different at the transmitter and receiver. Jc3s5h (talk) 20:25, 2 September 2011 (UTC)

Thenn we should say "bending" and not use more scientific-sounding jargon. Oh well, at least we don't have "backscatter" any more. --Wtshymanski (talk) 20:42, 2 September 2011 (UTC)

Advantages

I'm pretty sure that the bit about being able to detect the number of HF listeners via the EM of the circuits is not feasible. Haven't found any mention online or in any other source. — Preceding unsigned comment added by 67.233.139.238 (talk) 02:14, 9 February 2012 (UTC)

As far as I know this is quite feasible, because it was this emission that led n to the discovery of the Superheterodyne receiver. CodeCat (talk) 00:50, 10 February 2012 (UTC)

I doubt they can detect the "number of HF listeners" over long distances, but they can certainly drive down your street with a monitoring antenna and pick up the signal emitted from your radio. I think CodeCat is essentially right, because the way a Superhet receiver works is that a "local oscillator" (LO) radiates EM radio waves at a frequency that equals the tuning frequency plus (or minus) the "intermediate frequency" (IF). I've seen a first-hand demonstration this sort of spying done on an FM radio on the 88-108 MHz band. Knowing that the intermediate frequency of most FM radios is 10.7 MHz, if they detect a signal in the vicinity of your radio at 118.7 MHz (or 97.3 MHz, I forget whether the LO is offset above or below), then they know you're tuned in to 108 MHz. This technique relies on some standardization of the IF, e.g. 10.7 MHz in North America.

It also might be possible to spy on people by detecting the IF signal, which unlike the LO, contains the broadcast data. This signal can then be matched up to all the possible stations that you could be listening to.

To minimize this radiated signal would require shielding the LO and IF stages by wrapping them in conductive foil and grounding the foil, and possibly using additional filtering, both of which would make it more similar to a direct conversion receiver. --Mikiemike (talk) 03:23, 16 June 2012 (UTC)

new photo

Shortwave Radio Dial

may i point your interest to this photo? i took it today for the german article about shortwave. maybe you find it suitable for the opening section. i wanted to focus on shortwave, not on a universal radio receiver like the one in the intro of this article. Maximilian (talk) 23:28, 19 April 2012 (UTC)

I think a properly focused photo is better than the blurry one in the article now. Perhaps you could take another photo with a centimetre scale in it so people will know how big it is? Jc3s5h (talk) 23:37, 19 April 2012 (UTC)

the blurry photo in the article seems to show a LW/MW/SW receiver. if this is the case, it's a misleading picture for the article. my photo shows the ca. 3 cm wide display of a portable sony ICF-7600. a centimetre scale is, imho, not necessary for this photo and its message. the message is: we're tuning into 15 m band shortwave, bingo! Maximilian (talk) 23:23, 23 April 2012 (UTC)

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Merge World radio receiver here Comment

I see no indication in reliable secondary sources that "world band" or "world radio" receiver is anything more than a marketing term used by a few manufacturers to brand their radio receivers that are capable of shortwave broadcast reception. And it looks like this article duplicates material already covered at Shortwave_listening#Shortwave_radio_receivers. Considering the many errors and misstatements in this article, I think the topic be folded into Shortwave_listening#Shortwave_radio_receivers, rather than a separate article that creates the false impression that "world radio" is something different than a shortwave radio. - LuckyLouie (talk) 01:44, 15 October 2017 (UTC)

(copied answer from Talk:World radio receiver)

Please note the following:

• Shortwave listening Quote: "...Shortwave listening, or SWLing, is the hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kHz and 30 MHz..."
• Shortwave radio Quote: "...Shortwave radio is radio transmission using shortwave radio frequencies, generally 1.6–30 MHz (187.4–10.0 m), just above the medium wave AM broadcast band..."

None of the articles, by definition, are about shortwave radio receivers. So neither world radio receiver nor communications receiver should be folded into Shortwave listening nor Shortwave radio.

Tentative definition of "world band radio receiver": shortwave radio receiver that covers the most used international shortwave bands; as far as I can read: 49 meter to 13 meter bands.[1], Quote: "...These international stations transmit on bands called World Band Radio or "shortwave"...". Band useability: Shortwave bands, see best day/night listening, TABLE OF SHORTWAVE BANDS. Quote: "...A shortwave radio is a receiver which can pick up transmissions on frequencies up to 30 MHz, usually ranging between 1.6 and 30 MHz. These frequencies work well over very long distances, which is why shortwave radio is used for international broadcasts and why it is also sometimes referred to as “world band radio.”...".

There is missing an article with the name shortwave radio receiver, that could include references to e.g. world radio receiver and (shortwave) communications receiver. Most of the paragraph Shortwave_listening#Equipment should be transferred to shortwave radio receiver and used to differentiate between e.g. a world radio receiver and a (shortwave) communications receiver. I will volunteer to make or cooperate making that article, but this of cause depends on the discussion outcome.

This is correct and useable: world bands (means international shortwave broadcasting bands) (redirects to shortwave radio).

--Glenn (talk) 20:26, 17 October 2017 (UTC)

• Glenn is correct, and no merge should take place. But someone could write on shortwave radio receiver. Graeme Bartlett (talk) 09:35, 27 October 2017 (UTC)

• • In a short time, my intention is to move world radio receiver to shortwave radio receiver, and make some changes and addition to the article, that is consistent with the new name. Shortwave radio receiver is a better name. --Glenn (talk) 13:16, 30 October 2017 (UTC)

• I agree "world radio" or "world band" are marketing terms that correspond to shortwave radio. I think the lowest frequency considered part of "short waves" is not rigidly set, and there is no problem including frequencies between 1.6 and 3 MHz under the label "short wave" when the frequencies are being used for purposes similar to the frequencies 3 to 30 MHz. Jc3s5h (talk) 16:56, 30 October 2017 (UTC)

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Nomenclature

Hi folks, I notice the longwave article is called that but the shortwave instead of Shortwave radio. Is that right. scope_creep^Talk 00:37, 18 August 2019 (UTC)

Probably because a majority of the references refer to it as “shortwave radio” since the connected words are commonly used to connote that part of the spectrum. Whereas the term “longwave radio” isn’t a commonly used term either in references or in casual use. - LuckyLouie (talk) 01:37, 18 August 2019 (UTC)

Kilohertz/Megahertz

I'm curious as to why most references to frequencies in shortwave use kilohertz, despite being well into the megahertz range. Is this just the way its always been done? If someone knows the history could just write a quick blurb mentioning the convention it would be very helpful. Thanks Strangerpete (talk) 18:35, 17 January 2020 (UTC)

I haven't seen any sources discussing the history of how shortwave listening frequencies are given, except to say, "below 30 MHz this is customarily expressed in kilohertz" [2]. Most how-to books about shortwave listening note something to the effect of, "all shortwave frequencies are given in kilohertz"[3]. My guess is that giving shortwave frequencies in kilohertz was a custom that became formalized over time. - LuckyLouie (talk) 18:56, 17 January 2020 (UTC)

Broadcast AM, 540kHz to 1620Khz, is commonly in kHz. Broadcast FM, 88MHz to 108MHz, is commonly in MHz, with one digit after the decimal point, usually with the carrier a multiple of 0.1MHz. Below 10MHz, kHz seems fine. I am not so sure about that. Gah4 (talk) 01:36, 14 September 2024 (UTC)

Users

I'm surprised that the many private and commercial (two-way) operators on Shortwave are not mentioned. eg In Australia the "Flying Doctor" service was an essential part of outback life, and these days there are many 4WD clubs which maintain Shortwave (eg HF) networks for outback travelers. Likewise police, military, trucking firms, marine operators, aircraft, and others rely on shortwave communications for their daily operations and safety. — Preceding unsigned comment added by 180.150.22.107 (talk • contribs) 04:14, 6 September 2021 UTC (UTC)

I agree, but per WP:V, we need a citation to a reliable source for that. In the case of the Flying Doctors, it appears the use of HF (shortwave) radio has diminished to only a small percentage of users [4].- LuckyLouie (talk) 23:05, 6 September 2021 (UTC)

Found some sources, so I added a paragraph on two-way SW users, with mention of historical use by Flying Doctors [5]. - LuckyLouie (talk) 18:32, 9 September 2021 (UTC)

Advantages/Disadvantages

The Advantages and Disadvantages sections, supposedly illustrating how shortwave radio differs from "newer technology" consist mainly of questionable interpretations (e.g. Gorbachev was able to stay informed during a coup, battery-operation is better than hand crank, etc). None of these opinions are cited, which is a typical feature of unsourced WP:OR. - LuckyLouie (talk) 19:17, 11 January 2022 (UTC)

SIGFIGs

The frequency and wavelength section seems to have about 10 digits, or way more than is reasonable for SIGFIGs reasons. Many bands, I believe broadcast FM and TV, have a 2kHz tolerance. But otherwise, one is supposed to stay far enough from the band edge not to go past it. Gah4 (talk) 01:39, 14 September 2024 (UTC)