Talk:Radio

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[edit] Question on multiple frequencies

Is it possible to broadcast over multiple frequencies at once? Or possibly cycle through a lot of frequencies quickly? SidTheWicked 14:45, 1 Dec 2005 (UTC)

It depends. Its routine for many transmitters to send the same program out at the same time - radio and TV broadcast networks do this. Check out spread spectrum for different techniques to use many frequencies from a single transmitter - this is not used for broadcasting but is used for privacy and security of communications, in military and cordless phones, for example. --Wtshymanski 21:50, 1 December 2005 (UTC)

[edit] Television

1948 for television? Mechanical television existed in the '30s and used radio signals. Wake 04:45, 11 Nov 2003 (UTC)

[edit] DARPA

Can somebody clarify " In 1994, the U.S. Army and DARPA launched an aggressive, successful project to construct a software radio that could become a different radio on the fly by changing software.", please? Andy Mabbett 17:47, 20 May 2004 (UTC)


[edit] Current and voltage

I'm troubled by "When a radio wave passes a wire, it induces a moving electric charge (voltage)...". As I recall, a moving electric charge is in fact a current, while a separation of charge is a voltage. Wikipedia seems to back me up on this, but I'm too long out of my college E&M course to recall which is actually responsible for creating the received radio signal. Either the word "current" needs to replace "voltage" or "moving electric charge" needs to be replaced with "creating a separation in charge" - depending on which is actually responsible. --ABQCat 05:15, 12 Aug 2004 (UTC)

Depends on the wire. A loop antenna (a closed loop of wire) gets a current induced in it by the magnetic field. A dipole antenna (a broken loop of wire) gets an emf (or voltage) induced in it by the electric field. -- Heron 13:13, 12 Aug 2004 (UTC)

[edit] Wardenclyffe

Another question. Tesla is the subject of some pretty wacky claims and bad science, and this claim: "Wardenclyffe in operation may have allowed secure multichannel transceiving of information and may have allowed universal navigation, time synchronization, and a global location system." seems to be on that level, to me. There's no way (in my mind) that a single tower would have provided a global location system. Even if it propegated world-wide, such a system would only be able to provide on thing - bearing to the radio signal source. Correct me if I'm wrong, but the hype and bad science that people associated with Tesla propegate needs to be checked and we need to make sure this isn't that. --ABQCat 05:34, 12 Aug 2004 (UTC)

Although I agree with you about the general hype, and the need to protect Wikipedia from Tesla's wackier supporters, I think that this particular claim was based on real physics, but not, unfortunately, on real economics. He described the function of his planned World System of towers in "The Future of the Wireless Art", Wireless Telegraphy and Telephony, 1908, pg. 67-71. (quoted here). It might have worked if he had not run out of money after the construction of the first tower. -- Heron 13:13, 12 Aug 2004 (UTC)
Two things:
1. Tesla and economics do not mix. Tesla once tried to give free power to everyone on the planet using the earth as a conductor. He got the physics to work, but Mr. J.P. Morgan (I think it was him, not going to look it up) wouldn't pay for it.
2. You can get a HAM radio to do that out of your back yard in the right conditions. It is possible to bounce radio waves off clouds and (I believe) thermal layers in the atmosphere. Besides, Tesla did some things that we still don't understand. He once got a stage that he was lecturing on to emit light, with no visible light source. The light was apparently generated from the air itself. The only known props are two solid metal plates, and electrical engineers are still scratching their heads.--Ostermana 06:06, 12 December 2005 (UTC)

[edit] Transistor Radio Birthday

Regency TR-1 heise newsticker about the birthday (in german) --Deelkar 17:11, 18 Oct 2004 (UTC)

[edit] First news, first daily scheduled broadcasts: San Jose Calif, 1909-1917

The world's first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan. The world's first regular wireless broadcasts for entertainment commenced in 1922 from the Marconi Research Centre at Writtle near Chelmsford, England.

I believe Charles David Herrold (1875-1948) was on the air on a regular schedule from 1909 to 1917 in San Jose, California; and that his programming included music, news, and advertising (I think some of the advertisers may have been cinemas). Originally without a designation other than "San Jose calling", I have an idea he used a Poulsen arc for AM somewhere in the longwave spectrum. I think it may have been VLF. This page says that the audience consisted of "amateurs" rather than "ordinary citizens" but I doubt that also; I suspect one can find advertisements in old periodicals for receivers he sold. This article in Radio World indicates that "His students served as its DJs and newsreaders". It's my understanding the military shut down nearly all nonmilitary broadcasting in 1917 for a few years. I think the station was licensed as KQW AM in 1921. A public television station broadcast a special about it a few years ago. A museum in San Jose exhibits some of his equipment.

I suspect 8MK may have been the first licensed broadcaster. I don't know what "first" Marconi at Writtle can claim. Marconi has quite a number of "firsts" as it is. --Munge 07:29, 9 Mar 2005 (UTC) modified 10 March 2005


[edit] Tesla's 1893 demonstration

In 1893 in St. Louis, Missouri, Tesla made the first public demonstration of radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of radio communication. The apparatus that he used contained all the elements that were incorporated into radio systems before the development of the vacuum tube. He initially used magnetic receivers [1] (http://www.teslasociety.com/teslarec.pdf), unlike the coherers used by Marconi and other early experimenters.

St Louis or Philadelphia? I'm confused. What exactly did he demonstrate that was new that Hertz hadn't already demonstrated? Also, there seems to be some confusion about the lecture that Tesla gave in 1893. In this article (and elsewhere) it states that Tesla demonstrated his apparatus in 1893. However there are other sites that state that Tesla only gave a lecture describing the principles of his system of transmission. He was not able to give a demonstration until 1895. Jooler 12:13, 29 Apr 2005 (UTC)

I have a book on Tesla (Tesla - Man out of Time, Margaret Cheney, ISBN 0-7432-1536-2) that reads: "He moved scientific history forward again in the spring of 1893 when, addressing the Franklin Institute in Philidelphia and the National Electric Light Association at St. Louis, he described in detail the principles of radio broadcasting. At St. Louis he made the first public demonstration ever of radio communication, although Marconi is generally credited with having achieved this feat in 1895"

[edit] ??

What is this [1] even supposed to be? It just sits there with no caption a cryptic file name and no explanation of what it is. Not helpful.--Deglr6328 16:35, 18 August 2005 (UTC)

[edit] Bias against Marconi?

I believe this entry is in part biased against Marconi. See the difference:

In 1896 Marconi was awarded what is sometimes recognised as the world's first patent for radio ... The same year in the U.S., some key developments in radio's early history were created and patented by Tesla. The U.S. Patent Office reversed its decision in 1904, awarding Marconi a patent for the invention of radio, possibly influenced by Marconi's financial backers ... Some believe this was made for financial reasons, allowing the U.S. government to avoid having to pay the royalties that were being claimed by Tesla for use of his patents.

However, Tesla's patent was reinstated in 1943 by the Supreme Court. This decision was based on the fact that prior art existed before the establishment of Marconi's patent. Some believe the decision was also made for financial reasons...

[edit] First man to send voice transmitions over radio

The first man to send voice over radio was a Slovak priest in Wilkes Barre Pennsylvania Dudtz 8/25/05 6:55 PM EST

[edit] If don´t speak english doesn´t matter

August 27 of 1920 Radio Argentina begins regularly scheduled transmissions from the Teatro Coliseo in Buenos Aires. This is the first regularly scheduled transmission. The first radio show, Your information is incorrect, please, the next time, get a world enciclopedia, not only US and his europe tail. It s very disappointing findout this kind of mistakes in wikipedia.

[edit] Pulse Code Modulation PCM

From the line:

"Q1: Who invented 'wireless transmission of data using the entire frequency spectrum' (spark-gap radio)?"

The spark-gap was used to stimulate a Tesla coil. Tesla coils do not opperate over the entire spectrum. Each and every one must be made for a fairly narrow frequency range.

It should read, "Q1: Who invented 'wireless transmission of data using one or more specific carrier frequencys, and cycled them on and off' (spark-gap radio)(Very similar to PCM.)?"

[edit] unsourced?

Having the tag is unnecessary ... and the references are in the articles linked to (this one being a "top" lvl article to many sub-articles). Unless there is a good reason to have it ... it shouldn't be there. JDR 16:04, 1 December 2005 (UTC)

[edit] No mention of Tesla's "invention of radio" in the source

I have rewritten the following excerpt concerning Tesla's "invention of radio communication":

In 1893 in St. Louis, Missouri, Tesla made the first public demonstration of radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of radio communication. [2]

Read the article in the cited source and compare it to the excerpt:"radio communication" is not even mentioned there, all stuff there deals with the electricity. Below that excerpt a link to another source is provided [3], but it deals with device built in 1899.

The same can be applied to Jagdish Chandra Bose, an excerpt about whom I've rewritten too. Cmapm 01:41, 12 December 2005 (UTC)

In the book, "Tesla - Man out of Time" by Margaret Cheney, ISBN 0-7432-1536-2, on pages 95 and 96 is the quote

"[Tesla] moved scientific history forward again in spring of 1893 when, adressing the Franklin Institute in Philidelphia and the National Electric Light Association at St. Louis, he described in detail the principles of radio broadcasting.
At St. Louis he made the first public demonstration ever of radio communication, although marconi is generally credited with having achieved this feat in 1895"
--Ostermana 06:15, 12 December 2005 (UTC)
Well, you cited an American POV (a book by the U.S. author, published in the U.S). But I'll not cite any Russian sources, although almost all of them credit Popov as inventor of radio. I'll cite Encarta 2006 (Britannica says almost the same):
Aleksandr Stepanovich Popov (1859-1906), Russian engineer who independently invented a type of radio receiver. In 1895 Popov constructed wireless apparatus quite independently of Marconi, using a high vertical aerial and a coherer detector. However, Popov's equipment was designed for recording “atmospherics” (natural radio emissions) and was used as a detector of distant electrical storms, while Marconi's was specifically for wireless communication. Nevertheless, ever since then Italy and Russia have claimed their nationals as the inventor of radio.
No mention of Tesla there. And as I said IEEE site doesn't mention Tesla's invention of radio too. Cmapm 14:23, 12 December 2005 (UTC)

You said Popov first started playing with functional radios in 1895? Read this: http://www.pbs.org/tesla/ll/ll_hifreq.html and this http://www.pbs.org/tesla/ll/ll_whoradio.html I would also like to mention that your source does not say that Popov invented radio, just that he built one without outside assistance. It actually implies that Marconi beat Popov to it. Since Marconi "invented" radio using 17 of Tesla's patants (according to Tesla, anyway), this puts Tesla in first. I believe the cause of Tesla's notable absence from nearly all major sources is because no one has heard of him. I once, just for kicks, spent an hour and a half asking random people at my high school how many of them had heard of Nikola Tesla. of about 500 high schoolers asked, 3 knew who he was. 2 of the 3 were friends I had previously introduced to Tesla's work myself. Tesla has largely been forgotten by the general populace, yet he died with more than 700 patents to his name. He made the Hoover Dam work, every piece of electrical equipment origionally present had Nikola Tesla somewhere on the patent.--end rant--Ostermana 21:23, 17 December 2005 (UTC)

[edit] Tesla did in fact invent the radio

Tesla first publicly demonstrated what he called "wireless" in 1893, while marconi did so in 1895. Popov is credited here on wikipedia as doing so in 1896, though I don't know how accurate that one is. The US supreme court reversed a previous ruling so that Tesla is nationally credited with discovery. I've updated the History in Brief section to match. --Ostermana 06:09, 12 December 2005 (UTC)

If you don't believe Wikipedia, then possibly you should believe to the IEEE:
On 7 May 1895, A. S. Popov demonstrated the possibility of transmitting and receiving short, continuous signals over a distance up to 64 meters by means of electromagnetic waves with the help of a special portable device responding to electrical oscillation which was a significant contribution to the development of wireless communication. [4] Cmapm 14:23, 12 December 2005 (UTC)

According to PBS, in early 1895 Tesla was broacasting 50 miles (80.47 Km) or 125 times as far. The link is in my post in the previous section. Also, the article makes no mention of Popov inventing the radio, just that he developed one that worked.

[edit] Vital info missing!

WHY IS IT CALLED RADIO???

There isn't even a clue as to where did the name come from! Of course it might have something to do with radio frequency, but from where did that name come?? Don't you think it's important to put the reason this article is called Radio? (And the reason everyone all around the world calls the invention the very same way?) This is a common mistake around Wikipedia articles, as well as trying to explain everything except the vitals. Kreachure 16:56, 14 December 2005 (UTC)

OH MY GOODNESS!!! That's the quickest response I've ever seen around here! An entire subsection a few hours after I commented! Now this is the type of attitude that makes me feel proud of Wikipedia! Kudos to you, silent but effective Wikipedians!!! (I'm looking your way, GABaker and Heron!)

[edit] Radio founders

Well we had a link to everyone but Nikola Tesla. So I added one, you also had his name spelled wrong so I corrected that as well. Whispering 03:26, 24 December 2005 (UTC)

[edit] Mini Radios

In promotional items, they sometimes add mini ovalish shaped radios along with the item. Whopper 03:11, 23 April 2006 (UTC)

[edit] Digital telecommnication

can u solve my problem

how information can be added on radio signal? —The preceding unsigned comment was added by 203.27.220.135 (talk • contribs) .

Look at modulation. Imroy 07:12, 14 May 2006 (UTC)

[edit] Several technical errors in this article!!

I've noticed well over a dozen serious errors in this article. I will submit my edits over the next few days. thanks for your patience.

Could you please list them so we can know what the rest of us have missed? cmacd 16:56, 14 June 2006 (UTC)

[edit] Wholesale reversion

User:204.56.7.1 should know by now that wholesale reversion is a violation of Wikipedia principles. You need to collaborate with your peers to create an article. Please abide by Etiquette and discuss changes you wish to implement. "Q & A" formats are more appropriate for FAQs than encyclopedia articles. --Blainster 19:30, 29 June 2006 (UTC)

[edit] Removal of information; Check to put back in

http://en.wikipedia.org/w/index.php?title=Radio&diff=61235355&oldid=61005933

This needs a review. 134.193.168.244 23:30, 29 June 2006 (UTC)

  • If the history of radio is at Radio#History of radio and also at History of radio, some people will put new matter in one, and some will put new matter in the other, and the two will get different and out of step with each other, and readers will have to look in two places for information, until someone has to merge them. The same happened with Berlin#History of Berlin and History of Berlin, until they were merged. As I set Radio#History of radio, Radio was modern information only, not cluttered with old history, and getting the history on another window needs only a mouse right click and a mouse left click: that is what Wikipedia-type blue links are for. I did not remove the information, I merged it into History of radio.

We will now see if Radio#Brief history stays brief and does not accumulate matter which is not also put in History of radio, thus again forcing readers to read both to find all the history information. Anthony Appleyard 06:55, 30 June 2006 (UTC)

[edit] External Link - OnTheRadio.Net

ontheradio.net claims to have a database of commercials that played on radio stations, but I haven't found any commercials-related information on their site. I think they tried to do it, but the business model failed. Nor do they have play lists. As such the site is kind of junky, and it might be worth deleting the link.

[edit] Edits

Microwaves are not classed as radio waves, as they're produced by a magnetron, which utilizes a resonant cavity - the microwaves exit in coherent form. Radio, on the other hand, creates an oscillating charge by means of resonant circuits, and then transmits that charge to the antenna for transmission. Mugaliens 16:38, 22 August 2006 (UTC)

That turns out not to be the case. It's the same physics from VLF up to heat waves and beyond. --Wtshymanski 17:26, 22 August 2006 (UTC)

[edit] New Graphic Required

This needs a new graphic, as the current one wrongly lumps microwaves and radio waves together. Two good sources of appropriate graphics, if permission can be obtained, are:

http://praxis.pha.jhu.edu/pictures/emspec.gif

http://csep10.phys.utk.edu/astr162/lect/light/spectrum.html Mugaliens 16:40, 22 August 2006 (UTC)

The graphic is correct: Microwaves are simply short-wavelength Radio Waves. Both are a form of Electromagnetic Radiation, along with Light, Heat, X-Rays, etc. Gutta Percha 08:05, 26 September 2006 (UTC)


[edit] Some Feedback:

(1) The text is quite confusing in mixing terms such as "RF", "Radio Waves", "Microwaves", etc.

It needs to be plainly stated that all of these arbitrary terms fall under the broad heading of "Electromagnetic Radiation". The main point should be that RF, Microwave, Radio, Light, X-rays, etc are all the same thing, differing only in frequency.


(2) A discussion of "Who Invented Radio" is fairly meaningless without mentioning Maxwell and Hertz. Maxwell developed the theory behind Electromagnetism and Hertz developed the first practical demonstrations of the theory. All else follows from these two great men.

There is one rather sad exception: Prof. D. E. Hughes developed a working radio in 1879, many years before Marconi and the rest. He demonstrated his prototype to Preece, Crookes and others, who unfortunately declared his success to be due to "mere Induction". Prof Hughes was discouraged and abandoned any further work on his system:

ref: A history of Wireless Telegraphy by J. J. Fahie 1899

(3) "Early radios ran the entire power of the transmitter through a carbon microphone" No. They ran the antenna current through the Carbon Mic.

(4) "aircraft used commercial AM radio stations for navigation" Yes, but in Europe only. In most parts of the world, aircraft used Non Direction Beacons (NDBs) to navigate by. Where NDBs were not available, then normal B/C stations were used.

(5) "1930s, single sideband and frequency modulation were invented by amateur radio operators" These modes were certainly developed further by Amateurs, but they were not invented by amateurs.

(6) "AM broadcast radio sends music and voice in the Medium Frequency radio spectrum". In Europe there is also the much older Long Wave B/C Band (140 to 400 kHz).

(7) "In some countries, FM radios automatically retune themselves to the same channel in a different district by using sub-bands." This is meaningless. It should read, "In some countries the digital station identification is used to automatically re-tune mobile radios when they move out of range of the original station".

(8) "Marine voice radios can use AM in the shortwave High Frequency" No. They use Single Side Band (SSB).

(9) "..... marine radiolocation beacons, which share a range of frequencies just above AM radio with amateur radio operators."

No. NDB's are below the M/W broadcast band. Perhaps the author meant S/W beacons. Whatever, they don't share frequencies with Radio Amateurs.


That will do for now. Gutta Percha 09:47, 26 September 2006 (UTC)

I just quickly reviewed this article, and I was about to say something similar to point 1. I would suggest that radio waves (as a type of electromagnetic radiation) be in a completely separate article from the technology of radio (a medium for information and entertainment). As for 2-9, someone knowledgable should review the above and leave comments here. Walkerma 03:31, 29 October 2006 (UTC)

[edit] Aviation Radio History

I question the following statement.

Aviation voice radios use VHF AM. AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM's capture effect). Aircraft fly high enough that their transmitters can be received hundreds of miles (kilometres) away, even though they are using VHF.

I have never come across any reliable infromation supporting this often repeated claim. All information I can find indicates that Aviation Radio has remained on AM principly due to historical reasons and the sheer magnatude of any attempt to convert to a new format.

Both the Historical and the Technical explanations are clearly true.

With FM, "Capture effect" makes the strongest signal clearer at the cost of masking any weaker signals. AM however allows multiple signals to be heard at once. AM also resolves much weaker signals than FM. Gutta Percha 00:33, 2 November 2006 (UTC)

[edit] radio

I think that you people should tell more about radios like the hip-hop the one that plays that music because other than that im gonna make an F on my project for technology. Any suggestions.

[edit] Messy Introduction Paragraphs

The beginning of the article is very messy. The Spectrum should be moved into a subheading. Anything that would get rid of the initial clutter. --Davidkazuhiro 13:12, 9 February 2007 (UTC)

I've removed the following paragraph from the intro, and posted it here as I don't see any good place to put it...also, I question if it's really the right tone:

By addressing radio in terms of what Lyotard (1997:47) calls "stream[s] of cultural capital", scholars can explore the social construction and importance of wireless telegraphy.[1] Transmitting messages and information without wires was a major technological achievement, yet one dwarfed by comparison to the social and cultural implications of coming to terms with the novel electromagnetic environment. Indeed, when it first appeared on the social horizon, radio immediately became a significant site of cultural production and contestation. Rather than a type of cultural phenomenon, radio waves continue to function as a “zone of cultural debate” (Appadurai 1996:5).[2]Pace Adorno and the Frankfurt School’s view of radio as isolating people by encouraging atomized listening, radio, particularly in rural, "isolated" regions sustains imagined--albeit fractal, if not fragmented--communities.

Perhaps a section on Marxist analysis of radio is in order? But somehow I don't think the reader who looks up 'radio' is expecting a treatise about the Frankfurt School in the introductory section. Ethan Mitchell 14:06, 18 March 2007 (UTC)

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