Talk:FM broadcasting in the United States

Comment

There's a lot more information to be added here. Just for starters:

• Subcarriers go up as high as 95 kHz.
• The stereo difference subcarrier is not AM, it's DSB, which is decoded using a synchronous detector against the second harmonic of the pilot tone. Likewise at higher harmonics of the pilot tone for the other subcarriers (that's why they're all centered at multiplex of 19 kHz).
• I'm not convinced that W1XOJ (Paxton, Mass.) was the first licensed FM station; I would have expected Armstrong's own W2XMN to hold that title. Donna Halper has written an essay on John Shepard's experimental FM stations, including W1XOJ and its sisters W1XOK and W1XER.

Someone else can do the writing on this; I've got enough on my plate as it is.

18.24.0.120 06:38, 27 Jan 2004 (UTC)

Pages for Other Cities

On the bottom of the main FM radio page, please look at (but you don't have to click on) the Atlanta FM radio stations page. Can anyone who visits this post pages similar to it, the only difference is that it is for a different United States city??

FM broadcasting in the USA

This is a very good article, but it focuses solely on FM broadcasting in the USA. I propose that it be moved to FM broadcasting in the USA. Comments? If there are no objections by Monday 14 March, I'll move it. --Tony Sidaway|Talk 11:50, 8 Mar 2005 (UTC)

Done. --Tony Sidaway|Talk 23:37, 14 Mar 2005 (UTC)

Missmatching, inaccurate dates

The article mentions that the demonstration of the FM broadcast in front of the FCC took place at January 5, 1940. This piece of information, which has also been copied to the January 5 calendar page and quoted by other sites, seems to be inaccurate as

(a) it doesn't cite any source

(b) it conflicts with the biography of Edwin_Howard_Armstrong, where this event is mentioned to have happened on the July 17, 1936, including more details AND citation (to which unfortunately I have no access).

(c) instead, in many sites it is mentioned that what actually happened at January 4-5 1940, was a successful testing of signal being multiply relayed from Yonkers to Boston according newspaper and magazine articles

If there is no objection, I would take the initiative to change this date in both sites, add the extra date and add the citation complaint template

--Radiobuzzer (talk) 15:33, 19 January 2010 (UTC)

Merging from Edwin Howard Armstrong "#FM Radio"

The information provided on the section of Edwin Howard Armstrong for FM Radio, have more to do with technical and political updates of FM technology, and less on his involvement in these. In here are more info contained about FM broadcasting in the United States than in the article itself. Would we consider moving the information from there to here, and leaving a link behind, among the contribution of Armstrong himself?

--Radiobuzzer (talk) 15:56, 19 January 2010 (UTC)

Yes, I think that's a good idea. I would move at least the two paragraphs about Sarnoff getting the FCC to move the FM band. I would leave behind the first two paragraphs, and the one about Armstrong's tests from the Empire State Building, since those directly involve Armstrong. It would be nice to get some additional sources while we're at it, especially since we're accusing Sarnoff of some bad behavior. Rees11 (talk) 16:26, 19 January 2010 (UTC)

Stereo

I've never heard a claim that Armstrong invented stereo. He did, however invent FM multiplex, which is used to carry the stereo difference subcarrier.

While we're on the subject, the "Main article" History_of_radio#FM_radio does not exist. Rees11 (talk) 15:45, 2 April 2010 (UTC)

FM pre-Armstrong

I have found an article (Orrin E Dunlap Jr, 'A Radio Pioneer Steps Onward', Scientific American, October 1927, pp320-322) which suggests some use of frequency modulation in radio broadcasting prior to Armstrong's invention. The article describes the decision by KDKA in Pittsburgh to use an FM transmission system on shortwave frequencies (which, at the time, were considered the future of radio broadcasting because of the ability to fit in more channels than were available on medium wave). KDKA's use of FM is described as the result of research by Westinghouse engineers, building on the work on frequency modulation, between 1901 and 1908, of Professor Reginald Fessenden. The main reasons for KDKA's switch were robustness of signal and cost effectiveness - eliminating modulator tubes from the transmission system greatly reduces the power consumption of the system or, at least, allows power previously wasted as heat to be diverted to the transmitter.

The article claims that engineers and physicists did not support the efficiency claims made for FM and, in any case, KDKA was foolish in thinking that either broadcasters or listeners would be willing to support the enormous expense of replacing existing (medium wave) transmitters and receivers.

I have insufficient technical knowledge to determine to what extent this form of FM broadcasting resembles the Armstrong solution, so I haven't edited this Wikipedia page as I don't know if it is relevant. Perhaps someone with greater expertise could look into it? Danieljowen (talk) 12:20, 15 May 2017 (UTC)

chart

Is that chart really necessary? Frequencies go from 87.9 to 107.9 in steps of .2. Channel number assigned is 200+(f-87.9)/.2. Why take up half the page with such a list? Gjxj (talk) 12:37, 29 September 2020 (UTC)