Talk:Subsidiary communications authority

"If you own a shortwave radio that tunes below 100 kHz, and will demodulate FM, it can be used to listen to SCA broadcasts. Just tune your FM radio to the station, tune your shortwave radio to either 67 kHz or 92 kHz (in FM mode), then feed the baseband audio into the receiver's RF (antenna)input to de-code the signal"

This statement is problematic and should be removed entirely. Most stations that broadcast SCA will also broadcast in stereo. This will activate the stereo decoder circuitry in the FM radio and cause the demoulated signal to be fed through a low-pass (15KHz) and de-emphasis filter, removing any presence of a 67KHz modulated SCA carrier from the audio. The setup described may work with a stricly mono FM receiver, but then this should be noted.
 * Fixed Altaphon (talk) 19:03, 15 April 2011 (UTC)


 * Considering that the Short Wave band is between 3 MHz and 30MHz, you will be hard pushed to find a short wave radio that tunes that low. What you require is VLF radio (very low frequency) as those frequencies are even below what is regarded as Long Wave. 109.156.49.202 (talk) 12:37, 29 September 2011 (UTC)

Cleanup
Removing the following section per WP:NOTHOWTO. Wikipedia is not a "how-to" guide.

It's possible to also receive the SCA/SCMO signal using a radio that is able to tune and demodulate signals below 100 kHz in FM mode. In that case, the baseband audio (recovered from the discriminator of the FM receiver before multiplex decoding or filtering) is fed into the receiver's RF (antenna) input and the radio tuned to the subcarrier frequency (typically between 53 and 94 kHz, 67 and 92 are common) to extract the signal's contents. Alternatively, the baseband audio before deemphasis can be heterodyned with a suitable IF (intermediate frequency) (that is in the range of the receiver's ability to demodulate FM) and fed into the receiver (tuning it to the appropriate frequency in that case) or even fed directly into the demodulating stage (provided one has the technical knowledge required). — Preceding unsigned comment added by 97.115.31.184 (talk) 22:25, 2 February 2014 (UTC)

current
What is the current state of SCA broadcasts? It seems that many of the past uses are now obsolete, especially with streaming audio which could easily replace it. Is it too much to ask for a list of stations still broadcasting SCA? Gah4 (talk) 04:20, 7 January 2020 (UTC)

legality
I had thought that I knew from years ago, that home reception and decoding of commercial SCA was legal, as long as you didn't make commercial use of it. Even more, following FCC rules, you aren't allowed to pass on anything you might learn from it. That is, it is legal as long as you don't tell anyone, which pretty much reduces the chance of getting caught. But if there aren't any stations broadcasting commercial SCA, then it doesn't matter much. Gah4 (talk) 04:24, 7 January 2020 (UTC)


 * I too thought private reception of SCA was legal. But I found this:
 * https://www.fcc.gov/media/radio/subcarriers-sca
 * In general, tunable subcarrier receivers are prohibited because they violate Section 605 of the Communications Act of 1934, as amended, which states that no one may receive, or assist in receiving, any radio communication to which they are not entitled and use that information for their own benefit. In addition, 18 U.S.C. Sections 2510 through 2521 prohibit the manufacture, assembly, possession, and sale of any device primarily useful for the surreptitious interception of such radio transmissions.  See KMLA Broadcasting Corp. v. Twentieth Century Cigarette Vendors Corp. 264 F. Supp. 35 (D. Cal. 1967); see also Letter to Dr. Haghighi from Richard B. Engelman, Chief, Technical Standards Branch, OET. (One exception was made in 1984 for a tunable subcarrier receiver for a data service in which (1) the receivers could not receive other SCA transmissions, (2) subscribers who had not met their contractual obligations to the service provider were denied access.)
 * So it is illegal to enjoy your bootlegged Muzak?
 * All moot now of course. PRR (talk) 06:19, 1 August 2023 (UTC)

The FCC says:
According to the FCC: The Commission does not keep records of which broadcast stations are using subcarriers. Should we mention that? Gah4 (talk) 04:28, 2 April 2023 (UTC)