Re:Decoding the telephony signals in Pink Floyd's 'The Wall'
by plapsley on Sunday December 22, 2024 @04:48PM
(#42489426)
CCITT (ITU-T) version can be downloaded for free (!) from their website. https://www.itu.int/rec/T-REC-Q.140-Q.180-198811-I/en Specific download link in English is https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Q.14...
Re:Decoding the telephony signals in Pink Floyd's 'The Wall'
by jasomill on Monday December 23, 2024 @02:31AM
(#42492550)
Fascinating article. See also
https://web.archive.org/web/20120314023131if_/http://www.alc...
for an early technical article describing the implementation details of the familiar DTMF "touch tone" dialing system, noting that the precise details differ from the final implementation — in particular, the high group frequencies increased from 1,094/1,209/1,336/1,477 Hz to 1,209/1,336/1,477/1,633 Hz, possibly to mitigate the "pulling" effect described on pp. 251–252 (though I can find no reference for the rationale).
SS5 was derived from AT&T's US MF signaling system, described in "Signaling Systems for Control of Telephone Switching" by Breen and Dahlbom, Bell System Technical Journal, November 1960. PDF here: https://explodingthephone.com/hoppdocs/breen1960.pdf
The BSTJ article has a discussion on international signaling on pp. 1430-1441.