Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84 / QGSI 2.0; site qubix.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!hao!hplabs!oliveb!ios!qubix!msc From: msc@qubix.UUCP (Mark Callow) Newsgroups: net.video Subject: Re: Interpreting SONY's SL2710 Manual Message-ID: <1421@qubix.UUCP> Date: Wed, 10-Oct-84 14:21:06 EDT Article-I.D.: qubix.1421 Posted: Wed Oct 10 14:21:06 1984 Date-Received: Sat, 13-Oct-84 03:19:06 EDT References: <3788@tektronix.UUCP> <217@wjvax.UUCP> Organization: Qubix Graphic Systems, San Jose, CA Lines: 20 > Multiplex stereo broadcasts (FM or TV) are (or will be) identified to your > receiver by an 18KHz pilot tone (at least for FM broadcasts. I haven't heard > any specs for stereo TV). The presence of this carrier notifies the > receiver that a > stereo signal is present. The audio bandwidth of the > signal stops at 15Khz. > The multiplex filter takes out the carrier signal. The reason for this is > that if you are making a recording of the broadcast, the presence of the > tone can fool an automatic volume control, or noise reduction circuitry > (Dolby and Dbx get hopelessly confused if the MPX tone is present.) > The pilot tone is 19kHz. It is far more than an indication to your receiver that it is receiving a stereo signal. It controls the PLL (phase--lock loop) used to demultiplex the two frequency multiplexed channels. (l+r and l-r). -- From the TARDIS of Mark Callow msc@qubix.UUCP, qubix!msc@decwrl.ARPA ...{decvax,ucbvax}!decwrl!qubix!msc, ...{amd,ihnp4,ittvax}!qubix!msc "Nothing shocks me. I'm an Engineer."