Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!ginosko!uunet!n3dmc!gronk!johnl
From: johnl@gronk.UUCP (John Limpert)
Newsgroups: sci.space
Subject: Re: Voice channel beeps.
Message-ID: <566@gronk.UUCP>
Date: 24 Jul 89 21:03:51 GMT
References: <474@bach.nsc.com>
Reply-To: johnl@gronk.UUCP (John Limpert)
Distribution: usa
Organization: BFEC/GSFC Greenbelt, Maryland
Lines: 16

In article <474@bach.nsc.com> bill@berlioz (Bill Bencze) writes:
>What function do the ever present "beeps" serve in the voice
>communication between spacecraft and the ground? These are the 
>1~3 kHz beeps of about a half second in duration which seem to
>occur at random duning the transmissions.  Are they electronic
>"Over" signals automatically sent at the end of a transmission or
>some other type of timing signal.

The beeps are called "QUINDAR tones".  I believe QUINDAR was the
manufacturer of the equipment that decodes the tones.  The tones are
used to control transmit/receive switching in the air-to-ground voice
communications equipment.  Two tones are used, one when a transmission
begins, the other when it ends. 

-- 
John Limpert		johnl@gronk.UUCP	uunet!n3dmc!gronk!johnl