jtb@kitc.UUCP (J. Burgess) (08/22/85)
The following is excerpted from <29425@lanl.ARPA>, in net.kids.
(the discussion was about TVs. He began by saying he has a
satellite receiver as his TV feed.)
> ... Any of the 30,000 people with
>satellite receivers can listen to either side of almost every long distance
>phone call ( *NOW* ). With a scanner they could get both sides.
> Dave Wade
Is this true? I thought that
a) TV and phone signals would be transmitted over different bands,
b) phone signals were time-division and frequency-division multiplexed,
and/or
c) digitized.
Are all 3 of my assumptions wrong; i.e., phone conversations
are transmitted "clear channel" so that you don't need
any special hardware?
Or does your basic satellite down-converter (I think that's what
they're called) do that sort of stuff?
What is the "scanner" he's talking about?
Is it some sort of computerized demux?
Now, I realize it is probably possible to buy the equipment to really
do what he's talking about. How much would it cost?
Or how much to build?
Is anybody doing anything about it?
(like encryption or what?)
PS don't post any proprietary info in responses!
--
John Burgess
ATT-IS Labs, So. Plainfield NJ (HP 1C-221)
{most Action Central sites}!kitc!jtb
(201) 561-7100 x2481 (8-259-2481)dsi@unccvax.UUCP (Dataspan Inc) (08/24/85)
Wrongo...if your friend is hearing any conversations clearly, they
are most likely subcarriers on 'backhaul' feeds used by engineers in
setting up links, sending cue signals to alert on-site talent to the
critical events in a broadcast (such as time to sell some Budwiser) etc.
Real long distance phone calls on domestic birds are (correct me
if I'm wrong) all digital, in the T1/T1C etc time domain multiplexed
mode. I have once in a great while heard some garbled something that
sounded like speech (on Satcom F2) and you also can sometimes hear obvious
human speech being transmitted unintelligibly, i.e. a person 'whining'
but the information content is much worse than even single sideband
on an AM receiver.
The Soviets are evidently very good at intercepting domestic T1
transmissions and decoding them. They, however, purcahse a barn or
something (on the line of sight for terrestrial microwave) and install
a 10 foot or more dish inside. The channel demultiplexing equipment
is extremely expensive, you wouldn't just use a 'scanner.'
There is a treatment of this whole issue of telephone security (both
satellite, microwave, and hard wire) in one of the recent issues of
IEEE Spectrum. I think it was March or April, but the issue was definitely
published this year.
This is grossly oversimplified, but your friend doesn't really
have anything to worry about.
David Anthony
CDE DataSpan, Inc.
.prg@mgweed.UUCP (Phil Gunsul) (08/26/85)
[I ain't 'fraid uh no bugs] I'm not sure the other individual knew what a scanner is. The phone calls you hear on a dish cannot be understood with the normal satellite receiver. The baseband output can be connected to a single sideband receiver though and understood quite well. The original poster was correct in saying that you only here one side of the conversation. I guess this would be no different than listening to the normal mobile telephone repeaters. Phil Gunsul -- WB9AAX