Subject: RE: [USR-TC] Anyone familiar with Balance and Un-Balanced E1/PRI

From: [email-masked]
Date: Wed, 03 Jul 2002 15:37:22 +0000

Das ist true.

There is also balanced coax type cable and connectors (PL75-9's used a lot
in Video applications) that work on three wires: TX, RX and ground. The
ground is shared, as ground is, well, ground.

Rick
Team Solunet

-----Original Message-----
From: Jeff Mcadams [mailto:[email-masked]]
Sent: Tuesday, July 02, 2002 8:59 AM
To: [email-masked]
Subject: Re: [USR-TC] Anyone familiar with Balance and Un-Balanced
E1/PRI

Also sprach Charles Sprickman
>I'm pretty sure T1's are NOT balanced.  Think of the tx and rx pairs as
>two seperate lines, they aren't necessarily bundled together.  If it
>was balanced, you'd see three wires per tx/rx "pair"; you'd have the
>ground, positive and negative...  Haven't seen that (yet).  The closest
>I've seen is a shielded run...

Being balanced doesn't require a ground.  A ground just means that its
grounded.  Balanced is just having two signals of opposite polarity and
reading the signal as half the voltage differential between the two
wires.  Unbalanced is reading the signal as the differential between the
signal wire (just one) and ground.  Ground, in the unbalanced case, can
be a local ground, there doesn't have to be a ground in the cable to
measure against.  In fact, after a cable run, its likely to *not* have
the same potential as a real ground as there's a good chance that there
will have been current induced in it.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

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---

From: Charles Sprickman <[email-masked]>
Date: Wed, 03 Jul 2002 18:43:35 +0000

> Das ist true.

Ahh...  My only knowledge is with audio stuff, as in balanced/unbalanced
mics, line level stuff, etc. where there's gotta be three lines to be
"balanced".  Physically, the coil in the mike is tapped in the middle for
the ground reference and either end of the coil becomes the +/-.

Charles

---

From: Jeff Mcadams <[email-masked]>
Date: Wed, 03 Jul 2002 19:00:34 +0000

>Ahh...  My only knowledge is with audio stuff, as in
>balanced/unbalanced mics, line level stuff, etc. where there's gotta be
>three lines to be "balanced".  Physically, the coil in the mike is
>tapped in the middle for the ground reference and either end of the
>coil becomes the +/-.

Yeah, I almost mentioned the audio applications...

My understanding is that, even in audio-land, the ground isn't required
for it to be considered balanced, but, rather, that the ground is just
needed in general (where else is a hand-held mic gonna be able to get a
ground?).

I'm have rather less knowledge in the audio equipment realm
though...passing familiarity, but certainly no expert.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456