Telephony Abbreviations

4WTO - Four wire transmission only

In the context I see this I expect it really means bidirectional analog 
audio with no handshake signals.  Is that right?

I can't find a definition for this other than the first line above.

-- 

Rick C

On Sat, 4 Mar 2017 23:39:03 -0500, rickman <gnuarm@gmail.com> wrote:

>4WTO - Four wire transmission only
>
>In the context I see this I expect it really means bidirectional analog 
>audio with no handshake signals.  Is that right?
>
>I can't find a definition for this other than the first line above.


Well as I remember, the directions were EAST and WEST they called
them.

boB

On 3/5/2017 1:35 AM, boB wrote:
> On Sat, 4 Mar 2017 23:39:03 -0500, rickman <gnuarm@gmail.com> wrote:
>
>> 4WTO - Four wire transmission only
>>
>> In the context I see this I expect it really means bidirectional analog
>> audio with no handshake signals.  Is that right?
>>
>> I can't find a definition for this other than the first line above.
>
>
> Well as I remember, the directions were EAST and WEST they called
> them.

I think you are confusing telephony with railroads.  ;)

-- 

Rick C

On Sat, 04 Mar 2017 23:39:03 -0500, rickman wrote:

> 4WTO - Four wire transmission only
> 
> In the context I see this I expect it really means bidirectional analog
> audio with no handshake signals.  Is that right?
> 
> I can't find a definition for this other than the first line above.

Yes, you are right.

2W vs 4W.  The 2 wire (i.e. a single twisted pair) circuit uses hybrids 
at each end to achieve a bidirectional connection.  The 4W circuit is two 
unidirectional 2W circuits, eliminating the hybrids and improving the 
(frequency response, quality, whatever).

TO vs E&M.  TO "Transmission Only" means no handshaking.  E&M "Ear and 
Mount" (also, possibly historically "Earth and Magneto") means 
handshaking.



[anecdote] This reminds of when I used to work in broadcast radio, and we 
used a 4W stereo pair leased from a carrier to get the programme from the 
studio to the transmitter.
These were specially selected pairs, equalised for flatness, matched for 
phase and gain, and driven with a 40 ohm source impedance from our end 
(as opposed to the  600 ohm typically used for audio in those days).

One night I turned the radio on and it sounded a bit strange.  I quickly 
figured out (just by listening) that one of the (left or right) channels 
had been inverted with respect to the other one.  This has a distinctive 
"inside out" sound that is easy to recognise (and easy to recreate by 
swapping the speaker wiring polarity on one speaker only).

People had been ringing the station during the day, complaining about the 
long periods of silence (which turned out to be when an announcer had 
been speaking - these are panned exactly to the centre (L = R), so with 
the phase reversal (L = -R), receivers in mono mode would get something 
close to silence).

I checked the wiring at the station - nothing had changed, so it wasn't 
us.

Eventually we tracked it down to a technician at the phone company who 
had been swapping pairs around.  So much for specially selected and 
matched.

Allan

On Sun, 05 Mar 2017 10:35:33 +0000, Allan Herriman wrote:

> On Sat, 04 Mar 2017 23:39:03 -0500, rickman wrote:
> 
>> 4WTO - Four wire transmission only
>> 
>> In the context I see this I expect it really means bidirectional analog
>> audio with no handshake signals.  Is that right?
>> 
>> I can't find a definition for this other than the first line above.
> 
> Yes, you are right.
> 
> 2W vs 4W.  The 2 wire (i.e. a single twisted pair) circuit uses hybrids
> at each end to achieve a bidirectional connection.  The 4W circuit is
> two unidirectional 2W circuits, eliminating the hybrids and improving
> the (frequency response, quality, whatever).
> 
> TO vs E&M.  TO "Transmission Only" means no handshaking.  E&M "Ear and
> Mount" (also, possibly historically "Earth and Magneto") means
> handshaking.


s/Mount/Mouth/


Allan