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
Reply by Allan Herriman●March 5, 20172017-03-05
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
Reply by rickman●March 5, 20172017-03-05
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
Reply by boB●March 5, 20172017-03-05
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
Reply by rickman●March 5, 20172017-03-05
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