Talk:Duplex (telecommunications)

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tel me the real time application of this concept

both people on a telephone can talk at the same time and hear each other. you can upload and download the same amount of data at the same time.

[edit] examples

so of the examples, which are full duplex, half duplex, tdd, etc.?

[edit] Simplex vs. Half Duplex

I know that the article follows tha ANSI standard. Is there any documentation of how that came to be the standard? There are a couple of confusing points:

1. Using the road analogy, everyone agrees that (full) duplex corresponds to a 2-lane road, with traffic flowing in either direction, each in its own lane. Half of that would seem to be one lane travelling only in one direction.
2. Similarly, two of what ANSI calls half-duplex gets you full duplex plus a lot of overhead for managing the direction of traffic in either direction in either lane. When does two times a half equal more than a while? In duplex communication, I guess. Maybe we could call the result double-half-duplex and confuse everyone?
3. Before duplex communication was invented, people used one line to talk to each other (say on a telegraph). It seems odd that such a system would be called half-duplex, when presumably that was just the way it is prior to duplex.
4. Nobody that did not have a duplex telegraph in mind is likely to have invented a one-way circuit, so does that mean simplex requires duplex, but half-duplex came along independently and first?

If it is possible to document why the decision was made to make the current naming the standard, it might help inquiring minds make sense of the situation. Dpv 15:15, 8 June 2006 (UTC)

Hm, all my education in electronics has always taught me the ANSI spec.

To me, 'Dup-' as in 'Duplex' means two. Probably why '(full) Duplex' means two way communication. 'Simp-' as in 'Simplex' means simple, as in lowest working system, i.e. a one way broadcast like TV, FM radio stations etc. Certainly adding traffic management systems and controlling the flow over a single channel is not 'simple'.

'Half-Duplex' still contains the 'dup-' part, so to me it means its still two way, albeit over one channel with switching.

I don’t agree that two half-Duplex channels give you Full duplex. As the entire connection (both channels) can be switched to the same direction, then to me this is simply a wider bandwidth half-duplex channel. Assuming each channel had a 50mbit bandwidth, you then have a 100mbit Half duplex system, that can transfer 100mbit at a time, either up or down or a combination of the two with the proviso that one cant exceed 50mbit while the other is happening.

Whether it is done by allocating the available channels to different directions, and switching these as needed or allocating the same channel to different directions via a TDMA protocol, then its still a half duplex system to me. Bonding multiple half duplex systems just gives you a finer granularity than an 'up/down' system

Calling a one way system like TV/Radio 'Half Duplex' to me doesnt sound right. 'Uniplex' maybe?? :/

--87.127.25.131 07:28, 17 June 2006 (UTC)

I know that most people are trained according to the current standards, and once trained they tend to think what they were taught is logical. My question is how the standard came to be the way it is now. It seems odd that two half-duplex don't make a full-duplex. It seems odd that the way telegraphs worked before anyone had duplex is now called half-duplex. But I know standards don't make sense to everyone all the time. (Does anyone really use their favorite term for one-way only communication, whether half-duplex or simplex, for broadcast radio? I would normally only think of it for something like a telegraph wire with a morse-code key on only one end and a buzzer only on the other end. "Broadcast" is a good enough term for the radio example.) I really want to know if we can explain the current terminology with documentation of how it came to be the standard. Dpv 11:48, 17 June 2006 (UTC)

"These terms also apply to early PC sound cards, however almost all are now full-duplex." - is it really still possible to buy a half-duplex pc sound card?