Talk:Physical layer

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[edit] rewriting of article

Listen, I'm considering rewriting this article in the following way:

  • removing the discussion of 2B1Q (perhaps mentioning it as an example) and the "sublayer"
  • addressing the fact that the medium can be electrical, RF, or optical
  • addressing the complexities of physical layer signalling by linking to articles on: (assuming these exist)
  • adding a short discussion of physical layer interfaces in a typical PC

In general, I feel that the existing article somewhat confuses the role of the interface and overly simplifies physical layer processing as mere electrical pulses on a wire. This may be true for old standards, but certainly does not hold for any physical layer standard developed since the mid-1980's.

Any comments? RobertYu 21:41, 15 Sep 2004 (UTC)

Good points. I have tried to address them. Mange01 00:16, 9 November 2006 (UTC)

[edit] physical mail system

Would not a better analogy for the physical mail system be the vehicles that transport the mail, rather than "a specification for various kinds of paper and ink"? BevanFindlay 22:16, 18 July 2006 (UTC)

Agree. Or perhaps the entrance to roads that transport the vehicles that transport mail? Mange01 00:16, 9 November 2006 (UTC)
Agree, changed to roads. Conrad.Irwin 15:48, 14 December 2006 (UTC)

[edit] missing embedded system physical layers

I'm missing embedded systems in this context. If I'm looking for ISO/OSI there is only information about TCP/IP and PC's and so on. What if I use a simple microcontroller and want to comunicate with other hardware on a PCB?


Yes, we need to mention I²S, I²C, Microwire, Serial Peripheral Interface Bus, System Management Bus, 1-Wire, X10 (industry standard) ... please add them to the article. At least the article does mention EIA-485, which is one of the more popular embedded system interfaces.

[edit] names for the various parts

Is there a standard pinout for putting EIA-485 on a RJ-11 or RJ-45 connector? (Does 10BASE-T specify this, or are the signals on a 10BASE-T cable *not* EIA-485 signals?)

I would like to fill in the holes in this table:

  • "RS232D", aka "EIA/TIA-561", is the standard for "RS-232 on a RJ-45 connector"
  • EIA-530 is (?) the standard for "RS485 on a DB-25 connector"
  •  ???? is the standard for "EIA-485 on a DE-9 connector"
  •  ???? is the standard for "EIA-485 on a RJ-45 connector"
  • RJ50 is the standard for "???? on a ???? connector"
  • 10BASE-T is the standard using ???? on a RJ-45 connector.

This table distinguishes "the electrical voltages" from "the mechanical plug shape and how the wires are twisted" from "some standard that defines which voltage goes on which physical conductor". Is there a name for these 3 things? Yes, OSI model calls all 3 things taken together the "Physical Layer", but is there 3 different names for these 3 part?

--65.70.89.241 17:35, 2 August 2006 (UTC)

First, you'll want to correct the naming of "RJ-11" and "RJ-45" connectors. You mean modular connectors. RJ11 and RJ45 are telephone wiring standards. (Also, they don't have hyphens). I have recently updated some of the wikipedia articles on these to make that more clear. The RJ50 article is apparently incorrect in this same way, but I haven't had a chance to look up what an RJ50 registered jack really is.
Bryan Henderson 17:50, 9 September 2006 (UTC)

[edit] Lack of references.

I tagged this article for lack of references because the only reference given does not touch upon most of the subject matter in the article and computers, networking, and telecommunications is an area of expertise where it is easy to have misconceptions which, if material is unreferenced, will work their way into WikiPedia. I have 25 years of experience in this field an still find that I suffer from the occasional misconception concerning the details of some subjects. I have discovered some of these misconceptions while looking for references to articles that I wrote on WikiPedia so I am sure that finding references is a Good Thing :-) --mlewis000 00:56, 20 December 2006 (UTC)