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I agree to the mege of the Non-return-to-zero, inverted data here on the condition of resolution of the disputes about the data there.-- Mancini 17:46, 27 November 2006 (UTC)
I do not agree, they are two different codes, they should be referenced to each other under related topics, but not merged.
I also agree. -disgrutled EE student, 8 April 2007
I don't believe this is correct. I was of the understanding that RS-232 used +12V to represent 0 and -12V to represent 1, and that was it. ...but at the same time, I don't want to post a correction because I could be mistaken.
Just to respond to some of the points raise above:
-- Gadget1700 17:09, 18 June 2006 (UTC)
I'm not sure is image Image:Nrz-i.gif correct; in the article Non-return-to-zero, inverted there's another image and it's different. First image shows that zero is represented by change of level, while in the article we can read "One" is represented by change in level, "Zero" is represented by no change in level.. Best, 212.33.90.36
I changed the NRZI definition, it was wrong. The image is correct. Mojodaddy 19:29, 18 December 2006 (UTC)
In NRZ-I encoding a '1' bit is represented by 0 volts or +V volts depending on the previous level. The encoding of '1' depends on the current state of the line If the previous voltage was 0 volts then the '1' bit will be represented by +V volts, however if the previous voltage was +V volts then the '1' bit will be represented by 0 volts. A '0' bit is represented by whatever voltage level was used previously.
This means that only a '1' bit can 'invert' the voltage, a '0' bit has no effect on the voltage, it remains the same as the previous bit whatever that voltage was. Rait 13:27, 2 March 2007 (UTC)
There do seem to be a number of different definitions of these data encoding schemes depending upon the manufacturer of the communications device. Back in the 1986 the Intel 82530 Technical User Manual had NRZ with a 1 as a high level and a 0 as a Low level, NRZI with a 1 as no change in level and 0 as a change in level. More recently the Motorola 68360 User Manual defines NRZ with a 1 as a high level and a 0 as a Low level, "NRZI Mark" with a 1 as no change in level and 0 as a change in level and "NRZI Space" with a 1 as a change in level and a 0 as no change in level. These do not entirely match what is on the main page. It is also worth noting that the hardware between the comms chip and the physical comms line may invert the signals - thus apparently inverting the output. Thus an encoded "high" will be represented by - 12volts and an encoded "low" by + 12volts on RS232 for example Commsguy ( talk) 13:12, 16 September 2008 (UTC)
unipolar says:
"One is represented by one physical level (such as a DC bias on the transmission line).
Zero is represented by another level (usually a negative voltage)."
bipolar says:
"One is represented by one physical level (usually a positive voltage).
Zero is represented by another level (usually a negative voltage)."
which are really the same. Also from the image and the mention of On-Off Keying I'd guess that the unipolar should be when one level is zero volts.
Also, it says
"Disadvantages of an on-off keying are the waste of power due to the transmitted DC level"
which I'd contest. The DC level is a problem due to the spectrum and possible high-pass media, but not because of the power. Actually
OOK is the best for power saving, as there's no power transmitted for zeros, ie. roughly half the time.
Hoemaco (
talk) 08:23, 10 March 2012 (UTC)
The Nrz-s.gif has a bit pattern labeled on top as "101100011010". The misleading aspect is the first bit which should be unknown or a 'X'. The gif does not show the previous low state. Alternatively, the gif could be edited to omitted that first '1', leaving just a fraction of the first bit's end of low state. — Preceding unsigned comment added by 70.99.114.194 ( talk) 22:56, 9 May 2013 (UTC)
I think this article would be less confusing if - somewhere - it was explained what property or value is - or isn't - "returning to zero."
We're told that "NRZ can refer to any of the following serialiser line codes.." but even the linked reference doesn't say whether the "line codes" are a string of bits or a sequence of physical values! I suppose we can rule out the former, as bits can be zero and (I guess) have no place in discussion about NRZ schemes, so presumably "NRZ" refers to the physically encoded sequence that corresponds to a sequence of bits. On the other hand, it's claimed that NRZ(L) is a sequence of "raw binary bits without any encoding" so (again) it's not clear what isn't returning to zero!
Without knowing anything about this topic, I'll guess that a binary sequence like {1, 1, 0, 0, 1, 0, 0} would be mapped to a voltage function of (say) V(t)
= +12v, for t in [0, 1) seconds = +12v, for t in [1, 2) seconds = -12v, for t in [2, 3) seconds = -12v, for t in [3, 4) seconds = +12v, for t in [4, 5) seconds = -12v, for t in [5, 6) seconds = -12v for t in [6, 7) seconds
assuming a transmission rate of 1 bit per second.
Is this right? The voltage doesn't "return to zero" so does this qualify as an NRZ voltage stream? (Of course, I haven't specified how the start and end of the bit sequence is encoded, but you could (say) set V(t) = 1 for t < 0 and t > 7.)
I know a fair bit about computer science and electronics, but this article is such a mess that I can't even work out what it's try to say, let alone the details!
StandardPerson ( talk) 02:49, 30 March 2017 (UTC)
I think the first paragraph should have a simple sentence that mentions that there are many variants. Somerandomuser ( talk) 15:43, 29 September 2018 (UTC)
Non-return-to-zero § Randomized non-return-to-zero didn't actually contain any information about Randomized non-return-to-zero. Another editor who tagged the section recently and I are not able to readuly find any sources on this topic. I am inclined to delete the section outright but we have a lot of redirects pointing to this section. No pages on Wikipedia are actually using these redirects so perhaps they should all be deleted with the section. ~ Kvng ( talk) 00:05, 4 September 2021 (UTC)
This is the
talk page for discussing improvements to the
Non-return-to-zero article. This is not a forum for general discussion of the article's subject. |
Article policies
|
Find sources: Google ( books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL |
This article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||||||||||||||||
|
I agree to the mege of the Non-return-to-zero, inverted data here on the condition of resolution of the disputes about the data there.-- Mancini 17:46, 27 November 2006 (UTC)
I do not agree, they are two different codes, they should be referenced to each other under related topics, but not merged.
I also agree. -disgrutled EE student, 8 April 2007
I don't believe this is correct. I was of the understanding that RS-232 used +12V to represent 0 and -12V to represent 1, and that was it. ...but at the same time, I don't want to post a correction because I could be mistaken.
Just to respond to some of the points raise above:
-- Gadget1700 17:09, 18 June 2006 (UTC)
I'm not sure is image Image:Nrz-i.gif correct; in the article Non-return-to-zero, inverted there's another image and it's different. First image shows that zero is represented by change of level, while in the article we can read "One" is represented by change in level, "Zero" is represented by no change in level.. Best, 212.33.90.36
I changed the NRZI definition, it was wrong. The image is correct. Mojodaddy 19:29, 18 December 2006 (UTC)
In NRZ-I encoding a '1' bit is represented by 0 volts or +V volts depending on the previous level. The encoding of '1' depends on the current state of the line If the previous voltage was 0 volts then the '1' bit will be represented by +V volts, however if the previous voltage was +V volts then the '1' bit will be represented by 0 volts. A '0' bit is represented by whatever voltage level was used previously.
This means that only a '1' bit can 'invert' the voltage, a '0' bit has no effect on the voltage, it remains the same as the previous bit whatever that voltage was. Rait 13:27, 2 March 2007 (UTC)
There do seem to be a number of different definitions of these data encoding schemes depending upon the manufacturer of the communications device. Back in the 1986 the Intel 82530 Technical User Manual had NRZ with a 1 as a high level and a 0 as a Low level, NRZI with a 1 as no change in level and 0 as a change in level. More recently the Motorola 68360 User Manual defines NRZ with a 1 as a high level and a 0 as a Low level, "NRZI Mark" with a 1 as no change in level and 0 as a change in level and "NRZI Space" with a 1 as a change in level and a 0 as no change in level. These do not entirely match what is on the main page. It is also worth noting that the hardware between the comms chip and the physical comms line may invert the signals - thus apparently inverting the output. Thus an encoded "high" will be represented by - 12volts and an encoded "low" by + 12volts on RS232 for example Commsguy ( talk) 13:12, 16 September 2008 (UTC)
unipolar says:
"One is represented by one physical level (such as a DC bias on the transmission line).
Zero is represented by another level (usually a negative voltage)."
bipolar says:
"One is represented by one physical level (usually a positive voltage).
Zero is represented by another level (usually a negative voltage)."
which are really the same. Also from the image and the mention of On-Off Keying I'd guess that the unipolar should be when one level is zero volts.
Also, it says
"Disadvantages of an on-off keying are the waste of power due to the transmitted DC level"
which I'd contest. The DC level is a problem due to the spectrum and possible high-pass media, but not because of the power. Actually
OOK is the best for power saving, as there's no power transmitted for zeros, ie. roughly half the time.
Hoemaco (
talk) 08:23, 10 March 2012 (UTC)
The Nrz-s.gif has a bit pattern labeled on top as "101100011010". The misleading aspect is the first bit which should be unknown or a 'X'. The gif does not show the previous low state. Alternatively, the gif could be edited to omitted that first '1', leaving just a fraction of the first bit's end of low state. — Preceding unsigned comment added by 70.99.114.194 ( talk) 22:56, 9 May 2013 (UTC)
I think this article would be less confusing if - somewhere - it was explained what property or value is - or isn't - "returning to zero."
We're told that "NRZ can refer to any of the following serialiser line codes.." but even the linked reference doesn't say whether the "line codes" are a string of bits or a sequence of physical values! I suppose we can rule out the former, as bits can be zero and (I guess) have no place in discussion about NRZ schemes, so presumably "NRZ" refers to the physically encoded sequence that corresponds to a sequence of bits. On the other hand, it's claimed that NRZ(L) is a sequence of "raw binary bits without any encoding" so (again) it's not clear what isn't returning to zero!
Without knowing anything about this topic, I'll guess that a binary sequence like {1, 1, 0, 0, 1, 0, 0} would be mapped to a voltage function of (say) V(t)
= +12v, for t in [0, 1) seconds = +12v, for t in [1, 2) seconds = -12v, for t in [2, 3) seconds = -12v, for t in [3, 4) seconds = +12v, for t in [4, 5) seconds = -12v, for t in [5, 6) seconds = -12v for t in [6, 7) seconds
assuming a transmission rate of 1 bit per second.
Is this right? The voltage doesn't "return to zero" so does this qualify as an NRZ voltage stream? (Of course, I haven't specified how the start and end of the bit sequence is encoded, but you could (say) set V(t) = 1 for t < 0 and t > 7.)
I know a fair bit about computer science and electronics, but this article is such a mess that I can't even work out what it's try to say, let alone the details!
StandardPerson ( talk) 02:49, 30 March 2017 (UTC)
I think the first paragraph should have a simple sentence that mentions that there are many variants. Somerandomuser ( talk) 15:43, 29 September 2018 (UTC)
Non-return-to-zero § Randomized non-return-to-zero didn't actually contain any information about Randomized non-return-to-zero. Another editor who tagged the section recently and I are not able to readuly find any sources on this topic. I am inclined to delete the section outright but we have a lot of redirects pointing to this section. No pages on Wikipedia are actually using these redirects so perhaps they should all be deleted with the section. ~ Kvng ( talk) 00:05, 4 September 2021 (UTC)