Talk:Frequency modulation encoding

A fact from Frequency modulation encoding appeared on Wikipedia's Main Page in the Did you know column on 12 July 2022 (check views). The text of the entry was as follows:

Did you know... that early floppy disks used FM encoding that took up only half the available storage?

A record of the entry may be seen at Wikipedia:Recent additions/2022/July. The nomination discussion and review may be seen at Template:Did you know nominations/Frequency modulation encoding.

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Feedback from New Page Review process

I left the following feedback for the creator/future reviewers while reviewing this article: Re: Frequency modulation encoding I have the same concerns as posted as David. Plus the title is for something far more widespread than the narrow meaning stated here. E.g. see Frequency modulation.

North8000 (talk) 17:51, 23 May 2022 (UTC)[reply]

I was pinged......I'll expand a bit on concerns:

As per the discussion by others including @David Eppstein: above, it's not even clear what this article is about. A type of coding? An instance of use of a type of type of coding different than Manchester? An instance of use of Manchester coding? Identifying that would be step one of discussing any basis for keeping this as a separate article.
The title doesn't clarify; it's a much broader term "Frequency modulation" with another even broader word "encoding" added onto it ending up with a vague three word sequence that does not define a topic. I made a search on the three word sequence and none of the first hundred hits was anything in relation to this article.
I did a quick search of the given sources that were on on-line (which should have been plenty to see if the term exists) and don't see anyone using that term.

Sincerely, North8000 (talk) 17:32, 4 June 2022 (UTC)[reply]

@North8000: I just did this and received: "One of the earliest techniques for encoding data for magnetic storage is called Frequency Modulation encoding", "MFM encoding stores more information on a disk than does frequency modulation encoding and is used on many hard disks", "(mfm)...stores more information on a disk than does frequency modulation encoding", "The Miller code or the so-called Modified Frequency Modulation encoding is created from the frequency modulation coding...", "One of the earliest methods introduced to prevent long runs of 0's in recorded signal is the FM (frequency modulation) encoding." That's just the first page.

Of course, as the term is similar to both radio-related FM and disk-related MFM, one has to judiciously apply various search-engine tricks to pick out the wheat from the chaff. I used variations of "FM"|"frequency modulation" along with "single density"|"encoding"|"disk"|"floppy" and optionally adding "-modified"|"-mfm". Using, for instance, "single density FM" immediately returns many hits, like like this one or this one. The search engine on archive.org is often useless, but "frequency modulation disk" turned up hits for various disk systems, including, for instance, this one. It can also be found on numerous web pages, mostly to do with data recovery and retrocomputing, like this one for instance, or better, this example.

There are literally millions of hits to look through. I don't think I'm being unreasonable in suggesting you apply a little more google-fu before reaching any conclusions. Maury Markowitz (talk)

Thanks for your work. On the last note, how did you get "reaching any conclusions" out of what I actually said which is merely that I have concerns? North8000 (talk) 14:27, 11 June 2022 (UTC)[reply]

@North8000: I like to deal with issues one at a time. Do you wish to continue talking about items 2 and 3 on your list, or do my comments above sufficiently demonstrate the term is both "in use" and the proper title for the article? Maury Markowitz (talk) 14:37, 11 June 2022 (UTC)[reply]

It's enough to turn me into a neutral bystander on the issue. Sincerely, North8000 (talk) 21:25, 11 June 2022 (UTC)[reply]

@North8000:Ok excellent. This leaves only the first point to be addressed. The article corresponds to the third of your questions, "An instance of use of Manchester coding?" How would you improve the wording to make this more clear? Keep in mind, it's not just the encoding, but the overall format as well.Maury Markowitz (talk) 11:32, 12 June 2022 (UTC)[reply]

I'd need to read more in this specialized area to make any full informed comment. Lacking that, I can only just throw out possible ideas which I know will be wrong on the detail. One would be to rewrite the first sentence because it conflicts with what you just said. It says that it is a type of coding. So along the lines of "is an approach to storing data on disk drives using manchaster encoding" . An unrelated idea is to change the title to something like "Frequency modulation encoding (disk storage)" to clarify from the more common use of "FM". BTW I'm marking this as reviewed. Sincerely, North8000 (talk) 13:09, 12 June 2022 (UTC)[reply]

Instance of Manchester encoding?

I think this article, Run-length_limited and Differential_Manchester_encoding say that the frequency modulation encoding is a differential Manchester encoding erroneously. The encodings have the same aim of limiting run-length, but there are obvious differences (presence of the evenly-spaced clock and using sole change of frequency to tell 0 from 1 data bit apart in FME). None of the three articles has an inline citation for such claim and I couldn't locate one in Google/Google Books. PaulT2022 (talk) 07:00, 27 March 2023 (UTC)[reply]

Pinging @David Eppstein, as it appears to have been added following the Template:Did you know nominations/Frequency modulation encoding.

Is there a source for "It is the same code as the one described in differential Manchester encoding"? Am I missing something obvious by seeing them as different encodings? PaulT2022 (talk) 03:49, 28 March 2023 (UTC)[reply]

Our frequency modulation encoding article describes each data bit as being encoded by two time windows, with a single signal transition possible per window, and with the encoding of the bit determined by whether one or two transitions happen in these two windows. So does our differential Manchester encoding article. Do you think that one of these two descriptions is incorrect? Which one, and why? —David Eppstein (talk) 03:55, 28 March 2023 (UTC)[reply]

You're right! I was confused by wording of the Differential Manchester encoding article and assumed it refers to differential transmission of regular (biphase-level) Manchester code. The first sentence of its lead is ambiguous and can apply to either.

Compare what article says currently with how it's defined in Horowitz and Hill, for example: the bit value is encoded as presence or absence of a mid-cell transition, following a mandatory transition at the beginning. PaulT2022 (talk) 05:05, 28 March 2023 (UTC)[reply]