Re: Comments on pwelch.m

[Ted Harding]

On 08-Nov-04 Dmitri A. Sergatskov wrote:
> Joe Koski wrote:
>> 
>> Agreed, Dmitri, but the term "Hanning window" has been part
>> of the digital signal analysis jargon for many years. The
>> ancient text books on my shelf (Oppenheim and Schafer, and
>> Stearns) use the terms "Hanning" and "Hamming".
> 
> I believe the term "Hanning" was made by Tukey as a kind of
> joke or word play. The book by Blackman and Tukey may have
> this explanation -- I do not have it anymore, cannot check.
> Since many people do not check original works, it got propagated
> to other books and papers. The popularity of Oppenheim & Schafer
> book exacerbated the problem.
> I have seen "Hann", "Von Hann", and "Hanning" used. "Numerical
> recipes" uses "Hann" and I am pretty sure I can find a couple
> DSP books (besides the Humming's one) which use "Hann" as well.
> [...]

I have Blackman & Tukey (Dover re-issue 1959 of the two 1958
papers in vol XXXVII of Bell Sys Tech J).

>From what I read there, it seems the terminology may already
have been established. On page 14 (first mention):

  "5. TWO PARTICULAR WINDOW PAIRS
   [1st para skipped]
     A simple and convenient compromise is represented by the lag
   window (whose use is called "hanning")

     [formula for D2(tau)]

   [...]. An alternative comprimise is represented by the lag
   window (whose use is called "hamming")

     [formula for D3(tau)]"

Further information is on page 98 (Section B.5):

  "Second pair (sometimes called "hanning", after the Austrian
   meteorologist Julius von Hann)" [no reference given]

  "Third pair (sometimes called "hamming", after R.W. Hamming [26])"

Ref 26 is to an undated memorandum:

  "R.W. Hamming and J.W. Tukey, Measuring Noise Color,
   unpublished memorandum."

Without dates and better references it's impossible to trace the
etymology in more depth, but from this I guess that "hamming" at
least was invented and spread by Tukey. It could be that von Hann's
window had been in wide use for some time previously, with people
saying things like "Let's try to to Hann it" hence "hanning", and
Tukey simply copied this over to "hamming" as a result of his work
with Hamming. Alternatively it could be that Tukey started with
"hamming" and it went the other way round.

Either way, one must not forget that Tukey was notorious for
inventing terminology, often very graphic and memorable, and
appropriate (sometimes perhaps less so); and was very vigorous
in propagating it. If you wanted to follow what Tukey was up to
(and there was every reason for that), then you had to keep up
with his vocabulary! Once Tukey gave something a name, that was
its name (at least as far as he was concerned, but it usually
became what everyone else called it too).

So, when Tukey writes 'whose use is called "hanning"' it could
mean that this is what Tukey calls it, as from now, so that's
what it's called. Similer for "hamming".

Best wishes to all,
Ted.


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Date: 08-Nov-04                                       Time: 09:11:16
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