Who invented the Y-factor meeasurement technique?

Does anyone have a reference to the invention of the Y-factor technique used for noise figure measurement? I see it either not referenced at all, or references to HP/Agiilent application notes or books, but can't find the first publication of the method.

Anyone know why its called Y-factor?

But Y is admittance IIRC.

But what should HP have? Sure they have the application notes that describe using the y-factor method to compute noise figure or noise temperature, but that is it. Their application note (AN 57-2) makes no reference to it, and nor does SN 57-1, which itself has lots of references to old material. But the y-factor is not referenced - only mentioned.

Not in noise figure measurement.

Quoting from my HP 57-1, in the section "Measurement of Noise Figure and Te":

"The noise powers at the output of the DUT are often labeled N2 (corresponding to Th) and N1 (corresponding to Tc). The ratio N2/N1, is called the Y factor."

--- So you missed it or it got deleted in the ones you have. It is defined in the HP docs, and I presume HP was the original definer of the term, but I could be wrong about that. In 57-1 (which has lots of references to other work), I didn't see any references in the section where Y factor is defined.

So, to my knowledge, HP invented the term. I think they also invented S-parameters. More reason why I'm revolted by the HP/Agilent redefinition.

I've been rummaging through my references, and while I haven't seen the actual definition, two papers that I _do_ have mention that this method was standardised in around 1957.

Perhaps this will bring enlightenment...

H.A. Haus et al., "IRE standards on methods of measuring noise in linear twoports", 1959, Proc. IRE, vol. 48, no. 1, pp. 60 68, January 1960.

I'll try to look it up, but I'm afraid our library isn't old enough.

Regards, Jeroen Belleman

Thanks, I should be able to find that.

Someone else gave me these as possible sources

H.A. Haus, "Description of the Noise Performance of Amplifiers and Receiving Systems," Proc. IEEE, March 1963, p. 436-442 (and other papers in that issue)

C.K.S. Miller, et. al. " Noise Standards, Measurements, and Receiver Noise Definitions," Proc. IEEE, June 1967, p. 865-877.

these are from: R. Pettai, Noise in Receiving Systems, Wiley, 1984.

I know what it is defined as. I don't want that. Mr (Dr. or whatever) Wheatstone invented the bridge. I suspect it would not take me too much hassle to find where that was first published.

Whoever invented Y-factor, probably published it in a scientific journal. If it was invented inside HP, it might well be in the Hewlett Packard Journal, but I have no way of searching that. But their articles tended to go into IEEE journals too.

what makes you presume that?

No, I agree the reference is missing in 57-1. I think it should have been there. I am 99% sure I know the person who wrote that application note, and are 99% sure he would have added it, had he known it. But of course, that's an application note, not a PhD thesis.

It's also not obvious why it is called "Y" factor.

I can sort of understnad why scattering parameters have the name they do. particles scatter light both back and forward (and to the sides too it must be said). But Y factor I have no idea.

There is only God and MIT. What else do you want ?:-)

...Jim Thompson

I found the paper. It deals essentially with the effects of source and load admittance on the measured noise levels. So, though there are Ys all over it, it's not what you were looking for. It contains no other references either, so that's a dead end.

But you piqued my curiosity. I'll do some more searching.

Back later, Jeroen Belleman

Keerect ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

Why, Keith? Don't you believe in "intelligent design" ?:-)

...Jim Thompson

Smirk ;-)

...Jim Thompson

Jeroen Belleman wrote: [...]

So, I think I got the right one, this time. The earliest description of the Y-factor method of noise measurement I found is:

H.A. Haus et al., "Description of the noise performance of amplifiers and receiving systems", Proc. IEEE, vol.51, March 1963, pp436-442

At least the wording suggests that the concept was newly introduced here, and there are no further references. Then again, I did get the impression that Mr. Haus' commission had a habit of omitting useful references...

For a few days, you can get a scanned copy of the article on

Regards, Jeroen Belleman

Opposites?

No. I don't believe in Satan either, which is why I didn't go to MIT. ;-)

But not necessarily in that order?

:-)

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

Hi Dave,

Could you give some more details about the particular measurement process you are interested in?

It's a method of measuring amplifier noise figure at RF and Microwave frequencies.

A number of methods are documented in Agilent application note AN 57-1 titled "Fundamentals of RF and Microwave Noise Figure Measurement"

and the Y-factor is covered in detail in AN 57-2 titled " Noise Figure Measurement Accuracy: The Y-Factor Method (AN 57-2)"

Thanks.

Yes, I would agree it does, although the wording is no different from Agilent application notes, or most other references on the subject. They all seem to just mention it.

It's also not obvious that one or two people together came up with it either, with the 6 authors being from 6 different labs.

Yes, I agree there.

Thanks, my next challange it to try to find an earlier reference. I know a book