Simply call it " Make it to meet specification", N1UL In a message dated 9/17/2017 12:39:32 P.M. Eastern Daylight Time, magnus@rubidium.dyndns.org writes: Hi, The word "calibration" is overloaded with multiple meanings, and incompatible too. "calibration" is often used to describe adjustments to make a device operate correctly, such as passing the performance checks. "calibration" in legal traceability is about measure the performance against references to form a traceable record of deviations from the norml. This may include adjustment to ease compensation, but this is not necessary. Regardless of wither adjustments where done or not, the calibration record will indicate the errors that then needs to be applied to the measurement for the measurement to be traceable, and this in itself requires documented knowledge about how to do the measurement. Otherwise it's just a fancy indication. Adjustment to a reference thus do not imply legal traceability, or even full functionality. For full functionality, you have to go through the performance check and see that all values is within limits. "calibration" can thus imply different things. I regularly see people use these terms inconsistently. That people get disappointed when they get the wrong thing is to be expected. Cheers, Magnus On 09/17/2017 05:23 PM, Scott McGrath wrote: > As to the point most modern instruments have self calibration, Most of the time 'calibration' is simply the performance check adjustments are not performed unless necessary > > The difference being the instruments used in performance test are traceable to a national standards body. > > So whats referred to as calibration is in reality performance validation. > > How do I know this by becoming friendly with the local lab and years ago when i worked for govt i used to moonlight at one of the local cal labs. > >> On Sep 17, 2017, at 8:57 AM, KA2WEU--- via time-nuts <time-nuts@febo.com> wrote: >> >> Modern test and radio equipment have self calibration capabilities, older >> analog do not. Calibration is not always need for just simple test, but >> for specification conformation it is useful. A bit of luck also helps. >> >> >> >> >> In a message dated 9/17/2017 8:08:00 A.M. Eastern Daylight Time, >> drkirkby@kirkbymicrowave.co.uk writes: >> >>> On 15 Sep 2017 10:45, "Scott McGrath" <scmcgrath@gmail.com> wrote: >>> >>> Precisely my point, But when purchasing i expect to pay for a >> calibration at a minimum. >> >> I have on occasions requested sellers to send an item to the manufacturer >> (Agilent or Keysight) for calibration *before* shipping it to me, offering >> to pay the calibration cost, but stating that I expect a full refund if the >> item fails the calibration. >> >> If a test equipment dealer is confident that something is working well, >> they should not object to sending it to the manufacturer for calibration, >> as long as the buyer is willing to pay. >> >> Of course if a seller knows little about something, they are not going to >> do this, but the item should be appropriately priced. >> >> One UK seller (grace1403) declined to send an Agilent N9912A FieldFox to >> Agilent, because "Agilent were too fussy"., failing items for trivual >> issues. But he did agree to send it to one of the cal labs he uses. I >> thought it was a waste of time going to one of the less fussy outfits, >> but >> bought it anyway. It was then clear on receipt that it was faulty. (The >> spectrum analyser functionality was ok, but it didn't work as a network >> analyzer). He took it back, but then advertised it on eBay 6 months >> later. When asked, he said nothing had been done to it. >> >> eBay rules about who pays the return shipping charge for an item that is >> "not as described' keep changing, and may be different on different sites. >> But on a heavy item shipped internationally, the postage cost can be >> comparable or exceed the calibration cost. >> >> Dave. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

On 9/17/17 9:42 AM, KA2WEU--- via time-nuts wrote: > Simply call it " Make it to meet specification", N1UL > > > In a message dated 9/17/2017 12:39:32 P.M. Eastern Daylight Time, > magnus@rubidium.dyndns.org writes: > > Hi, > > The word "calibration" is overloaded with multiple meanings, and > incompatible too. > <snip> > "calibration" can thus imply different things. > > I regularly see people use these terms inconsistently. That people get > disappointed when they get the wrong thing is to be expected. > > Cheers, > Magnus > Indeed - in my business, we have to be careful about the word "test" vs, say, "characterization". A "test" has a pass/fail criteria associated with it, while a "characterization" might just need recording what the value is. "tests" have institutional requirements for witnessing, etc. that "characterizations" do not, for instance. And this gets into the whole "knowledge" vs "control" - I may not care if a XO changes frequency 10ppm over temperature, as long as it's repeatable and I can know the actual frequency within 0.5 ppm. As Magnus points out, "calibration" can mean many different things, and some of them are historically derived. Back in the day, there may have been some sort of physical adjustment required to, for instance, set the scale factor of a display - but now, it's "calibrated by design", and the "calibration process" (as in "sending it to the cal lab" to get a "cal cert") is more about verification that it's not "broken". I also used to (and still do) get bent out of shape when you'd send something like a power supply out for cal, and it would come back with some problem (like a non-functioning pilot light). And the cal lab would say: "we checked the output voltage and it is within spec". Yeah, but isn't "proper function of all features" covered - and the response would be "no, it is not, we don't see 'verify function of pilot light' on the cal procedure we have" ANd then there's the "calibration/validation" phase of instruments in space - that's a completely different kind of thing, more akin to characterization.. The 'val' part is yes, verifying that the instrument is working as designed,but the 'cal' part is more about relating instrument measurements to some other reference, and from that, relating it to some physical property of interest. And that can happen at many levels. A spaceborne scatterometer to measure winds can be cal/val at 1) Does the instrument work, and are the instrumental effects accounted for - if it measure a particular backscatter cross section, is that what the backscatter cross section really is? 2) Does the "retrieval model function" that turns backscatter measurements into wind speed and direction work? And particularly for #2, a lot of it is inferential - comparing one model against another, since there's not really "ground truth" available.