Caveat Emptor

Kirt's Cogitations™ #189

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Caveat Emptor

Caveat emptor. Now there is a fine Latin phrase that is oft repeated. Although it is hard to imagine anyone not knowing what it means, the common translation is, “Let the buyer beware.” The admonition applies not just to the paying of cash for a product, but also to the accepting of or assuming that information is accurate as presented. The universal warning to not believe anything you read on the Internet is gross overkill, but a healthy dose of skepticism is definitely in order when researching data that will be used in the critical projects. Verification is mandatory. Trust but verify.

On rare occasions while collecting data for inclusion RF Cafe, I have run across websites, printed material and software that, upon cross-checking, have proven to be inaccurate. Filter equations are a good example. Without citing specific names, titles or URLs, I will tell you that there are many instances of incorrect transfer functions for denormalized transfer functions – particularly bandpass and bandstop. I have discovered inconsistencies in college textbooks, websites and even in software. Inductance and capacitance calculations are another area where with little effort, one can locate numerous different equations for the same calculation. These differences I write of are not just due to rounding errors in constants or multipliers; many times the errors are due to misplaced parentheses or a plus sign where a minus sign should be. Such little mistakes can produce results that have the potential to doom a design attempt if not caught in time. Most publishers, I have to believe, are very conscientious about cross-checking their work since not only is their reputation on the line, but they sincerely would never want to mislead anybody.

Unfortunately, there are too many websites that are composed primarily of pages copied directly from other people's work. This often leads to the perpetuation of erroneous information. I have run across many instances of exact copies of RF Cafe web pages (as well as of other website authors' work), some so blatant that the thieves were too lazy (or dumb) to remove the list of keywords that include “RF Cafe.” Many of my original graphics are replicated on other websites. To my knowledge, RF Cafe has no unauthorized versions of anyone else's material of any sort. Visitors are encouraged to report any suspected instances.

Mea Culpa. That is another familiar Latin term whose translation is not as well known. It means, “I am culpable.” Basically, it is an admission of guilt. Here is my mea culpa. Over the six-year span of RF Cafe's powerful online existence, there have been a few instances where visitors have written to notify me of erroneous data on the website. To the best of my recollection, most of the discrepancies have been things like misplaced decimal points in tables of data. All claims of errors are researched and corrected if found to be justified. Usually the person who notifies me is right, and I appreciate the feedback. As time permits, I review the pages on RF Cafe to look for undiscovered problems with text, equations and images. Again, you are encouraged to report any suspected oversights.

When corrections are made, I place a notice on the page, as with the “Drill Sizes – Numbered” page. An example of something other than a misplaced decimal point is on the “Inverse Trigonometric Identities” page. Most people are cordial in reporting the errors. In the case of the Trig Identities error, the reporter pretty much lambasted me for all the high school students I have probably misguided due to sloppy proofreading. I will try to do better. Fortunately, the Mars Climate Orbiter crash in 1999, caused by an incorrect conversion between English and metric units, predated RF Cafe so I will hereby absolve myself any responsibility for that misadventure.

Carpe diem.