Spec Sheets as Foundation for System Design
In the next couple of weeks, ISC West 2008 will be upon us and all the manufacturers will be there to show off and demonstrate their new products. It’s a great opportunity for them to introduce new technology, highlight product upgrades or simply just showcase the depth and breadth of their product line. And if there’s something that really catches your eye, there’s usually product literature available in hard copy or on a disk for you to take along and study afterward.
These data sheets are essential documents that describe exactly what the device is capable of doing and hopefully will save time and help prevent erroneous system designs. In general, the overview of the product purpose and its features is usually found on the front, near the top of the page where it can quickly be scanned for information. Further down the page or on the reverse is more in-depth information about the functions and technical characteristics of the product as well as what accessories might be offered. Finally, the data sheet usually contains information on the company including sales locations and contact information.
Creating a Spec SheetSome spec sheets are better than others in presenting the data and I can only imagine it is due to the number of people involved in developing the literature. Let’s take the example of a spec sheet for a new camera and have a lighthearted look at how a data sheet might go from conception to completion.
The initial information is probably provided by the design engineer who, like most engineers, wants the world to see and know every possible detail that has been designed into the device – like the 150+ functions available on the camera menu. All of this information must of course be edited by the product marketing people who, in addition to highlighting the salient points, want to make their camera look better than any others on the market. While a zoom speed of 100 feet/second is incredible, it’s not necessarily going to make for a great image.
Be More “Tolerant”Meanwhile, the product needs to be tested to ensure that it meets the minimum and maximum (tolerances) specifications indicated by the designers. Do they really rent an opera hall and set up candles across the front of the stage to get a foot candle (lux) reading for minimum light requirements or, more likely; do they depend on a guarantee by design? This means the design of the camera ensures that if certain parameters, which are tested, remain within their correct ranges, then others will do so as well and need not be actually tested. The word “typical” often comes into play here and, as a word to the wise, should not be relied upon for non-standard operating environments or applications.
The application and test engineers are also responsible for rooting out those little quirks that the design engineers and product marketing may want to overlook. For instance, installing the camera on a pan/tilt unit that pans at 300°/second while simultaneously zooming the lens at the maximum rate of 100 feet/second and also employing the 25X optical digital zoom may cause severe motion sickness not to mention an illegible image. Or, if the day/night switching function is so highly sensitive that it responds to the slightest change in illumination such as a cloud creating a shadow and is therefore constantly switching back and forth between day and night operation; or the automatic masking feature is immune to the color red; or the motion detection function only works with motion detection devices of a proprietary nature.
There’s a Marketing AspectOnce these tests are complete and the spec sheet has been amended accordingly, the data sheet probably goes back to marketing or corporate communications where it will be “wordsmithed” – i.e. “proprietary nature” is changed to “see manufacturer’s list of compatible devices.” Also at this time, the layout and format for the spec sheet is usually implemented and the information about those quirky little issues that the application/test engineers discovered will be made available in a 2 point size font and not relevantly located to the specification.
I would also guess that somewhere around this time the spec sheet must be reviewed by the legal department, who is generally paid by the word. Basically, they add the standard clauses which say that whatever might happen when the camera is used isn’t the company’s fault and we told you not to and therefore we’re not liable and everything is subject to change.
On a more serious note, spec sheets do serve a needed and specific purpose and for those of us who are designing and specifying systems, a well thought out and informative spec sheet is a little nugget of gold.