"An ounce of prevention is worth a pound of cure." Haven't we heard that before? But do we apply this simple axiom to our business in order to maximize our profits and minimize our losses? Let's see how two ounces (that's the weight of ScanEM probe) of prevention can help your company to improve its bottom line in a way that was not clearly visible before.
Many engineers think that the work on electromagnetic compliance begins after the engineering prototype is finished and is "thrown over the wall" to the Compliance Engineer. Should this be happening in your organization, may we suggest renaming the position of the Compliance Engineer to Damage Control Specialist. The only effective remedies this specialist could apply at this point would be choking the abundant emission in your product by adding shielding and ferrite filters, raising the product cost and causing nightmares for Manufacturing, never mind weeks of delay in the Engineering schedule. However, it is entirely possible to design even high-speed computer equipment without or with absolutely minimum amount of shielding, and not to spend weeks in the lab and a fortune on copper futures. Please see Timing is Everything for more details.
When you project the cost of your future product, do you count in the last-moment additions to the product that do absolutely nothing to improve its functionality nor expand its features, but add "unforeseen" shielding, conductive paint, ferrites and other such additions in order to pass EMC regulations. The cost of "afterthought" compliance may easily add $10 to $20 (or even more) per unit. And what about several precious weeks at the end of the development schedule when time is at premium and all your engineers do is add cost to your product? Did we mention the exuberant fees that EMC consultants and labs charge to bring your product in compliance that late in the game?
A day spent on electromagnetic compliance early in the project will save you thousands of dollars and weeks of delay at the end, and may substantially reduce product cost
Simple following good engineering principles will assure that your design will have a fair chance of meeting EMC requirements the easy way and without much "damage control."
And may we suggest that ScanEM probes are the most practical tools to use at every stage of product development -- from the first prototype to the trip to the EMC laboratory. Equip your engineering team with ScanEM probes so they can use them as diligently as an oscilloscope or a multimeter, and you will assure smooth sailing through the compliance waters (you wouldn't want to travel without the compass, would you?).
Soon you will discover that ScanEM probes can help you in other areas of your design. Have you ever had a situation when your malfunctioning board doesn't work until you connect an oscilloscope probe to it? An oscilloscope then doesn't show anything suspicious, but the product still refuses to work properly unless attached to an oscilloscope. You may have signal integrity problem. Check how you can use ScanEM probes with an oscilloscope to see what your ordinary oscilloscope probe was hiding from you. Also, please see Application Notes AN103.
EM Pre-Compliance and Troubleshooting
Just like it is good idea to test your product before you ship it, it is also good idea to check whether your product has a chance to pass compliance test before your take it to the certified laboratory for test. The main task the laboratory is charged with is to test your product in accordance with the required standards and to tell you whether you passed or failed.
You can perform your own pre-compliance test at your company with reasonable correlation with the "approved" test site using Laplace complete EMC System. Performing pre-compliance test at your site will save you time and money and will put you more in control of your design and your bottom line. Please check Laplace EMC System here.
The standard radiated EM compliance test is conducted in the far field (typically at the distance of 10' or 3m away from the product). The far field test can tell whether the product passes or fails but it cannot point to the source of the problem. It is similar to trying to find out what specifically makes a noise under the hood of a car from a distance of 10 feet (3m). One can guess that it might be a belt by its "signature" squeak, but which one out of three or four is impossible to tell; and it may not be a belt at all.
In order to locate the source of the problem, why not come closer to the car and take a look? As with a car, electronic assemblies also need "close up" inspection. Unfortunately, far-field antennae won't be able to help --- they are just too big for the job. The right tool is called a near-field probe. It can identify the exact sources of emissions down to a component or a trace. With its help the whole product can be scanned in a matter of minutes and the leaks and problematic areas can be located on the spot.
With ScanEM you should be able to reliably predict EM behavior of your product and to locate emission sources in a matter of minutes. Then, when the product is taken to the laboratory, the probability of surprise is greatly reduced, or, at least, is predictable. Check your product for sources of strong emission and EM "leaks" before it leaves for the final test, correct any problems in your laboratory, and take it to the test lab only when it is ready.
Should the worst happen and your product still fails the test, pull your ScanEM probe and check on site what is wrong and where the strongest emission are coming from. Often, the far-field test can show excessive emission at frequencies, which didn't seem likely in the near-field test.
High-level radiation registered with the near-field probe is not necessarily an indication of a problem in the far field. Just the opposite could be true -- the near-field probe may not show the field strength of the area, which is the cause of the compliance failure. In order to understand why, one needs only to realize that in the near field the probe picks the signal only at a particular spot, while in the far-field the field strength greatly depends on the antenna properties of the radiating object. As an example, a short trace on the PCB with a strong emission level may be much less dangerous than a longer one with a lower emission level. A single small-size strong emission leak from an otherwise shielded enclosure may be much less dangerous than "lukewarm" radiation from a large area or around a long seam in the shield.
If the offending frequency is well known and if the field carrying it is not the strongest one in the product, a spectrum analyzer will be needed. If the probe is used in the early stages of development where it is not yet clear what frequency will be of concern, a simple broad-band level indicator will do an adequate job. In many cases it may actually do a better job than a spectrum analyzer in searching for the highest emission level, since the spectrum analyzer may not provide a total signal level in the band readings. It is difficult to subjectively judge it by looking at the screen.
A day spent at the beginning of the project preventing EMC problems saves a month of fixing these problems at the end. Check your product with ScanEM® early in the design stage and prevent expensive and embarrassing delays in your schedule.
Your engineers designed the product in full compliance with FCC p.15 and CE regulations for a good reason. In order for virtually any electronic product to be sold in most countries, it needs to satisfy government regulations limiting the amount of electromagnetic emissions it produces (this is called electromagnetic compliance, or EMC). It is illegal to ship a non-compliant product that is labeled as compliant with FCC and/or CE regulations. The last thing you want to do is expose your company to penalties, product recall or even being banned from the market by shipping a product which is falsely labeled as compliant.
And yet this can easily happen. A loose or missing screw, a wrong washer, improperly placed or missing shielding, incorrectly routed cables, missing ferrite chokes, etc. - all the things that are process-sensitive and completely undetectable by typical production test procedures can negate some or most of the counter-emission measures that your engineers designed into the product in order to comply with the regulations.
Now you have the opportunity to assure every production unit's compliance. For this you won't need a shielded anechoic chamber, an expensive spectrum analyzer, a web of huge antennae, or a specially trained personnel.
The only tool your QA inspectors need is the ScanEM-Q probe kit, and you will never ship a non-compliant product! After all, FCC field inspectors use ScanEM-Q probes to enforce compliance of products (visit the FCC web site at http://www.fcc.gov/cib/News_Releases/comsimp.html). Credence Technologies manufactures a line of ScanEM probes that are used at different stages of product design, manufacturing, QA and service. ScanEM probes are sold all over the world. They have received awards from such prestigious trade publications as EDN and Test & Measurement World.
ScanEM-Q probes were originally designed for, and in cooperation with, the FCC in order to enable their inspectors to check for violators of rules in the field. After their successful test and adoption of the ScanEM-Q probes for FCC use, now these probes are available for engineers, technicians and QA inspectors to test their products the same way the FCC does.
Accelerate repair of PC boards by comparing emission coming from the components on a "good" board with those on a board in question. Emission pattern coming from properly working circuit is different from the defective one. This quick test will help you to identify defective parts even without detail knowledge of the circuitry. Both ScanEM and ScanEM-C probes will work in this application. ScanEM probes are good tools to check for proper connections and shielding in RF and network cables. Please see Application Notes AN104.
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