Last week we put our prototype through its paces and performed our first run of exploratory EMC tests. EMC stands for electromagnetic compatibility and passing EMC testing is a requirement to be able to sell an electronic product. If you look at the back of your electronics equipment you should be able to find the markings that indicate EMC compliance. Take this iPhone for example, the FCC marking and the CE marking indicate that this product has passed the tests required for EMC compliance in the US and EU respectively.
What is EMC and what is the significance of EMC testing?
Some people may recall back in the 70s or 80s when using the blender in the kitchen would cause the TV in the living room to go temporarily fuzzy. This was caused by unintended electromagnetic noise generated by the appliance during its operation.
I found a little piece of gold on youtube that shows this very phenomenon way back in 1985.
From this video you can see how electromagnetic radiation generated from one device can interfere with the operation of another device. A fuzzy TV was just a minor inconvenience back in the 1980s, but as we have become more dependent on electronic devices in our lives, the outcomes of interference could be more catastrophic. Imagine a pacemaker that stops each time you use the mixer, a phone that stops working each time you use the microwave, an airplane’s navigation system that fails because someone used their phone, or an entire company’s computer system that shuts down because someone turned on an air conditioner.
To ensure that electronic devices can be safety operated together, governments around the world now impose mandatory electromagnetic compliance testing (EMC) on products to ensure that they do not emit too much unintended electromagnetic noise. Once your product has passed testing for each jurisdiction, you are then able to place the FCC, and CE and other markings on the product and offer it for sale.
EMC testing is expensive, and depending on the product it can be very difficult to pass. The cost of the testing alone is usually between $10,000 and $50,000 depending on the complexity of the product and number of jurisdictions you want to cover. Formal testing generally requires the use of specially built electromagnetic ‘quiet’ chambers that cut out all of the background noise and allow the equipment to scan only the signals coming from the product being tested. This image shows a multi-million dollar test chamber in Melbourne, Australia being used to scan the electromagnetic noise coming from a microwave oven.
Before spending a whole lot of money performing final EMC testing in a facility like this one, you want to be sure that your product will actually pass, and this is what exploratory EMC testing is for. Last week we did this with the GoFar prototype using the current clamp method. The test setup can be seen in the image below.
Basically the equipment takes a background electromagnetic noise reading, and then reads the noise produced when the unit is turned on and in various operating modes. This gives us a good picture of how the electronics are performing with relation to EMC and identifies if there are any risk areas.
Some of the results from our testing can be seen in the image below, and good news….. we are looking good for EMC!
If you would like to know more about EMC testing, here are a few interesting references:
An article from Gizmodo: http://www.gizmodo.com.au/2012/12/giz-explains-what-the-strange-symbols-on-your-gadgets-mean/
And a more detailed article from Wikipedia: https://en.wikipedia.org/wiki/Electromagnetic_compatibility