I'm about to sell a project essentially based on atmega328 @16MHz, 74 logic, linear and switching regulators, keyboard, display, some relays and mosfets.
Since I haven't much money to spend with proper EMI tests, I'm trying to understand how much radiated emissions my project generates, and basically, I need to know only if I'm into the EU directive, doing a sort of pre-compliance test.
With a 15-2700MHz RF explorer, a 50MHz DSO and a couple of beehive magnetic and e-field probes (with no preamplifier in between), I've analyzed the emissions of my project.
Only with the probes really, really close (near contact) to a specific zone of the MCU, I've seen a 31.071MHz, 59dBm main peak and some harmonics up to 150MHz (with lower energy) using the magnetic field probe, and a 150KHz electric field near in contact with the switching regulator using the e-field probe and DSO.
All the rest of the PCB areas shows basically no considerable activity.
The problem is: how can I say that I'm in the directive or not for radiated emissions? I've NOT a RF test chamber nor a proper antenna, neither the proper instruments.
Well, I guess that I can compare my project's emission values with similar projects that has already been CE approved: Arduino UNO boards, LiPo chargers that uses atmega328 and so on...
Doing this, I discovered that my project radiates less or the same emissions compared to that devices.
I know that this is really a poor man's test, but I'm confident that this method has it's own logic and that it does have sense: if they are EMI ok with those values, me too.
What do you think about this testing? Can I trust my pre-compliance method for radiated emissions?