EMI/EMC pre-compliance
About me
My name is Goran
I am not an RF expert
Since 1997 NLnet foundation (after its historical contribution to the early internet in Europe) has been financially supporting organizations and people that contribute to an open information society. It funds those with ideas to fix the internet. The procedure is fast, competitive and open to anyone. The articles of association for the NLnet foundation state: "to promote the exchange of electronic information and all that is related or beneficial to that purpose".
NLnet has contributed funding to many important and very visible projects around fundamental standards from securing the core routing protocols and the domain name system of the internet to safer email, vendor-independent videoconferencing, more reliable wireless networks and private instant messaging - all based on open standards and verifiable open source software and/or hardware. It spawned the world-renowned NLnet Labs, and supported great open source projects like Jitsi, ARPA2, WireGuard, NoScript, Tor Hidden Services, GPLv3, GNUnet, and webODF. And many more ....
What is EMC
https://www.academyofemc.com/post/what-is-emc
EMC stands for electromagnetic compatibility. Every electronic device/machine on the market must be EMC compliant, meaning it must fulfill the EMC regulations and standards defined by the country where the product is sold.
-
... NOT interfere with other devices/machines in its environment (emission).
-
... NOT being upset by other devices/machines in its environment (immunity).
-
... NOT interfere with itself (signal integrity).
-
... NOT be destroyed or malfunction when touched by a human (electrostatic discharge, ESD).
What is EMI
Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.
You need to comply!
All electric devices or installations influence each other when interconnected or close to each other, e.g. interference between TV sets, GSM handsets, radios and nearby washing machine or electrical power lines. The purpose of electromagnetic compatibility (EMC) is to keep all those side effects under reasonable control. EMC designates all the existing and future techniques and technologies for reducing disturbance and enhancing immunity.
The Electromagnetic Compatibility Directive (EMCD) ensures that electrical and electronic equipment does not generate, or is not affected by, electromagnetic disturbance.
CE price
Rounded prices in Croatia
Battery powered device with ESP32
~€3K
DC powered device that communicates with computer with ESP32
~€5K
No WIFI device that is powered from AC
more then €10K
One hour of chamber
~€300
How to make it bearable
When you start designing you device follow as many rules you can!
You can find complete design guide on NASA page
https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/High-Speed%20PCB%20Design%20Guide.pdf
It has example pictures of good and bad practices so make sure you understand each example they show.
Return current
Board stackup
Pre-complience and DIY
In almost 90% of the cases, the CE marking regulations allow products to be self-certified for CE marking.
In other words, you can do the CE marking yourself and you are not required to have the product certified by a third-party certification body.
Obviously, CE marking self-certification can save your company a lot of time and money.
Even if you need to do it at 3rd party certification body it is best if you can do pre-complience yourself!
SA and near field probes €€
DIY - cheaper option
TinySA
More equipment
Industrial €€€
DIY - PrusaProbe
Results
It was hard to read those traces
TinySA dashboad FLOW
TinySA instrument
Near filed probes compare
30MHz to 1GHz
AliExpress - red
opensource - green
H20 from TekBox - yellow
All probes are H-Field probes with similar loop hole.
10 minute scan with each probe
OpenSource probe if good enough for our work!
EMC chamber - industrial €€€€€€
DIY chamber - v0.1 - repurpose microwave!
Compare with known device
RP1 - on the edge
ULX3S - PAWSv2
MAX HOLD on empty chamber - yellow
Subtract yellow from measures
Microwave conclusion
You can get decent results with microwave tests.
Combine with probe tests to locate exact location of EMI.
Microwaves are built in a way to reflect signals.
We will get lots of reflections and our measurements
may not be as good as we want.
Searching for blocking none reflective material
DIY probe's holder
DIY probe's holder
Results
After testing many materials I had around in my house I have concluded that this special foil is the best choice, and second best choice is just a simple aluminum tape!
So I have decided to combine those two!
Noise Suppression Sheets part no:
IFM16-030GB300X200
DIY chamber - v0.2 - OpenScad box
DIY chamber - v0.2 - video
DIY chamber - v0.2 - results
DIY chamber - v0.2 - sweeping
TinySA ultra inside of the box and it is doing sweeping at -40dBm
Industrial GTEM cell €€€
EMARD's chamber - Xnec2c
EMARD's chamber - why pyramid
Pyramid is easy to assemble
Bounced signals should have hard time to reach pyramid peeks
Combined with absorbing material should be better then box
EMARD's chamber - v0.1
EMARD's chamber - assembly
EMARD's chamber - isolation
EMARD's chamber - edges
EMARD's chamber - assembled
EMARD's chamber - quiet environment
EMARD's chamber - better antenna
EMARD's chamber - KiCad antenna
Antenna design will be tested on BalCCon
Blocking external signal in noisy environment
Noisy environment
EMARD's Pyramid assembly demo
Just give me a sec!
Thank you and join us in lobby!
https://github.com/intergalaktik/EMC-experiments
https://www.envox.eu/
https://discord.gg/qwMUk6W
https://slides.com/goranmahovlic
EMI/EMC pre-compliance on cheap
By Goran Mahovlić
EMI/EMC pre-compliance on cheap
Supported by NLnet grant
