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Computing => Cloud Computing + IoT => Topic started by: Jester on May 11, 2020, 08:57:18 am

Title: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: Jester on May 11, 2020, 08:57:18 am
For those that have used a FCC/IC stamped and certified WiFi or Bluetooth module for example Laird or Espressif for an IoT product, where the other aspects of the design would typically be low risk or benign from a EMC perspective i.e. opamp type circuits or no or low power switch mode converters < 10W. Did you breeze through EMC testing with a comfortable margin (say 3dB) or did your design need tweaking after prescan?

My experience to date has been good as long as the remainder of the circuit is low power with a decent ground plane, and not quite so good with higher power circuits.
Title: Re: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: gooligumelec on August 07, 2020, 06:52:22 am
For those that have used a FCC/IC stamped and certified WiFi or Bluetooth module ... Did you breeze through EMC testing with a comfortable margin (say 3dB) or did your design need tweaking after prescan?

Hmmm, no answers to this so far...

I'm very curious myself - have been developing a BLE product, using an FCC certified module.  But I've never done FCC/CE RED/RCM testing before.  Should be ok, but a little concerned that I'll spend good money on testing (even a prescan will cost), then have to spend time trying to revise the design, then more money and maybe still repeat.  So it would be great to get some sense of how other people have gone.

And as an aside, it seems that EMC testing is hush hush.  Secret engineers' business?  There's always plenty of discussion of component selection, PCB design and assembly, but from forums like this you'd almost think that hardly anyone gets their designs tested!
Title: Re: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: Tomorokoshi on August 08, 2020, 04:31:32 pm
...
And as an aside, it seems that EMC testing is hush hush.  Secret engineers' business?  There's always plenty of discussion of component selection, PCB design and assembly, but from forums like this you'd almost think that hardly anyone gets their designs tested!

There are a few threads around here on that, but there doesn't seem to be consistent experiences. With a project I'm on we're finding that while a module may have some ostensible approvals, they don't mean much once it's installed in our system, and it's unlikely that the testing agency will accept the the module approvals as-is. Get quotes early and talk to multiple agencies.

I've suggested a couple times that the forum really needs a couple new categories, something like:
"Standards, Testing, and Approvals"

and:

"Project Management and Corporate Silliness"
Title: Re: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: gooligumelec on August 12, 2020, 07:05:38 am
Thanks, that's good advice.

I do see people asking questions about compliance testing (which can be more than EMC), just not a lot of discussion.

I've suggested a couple times that the forum really needs a couple new categories, something like:
"Standards, Testing, and Approvals"

and:

"Project Management and Corporate Silliness"

Indeed.  Especially the first.  Although I'd be happy to discuss the silliness of applying Agile to EE anytime.  ;)
Title: Re: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: Tomorokoshi on September 01, 2020, 04:33:13 pm
...
Indeed.  Especially the first.  Although I'd be happy to discuss the silliness of applying Agile to EE anytime.  ;)

Here in an example of an incident that has now occurred a couple times.

First, consider the lessons learned from "The Mythical Man-Month" by Brooks. [1][2]

Now, apply the core lessons to a project under Jira control. With the Jira concept of frenetic "tasks", the long and complex arcs of development get chopped into slices that are exceedingly tempting for management to distribute out to other engineers. This is effectively in direct violation of the key lessons from Brooks.

In this case my part of the project appeared to be late [3], so another engineer was re-tasked to "help" by taking on part of my collection of tasks and responsibilities. After that sprint we returned to our regular tasks.

Now I have even more to do as I unwind the knots and errors he introduced into my work, while his work is delayed by a sprint cycle.

[1] https://en.wikipedia.org/wiki/The_Mythical_Man-Month
[2] I can't refer to my copy right now. Seven months ago I lent it to a marketing manager, and I've yet to get it back.
[3] That wasn't actually the case. However, according to the Jira backlog, it was.
Title: Re: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: Wilksey on September 01, 2020, 06:08:19 pm
I have designed a CE/RED certified product that uses a UBLOX (ConnectBlue) OBS421x and a u.Fl to SMA pigtail and a 3db panel antenna, inside is also a Cinterion EHS6 and a Maestro GPS receiver, both have 2J PCB antennas.

From memory when it went to EMC testing it had no issues and flew through compliance.
Title: Re: EMC compliant Bluetooth modules & compliance testing - Did you pass first time?
Post by: miceuz on September 01, 2020, 08:02:49 pm
I had good luck with one notified body in EU - they didn't require any special testing for RED directive (characterizing the RF frontend at low level) and general EMI tests flew with no problems with Laird BLE module. It was low power design on 4 layer board with good ground plane and pretty good following of "no go" zones defined by Laird when doing layout.