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Author Topic: Passing FCC without RF experience?  (Read 956 times)
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nubelube
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« on: November 17, 2012, 06:00:58 06:00 »

I'm making a Bluetooth LE 4.0 device and plan to use an FCC-preapproved module in prototyping. However, if we go into production then it looks like it may make sense to do a custom design and pay the $5k for FCC testing.

Question 1: Do I need to find an RF person to design the RF circuit, or is it likely that I could just follow an application note and get a circuit that passes FCC? I have ZERO experience with RF circuits. If I needed something unusual, I would definitely get an expert; but this is the typical use case for radio ICs, so it wouldn't surprise me if manufacturers tell you exactly how to do it.

Question 2: It seems existing FCC approved modules cost $10-15. And radio ICs like TI's CC2541 cost ~$2.50 in 2500 volumes. Assuming I go with a PCB antenna, what other costs would I be looking at? I think there are a few passives (do I need expensive high quality ones?), and I'm not sure what baluns cost. I would probably also need to go up to a 4 layer board. Do I need to license a bluetooth software stack or do the IC manufacturers typically provide a basic one for free?

I fully admit that I don't know shit about this, so my questions may be idiotic. I could start reading about it and get a better idea of what is involved, but I'm hoping someone can tell me beforehand if it's too difficult and I would be wasting my time.
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solutions
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« Reply #1 on: November 17, 2012, 06:44:15 06:44 »

The answer depends on the volume of product you will make.

You not only need a design, you also need to set up testing on the bench and on the shop floor

AND you need to sample devices for compliance on a continuing basis, if I remember correctly. Failure could mean shutting down your line and product revenue and a lot of head-scratching because you do not have the tools or knowledge to characterize or troubleshoot the radio.

And you have to factor yield - RF failure takes out the whole board. There is little to no failure in a pretested module.
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Gallymimu
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« Reply #2 on: November 17, 2012, 09:10:10 09:10 »

BLE is pretty easy,

If you go with TI they give you their stack.

Nordic Semiconductor will almost do your hardware design for you.  If you do a layout they will look at it and help you make sure it will pass FCC.

If you use a chip antenna that also simplifies the design.

As for additional passive components it should be pretty minimal if you go with TI.  Their app notes are pretty thorough, follow them!  You will need a 4 layer board at least.  These radio circuits are pretty sensitive to proper bypass/decoupling and a proper ground plane is mandatory at those frequencies.

Where are you getting FCC for $5k?  Most people who have been through it (I haven't done FCC for an intentional radiator myself) say that the whole process (testing and certificate) was closer to $20k-$40k (that's all said and done not just one 3 hour test lab rental)

another nice thing about the modules is the stacks are very easy to use.  We are doing some medical instrumentation with BLE using bluegiga and have blueradios as a fallback (the blue radios support people are NOT friendly though so I'd avoid them).

I'd look seriously at nordic if you are inexperienced.  They seem to be VERY willing to help people using their products.  Your questions aren't stupid and this stuff is in the realm of reason to accomplish, but expensive.
« Last Edit: November 17, 2012, 09:14:12 09:14 by Gallymimu » Logged
nubelube
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« Reply #3 on: November 23, 2012, 01:07:06 01:07 »

Awesome, thanks for the tips! I only got the $5k price for FCC certification by Googling "FCC certification cost" or something like that. So I trust your numbers way more. Based on http://electronics.stackexchange.com/questions/16935/things-to-watch-out-when-applying-fcc-ce and http://electronics.stackexchange.com/questions/5196/which-products-should-have-fcc-certification-and-about-how-much-does-that-cost, perhaps I was looking at estimates for unintentional radiators or something.
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Gallymimu
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« Reply #4 on: November 23, 2012, 04:38:27 04:38 »

Awesome, thanks for the tips! I only got the $5k price for FCC certification by Googling "FCC certification cost" or something like that. So I trust your numbers way more. Based on http://electronics.stackexchange.com/questions/16935/things-to-watch-out-when-applying-fcc-ce and http://electronics.stackexchange.com/questions/5196/which-products-should-have-fcc-certification-and-about-how-much-does-that-cost, perhaps I was looking at estimates for unintentional radiators or something.


Do me a big favor and post back as you get this all figured out.  I'll be interested to know how your experience and costs end up.  Don't trust my numbers too much as they are 3rd hand.  Good luck!
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