FCC and rf modules

jgschmidt · Joined: 03 Dec 2008 Posts: 184 Location: Gresham, OR USA

Hi,

Does anyone have any comments about developing low-power rf systems that use the "unlicensed" 2.4GHz and 433MHz bands in the USA.

I know that I can build a few systems for my own use, however, what has been your collective experience when it comes to

A) Making a single system for a customer
or
B) Making multiple systems, in the dozens range, NOT 10K to 100K units for wide distribution.

Neither of these maintain a continuous connection, there are just short bursts for remote control and monitoring.

I have customers for both A and B scenarios but don't want to go through the costly FCC certification process. I know I can get FCC certified modules but there are two issues with those: 1) they tend to be too big for key-fobs and 2) some forums I checked said you still need to get the final product certified.

Any thoughts on your professional experiences with this will be appreciated.

Cheers,
_________________
Jürgen
www.jgscraft.com

asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

answer:
all the cheap 432mhz ISM global units exceed allowed RF power, AND the allowed channel mask deviation, as specd' by FCC CFR47 part I.

For you to to use one-off experimentally is one thing, and the enforcement risk is non existent,
BUT in a product, you need to do real engineering of your own and get a compliance certification from an FCC approved 3rd party test lab.

also see
http://www.fcc.gov/document/action-empowers-broadband-and-health-it-transform-health-care

then there is the function issue:
sending RTZ, asymmetric data patterns (ala RS232) RELIABLY using the low end of this technology is VERY VERY sketchy at best ......

if looking for an FCC compliant design - with better than average data
capability - check the microchip MRF49XA

in volume production, will not be too expensive to field either.

temtronic · Posted: Sun May 12, 2013 1:45 pm

Frankly I wouldn't want any product , especially 'remote control and monitoring' (I'm real familiar with remote energy systems), that isn't dead nuts reliable !
The only thing worse than one unhappy client, is 2,3 or more. Spend the extra time, energy, research and get RELIABLE communications. I cannot stress the importance of that. Though I've only got 2nd hand info on 'RFDigital' products, they have a combo tranceiver with PIC at a good price,tons of feature..meager power usage.

On the same line, if using batteries (you did say keyfobs..) buy GREAT batteries NOT itty bitty cheap low amp types. Again, RELIABILITY.

ok, sermon over, back to our regular programs...

hth
jay

jgschmidt · Joined: 03 Dec 2008 Posts: 184 Location: Gresham, OR USA

Thanks, guys. As always, I appreciate your comments.
_________________
Jürgen
www.jgscraft.com

newguy · Joined: 24 Jun 2004 Posts: 1907

Have you considered using an off-the-shelf FCC certified 3rd party module? Much easier than reinventing the wheel.

jgschmidt · Joined: 03 Dec 2008 Posts: 184 Location: Gresham, OR USA

Yes, I'm looking for those right now. The most suitable thing I've found so far is from RF Digital www.rfdigital.com It looks like they've addressed all my application areas, including the binding (they call it "learning") of module sets so they don't interfere with each other. They're not cheap ($15) but for the low volume I'm looking at and the amount of software development time I'll save it's worth it. I've ordered a pair to try out.
_________________
Jürgen
www.jgscraft.com

temtronic · Posted: Mon May 13, 2013 5:03 pm

A friend's used them, got over 2Kms on them using 3v coin cell ! I looked at the embedded PIC version, but lost the R&D contract to someone else...

hth
jay

FvM · Joined: 27 Aug 2008 Posts: 2337 Location: Germany