Vitaliy wrote:
> Bob Axtell wrote:
>   
>> You can perform some up-front work that will save yourself a LOT of grief.
>> For example, suppose you need to get FCC part 15 certification for a
>> PIC-based product.
>>
>> Purchase a simple broadband "sniffer". I bought mine from a kit store;
>> it detects RF radiation from 2Mhz to 1000Mhz and makes an alarm
>> when any is detected. I KNOW I paid less than $100USD. (It was
>> sold to detect "bugs" by private investigators). Its the best $100 I
>> ever spent... (well, there WAS that cute Irish girl in Boston I once
>> had dinner with... but that's another story.).
>>
>> Place the product, RUNNING, on a non-metallic tabletop and walk around
>> it with the sniffer. If you can't detect any signal in less than 10'
>> (3.3m), you
>> will NOT have an issue when you need to get a certificate.
>>     
>
> Wouldn't the distance depend on the sensitivity of the sniffer? 
>
>   
Er.. didn't like my sniffer..?

Of course. Mine was able to track the internal wiring of my cable system 
as it passed through the
building, by being about 1/2m away from it. I simply played with it 
enough to have it "calibrated"
in my head, then I used it for years. I still have it. It runs on two 9V 
batteries. It usually picks up
PIC noise when the antenna is 1" away from the PIC.

The  FCC part 15 spec calls for testing done at  1, 3 , and 10 meters 
(may have changed), on a
non-metallic turntable. The max amplitude of the signal at those 
distance is used to pass or fail the
product, by calculating the RF field strength.

Where the costs get very high is when it FAILS. Then the test engineer 
will be obligated to  determine
the cause, and he will bill you at $150-250USD per hour. So it is your 
job to make sure it passes
the FIRST time.

MOST companies have high test costs only the FIRST time; thereafter, 
they buy their own spectrum
analyzers (the same thing that the FCC Testing companies use) and make 
sure it passes. NOTE: you
can RENT test facilities by the hour, and it usually includes the test 
engineer. So you can make sure
it will pass, by simply spending $300USD for 1.5hrs of joke-telling and 
5 minutes of real work.

You need to be aware that some products are completely exempt from FCC 
Part 15 and some are
exempt from UL testing as well. FCC exemptions include power company 
controls and instruments,
some medical devices, and many industrial items, from robots, and mining 
equipment and including
oil-well tools. The products I am making for power company testing are 
all exempt.

--Bob Axtell


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