Tim,

 

See FCC Part 15, Section 15.33 (4). 

In case equipment contains both intentional radiator and digital device, the
radiated test frequency range is determined based on (Nth harmonics of
operating frequency-intentional radiator portion) and (5th harmonics of
digital device portion), whichever is the higher.  

 

Thanks, 

 

Ben

 

Section 15.33 Frequency range of radiated measurements.

(a) Unless otherwise noted in the specific rule section under which the
equipment operates for an

intentional radiator the spectrum shall be investigated from the lowest radio
frequency signal generated in the device, without going below 9 kHz, up to at
least the frequency shown in this paragraph: 

(1) If the intentional radiator operates below 10 GHz: to the tenth harmonic
of the

highest fundamental frequency or to 40 GHz, whichever is lower.

(2) If the intentional radiator operates at or above 10 GHz and below 30 GHz:
to the

fifth harmonic of the highest fundamental frequency or to 100 GHz, whichever
is lower.

(3) If the intentional radiator operates at or above 30 GHz: to the fifth
harmonic of the

highest fundamental frequency or to 200 GHz, whichever is lower, unless
specified otherwise elsewhere in the rules.

(4) If the intentional radiator contains a digital device, regardless of
whether this digital

device controls the functions of the intentional radiator or the digital
device is used for additional control or function purposes other than to
enable the operation of the intentional radiator, the frequency range shall be
investigated up to the range specified in paragraphs (a)(1)-(a)(3) of this
section or the range applicable to the digital device, as shown in paragraph
(b)(1) of this Section, whichever is the higher frequency range of
investigation.

 

 

 

From: emcp...@aol.com [mailto:emcp...@aol.com] 
Sent: Wednesday, July 14, 2010 11:01 AM
To: emc-p...@ieee.org
Subject: Re: Radiated EMI for ITE with Wireless

 

So far I have a 50-50 response on this. Thanks to those that replied. Does
anyone have some text from the standards to back up the answers?

 

1.  I understand that FCC rules say to consider the highest frequency used in
the product for testing above 1GHz. This would mean that we need to test above
1GHz, considering the 2.4GHz bluetooth.

 

2.  One could justify not testing above 1GHz considering the fact that the
bluetooth has already gone through testing and certification on its own. In
this case we would only be concerned about the digital device portion which
has a maximum frequency of 16MHz.

 

Thanks,

Tim

 

 

 

 

In a message dated 7/13/2010 7:15:34 P.M. Pacific Daylight Time,
emcp...@aol.com writes:

        Hello,

         

        I have a class B digital device that incorporates a wireless module.  
Other
than the 2.4 GHz bluetooth, the rest of the device has a maximum oscillator of
16 MHz. The bluetooth part is already approved with a modular approval so I'm
not concerned about the intentional radiator part.

         

        I'm only doing the regular unintentional radiator portion for FCC and CE
(CISPR 22). The question is how high in frequency should this device be
tested? Does the bluetooth count toward the highest clock even though it is
already approved? All other clocks/oscillators are well below the 108 MHz
cutoff for testing above 1 GHz.

         

        Thanks

        Tim Pierce

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