There was some discussion in a post about range of Part15 FM concerning whether or not the 150 uV/M was a typo.
There was some discussion in a post about range of Part15 FM concerning whether or not the 150 uV/M was a typo.
For those who are interested, FCC Rules in the 88-108 range including some other areas, differentiate between INTENTIONAL and UNITENTIONAL radiators.
That being said, Digital or Computing devices are UNINTENTIONAL radiators and are subject to the 150 uV/M limit. INTENTIONAL devices like radio transmitters are allowed 250uV/M at 3 meters distance, BUT have a bandwidth limitation.
Since digital devices generally sprog all over the place they are naturally confined to a tighter emission spec.
Hope this helps.
John,
Thanks for clairifying this.
My FM tx. is used exclusively for my movie audio where I am within a few feet of the transmitter. I have purposely limited the range because of this. I have noticed when I go upstairs and my tx. signal weakens the walkman picks up some really bad hash interference. Last night I traced it to my wife's LCD computer monitor. If the monitor is compliant, then this shows that it doesn't take much to cause a problem with reception even at 20 feet from my transmitter.
Neil
I think I was the one who brought up that question, WDCX. Great answer and thanks for the clarification. I'd been finding it a bit confusing.
Daniel