The history of Part 15 Rules
‘It is generally easier to explain unlicensed devices in terms of what they are not, rather than in terms of what they are’’ (Carter et al. , 2003)
Now I understand everything.......
Neil
"What we are concerned with immediately is the problem of interference. If certain low power devices can be used without interfering with radio communications, there would appear to be no engineering reason for suppressing their use."
One of the important things wich cause interference is the fieldstrenght. So Carl, again the question: The chicken or the egg??? I think the fieldstrength was the first limitation and because of the complexity of the fieldstrenght measurement there's a power and antenna limitation.
And having say that, is this a topic for a ALPB discussion??
Rob Veld
Dear Members of the ALPB:
Mr. Rob Veld from the Netherlands has suggested we are chicken when it comes to discussing the relationship between field strength and interference, but he also suggests we serve eggs at the same time.
I was able to translate his message directly from the Dutch lanquage.
Not quite Carl, it was the relationship between fieldstrenghth and the egg and secondly between power and chicken. So the ALPB members sitting on their eggs to hatch. I know Dutch is a difficult language.
Now seriously. When I was a FCC agent and I was visiting KDX and I measured the fieldstrength and it was below the limit even if your SSTRAN is 250 mW then I wish you good day, lots of success and ofcourse thanks for the coffee.
Now in Dutch, especially for Carl, others could try to translate this in google translate:
Niet helemaal Carl, het was de relatie tussen veldsterkte en het ei en ten tweede tussen vemogen en kip. Dus de ALPB leden zitten op hun eieren te broeden. Ik weet dat Nederlands een moeilijke taal is.
Nu serieus. Als ik een FCC-agent was en ik op bezoek bij KDX was en ik de veldsterkte heb gemeten en het was onder de limiet zelfs als de SSTRAN 250 mW maakt, dan wens ik je een goede dag, veel succes en natuurlijk bedankt voor de koffie.
Rob Veld
How do the 100,000 watt FM stations(and 50,000 watt) AM stations broadcasting from a tower hundreds of feet high(the CN tower here in Toronto) not cause interference?
If more field strength causes more interference with our little transmitters...how do they do it?
Just thought I'd mention this since field strength and interference came up in this thread.
Mark
Hold on, I am not going to rob Mark.
What I mean is, Rob Veld spoke to me (and the forum) in flawless Dutch.
Since I only have limited skill, my response is short:
Figglestrup emsa klabunde. That's about it.
Now I respond to Mark... Yes, 100 kW and 50 kW FM & AM stations are licensed to cause blow-torch interference. Have you ever heard their programming?
The only time Part 15 stations cause interference is if someone with a grudge actually hears it and gets righteous by filing a complaint.
You have permission to interfere with me but I am not allowed to interfere with you. Someone in Washington came up with it.
Commercial and Public broadcasters are primary users of the airwaves, and if not then it's written in the license. Now Part 15 stations got no license and that means you can use the airwaves on secundary basis.
Wich ment: A secundairy user is wrong when he/she interfer with a primary user.
When a secundairy user interfer with a secundairy user well ....... thats not the problem of the FCC. When a primary user interfer with a primary user ........ that's a serious problem! But .............. not our (part 15) problem.
Rob Veld
If not properly wired a radio station can interfere with itself. We must accept it while not being allowed to do it.
I agree if interference is caused by a Part 15 device there is a legitiment reason for action be that what it may. That's what the rules are for to mitigate interference.
What I don't agree with is unwarranted action for simply being heard whether you are in compliance or not. If there is no interference where's the beef?
Even if a signal can be heard at great distances due to power without interference what's the difference if the signal originates next door or miles away?
But until that time we have to work within the limits and hope the rules are.not subject to official arbitrary interpretations.
Don't worry, Be happy! Join The ALPB.
Love that answer Carl!......Perfectly true when you think about it.
Mark