[Halld-controls] Measuring radiated noise - not

[Elliott Wolin]

Hi Dave,

Fernando says he's done things like that and prefers not to, but maybe 
we could.  Still it's hard to draw quantitative conclusions from such 
measurements.





On 04/05/2012 04:54 PM, David Lawrence wrote:
>
> Hi,
>
>  This may be a silly question, but can't we just hook a cell-phone 
> antenna to an oscilloscope with a FFT feature? The antenna are 
> designed based on a fractal pattern and so have are sensitive to a 
> very wide range of frequencies, but are compact and so can be used to 
> localize the source to a smaller area. We'll have portable scopes 
> around anyway.
>
> Regards,
> -David
>
> On 4/5/12 4:47 PM, mark stevens wrote:
>> Hi Elliott,
>>
>> The spectrum analyzer with a hand-made antenna is all I have seen 
>> used here at Jlab.  I did a property search with the terms "emi" and 
>> "noise" and saw nothing.   I have previously used a portable AM 
>> radio, tuned between stations, to pick up noise - it is remarkably 
>> sensitive (it will pick up SCR noise, for example, like that coming 
>> from light dimmers or switching power supplies).  There are 
>> commercial products that are "EMI Noise Analyzers", but they are 
>> expensive.  Some companies will rent them.
>>
>> Best Regards,
>>
>> Mark Stevens
>>
>> On 4/5/2012 2:08 PM, Elliott Wolin wrote:
>>> Hi,
>>>
>>> Fernands says he currently has no good way to measure radiated noise
>>> other than jury-rigging something together using a piece of wire and
>>> some sort of spectrum analyzer.  Does anyone know of real system at 
>>> JLab
>>> that can measure radiated noise?
>>>
>>>
>>
>>
>>
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>
>
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-- 

				Sincerely,
					Elliott


================================================================================


  Those raised in a morally relative or neutral environment will hold
		    no truths to be self-evident.
				

Elliott Wolin
Staff Physicist, Jefferson Lab
12000 Jefferson Ave
Suite 8 MS 12A1
Newport News, VA 23606
757-269-7365

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