RFI
[Top] [All Lists]

Re: [RFI] Wiring practices to minimize emissions

To: nm8rmedic <nm8rmedic@rocketmail.com>, "rfi@contesting.com" <rfi@contesting.com>
Subject: Re: [RFI] Wiring practices to minimize emissions
From: "James Gordon Beattie, Jr." <w2ttt@att.net>
Date: Tue, 12 Jul 2016 11:00:57 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Scott,

A couple of key points to consider for the benefit of both the public and the 
city:


1. Noise from large industrial or commercial equipment can be as tough to 
predict and mitigate as consumer devices. 


2. Noise from Part 15 anf 18 compliant devices can raise the overall noise 
floor and impact spectrum through 900 MHz and beyond.  


3. Public safety, cellular, landmobile radio and Amateur Radio can all have 
their effective coverage reduced, which endangers, or least inconveniences the 
public and officials while also driving up costs related to overcoming or 
mitigating the noise.


4. AM, FM and TV broadcast reception is also impacted, which is a further 
inconvenience and safety issue.


5.  All of these can be subtle, but it is when systems are challenged to 
perform at their limits, they don't need additional issues with noise.

Your point about integration testing should be in your acceptance plan. 
 Getting solid before and after data is going to be key.  The additional 
challenge is that there is so much in the way of noise sources in the existing 
RF ecosystem, that you may have trouble getting a solid, but relatively quiet 
baseline.


One idea is to measure similar sites when they are online and offline as the 
basis of comparison.  Getting to a station during an offline or maintenance 
period may be tough, but you may be able to measure the system as it cycles on 
and off under load as a baseline.


The use of an R&S PR-100 will reveal things not normally seen with standard 
spectrum analyzers.  For low frequency stuff, Radar Engineers has some 
interesting tools that you might want to investigate. 


Finally, the Part 15 and 18 regulations and standards are set up to eliminate 
the most egregious devices from going directly from the production line to the 
field and their standards are generally weak and device-oriented instead of 
being system-oriented.  Even with those standards, but even with them there are 
plenty of.non-compliant, or marginally compliant devices generating RF noisE 
and causing issues.  


There is nothing preventing you as the customer from specifying a higher 
performance objective than what is defined in the FCC regulations and the 
standards they reference.  Put the higher quality requirements in your RFP/RFQ. 
 I'm not sure where I would start, but perhaps somewhere in the 20-30 dB better 
than what the regulations and standards require would be a good starting point, 
as you want to protect the public from these aspects of RF emissions.


Systems need to be checked as a whole and re-checked as part of annual 
maintenance.  You might consider putting that in your RFP/RFQ as well.


Vy 73,

Gordon Beattie, W2TTT

201.314.6964

Sent from AT&T Mail on Android

From:"nm8rmedic via RFI" <rfi@contesting.com>
Date:Tue, Jul 12, 2016 at 11:56
Subject:[RFI] Wiring practices to minimize emissions

There are a couple participants on this board who have direct experience with 
industrial wiring practices that minimize radiated EMI emissions. 

I am a city manager and have the opportunity to discuss with a major 
manufacturer the wiring design of a large sewage lift station they are building 
for us, to minimize EMI emissions.   

They tell me that while the individual components meet Part 15 and Part 18, 
they have never tested the package as a whole. 

I would appreciate some input from the group on talking points.  This could 
also be the chance to influence wiring design for many of this manufacturer's 
lift station packages.

Scott
NM8R






and want to maximize the opportunity when I speak with the engineers.

What 
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi

_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi

<Prev in Thread] Current Thread [Next in Thread>