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
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