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RFI

B

Bob La Londe

Jan 1, 1970
0
I had a custoemr call on Friday. Their system started showing some RF
devices dropping out of the system within seconds of their firing up a new
wireless 802.11 network. I guess RFI detection works just fine with Napco.
They shut down one of the computers on the network and the problem cleared
right up. A quick test of several of the devices showed them working
properly. Sounds like a noisy card on that one computer was generating RFI.

Anway, atleast this one Napco system worked properly. The RFI problem
showed up instantly, and reported properly as RF trouble, not fasle alarms.
I also got accurate signal reporting that helped to pinpoint the problem at
the central station.

Sure its anecdotal, not statistical, but I am satisfied with this wireless
system.
 
M

Mark Leuck

Jan 1, 1970
0
That almost sounds like something else, Napco RF operates at around 344mH
but 802.11 runs at 2.4 ghz

Good thing the customer didn't have crappy headphones :)
 
A

anomynous

Jan 1, 1970
0
I had a custoemr call on Friday. Their system started showing some RF
devices dropping out of the system within seconds of their firing up a new
wireless 802.11 network. I guess RFI detection works just fine with Napco.
They shut down one of the computers on the network and the problem cleared
right up. A quick test of several of the devices showed them working
properly. Sounds like a noisy card on that one computer was generating RFI.

Anway, atleast this one Napco system worked properly. The RFI problem
showed up instantly, and reported properly as RF trouble, not fasle alarms.
I also got accurate signal reporting that helped to pinpoint the problem at
the central station.

Sure its anecdotal, not statistical, but I am satisfied with this wireless
system.

Now try it with the system armed, will it still report as a trouble or will
it be a false alarm now?
 
B

Bob La Londe

Jan 1, 1970
0
Mark Leuck said:
That almost sounds like something else, Napco RF operates at around 344mH
but 802.11 runs at 2.4 ghz

I figured the same thing, except when one PC on the network was turned off
the problem went away. I figure it was putting off some noise. For all I
know it could be a grey market PC and it might be putting off all kinds of
RF noise.
--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com
 
J

Jim Rojas

Jan 1, 1970
0
It's probably the PC power supply, or the monitor that is putting out all
the RFI.

Jim Rojas
 
A

Al Colombo

Jan 1, 1970
0
I think you may have hit the nail on the head when you pointed out the
possibility that the PC might be causing RFI over a wide area of the
spectrum. Although I'm not sure what connection this would have with
the 802.11 wireless network, it is still a possibility. However, the
fact that the problem did not show up until the 802.11 went into
operation would make you wonder whether the wireless system might not
be transmitting harmonics. If the computer is a home-brew rig, we know
it probably did not go through a valid RF testing lab. I put a Napco
system through a UL third-party testing lab in Glenview, Il. for one
of my Work Bench Review stories, when I was with SDM in Chicagoland,
and it passed with flying colors. It passed both for emissions and
susceptibility. Of course, that was a hard-wired fire alarm system and
not a RF-based burglar alarm.

What did you do to solve the problem, or is it on going?

Al


--
Allan B. Colombo, technical writer
P.O. Box 30076
East Canton, Ohio 44730
USA
Come and visit with me at
www.securitymission.com
www.tpromo.com
 
A

Aegis

Jan 1, 1970
0
Hey Al... Just did 2+2 and realized you are THE Al Colombo... Cool!

I'm taking my copy of SS&I to the shop tomorrow to show them your fire side
chat article... Specifically the "Prime Contractors Advise Clients" part.
Way too often, we've been backing down from the customer/GC and just
"installing what they asked for" even when we KNOW it's not fully
compliant... I mean the gray-area stuff; we won't do just anything under
that umbrella. This shines a light on that gray area. Thank you for the
great article.

I was also reading tech talk with Bob Dolph... He came SOOO close to
actually addressing the RFI/EMI issue (the one our Belgium yahoo is always
screaming about). That little Zap Checker device has me curious.
 
A

Al Colombo

Jan 1, 1970
0
Thanks for the kind words concerning my recent column in SSI. I have
always looked at it in this manner, even before NFPA addressed this
issue: "Who's the guy with the fire license? That's the guy that's
going to take the hit if it's wrong."

About the gray area, there really isn't a whole lot of gray stuff left
in the area of fire alarm installations as NFPA has set the standard
on just about every aspect of installation possible. No matter what
we look at, there's a code to fit the issue.

The problem that I am seeing in the field is that many installers
don't even own a copy of NFPA 72, which is what almost all
municipalities have based their fire codes on for decades. All of that
is about to change as ICC gains acceptance at state level.

A few days ago I stopped at a new home in the finishing stages to
check out the rough-in so I could bid the thing for the homeowner.
Guess what kind of wire the alarm dealer that roughed it used for the
smoke detectors? If you said power-limited fire wire you would be
wrong. They ran the cheapest telephone station wire that I've ever
seen! Amazing. Oddly enough, every system he installs is like this,
so how does he pass rough inspection? (Perhaps he knows someone?)

About Bob Dolph's column this month, very good. I covered that RF
sniffer some time ago. He does a great job writing his stories and I
think this one was a good one. He's an extremely knowledgeable
technician. I follow his column every month.

I recall a story I wrote many years ago for AID or Security Sales (one
and the same). This was when I wrote for them as a freelancer under
the name of Carl Sloan. It dealt with eliminating false alarms due to
RFI. My focus was on real life application, as it was the field I
came from when I began writing full time for SDM in 1990 (since 1974,
30 years total). Perhaps we'll have to dig that story out of mothballs
and make it available on www.securitymission.com. It provided
real-world solutions to RFI issues involiving hardwired systems. I'll
let you know when it's up if you're interested.

In any event, thanks for the great response. It's always nice to hear
from one's readers and fellow alarm dealers. If you or anyone else has
an idea or two for future feature stories or my Fire Side Chat column,
please let me know. I can always use the help.

Thanks,

Al Colombo
 
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