---------- Forwarded message ----------
From: Art McBride <kc6uqh@cox.net>
Date: Sat, May 9, 2009 at 11:23 PM
Subject: RE: [RFI] Alarm Systems and EMI/EMC
To: Dennis Vernacchia <n6ki73@gmail.com>, John Kuivinen <wb6iqs@att.net>,
Kerry Banke <kbanke@sbcglobal.net>
Sensors typically operate on 315, 319.5, 345, 418 and 433.92 MHz. Each hour
they send a supervisory transmission to say they are in service. Only the
433.92 frequency falls in the Amateur Radio band.
Expected points of entry for HF operation are at the panel, the Phone Line
and the Power line. No surprises here and no wires to sensors hence less
pickup of EMI. Should be much better than the wired type, and the phone and
power line are in one place and easy to filter using standard components.
Digital encoding with CRC check of serial data all but eliminate a false
signal. (1/16 e6 chance)
The Wired alarms of the 70’s were much worse. I installed a 1 KW commercial
shore station for NMF in the B Street pier building (long before cruse
ships). EMI form that station rolled 15 fire trucks before the alarm co
spent 3 days filtering all of the lines to their panel.
Next was the 0.01 uF. ceramic disk capacitors across all of the carbon (T1)
mike elements in the telephones.
NMF became a swear word for the first month or so until all of the
interference was quieted down.
Art, KC6UQH
------------------------------
*From:* Dennis Vernacchia [mailto:n6ki73@gmail.com]
*Sent:* Saturday, May 09, 2009 12:36 PM
*To:* John Kuivinen; kc6uqh; Kerry Banke
*Subject:* Fwd: [RFI] Alarm Systems and EMI/EMC
Can any of youse guys answer Mikes Query ?
---------- Forwarded message ----------
From: *Michael Tope* <W4EF@dellroy.com>
Date: Sat, May 9, 2009 at 12:28 PM
Subject: [RFI] Alarm Systems and EMI/EMC
To: RFI@contesting.com
Does anyone on the list have any experience with remote monitored home
security systems and EMI/EMC? Looks like some of the new systems use
wireless sensors. I am wondering what frequency these sensors operate at?
A friend who does a lot of topband oeprating mentioned that ADT sensors
use 319.5 MHz? Is this pretty much the standard?
This system will be for a remote site, so ideally I would like to be
able to
transmit without false alarms and recieve without RFI on HF while the system
is armed.
Anyone know any home security equipment dealers who are hams or who
know anything about EMI/EMC?
Thanks,
Mike W4EF........
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