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Wired vs. wireless?

  • Thread starter Jeffrey J. Kosowsky
  • Start date
J

Jeffrey J. Kosowsky

Jan 1, 1970
0
We are looking into getting a security and fire/smokealarm system for
our (new) 100+ year old, 3-floor Victorian.

Wireless comes out to be 3000+ cheaper since there is no need to snake
wires up through walls.

Given that I am trying to understand the pros and cons of wired
vs. wireless.

I see the following:
Wired advantages:
Reliability
No batteries to change
More "bidirectional" function


Wireless advantages:
Cheaper/easier to install
Fewer holes in the wall (though we are going to get the interior
painted so holes don't bother me that much)


What would you recommend?
 
N

Nick Markowitz

Jan 1, 1970
0
I prefer hybrid wire were you can wire and wireless the rest.. How ever i do
have a minature version of the falling water house i did that was all
concrete and is 95% wireless . Wireless works well when properly installed
and maintained to prevent problems .
I have had sevral sucessfull captures with break ins were alarms worked as
required and had a wireless fire system save 3 lives..


--
Nick Markowitz Jr.
Owner
Markowitz Electic Protection
Private Industry Fire Investigator.

Contributing Editor Pa. Firemans Magazine
Staff Editor www.securitymission.com
Senior Correspondant www.1strespondernews.com
Exclusive Correspondant www.nbfd.us
Contract Broadcast Engineer WAVL 910 AM apollo Pa.

"To error is human to realy foul things up requires a computer"
 
M

Marc

Jan 1, 1970
0
I personally do not trust wireless smoke detectors. Not sure why because
they do work fine. I've always felt that functionality and reliability of
hard wire smokes are much better.

Wireless has lots of potential problems.

I have a customer who has more problems from wireless than any customer I've
ever had. Some sort of interference occurs randomly and sets it off. So i
turned off the RF jamming crap and now these couple of zones can be defeated
much easier.

To me wireless is the lazy mans way out of a job. I would get several
estimates and talk to a couple of other local alarm companies and see what
they say.
 
R

Reg Siemens

Jan 1, 1970
0
One of the biggest arguments against wireless is that it's all proprietary.
If the manufacturer you (or your alarm installer) chooses drops the line or
changes the wireless frequency between now and when a transmitter fails you
are looking at replacing your entire system. This has happened in the last
couple of years even with major brands e.g. those who installed 900mhz DSC
wireless products are out of luck when they want to expand or repair their
systems because they've switched to 433mhz.

Unless you have an absolutely horrible house to wire, hardwired should not
be that much more money. Consider a door contact cost - hardwired $1.50 &
maybe $.50 wire...total hardwired equipment cost $2.00. Depending on the
brand, a contact and wireless transmitter will be around $50. This
difference should be close to cost of labor in all but the most difficult
houses. Add to that the cost of battery replacement over the life of the
system and the fact that you have bulkier, less attractive transmitters at
each protection point and I'd go hardwired everytime.

How many quotes have you obtained. Might it be that they priced the
hardwired system far higher cause they don't have the expertise to do it
properly?

Reg Siemens
Tower Security Systems Inc.
 
P

Paul ... .

Jan 1, 1970
0
What is the basic difference between wired and wireless alarm systems?
It boils down to the "connections link" between sensors and control
panel of both systems, besides that sensor data connection link both
systems are alike.

So the comparison is easy, the WIRED WIRES versus a WIRELESS data link
between sensors and the control panel.

WIRED:
- Each sensor has "hiss own" cabling, hiss own data transmission link.
All attempts to tamper sensor boxes, short or cut sensor wires are
detected without any ambiguity an with no delay.

- At a first glance the wired links are of the non-frequency selective
type and as such are more prone to capture a greater Radio Frequency
(RF) spectrum range of signals.
The data transmitted on sensor wired lines are of the low frequency
type and as such can easily be filtered at all inputs entering the
control panel.
This makes the system data link low frequency selective by
attenuating the eventual High Frequencies reaching the equipment by
huge power transmitters.

- The level of the transmitted signals on the wired lines are around
"2Volt" to switch from on to off (to be more precise, 400mV
interference free immunity for TTL circuits).

WIRELESS:
- All the sensor data is vehicle via ONE wireless data link composed
of a low power transmitter in the sensors and a sensitive receiver at
the input who has around 4 microvolt input sensitivity (wired 400
millivolt (mV) / wireless 4 microvolt (uV) = ratio 100 000 times less
power required to disturb wireless systems)

- The wireless data link contains all the information required to have
a reliable connection as long as there are no other transmissions
present who block the data communication.
The wireless RF receiver collect in normal circumstances the data and
decode it. This data contains an ID (rolling code), alarm, tamper
attempt, battery low and more information. When the signal is
disturbed, EVERYTHING is, ID can't be recognized...

The receiver:
The receiver is made as much as possible frequency selective and
sensitive at signals on the frequency in order to capture the week
signals emanating from the sensors (see below).
They "attenuate" more or less, depending on the quality of the
receiver, the frequencies beside that privileged frequency, its called
the bandpass attenuation range (essential quality comparison data not
provided and published by the manufacturers in order to mask how bad
the bandpass is).

The sensor transmitters:
In wireless alarm systems the transmitting power is limited by law
and by reasonable battery live time.
The RF transmitter power of the sensors is of the order of 10
milliwatt (mW), low, very low.

COMPARISON:
- The receive end is 100,000 times more sensitive to signals in
wireless versus wired (4uV / 400mV);
The ratio is even higher because the high frequencies, where
disturbing transmissions occurs, are attenuated by low pass filters at
the input of the wired lines.

- The link in wired systems are wires who can be filtered/shielded
against RF interferences (and by location of the wires); in wireless
it is the open air reachable by everybody, no shielding possible.

CONCLUSION:
- An external RF transmitter can disturb both systems but the power
required to do this is much higher in wired systems (>100,000 times).
- In wireless systems, the power required to interfere and disturb the
system is similar to the sensor power (10mW) when generated at the
same distance, RFI power should be increased if the distance is
increased.
- Wireless alarm systems are not reliable, they can be interfered and
disturbed/muzzled due too and by an outside transmission.

FINAL NOTE:
- Don't forget that in order to interfere wireless alarm systems that
the RF disturbing signal source should satisfy some frequency
requirements.
For example; cell phones with theyre 2 watt power don't satisfy that
frequency dependent requirement and as such don't disturb normally.

Paul
 
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