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Message |
Guest
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 Posted:
Thu May 26, 2005 8:35 am Post subject:
15. Wired / Wireless alarm systems? |
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Why are wired alarm systems more reliable than wireless alarm system?
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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Softy
Guest
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| Posted:
Fri May 27, 2005 12:36 am Post subject:
Re: 15. Wired / Wireless alarm systems? |
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Hmmm,
Almost correct. You have negated to mention 2-way wireless systems where
both the panel and the detection devices are both transmitters & receivers.
RFI jamming is correctly detected and the better systems only report jamming
when it knows that a detector signal has been jammed. How does it know?
Simple, the panel expects a message from the detectors every nth period
defined in the wireless protocol used. If jamming is reported and the panel
is armed, the panel can behave accordingly. What about a random detector
activation?. Easy, because the system is 2-way all activations by the
detectors require an acknowledgement from the panel. If the detector does
not get an acknowledgement it sends the signal again...and again either
until an acknowledgement is received or until the jamming period is reached.
Once this period has been reached the detector can shut down safe in the
knowledge that the panel will now report jamming. In short, if any detector
activation signal is lost the panel can report jamming.
You are correct though when you mention that wired is more reliable than
wireless. Always will be the case. No argument. However 2-way wireless
systems do provide a reasonable bridge between wired (longer to install,
cheaper & very reliable) and uni-directional wireless (easier to install,
more expensive & not as reliable).
Have fun
<-pull@shoot> wrote in message
news:p6la91hmmjldg5mvebccqk3kspfcfgis4l@4ax.com...
| Quote: |
Why are wired alarm systems more reliable than wireless alarm system?
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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Guest
|
| Posted:
Fri May 27, 2005 8:35 am Post subject:
Re: 15. Wired / Wireless alarm systems? |
|
|
On Thu, 26 May 2005 20:19:03 GMT, "Softy" <jimveal001@yahoo.com>
wrote:
| Quote: | Almost correct. You have negated to mention 2-way wireless systems where
both the panel and the detection devices are both transmitters & receivers.
RFI jamming is correctly detected and the better systems only report jamming
when it knows that a detector signal has been jammed.
|
True what you say BUT bidirectional handshake wireless alarm systems
for non specific professioan applications is NOT EXISTING (nor
allowed).
|
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Softy
Guest
|
| Posted:
Fri May 27, 2005 8:35 am Post subject:
Re: 15. Wired / Wireless alarm systems? |
|
|
Domestic bi-directional is existing and is allowed in the UK. I saw several
systems at IFSEC this year.
<-pull@shoot> wrote in message
news:lk5d915tn2d1flcufjnqd11gn3nedl9ioh@4ax.com...
| Quote: | On Thu, 26 May 2005 20:19:03 GMT, "Softy" <jimveal001@yahoo.com
wrote:
Almost correct. You have negated to mention 2-way wireless systems where
both the panel and the detection devices are both transmitters &
receivers.
RFI jamming is correctly detected and the better systems only report
jamming
when it knows that a detector signal has been jammed.
True what you say BUT bidirectional handshake wireless alarm systems
for non specific professioan applications is NOT EXISTING (nor
allowed). |
|
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| Back to top |
|
|
Guest
|
| Posted:
Sat May 28, 2005 12:36 am Post subject:
Re: 15. Wired / Wireless alarm systems? |
|
|
Easy give brand and type so that i can believe you.
Tel also at what frequency this equipment is operating on.
I'm wondering...
On Fri, 27 May 2005 05:55:56 GMT, "Softy" <jimveal001@yahoo.com>
wrote:
| Quote: | Domestic bi-directional is existing and is allowed in the UK. I saw several
systems at IFSEC this year.
-pull@shoot> wrote in message
news:lk5d915tn2d1flcufjnqd11gn3nedl9ioh@4ax.com...
On Thu, 26 May 2005 20:19:03 GMT, "Softy" <jimveal001@yahoo.com
wrote:
Almost correct. You have negated to mention 2-way wireless systems where
both the panel and the detection devices are both transmitters &
receivers.
RFI jamming is correctly detected and the better systems only report
jamming
when it knows that a detector signal has been jammed.
True what you say BUT bidirectional handshake wireless alarm systems
for non specific professioan applications is NOT EXISTING (nor
allowed).
|
|
|
| Back to top |
|
|
Softy
Guest
|
| Posted:
Sat May 28, 2005 3:36 pm Post subject:
Re: 15. Wired / Wireless alarm systems? |
|
|
What?. I saw them at IFSEC. I was there. I was shown them. They exist.
Period. I'm not about to sit here trying to 'convince' you that they exist.
They do. live with it.
The transceiver based systems I saw were on 868 although I seem to remember
at least one that came in 424 or 868Mhz flavors.
Paul, I have no desire to get into an argument with you. If you do not
believe me then that's that. I know this year will see quite a few
transceiver based alarm panels coming onto the market as I saw then
showcased at IFSEC. Whether they are available today I don't know. I just
know that they exist. I will be proven correct. As to what brands...I can't
remember. I'll enquire and post back.
<-pull@shoot> wrote in message
news:un8f91d737t67vps4pq2di1fsf5ooh0ltt@4ax.com...
| Quote: |
Easy give brand and type so that i can believe you.
Tel also at what frequency this equipment is operating on.
I'm wondering...
On Fri, 27 May 2005 05:55:56 GMT, "Softy" <jimveal001@yahoo.com
wrote:
Domestic bi-directional is existing and is allowed in the UK. I saw
several
systems at IFSEC this year.
-pull@shoot> wrote in message
news:lk5d915tn2d1flcufjnqd11gn3nedl9ioh@4ax.com...
On Thu, 26 May 2005 20:19:03 GMT, "Softy" <jimveal001@yahoo.com
wrote:
Almost correct. You have negated to mention 2-way wireless systems where
both the panel and the detection devices are both transmitters &
receivers.
RFI jamming is correctly detected and the better systems only report
jamming
when it knows that a detector signal has been jammed.
True what you say BUT bidirectional handshake wireless alarm systems
for non specific professioan applications is NOT EXISTING (nor
allowed).
|
|
|
| Back to top |
|
|
Guest
|
| Posted:
Sun May 29, 2005 12:36 am Post subject:
Re: 15. Wired / Wireless alarm systems? |
|
|
Thanks Softy for the FUTURE flavor you explained.
No other comment.
On Sat, 28 May 2005 10:36:01 GMT, "Softy" <jimveal001@yahoo.com>
wrote:
| Quote: | What?. I saw them at IFSEC. I was there. I was shown them. They exist.
Period. I'm not about to sit here trying to 'convince' you that they exist.
They do. live with it.
The transceiver based systems I saw were on 868 although I seem to remember
at least one that came in 424 or 868Mhz flavors.
Paul, I have no desire to get into an argument with you. If you do not
believe me then that's that. I know this year will see quite a few
transceiver based alarm panels coming onto the market as I saw then
showcased at IFSEC. Whether they are available today I don't know. I just
know that they exist. I will be proven correct. As to what brands...I can't
remember. I'll enquire and post back.
-pull@shoot> wrote in message
news:un8f91d737t67vps4pq2di1fsf5ooh0ltt@4ax.com...
Easy give brand and type so that i can believe you.
Tel also at what frequency this equipment is operating on.
I'm wondering...
On Fri, 27 May 2005 05:55:56 GMT, "Softy" <jimveal001@yahoo.com
wrote:
Domestic bi-directional is existing and is allowed in the UK. I saw
several
systems at IFSEC this year.
-pull@shoot> wrote in message
news:lk5d915tn2d1flcufjnqd11gn3nedl9ioh@4ax.com...
On Thu, 26 May 2005 20:19:03 GMT, "Softy" <jimveal001@yahoo.com
wrote:
Almost correct. You have negated to mention 2-way wireless systems where
both the panel and the detection devices are both transmitters &
receivers.
RFI jamming is correctly detected and the better systems only report
jamming
when it knows that a detector signal has been jammed.
True what you say BUT bidirectional handshake wireless alarm systems
for non specific professioan applications is NOT EXISTING (nor
allowed).
|
|
|
| Back to top |
|
|
Guest
|
| Posted:
Sat Jul 02, 2005 2:28 pm Post subject:
Re: 15. Wired / Wireless alarm systems? |
|
|
On Thu, 26 May 2005 06:48:46 +0200, -pull@shoot wrote:
| Quote: |
Why are wired alarm systems more reliable than wireless alarm system?
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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