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CCTV, Alarms and other Physical Security - CCTV, fire alarms, secure access technologies
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Posted by on June 23, 2005, 5:45 pm
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Why are wireless alarm systems sensitive to Radio Frequency
Interferences (RFI)?
House alarm wireless systems with theyre 10 milliWatt sensor
transmitter power are ONLY allowed to operate on 434 MHz and/or 868
MHz.
Those frequencies are provided for free general use, they are
uncontrolled, unprotected against disturbances.
Those frequencies are very crowded with all kind of non alarm purpose
equipment.
More, the very low power (<10 milliWatt) of the transmitters
contained in the sensors make the receiver very sensible to external
unwanted signals called RFI..
Even in a normal undisturbed frequency condition the reviver signals
from the sensors are week and require attention subject location.
Its why "some" wireless alarm systems are equipped with a signal
monitoring circuit to help correct installation.
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Posted by Roger on June 24, 2005, 3:54 pm
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> transmitter power are ONLY allowed to operate on 434 MHz and/or 868
> MHz.
> Those frequencies are provided for free general use, they are
> uncontrolled, unprotected against disturbances.
> Those frequencies are very crowded with all kind of non alarm purpose
> equipment.
Yet again you are wrong.
868MHz has strict rules and is controlled.
Read the appropriate documents and you will see that 868Mhz is treated
completely different than 434MHz.
Tut tut. Lies again Paul.
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Posted by on June 25, 2005, 6:15 am
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>> transmitter power are ONLY allowed to operate on 434 MHz and/or 868
>> MHz.
>> Those frequencies are provided for free general use, they are
>> uncontrolled, unprotected against disturbances.
>> Those frequencies are very crowded with all kind of non alarm purpose
>> equipment.
>Yet again you are wrong.
>868MHz has strict rules and is controlled.
>Read the appropriate documents and you will see that 868Mhz is treated
>completely different than 434MHz.
How can the 868MHz frequency be controlled, rulled yes but controlled?
In what is it different from the 434MHz?
In what official document dit you read that?
My reference is www.ero.dk official info and yours?
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Posted by Roger on June 25, 2005, 9:21 am
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> How can the 868MHz frequency be controlled, rulled yes but controlled?
To sell an 868MHz product in the EU it has to conform to current standards.
Those standards are controlled. The company I work for activley looks at
868MHz products and tests them to see if they fall foul of the usage rules.
If they do they are reported and the equipment is usually removed from the
market place. In this way it is controlled. Rulled AND controlled.
> In what is it different from the 434MHz?
Do the work yourself. Get a copy of REC70-30. You will see that there are no
band occupancy rules. There are for 868MHz and this is one of the reasons
why 868MHz is a much better band for security equipment than 434MHz.
> In what official document dit you read that?
> My reference is www.ero.dk official info and yours?
The ONLY official documents - REC70-03 (Europe) and IR2030 (UK).
If you actually bother to study the documents you will see that bands set
aside for security equipment cannot be used for other non compatible
equipment. For example audio. And there are strict band occupancy rules that
are tested for at approval stages of product design.
On the subject of wireless jamming detection, why don't you get a copy of
EN50131 and check out the class 1-4 jamming detection requirements. Again,
for security equipment to pass EN50131 at any class it has to provide
defined jamming detection and reporting. All an installer has to do is buy
an approved wireless system to get a reliable wireless system. You get what
you pay for. If you buy a product that doesn't meet any standards then you
get what you deserve.
Paul, why do you bother to 'pretend' that you know what you are talking
about?. Be subjective not stupid.
So, just to repeat myself once again, you are wrong as usual Paul.
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Posted by Crash Gordon® on June 25, 2005, 10:38 am
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it's like arguing with a 5 year old.
what's "rulled" mean anyway?
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| > How can the 868MHz frequency be controlled, rulled yes but controlled?
|
| To sell an 868MHz product in the EU it has to conform to current standards.
| Those standards are controlled. The company I work for activley looks at
| 868MHz products and tests them to see if they fall foul of the usage rules.
| If they do they are reported and the equipment is usually removed from the
| market place. In this way it is controlled. Rulled AND controlled.
|
| > In what is it different from the 434MHz?
| Do the work yourself. Get a copy of REC70-30. You will see that there are no
| band occupancy rules. There are for 868MHz and this is one of the reasons
| why 868MHz is a much better band for security equipment than 434MHz.
|
| > In what official document dit you read that?
| > My reference is www.ero.dk official info and yours?
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| The ONLY official documents - REC70-03 (Europe) and IR2030 (UK).
|
| If you actually bother to study the documents you will see that bands set
| aside for security equipment cannot be used for other non compatible
| equipment. For example audio. And there are strict band occupancy rules that
| are tested for at approval stages of product design.
|
| On the subject of wireless jamming detection, why don't you get a copy of
| EN50131 and check out the class 1-4 jamming detection requirements. Again,
| for security equipment to pass EN50131 at any class it has to provide
| defined jamming detection and reporting. All an installer has to do is buy
| an approved wireless system to get a reliable wireless system. You get what
| you pay for. If you buy a product that doesn't meet any standards then you
| get what you deserve.
|
| Paul, why do you bother to 'pretend' that you know what you are talking
| about?. Be subjective not stupid.
|
| So, just to repeat myself once again, you are wrong as usual Paul.
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