Regardless the brand, wireless alarm systems ARE unreliable whatever the "so called low level electrician" pro's attempt to let you believe.
Its brand independent because radio waves behave alike in all country's and the Radio Frequency (RF) receivers undergo the same nuisances.
If you like to purchase an alarm system "GO WIRED".
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.
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, the line receiver module. 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 micro volt input sensitivity (wired 400 millivolt (mV) / wireless 4 micro volt (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.
- Wireless alarm systems are unreliable when there is a Transmitters in the vicinity operating:
- ON the wireless frequency
- Saturating the receiver
- provoking intermodulation
- having harmonics
- Falling aside in the receiver bandpass
- On the IF frequency
- and more... In essence the problems caused can be defined as a "Radio Frequency Interference (RFI)" and is the fact that by no way two (or more) systems can use simultaneously the same receiver input. THIS RFI muzzle and jeopardize completely the normal operation you expect from an alarm system.
For example; cell phones with theyre 2 watt power don't satisfy that frequency dependent requirement and as such don't disturb normally.
If the above don't convince you to "GO WIRED", well... Will seller talk without reliability measurement tools and required electronic and radio technical knowledge and manufacturer support about theyre wireless performance and reliability warranty clause convince you, well be Happy, your ON.