Thursday, September 17, 2009

The trouble with wireless system

Marketing literature regarding wireless systems (of all types) generally paint a picture of effortless installation with uncompromised operation. Unbelievably these wireless products don’t always live up to the promises made in the bumf. I will never forget when a colleague of mine installed a satellite navigation system with a Bluetooth wireless connection between their PDA and the GPS device. Both the PDA and GPS devices had batteries that lasted about an hour, so for most journeys they both needed to be plugged into the car's cigarette lighter socket. As there was only one socket my colleague required another device to allow the connection of multiple plugs. The Bluetooth connection between the devices would work fine, until you got to a tricky roundabout in Paris and then it would stop working inexplicably. This meant another cable was required to connect the PDA to the GPS. In addition, to fix the PDA in position a large piece of plastic with a sucker on one end was required. With wires dangling everywhere the whole thing felt like Darth Vader’s bathtub. Definitely not as advertised.

Sometimes wireless systems just don’t work properly. Any of you with experience of the cheap and cheerful intruder alarm systems that have been available from DIY stores for years will know what I mean. It may or may not be the case now but these systems have a well earnt reputation for being unreliable. The problem seems to be not only the wireless technology used but also the way it has been incorporated and used in the system design. Whatever the reason it’s no good.

Whichever way you look at it a wireless connection is not as reliable as a wired connection. Wireless links are affected by their environment and this can change in ways that can be anticipated and ways that can’t. Large metal things like cars being parked in the wrong places can cause problems for example. In addition, every building has a unique environment and this makes specifying what equipment to put where very difficult. 

Having spent the last few paragraphs chiding wireless systems I would like to announce that Paxton Access are soon to release a wireless Net2 control unit. 

It’s called the Net2 nano control unit and it has been designed with all of the above problems in mind. The 'wireless bit' is the data connection from the PC to the control unit. Here are my answers to some of the issues raised in the earlier paragraphs:

If I still have to wire in the power supply, reader and exit button then what’s the point?
Wiring a dedicated RS485 network is often the most time consuming and problematic part of a Net2 installation. Not having to cable round the building is a big plus for a lot of projects. We sell a lot of Switch2 stand alone systems precisely because you don’t have to wire all the control units together. We can now offer PC based features with the ease of installation that comes with stand alone systems (does that sound too much like the marketing material I was berating in the first paragraph?)

How can I specify what equipment to use if every building has a unique environment?
We have an installer tool called a Net2Air site surveyor. This consists of two parts, a USB plug-in transmitter, and a battery powered keycard with signal strength LED’s. When doing a site survey, plug the transmitter in where the Net2 server PC would be located. Walk around to each door checking the signal strength on the keycard. If you get green LED’s lighting up then that’s fine. If you can only see red LED’s then the signal strength is not good enough.

What happens if somebody parks a bus in front of the control unit and breaks the wireless connection?
It doesn’t matter. The wireless connection is only used for transferring data such as access events and new access privileges. All decisions regarding access are made locally at the control unit. This distributed intelligence means that if the wireless connection is broken the system continues to allow access to authorised users in the usual way. When the connection is restored the events are uploaded to the PC.

What if I install the system and it just doesn’t work?
If you install a control unit and it is out of range we have a TCP/IP wireless repeater. This device plugs into the computer network at any point and will extend the wireless network in all directions around that point. This device has the option of using Power Over Ethernet for convenience.

Will the wireless signal damage my children and make them go orange?
No. The type of wireless communication used by Paxton Access is a low power technology designed to work using batteries. The specifications have been determined by the IEEE commission (the people responsible for WiFi) and its signal strength is approximately 5 times weaker than that of the wireless PC networks that most people currently have at work and in their homes. Signal strength should not be confused with the range as in many cases the range of our low power technology is equal to that of WiFi.

What if the Net2 nano wireless control unit just isn’t suitable for use on a particular door?
No problem, use one of the other Net2 control units (Net2 classic, RS485 or Net2 plus, TCP/IP). All Net2 control units are designed to be mixed and matched as required.

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