Recently in General Category

The best time of the year... Spring is on us. Yay!

When my friend showed me the Christmas lights people were decorating their houses with in some areas in Centurion, I was amazed since I never realised we have some of the spirit one can find in Europe...

Here are a couple of pics.

I have had my B.Eng (Electrical) degree since 1999 - that is 7 years. Only today I found a practical, worth while use for it.

It is one HELL of a good bug smashing stick....

Do you know what a CAPTCHA is? It is one of those small graphics people (like me) use whenever a turing test is to be performed - i.e. a human be told apart from a computer. Typically this is used in blogs to allow only human commenters, registering for email/online accounts etc. The idea is to display some warped text on a distracting background so that OCR programs have difficulty recognising the characters from the noise, but not humans. The primary use is to fight SPAM. But...........

For the first time in my life since I got SPAM (and I have received literally tens of thousand junk mail in my lifetime), I had a laugh at the wit of one of the spammers...

(WARNING: Adult content following - only read rest of article if you are older than 30).

Every Christmas, calculations are made to try and explain why Santa Claus cannot deliver all his presents to every child around the globe and still be within the bounds of physics. However, this year four physicists had been instructed to solve this paradox.

To quote an exert:

Every Christmas, calculations circulate that have been dubbed "The Physics of Santa Claus". The calculations cast doubt as to whether Santa Claus could possibly deliver gifts to all the world's good children - and still remain within the laws of physics. To deliver gifts to all who deserve them, they assert, Santa would need to move so fast that he would vaporise due to air resistance, be torn to pieces by gravitational forces or suffer other terrible fates we wouldn't wish for Santa Claus.

Many fall for these calculations. Yes, there has even been one instance in which a vicar was criticised for using them to explain to small children that Santa does not exist. Luckily, some would say, the vicar has apologised to the traumatised children.

Because, even though the physics of the calculations is apparently good, the reasoning rests on a completely wrong premise, namely that Santa Clause does not exist. Even small children understand that this premise is completely wrong!

How will Santa Claus ensure that all the good children receive their presents and once again save Christmas? To clear up this important question, Internet magazine forskning.no has gathered four the country's sharpest researchers: astrophysicist Knut Jorgen Roed Odegaard, professor of physics Gaute Einevoll, professor of mathematics Nils Lid Hjort and Elf expert Ane Ohrvik.

They've taken the job very seriously.

Ion-shield

If Santa Claus is to deliver all the gifts to all the good children, his sleigh must fly so fast that he would burn up due to air resistance. But it has already been documented that Santa has no problem climbing down a chimney with a fire burning below. So how does Santa solve the problem of heat?

"Santa obviously has an ion-shield of charged particles, held together by a magnetic field, surrounding his entire sleigh. This is how he solves the heat problem," points out Knut Jorgen Roed Oedegaard, who also casts a new light in the night sky:
..."

If you are a regular slashdotter, you would know about this story. Otherwise, read the full story.

As you can see, the old Gamma web site has been removed in favour of this blog. Since most of the content there were anyways just information oriented, I think it is much more meaningful (and easier) to add that kind of content using a publishing platform such as this.

Therefore I have moved all those entries on to this blog, under yesterday's date. They might not all look perfect, but at least that information is still available and searchable now too.

It has been quite a while since I last posted here. The reason is that we have just moved to a new townhouse, and Telkom does not yet have any lines available in the complex so I am without ADSL :(

The burglar alarm installation went well bar the misconception regarding the time it took to have installed it. After a week of struggling I got it in and fully working - finally! There were 22 cables I had to pull through the roof, which was no easy job...

So you are interested in the performance of the system? I love the Optex sensors, they work brilliantly. So far I only had two false alarms - one from an unknown source in the dining room, and one from the garage where my cat was locked in.

I am however finding that the garage beams sometimes causes problems in that they go open in the afternoon. I am 99% sure this is attributed to the fact that at that time, the sun is shining directly into the sensor at a 45 degree angle. When it is cloudy or night the problem disappear and the sensor closes.

The Paradox Graphica keypad is nice. I like its look and feel. The only thing I do not like is the fact that it does not provide macro like shortcuts where I can define a certain key sequence and have the system replay them. This would be useful to store some common bypass and arm situations.

The Paradox controller is very powerful and rather trivial to install. However, I have encountered some bugs. The bell squawk does not work as they say - it does not consistently squawk once on arming and twice on disarming. Also, if a follow zone is violated without the corresponding entry zone being violated first, a 90 second entry delay is triggered - not what is explained in the manual. According to the manual (and common reasoning) the system should see the follow zone in that scenario as an instant zone.

So far I am very happy with it despite these minor inconveniences, and love the fact that I have a constant stream of event information being fed to my computer via the RS-232 adaptor. It makes troubleshooting and investigations easier. This reminds me that once Monitor Net (the armed response company I signed up with) phoned me about an alarm on my premises. They said they would send out someone immediately. Normally there is no accurate way of knowing when they arrived at your premises to assess the cause of the alarm. In this case, I had a running log on my computer. I found out they only arrived 1 hour 35 minutes after the initial alarm went off, then triggered the alarm 4 more times by jumping into my garden. This is obviously unacceptable, thus I terminated my contract with them immediately and am now signed up with ADT. At least their worst response time thus far was 6 minutes.

All in all, I would recommend the components I bought. I would not however recommend installing it yourself unless you are a masochist. Find someone who can give you good referrals, and follow up on those to ensure the work is of high standard.

One other thing I did encounter while installing the system is that a glue gun is useless to fixate the components and wiring. I ended up using the glue gun in combination with a clear silicone gun - very work intensive but it works. I recommend using those bostik glue sticks which the professional installers use should you decide to perform the installation yourself. It will cause less burns and allow you to work a bit neater than what I could muster.

A while ago I had a security company (whose name I will not mention - for now) install a burglar alarm system for my new home. As I was not technically clued up on the vast array of different options and choices one have with purchasing an alarm system, I made a grave mistake. I asked advise from the security company on what I should purchase.

My experiences thus far always pointed back to the one fact, that most security companies do not know anything more than what is written on the side print of the boxes the alarm system components get delivered in. Since I make a point of going on to the Internet before I purchase anything of value, I am usually clued up more than the sales people! In this case I did not consult the Internet since I could not really find useful information.

To come back to my opening statement, the reason I said I made a grave mistake is that they did an absolutely pathetic job. I will not go into all the details, just those most applicable. Firstly, nobody asked me in detail how my house is laid out, whether I need perimeter protection or not, explain the different kind of sensors etc. They assumed an 8-zone IDS system would suffice. I specifically asked for an outdoor sensor since I knew I wanted perimeter detection, so that was added to the list. In the end everything got installed but now I have several issues:

• The IDS 8-zone unit is not intelligent enough to perform many of the tasks I require


• It is limited - 8 zones are insufficient


• It does not support frequency (code) hopping


• Tamper resistant switches have not been installed


• The wiring and drilled holes are very crude and looks horrible


• I have the wrong sensors installed, yielding many false alarms

So now I bought a new home and obviously need a burglar alarm system to be installed. This time however I decided I'll go the DIY route. I must firstly warn you, do not attempt this if you do not have experience in wiring electrical systems, understand basic programming and can not explain to me what a Fresnel lens is. You'll need to be technically adept to install a burglar alarm system. Since I have a B. Eng (Electrical) degree, write computer software programs professionally as well as have experience with embedded systems, I guess I should be able to handle the installation all by myself.

I want to explain to you how I went about planning the layout, as well as the components I chose. Currently I purchased everything I needed, I just need to install it. Hopefully I'll do that 2-3 October.

Firstly I spent about 3 evenings on the Internet, trying to find as much as possible information on the technology out there. Once I understood this, I had a basket of tools to my disposal in designing the alarm system.

Secondly, I am a firm believer that one should not want to know when an intruder enters your house, you should want to know the moment the intruder is in close proximity to your house, still outside. Believe me, I woke up at 03:00 from my burglar alarm going off and it takes me at least 10 - 15 seconds to be in such a state as to understand what had happened. If the alarm only goes off when the intruder breaks your window, you'll have less time to respond.

Therefore I have a full perimeter protection. Once I am sure that the intruder cannot come close to my house without triggering the alarm, I need a second layer of defence - entry/exit point monitoring. This usually includes doors and windows. I want to know the moment someone opens any doors or windows that might give them entry.

The third layer of defence is the interior motion sensors. I want to know when someone is moving around in my house, in the strategic rooms. The fourth layer of defence is panic buttons located at strategic places to initiate an emergency condition. This is useful when the alarm system is not armed, but you find yourself face to face with an intruder, or even just any emergency situation such as a serious cut etc.

The final layer of defence is more passive and not really an intrusion detection function, rather a safety feature. I need smoke detectors in strategic rooms such as the kitchen (we use a really nice gas hob).

The idea is this - you have three kinds of arming. The first is when you are away - not at home. The second is usually when you are at home in the evening, but not yet asleep. The third is when you are sleeping. The idea is this:

Away
Arm all entry/exit points as well as all interior zones. Disarm perimeter - since I live in a townhouse complex, garden services sometimes comes in the garden to cut the grass; obviously they'll trigger the alarm. This is debateable however.

Stay
Arm all perimeter zones and entry/exit points. Disarm interior zones. The idea is simple - you are at home, thus moving around inside. But you do want to know when someone is in your garden or tries to break in through an entry/exit point. Garden services should not be in your garden at night.

Night
Arm all perimeter zones and entry/exit points, as well as selected interior zones. The interior zones to activate depend on your sleeping patterns - if you wake up to go to the kitchen or bathroom, then do not activate those zones. I never go into the study at night, therefore I will arm that interior zone.

So in order to achieve this, I had to purchase the right components. Although I have selected and purchased the components, I have yet to install them and actually verify that I did not make a mistake. On that I'll report later.

A security system consists of basically five important components:

• Controller


• Keypad


• Modules


• Sensors


• Support Components

Controller
This is the single most important part of the security system, since it is responsible for connecting up all the other components and provides the logic for handling events and dispatching them. It also determines the amount of zones (distinct area's) you can have.

Keypad
The keypad is most probably the most visible part of any security system as this is the component you will be interacting with. It provides visual feedback on the status of the controller (usually there are three kinds - LED's, LCD and Graphic LCD). It also allows you to arm/disarm the system and program it.

Modules
This includes zone expansion modules, wireless modules etc. Anything that allows you to extend the behaviour of your controller falls under this category. It is not compulsory to purchase any additional modules.

Sensors
These are the eyes and ears of the alarm system. They detect motion/state changes and are responsible for feeding the controller information on intruder activity. Picking the correct sensors are vital.

Support Components
These are your backup battery, AC adaptor for your controller, cabling etc. I mention it separately since you will not get it bundled with, you need to purchase it separately.

I decided on the Paradox DigiplexNE DGP-NE96 controller, the Paradox Graphica LCD keypad, Optex VX-402 perimeter PIR sensors, Optex AX-70T photoelectric beam, Optex indoor pet sensitive RX-40PI PIR sensors and an Optex DX-40E integrated PIR/microwave sensor.

The reasons for my choices are that these components provide me with a high level of flexability in configuring the components, good protection against intruders whilst minimizing false alarms due too my two cats and other sources, and not being too expensive.

I'll write later on how the installation actually went and whether I made the right choice.