Dynamic DNS in Wireless CCTV Systems (For Beginners)

Wireless internet CCTV, also known as IP CCTV, communicates through your broadband line and onwards to the internet.  This can cause problems if your home broadband has a dynamic IP address, because when you want to connect to your cameras from outside, you won’t know what that address is.  This article shows you how to overcome the problem by using Dynamic DNS.

Most home ADSL packages still give you a dynamic or changing IP address, which is simply the address of your home’s network on the internet.  These addresses are allocated from a pool of available addresses and allow the internet provider to have fewer addresses than customers, saving money. 

This used to work well because early broadband modems “dialled” a connection when the attached computer requested it, rather like the old dial-up modems.  Nowadays, though, modern wireless modem/routers tend to remain connected permanently, so we are reaching the point where the internet provider is having to allow one IP address per customer, and may as well allocate a static or unchanging one.  However, as of today most people have dynamic addresses and this is an obstacle to contacting your wireless internet camera from the outside world, as I will explain in the next section.

Just as your broadband line has an IP address, so your camera has its own address or port.  For example, if your home IP address is 91.103.218.59 and the camera’s port is 8765, assuming your router is set up with port forwarding (outside the scope of this article) you can contact your camera by typing “http:// 91.103.218.59:8765” into a browser window.  This may work today, but by tomorrow that  91.103.218.59 IP address could have been allocated to someone else, and you will not find your camera on the end of it any more.  This is where Dynamic DNS or just “DDNS” comes in.

DDNS allows you to contact your wireless internet CCTV camera using an address that never changes, even when your broadband’s IP address changes.  It requires two things in order to work: a DDNS service provider and a router or camera that offers DDNS support.

Most modern wireless routers offer DDNS support, but few internet CCTV cameras do.  As long as either the camera or the router offers this feature, all is well.  First, you visit the website of the DDNS service provider and sign up for an account.  The most popular provider is dyndns.com and it’s free.  You choose your own unique internet address such as “mywirelesscamera.dyndns.org” and you will also have a user name and password.  (Incidentally, the purpose of this service is simply to make that link between your IP address, whatever it happens to be at the time, and a fixed address or domain name.)  Having registered a DDNS account, next you log into your router’s administration pages and find the DDNS section.

Here you simply key in the DDNS provider name, your account details and the address that you chose.  Now, whenever your broadband provider changes your home IP address, your router will tell dyndns.com, and this means you can always contact your camera from wherever you happen to be, by keying the same unchanging address into a browser window, in our example: “http://mywirelesscamera.dyndns.org:8765”.

Using Wireless Internet CCTV to Detect Fire and Flood

Wireless internet CCTV cameras are more than just CCTV cameras. These cameras allow you to see your property from anywhere, over the internet.  More than this, they can be used to alert you not only to movement within the camera view, but also to emergencies like fire and flood as this article explains.

Most internet CCTV cameras have the ability to raise the alarm when motion is detected within the camera’s field of vision, giving you the chance to log in over the internet and see what’s going on.  However, many of the good quality cameras can raise the alarm when other events happen in the vicinity.  They do this by “listening” for signals that are sent from sensors when conditions change, for example in those extreme cases when there is a fire or flood, and by sending text messages or email alerts when such signals are received.

The type of sensor you use will depend on the type of event you want to protect against.  You could buy a heat sensor and set it to trigger when the temperature exceeds a certain level.  This could be used to detect a room becoming too hot, a freezer breaking down or a refrigerator getting too warm inside, for example.  You would use a moisture sensor to protect against flood.  This could be placed in a basement or near a washing machine.  Normal industry-standard sensors will work with all good makes of camera, but you should check the trigger voltage and wattage of each to make sure.  In all cases the sensor will send a change in voltage to the camera so that it can take action, as the next section explains.

To attach sensors to your camera, it needs to have a so-called digital input port.  Most of the reputable makes of internet CCTV camera have one.  Two wires are attached to connectors that make up the physical exterior of the port, and these wires run to the sensor.  The camera is programmed to recognize a change in voltage at its input port caused by a signal from the sensor, and to act upon it immediately.  Typically it will send you an email and also an instant SMS text message to your mobile phone or as many mobile phones as you choose.  You can then log in over the internet to see what is going on, and if necessary call the emergency services, all within seconds of your sensor detecting a problem.  Of course, it takes some technical work to get your camera working in this way, and you will need external service providers to handle things like sending SMS text messages.  If you don’t like the thought of setting this up yourself, I always advise getting a pre-configured camera and monitoring service from an internet CCTV provider.

Using wireless internet CCTV cameras in this way really broadens their role.  Seeing your home from wherever you are is just the start.  Attaching sensors and programming the cameras to act upon their alerts turns your camera into an all-round automated property monitoring system that keeps you informed about any problem in your property, within seconds of that problem arising.

Door Monitoring and Control with Internet CCTV

Because internet CCTV cameras are intelligent, as opposed to the “dumb” traditional CCTV cameras, you can use them to see your property from wherever you are in the world, over the internet.  That, however, is just the start.  By joining these cameras to simple alarm and control circuits, they can be used to monitor and control doors.  In part one of this two-part series, I will show you how the monitoring side of the equation works.

Seeing your home, business or family from the other side of the world is amazing enough, but wireless internet CCTV cameras can do so much more than even this impressive feat.  Most of the best of this type of camera will have a digital input/output port, or I/O port, that allows the camera to be connected to electrical circuits.  The two input connectors on the port can be used to monitor an alarm circuit and trigger an alarm as I will explain.

The input connectors can be wired to each end of a so-called alarm circuit that in reality is nothing more than an unbroken loop of low-voltage wire, connected to, say, a pair of magnetic door contacts.  These are a standard part of any alarm system, but for those of you who have not come across them, you basically get two magnets, with plastic mounts.  One of them has connectors for the two wires of the alarm circuit.  You screw this one with the wires to the door frame, and the other one to the opening door so that they are lined up very close to each other when the door is closed, which keeps the circuit unbroken.  This is known as a “normally closed” or “NC” circuit, because in its normal state, the circuit is complete or closed.  When the door is opened, the magnetic contacts separate and the circuit is broken.

The wireless internet CCTV camera will detect when the circuit is broken because there will be a change in voltage at the input connectors and the camera is programmed to raise the alarm when this happens.  So, when the door is opened your camera can send an immediate message across the internet to a central computer.  This computer is programmed to send a text message to your mobile phone, and perhaps an email too – all within seconds of the door being opened.  Of course, if you want this great feature without “getting your hands dirty”, you will need a specialist “internet CCTV” company that can provide you with a camera pack ready-configured to work with your alarm circuit, so you can just plug it in.

We looked at how your wireless internet CCTV camera can monitor the area in front of an external door, and raise an alert when someone approaches the door.  In this final part of the series we are going to look at the next step in the process; how to use your camera to unlock the door.

You may remember from part one that most good quality internet CCTV cameras have a digital input/output port, or I/O port.  This is simply a series of connectors that allow the camera to be attached to electrical circuits.  I have shown you in part one how the two input connectors on the port can be used for monitoring an alarm circuit and raising an alert.  In a similar way, the two output connectors can be used to switch electrical equipment.  Your camera can be configured so that a current is sent to the output connectors under certain circumstances.  This gets very interesting, because unbelievably you can use the camera to actually open the door! So how can a wireless CCTV camera actually open a front door?  I will explain how in the next few sections.

The first piece of equipment you will need is an electronic door release, which you fit to the door frame.  This is a common piece of equipment in home and business security systems and can be obtained inexpensively by searching for “electronic door release” on the internet.  The door release is fitted to the door frame so that the catch on the door lock fits into it.  The door lock is untouched and the door can be unlocked with a key as usual, but the electronic door release can also open the door.  It does this by freeing the catch from the door frame without unlocking the lock, when a current is sent along the attached wires.

The next step is simply to run the wires from the door release mechanism to the output connectors on the internet CCTV camera’s I/O port. The camera has to be programmed so that it will accept an “open door” text message from your mobile phone or from a web page, and send a current to release the door.  Of course, you may be happy enough fitting the door release mechanism, but programming the camera to work with it is a specialist task.  I always recommend getting in touch with an “internet CCTV” provider for a ready-programmed camera that you simply plug in, so you get this great feature without needing any technical knowledge.

Once you have everything connected, here is how it all works in practice.  Let’s say you get a text message alert from the camera to tell you that someone is at the door, and you know it’s about the time your son gets home from school.  You log in using your mobile phone or PC and see a live picture of your son standing outside the front door, unable to get in because he’s forgotten his key.  You can simply send a text message from your phone to a central number, with your password, user name and a simple command such as “open front door”.  A central computer program gets your text message and processes it, checking your credentials.  Then, the system sends a message across the internet to your internet CCTV camera, and the camera then sends a current to the door release mechanism, which opens the door for your son, all within a few seconds!

New applications for wireless internet CCTV such as door monitoring and control bring the technology to a different level when compared to traditional CCTV.  This is yet another reason why these intelligent digital cameras are fast replacing dumb analogue cameras the world over.