Wired or Wireless Analogue / IP CCTV cameras

Should I use wired, (cabled), or wireless analogue CCTV cameras? 

Choosing whether to use wired or wireless should be an easy decision.

There is only one question to ask: can I run a cable from my camera to recorder? If the answer is “yes” then you should always run a cable. If it is very difficult to cable then using a wireless camera may be an option, but only as a last resort.

Advantages of a cabled CCTV camera:

• Reliability – a physical cable will always be a lot more reliable than a wireless camera
• Less chance of interference – wireless cameras are prone to interference from many sources
• Less expensive – wired cameras generally cost less
• More professional – wireless cameras are only used in cheaper home systems
• Security – wired cameras are very difficult to jam. Wireless cameras can be blocked very easily by many different pieces of electronic equipment, eg: Wireless Access Points, mobile phones, microwave ovens, TV’s, two way radio equipment, gaming equipment, energy efficient lighting, the list goes on....
• Privacy – nobody else can see the cameras on your CCTV system, (CCTV means “Closed Circuit”), wireless cameras can be easily viewed by anybody with the right receiver, including your nosey neighbour!
• Generally better quality.
• Wired cameras can be connected to just about any CCTV recorder. Wireless cameras need specific wireless receivers, so they generally can’t be used from one system to another.
• Higher quality CCD image sensor, gives a clearer, better balanced picture. Many wireless cameras use cheaper CCD sensor, the images look murkier.
• Huge range of cameras to choose from, from Rs. 2500 up to Rs. 7500, wired cameras are available to suit just about any need, no matter how specialised.

Advantages of a Wireless CCTV Camera

• Easy for non-professionals to install
• Can work out cheaper – ideal for when capturing reliable, clear images isn’t important
• Easy to receive the images with cheap wireless receivers – your friends and neighbours can easily see the images from your cameras too.

So there you have it, the answer is clear, never, ever use a wireless camera solution if you can avoid it. If you need to use a wireless solution because of the long distance involved, then use wireless transmitter.

5 Important Locations in Your House That Need To Be Secured

1.     Front Door

Experts state that almost 34% of all intruders enter through the front door. You will have to select a safe location for this camera and preferably place a protective covering over it so that the risk of tampering is minimized.

2.     Back Door

Expert state that 22% of all intruders use the back door hence this is also an important spot to place a surveillance camera. Make sure you place it at a location where it is out of reach and safe from projectiles.

3.     Off-Street Windows

Burglars often use windows that are not visible from the streets, to break into houses as this reduces their chances of being caught. Motion detectors or glass-break detectors are designed to detect such break-ins.

4.     Backyards

These can be an ideal place for robbers or burglars to start off at night. Night-vision surveillance cameras can be used in backyards along with motion-sensor floodlights.

5.     Basement Stairs

Basements usually have multiple small entry points like hatches, doors or windows which can be used to sneak in. A motion sensing alarm can be placed here to help catch any intruders.

Whether, its wired or wireless, surveillance cameras play a central role in protecting you and your loved ones. Installing surveillance cameras at the right points and keeping on top of your security system is essential and necessary.

CMOS Sensor Operation in Camera

Until recently the industrial digital vision sensor market was dominated by the CCD array. However technological advances in CMOS production techniques have led to a gradual increase in the popularity of this sensor type. Like CCD arrays, CMOS sensors are also formed on a silicon substrate but the structure is more akin to that of other CMOS technology such as RAM and ROM memory devices.

The diagram below is that of an actual CMOS sensor showing the active pixel area in green and the area occupied by the on chip circuitry in yellow, which replaces that of the shuttered area on a CCD based sensor. The on chip circuitry actually converts the charge into voltage on each pixel whereas the CCD sensor shifts the charge vertically row by row, and then horizontally pixel by pixel to be converted to voltage when it reaches one or more output nodes. This gives CMOS sensors an advantage when it comes to windowing or a region of interest as the pixels can be read out randomly. CCD sensors can only limit its region of interest vertically with the resulting image always containing the data for the full image width.

The on chip active amplifier and the sampling capacitor give CMOS sensors advantages in terms of speed, full well capacities and much improved response characteristics yet introduce dark current level noise and higher black pixel content. CMOS sensors can also produce higher levels of fixed pattern noise than that of CCD, but this type of noise can be easily removed with a software filter.

The development of CMOS sensor technology has been a rapid and varied process. The initial aim of CMOS sensors was to match the imaging performance of CCD technology, with lower power requirements and at less cost. To achieve this performance it was discovered that a much greater level of manufacturing process adaptation and deeper submicron lithography were required than initially expected. This led to the desired CMOS performance but increased development costs more than anticipated.

At first the low power feature of the CMOS imaging sensors was set to be one of their distinct advantages, however the improved development of CCD sensors means that while CMOS has the advantage in this area, the margin is now much smaller.

The integration of on chip control circuitry with the CMOS imager provides the sensor with greater flexibility and integration, the downside has been the introduction of greater noise levels. Both CMOS and CCD imaging sensors still require support chips to process the image, however CMOS imagers can be produced with more functionality on the sensor chip, as shown below.

The spectral response of a CMOS sensor differs from that of the CCD sensors in that the peak response is sited at around 700Nm. Both sensors operate over the same range, typically 200Nm to 1100Nm.

The main advantages of CMOS imaging sensors still remain as faster response, increased integration flexibility and lower on-chip power demands. However the image quality has yet to match that of the CCD and the supporting chips required to increase the CMOS image quality goes some way to squander its previous advantages. Yet neither sensor is categorically superior to the other. They both have their own advantages and disadvantages and with CMOS developers working on the image quality, and CCD developers aiming to reduce power demands and increase flexibility, the existing margins in place to decide which sensor is most suitable for an application look to narrow further.

CCD Sensor Operation in Camera

This diagram illustrates the general layout of the most common type of CCD array, the Interline Transfer CCD. The CCD is composed of precisely positioned light sensitive semiconductor elements arranged as rows and columns. Each row in the array represents a single line in the resulting image. When light falls onto the sensor elements, photons are converted to electrons, the charge accumulated by each element being proportional to the light intensity and exposure time. This is known as the integration phase. After a pre determined period of time the accumulated charge is transferred to the vertical shift registers.

In cameras conforming to the video standards mentioned above the charge transfer to the vertical shift registers is accomplished in two stages. Initially the charge in the odd numbered rows is transferred, followed by the even rows. Next the charges in the vertical registers are shifted into the horizontal shift register and clocked to the CCD output. Consequently all the odd rows are clocked out first (odd field) followed by all the even rows (even field). The rate at which the charge from the horizontal shift registers is clocked out is governed by the number of elements (pixels) per row and the video standard the camera complies with.

An inherent problem associated with the interline transfer CCD lies in the fact that the vertical shift registers running across the array are insensitive areas and as such act as blind spots. One way of overcoming this is to fabricate micro lenses over each element thereby increasing the effective area of the cell. The lenses also help with the smaller format CCD. Because of the electrical characteristics of the semiconductor substrate on which the CCD is formed each cell has an absolute minimum separation from adjacent cells. Therefore smaller CCDs require smaller cells. Reducing cell size reduces the amount of accumulated charge, using lenses increases the incident light.

Another way of overcoming the problem caused by the vertical shift registers is to do away with them and utilize a different charge transfer mechanism. Frame Transfer CCDs do exactly that. This type of CCD has a separate storage area into which the charge is directly transferred from each cell. This process has to be performed rapidly in order prevent blurring as transfer occurs during the exposure time. Once in the storage area the charge can be clocked out in a similar manner to the interline transfer device.