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can you please explain the difference between analog camera and digital camera,
how to identify the camera is analog or digital and which one is better for video monitoring system either analog camera or digital camera.
Not quite sure how far back you are going in history here! The original analogue camera is the one that uses film but that is not exactly what you are looking for here is it?
Basically, all electronic cameras are based on what is known as a CCD (Charge Coupled Device) and those are tiny circuits that are sensitive to light and in the colour versions, they also pick up the levels of red, green and blue light separately. The size of the chip physically, is not always a good indication of its sensitivity but generally cameras are now graded by the number of pixels they render from the image. It is that information that is digital and then processed to give a required output which could (and often is) analogue. Thus all electronic cameras are digital at the ‘sharp end’, that is the bit that does the sensing because light is actually an analogue waveform, the chip is an ADC (Analogue to Digital Coverter). For your purposes it would be best to have at least 5MP (Mega Pixels) if you want clear images although for close range you may get away with as little as 2MP
The output from a camera can be in digital or analogue format and most that are easily available are analogue output, often including a small microphone, with separate leads for audio (white plug) and video (Yellow plug) plus a power connection. It is possible to get wireless versions but the batteries tend to not last very long and as the whole purpose of a security camera is for it to be difficult to see or tamper with, changing batteries becomes a real problem! It is better to go for a hard-wired system. More expensive versions are split RGB and that can be either in standard analogue or digital, it all depends how much money you have to spend or burn!
For security monitoring, you really need to have a camera with the lowest possible ‘LUX’ rating. This is the camera’s ability to pick up images in low light and also they should be sensitive to infra-red light (IR) at fairly low level. All CCD chips are in fact sensitive to IR but not all do it well. Some cameras are now fitted with a halo of IR LEDs that are effective up to maybe ten meters but if you want to have better range than that at night, there are also IR LED flood lights that make the images look like it was daylight.
The lense is also a major factor. As in any photography, TV, Film etc., a good quality lense will make a lot of difference to the images but having said that, a pin-hole camera for short range is often perfectly adequate, I would use them up to 5 meters but much further than that, face or number-plate recognition requires some magnification and precise focus.
Bottom line? For cost effective monitoring, a good CCTV camera with a LUX level of 0.5, IR LED illumination and a simple video/audio output for a small area will give you a similar quality image to a basic computer web-cam. in fact, that is a digital output at the bottom end of the market and I have seen them used as simple shop CCTV cameras. If you want to use multiple cameras there are add-on boards for computers that will take the analogue camera inputs and record all at the same time. To be honest, it is better to get a dedicated recorder though. Again, here there are variations. Some record in AVI format which takes up a lot of disc space and some in MPEG which takes less space and gives more recording time. Then or course it is possible to have an analogue recorder using VHS tapes but the biggest problem with those is that people tend to re-use the tapes and quality falls dramatically to a point where the recording is pretty useless for any means of indentification. The heads wear, the tapes wear and the cost of maintenance is high.
It’s all really a matter of what the budget avaiable will afford. BUT just spending a lot of money on a top name brand does not mean you get the best quality or best value! Shop around and read the specifications carefully.
Thanq Mr Pete Braven
your comment is useful for me.
i need some example and its properties of analog camera and digital camera.
Hiyah Venkatesh,
as I’m not entirely sure of the precise nature of the ‘monitoring system’ you are looking to apply this to, the possibilities are almost endless.
What most people use is a simple ‘surveillance camera’ which has an analogue output along what is called ‘shot-gun cable’. This is not to say that it goes bang, at least it doesn’t if it’s wired correctly, it is the shape of the cable in that it is two cables joined together that look, in profile, like a shot-gun barrel. One cable carries the power to the camera and has a twin wire core, the other carries the signal from the camera and is a screened lead. It has to be screened so that it does not transmit or pick up electrical noise.
If you do an internet search for these surveillance cameras, you may well find the ebay guide (A Guide To Choosing CCTV Security Camera Systems) which has a lot of useful pointers as to what to look for, depending on your requirements. They have literally thousands of listings from a few dollars to hundreds of dollars, it really depends what you are looking to achieve and in what sort of environment.
I often think when trying to answer questions or repair a piece of broken equipment, that it would be very handy to have a crystal ball in my toolkit. Unfortunately, they seem to be unavailable, or the ones that are, don’t work! Thus I can only make a guess and suggest that you opt for an analogue output and hard-wire it to the monitoring system.
As this is obviously some form of security I cannot expect you to publish here all the details, or the system would be rendered public knowledge and the whole point of CCTV security is that it remains private.
I don’t sell this stuff but I do use it a lot. Not only for security but also I have two cameras in the back of the truck to give me rear vision when reversing, I also have what has become known as a ‘road-cam’ which is a small camcorder that records my journeys in a continuous loop of a few hours duration. If there was some incident that required me to show what happened, such as a collision, it is easy to to just show that video. It also makes for funny clips of motorists doing crazy things that end up on youtube! Having one makes me a better driver as I really don’t want to be in one of those clips myself.
As you can appreciate, the applications are many and really varied. The best way to learn is to find the specification sheets on the internet for as many different devices as possible,.. then shut youself away and read all of them carefully. The way in which you build your system is only limited by your imagination, that is why electronics advaces so fast. There is always a new way to use existing technology and sometimes a small innovation can make a whole new range of products we never thought possible.
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