These are the CRUCUAL things you need to know before buying Vehicle Rear View Systems and CCTV (Closed Circuit TV)
It’s essential for you as a buyer to know the basic differences so you can compare like for like, otherwise you may be sold a Pup! We’re only considering colour systems here as Black & White are not very common now.
If you’re looking for a vehicle rear view camera system, or a home security system, and you don’t have time to become an expert on the subject, it’s truly baffling…..all the different technology and terminology concerning CCTV cameras and monitors!
Let me put your mind at ease - (for a round up, have a look at the end of the article)
An important feature of the camera is that it must have a quality sensor. This is the bit that picks up the light image and converts it into an electrical signal that the monitor can use to display the image.
There are two main types – CMOS Complementary Metal Oxide Semiconductor and CCD Charged Couple Device
The actual size of all of the above is around the size of a 2p piece. The sensor is the small rectangle in the middle, typically 1/3" or 1/4" diagonal size
CMOS types are really only suitable for CCTV where a clear picture is not the most important factor. Have a look at some of the CCTV footage on ‘Crimewatch’ for example, you can’t even make out the villains’ faces most of the time!
- Are 380 TV lines or less (Low Definition) = Blurry picture
- Have poor handling of changing light conditions - a real problem for vehicle based camera systems.
- Have a very slow reaction to different light conditions (about 10 seconds form fully light to fully dark) and sometimes ‘locks up’ altogether requiring the camera to be switched off and on again.
- Have a low tolerance of direct sunlight - need large sun hoods - direct sunlight causes lens internal refraction (colour cast) obliterating picture and can permanently damage sensor
Whilst none of these factors are too important for CCTV, it’s hopeless for vehicle based camera systems.
BUT... and it is a big BUT (notice only one 'T').... at last there is a new CMOS sensor out without the aforementioned disadvantages, the new sensor is a 0V7949 type instead of the usual one and provide many of the CCD advantages without the CMOS disadvantages, the only penalty is slightly less resolution but for vehicle type camera ork is not noticable. They are also smaller than the CD types and have less power requirements. We have tested samples and found them to be excellent and are now including them in our range. These are new out and we will be one of the first UK suppliers to use them.
CCD types are best for both CCTV and Vehicle based camera systems have
- 420 + TV lines (High Definition) = Sharp, crisp picture
- Superior handling of changing light conditions
- Rapid response Auto White Balance and Exposure (typically less than 1 sec from fully light to fully dark) Perfect for vehicle use
- Direct sunlight not a problem. Minimal internal refraction (colour cast) caused by sun exposure. Doesn't get 'swamped' with light
Q. So why doesn’t everyone sell CCD?
A. Because (old) CMOS are CHEAP and you can make more profit! CCD sensor cameras are typically twice the cost price of CMOS
CMOS video cameras were really developed for covert surveillance uses, due to the small size and mass production, there are plenty about and seem to be used for numerous basic applications. The problem is that the technology hasn’t really improved over the years. (See above addition in bold)
CCD in contrast uses the latest technology with a trade off - it uses a bit more power (not so good for battery powered covert use) but great for all other applications, with superior features and picture quality.
Q. So how do I know if the one I’m looking at has a decent sensor?
A. Basically, if the product has a CCD sensor in it, the retailer will ‘shout it from the rooftops’ because it’s a real advantage to the customer.
If the sensor type is not mentioned – you can bet your last quid that it’s inferior CMOS.
Some less scrupulous retailers will even lie about it and say that it has a CCD sensor even though it has not, but the secret give-away is that they usually list the resolution as 380TV lines (or worse). CCD are usually 420 TV lines and upwards (the highest number of lines generally used for professional use)
Wired v Wireless.
Wired systems have both the signal (and sometimes the power) carried along a cable from the camera to the monitor, often via a voltage stabilising box (see ours and more about this later)
Wireless as the name suggests wireless cameras transmit the signal through the air to the receiver/voltage stabiliser and in turn to the monitor, much the same as a Bluetooth mobile phone transmits to the earpiece. They still need a wire to them to provide the power, but this can be ‘pinched’ from a leisure battery (in the case of a caravan, motorhome or horsebox) or from a sidelight feed.
The thing to watch with wireless systems is that you don’t buy a 1.2 Gigahertz (GHz) system as these are illegal to use in the UK.
The most popular legal frequency is 2.4GHz and this frequency is the same as bluetooth phones, so some picture interference may be encountered if using a bluetooth device at the same time. The interference can cause slight patterning of the picture, but is usually no worse than this and wireless cameras don’t seem to disrupt the mobile phone operation.
Range of transmission when used on a vehicle is never normally a problem, although we can supply an external magnetic mount antenna for the receiver. We have never known of these to be needed in a vehicle situation, and never had to supply one – but they’re here in case you need to fit a kit to your ‘Centurion Tank’ where the metal thickness may be a problem.
Q. What size do I need and what do the specifications mean?
A. For vehicle use we find that 5” to 5.5” (diagonal) screens are the prefect size – any larger, say 7” are just too big inside a vehicle and dominate the drivers’ view – any smaller are just to difficult to see a picture without really studying (not good when you’re driving). Most types available use the flat screen TFT-LCD Thin-Film Transistor Liquid Crystal Display type displays. Early screens suffered from the display not being bright enough, but most quality units today are OK.
Contrast ratio: 150:1 and above is good
Brightness: 300cd/m2 and above
Viewing angle: Our monitors have a good range 15° (up), 35° (down), 50° (left/right) but there are loads of cheap ones about with a poor viewing angle. This means if the monitor is not flat to your face, the picture will be indistinct.
Another important thing to know is that because manufacturing LCD-TFT screens is a tricky business and each little dot on the screen (look closely at your monitor if it’s a flat screen) is a light emitting transistor (Red Green and Blue), the chance of getting the thousands of pixels (or millions on larger screens) all to work is not always possible. This means that often larger screens with the odd group of pixels which don’t work, get re-cycled into smaller screens. We don’t agree with this and all our screens are ‘Guaranteed Brand New’ unlike most others.
Did you know that the 12 volt battery supply in your vehicle can be as much as 14.5 when being charged by the engine generator, and correspondingly larger for a 24 volt vehicle? This is sufficient to damage any equipment designed to run off 12 volts and not specifically designed to be used for vehicle applications. So a lot of the monitors you see are actually designed for running off a 12 volt battery in the kitchen (or wherever) and although they will work for a while in a vehicle, the extra voltage will overstress them and they will fail quite soon.
Our solution is to have a dedicated power converter for both the wired and wireless types, which regulates and provides a steady ‘clean’ 12 Volt supply to the monitor. The power input to the converter can be as much as 32 volts without any problems, so it can be used on commercial vehicles running on 24 volts also!
Check also that the monitor and camera will withstand G-Force. There are quite considerable G-Forces in action in a car. Just going over a pot-hole can damage equipment if it is not intended for vehicle use.
Hmm, have you seen some of the badly translated non-English origin guides on how to put things together and use them? Mostly they are incomprehensible, and leave you more baffled when you have struggled through them. Most retailers are just ‘Box Shifters’ and have no interest other than ‘flogging on’ goods and give scant regard to details like instructions.
We take an active part in designing and specifying our products and where we think the instructions are not good enough, we add or our own ‘Quick Start’ guide to help you on your way.
A bit about us
Although we are now selling on ebay, we have had a web based business for many years selling quality camera systems. Our staff are qualified and experienced in both vehicle and electronic engineering. Our latest incarnation of the website is currently under re-construction as I write (March 2008) but due to be re-launched soon.
A quick round up of what you need to consider when buying.
¨ Is the equipment specifically made for vehicle use (G-Force and Power-surge proof)?
¨ Is the camera a CCD type?
¨ Is the monitor resolution and viewing angle sufficient?
¨ Can it handle wide voltage fluctuations and also cater for commercial vehicles?
¨ Is the camera waterproof to IP67?
¨ Do you get a 12 month warranty by a British company with its own UK workshops?
¨ Can you buy spares or accessories?
¨ Do you get a proper money back guarantee?
¨ Can you get support via phone & email?
We invite you to look around and see who’s selling what, but if you cannot say YES to ALL of the above points, do you really want to risk your ‘hard earned’?
Needless to say, we are proud to offer all of the above features with our equipment.
Satisfaction Guaranteed. Please see our feedback.
Have a look at OUR SHOP to see what we offer. We sell many different variations of kits with unique features not available elsewhere (designed by us)
We hope this guide will enable you to avoid the common pitfalls when buying these types of goods and whatever you choose to do, we wish you the very best. Phil Greenwood.