SD CCTV FAQ

Here are the answers to some of the common questions we receive from clients who are looking at standard definition or analog CCTV systems. If you can’t see the answer to your question here please send us an email or call 0508 11 00 22, we’d be pleased to help.

You may see standard definition CCTV referred to SD (standard definition), traditional, conventional, digital or analog (or analogue) CCTV. All these terms usually refer to the same CCTV technology.

An analog CCTV surveillance system is made up of:

  • Security cameras
  • A DVR (Digital Video Recorder) with a hard drive which will record and allow playback of the video footage
  • A monitor (or other option) for viewing the live and recorded footage
  • Cabling to connect the CCTV cameras to the DVR and the system to power

Analogue CCTV system diagram

Can I use a mix of SD CCTV cameras?

Yes, you can mix and match any brand or type of analogue digital security camera with any brand of DVR if you are purchasing all new product.

If you are looking at upgrading your existing security system, as a general rule of thumb, if it was installed reasonably recently (in the last 18 months or so) your existing security cameras will probably be compatible. If you have an older system, or you are not sure what brand of cameras you have, we will need to get a few details about them first. Please contact us to discuss.

Is there an analog CCTV camera that will record in colour at night?

No. All security cameras with infrared will record in colour in the day and black & white (or monochrome) at night.

Should I use a low light true day/night CCTV camera or one with infrared for the best image at night?

It depends on the environment, where the security camera will be mounted, and how big an area you would like the camera to monitor.

If the entire area you want to monitor is well lit from multiple light sources then a low light CCTV camera will likely capture the best picture. In comparison, infrared illuminators (often built into the camera housing) may not have enough power to light the entire area. Using a standard high power illuminator can put out too much IR (infrared) light close up to the camera washing out the image or creating glare. Technology such as Hikvision’s Smart IR help alleviate this problem by reducing power to the IR illuminator as the subject approaches the camera. This dramatically reduces glare and allows the use of higher power illuminators.

If the area is relatively small or indoors IR illuminators often work well as the IR will reflect off the walls and floor lighting the room up.

How do I view the surveillance footage?

16 channel 4:3 aspect LCD monitorThe security cameras are all connected back to the DVR which records the surveillance footage. The DVR can connect to any computer monitor or to the AV input on your TV. If you want to view the cameras on a dedicated monitor we recommend a 4:3 aspect ratio monitor otherwise the image will be stretched.

You can also view the cameras remotely via almost any internet connected device including your laptop, iphone, iPad or smart phone. Your device will need to be configured for this. Please note that you cannot plug your laptop directly into the DVR to view the video because the DVR needs to connect through your computer network.

How far away can the security camera be from the DVR?

The maximum distance a cable length can be run between an analog camera and a DVR depends on the type of cable you choose.

We use commercial grade UTP (CAT5/6) network cable in all our installations which allow video to be sent several kilometers if using active baluns or 300-400m using passive baluns. It has the added advantage of being thinner and easier to run and also means if you want to upgrade to IP cameras at a later date we can use the same cable. UTP cable is less prone to interference than traditional coax cable.

If you are purchasing product from us to install yourself, or using your own electrician or installer, we have a number of options. You may prefer to use CCTV combo cable which has a coax and twin core power cable in one outer sheath. Our commercial grade cable is available in 100 metre rolls and is suitable for runs of up to 400 metres. Our economy cable rolls are suitable for up to 80 metres. We also have a range of pre-terminated (with BNC and DC power plugs included) in 10m, 20m and 30m lengths.

How do I keep the CCTV cameras recording if there is a power cut?

A UPS or Uninterruptable Power Supply can be installed as part of the CCTV system. This battery back-up makes sure the security cameras can keep running if their is a power cut. It also acts as a surge protector and regulates power supply to the hardware reducing the risk of damage from electrical spikes. A UPS is a cost effective addition to your CCTV set-up.

What are pixels?

Simply put, pixels are dots. The number of pixels, or dots, in an image is what is described as the resolution of an image.

The more pixels that are used to create the image the cleaner and crisper the image quality.

For example a 600TVL security camera has a resolution of 795X596 pixels. This means the image has 795 dots horizontally and 596 dots vertically, making a total of 473,820 dots in the image.

The number of pixels in the image directly affects the quality of the image especially in an application where detail is important such as face ID shots. Industry best practice allows 450 x 450 pixels to cover a 1 square meter area when used in a high detail application. So if you want to use an 600TVL camera to get ID shots for example of customers entering or leaving your retail shop it is important that the camera only cover an area of about 1.5m wide (eg a doorway) to get useful images. An area any larger than that will mean a poor quality image that is difficult to positively ID someone. Position of the camera and lens choice are also important as the further away from the camera the more zoom is required to keep the field of view down to the 1.5m wide target size.

How do I get a high resolution image from my CCTV camera?

The resolution of an analogue security camera is usually represented by how many horizontal TV lines (TVL) it has. A 420TVL camera is low resolution of 500X582 pixels whereas a 600TVL (795X596 pixels) or more will provide a higher resolution image.

However it is important to know that the maximum viewing and recording resolution of an analogue surveillance system is determined  by the DVR not the camera. If your DVR only records at CIF resolution (352×288 pixels) connecting a 600TVL camera will not improve the resolution as the DVR is only recording at the lower CIF resolution.

For true high resolution images we recommend looking at a HDCVI or ideally IP systems.

What does the Lux measurement of the camera mean?

Lux relates the energy per unit area falling on a surface to what the human eye can see. The light sensitivity of a camera is measured in Lux and indicates to what light level the camera will be able to record to.

  • Direct sunlight is 100,000 – 130,000 Lux
  • Daylight is 10,000 – 20,000 Lux
  • An overcast day is 1,000 Lux
  • An office is around 200 – 400 Lux
  • Twilight is 10 Lux
  • Full moon is 0.1 Lux
  • Quarter moon is 0.01 Lux
  • No moon in a clear night sky is 0.001 Lux
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