Outdoor Video Surveillance and Recording Systems
Outdoor cameras covering your front gate, pool or other area that record 24 hours a day are a great way of keeping track of what's going on around your property particularly useful if you suspect you've had an intruder. The simplest installation being cameras on the outside of your house with video cable (co-axial cable) and low voltage power cable run back to a Digital Video Recorder (DVR) for live monitoring, recording and playback of video recordings.
The resolution of analogue surveillance cameras is measured in TLV, which stands for 'television lines' or the number of lines resolution across the screen. The number of lines from top to bottom is fixed with PAL (Australia, NZ and European TV system) to 625 lines or with NTSC (USA, Japan) 525 lines. The best standard definition (SD) video surveillance cameras are 720TVL, which are called D1. There is also a wide screen SD format that has 960 TVL that is called 960H. Anything higher than this is rated as high definition (HD) video. High definition analogue cameras are called AHD or HD-SDI, which are two different systems that enable HD video to be possible with the same video cables as SD. Analogue HD cameras normally come in 1024 TVL and 1920 TVL or the same as a 1 Mega Pixel (720p) and 2 Mega pixel (1080p) digital cameras.
Seeing in the Dark
The low light performance of cameras varies quite a lot, generally cheaper cameras don't work so well in low light but if they have night vision they will have a built in Infra red LED Light that comes on automatically when it gets dark so the camera can still see at night time although it is in black and white. The distance the night vision works generally relates to the viewing angle of the camera lens, if it has a wide viewing angle then the night vision will only work to 15m as any further this this isn't sharp enough to worry about anyway. Cameras with a medium viewing angle will have night vision to 20m or even 30m and cameras with long viewing angle will go to 40m to 70m. Infra red is used rather than white visible light because people can't see it so it won't disturb your neighbours and it will record what ever sneaky things intruders are up to without them knowing.
Out of all the technical specs listed with a camera the most important for video surveillance is its viewing angle. If the camera is quite close to a gate, pool area or other subject then a wide viewing angle such as 90o is needed to cover as much as possible although if the camera isn't high definition you're better off using two or more cameras with a medium viewing angle such as 60o so you get more detail. If the camera is a long way from the gate or other subject then a long viewing distance or narrow viewing angle is required such as 30o that is zoomed in.
Why High Definition?
If you catch someone doing something they shouldn't on camera you can see more detail with a high definition camera so are more likely to be able to recognize who they are or read the number plate of the vehicle they're in and you can see further into the distance with the same angle of lens. A 1 Mega pixel camera captures the same detail as 3 x SD cameras and a 2 Mega pixel camera about the same as 6 x SD cameras.
Digital Video Recorders (DVRs)
All recorders for video surveillance these days are digital that is they record video onto a Hard Drive like the data on your computer. Long gone are the days when video is recorded on Tape. D1 standard definition DVRs record video at a resolution of 720 pixels x 576 pixels for PAL (Australia, NZ and Europe ) or 704 pixels x 480 pixels for NTSC (America and Japan). 960H standard definition DVR's record in a wide screen format that is 960 pixels wide and the same height as D1. These recorder have 4 or more analogue video inputs where each camera must be connected and all cameras are recorded at once and can be played back in groups or individually. Generally with a D1 DVR any D1 or less resolution camera can be connected. With a 960H DVR you must use 960H cameras. With AHD or HD-SDI you can use the same cable as SD cameras but you must use AHD cameras with an AHD DVR and HD-SDI cameras with an HD-SDI DVR, although if you want to upgrade an old SD system with HD its simply a matter of replacing the cameras and DVR with the matching type. An added advantage of modern DVR's is they can be connected to the internet so cameras can be viewed using an App on a Smart phone.
Power to the Cameras
This is normally 12VDC from a power adapter (plug pack) and requires a cable run along side the video cable. Normally all cameras are plugged in at the DVR and quite often cables are provided with both a video cable and power cable in one, making things bit easier.
Wireless Analogue Video Cameras
Installing video cable for cameras on the same building generally isn't too difficult as cable can be pulled through ceiling cavities, walls and run on the surface in trunking but running a cable between a post near a gate or pool area and a building requires excavation, which is expensive and messy so having a wireless camera is an attractive option here. Well the camera itself isn't wireless but you can make a video cable wireless by installing a video transmitter and receiver unit.
One thing to watch with video transmitters and receivers is if they use 2.4Ghz, this is the same frequency as WiFi, Bluetooth, baby monitors and cordless phones so may suffer from interference so its best to get one that uses 5Ghz, 1.2Ghz or 900Mhz as these are much less prone to interference or one that is digitally encoded and uses anti-interference frequency hopping technology. Also you will need power for the camera and transmitter. If the camera is for an automatic gate then you could use the same power as the gate motor although if it is solar powered best not to as it will drain the solar system too much stopping the gate from working.
If the camera is a long way from a building then you can normally replace the small antenna that comes with the video transmitter and receiver with a a larger and directional antenna that will go a lot further.
The more directional an antenna the further it will go. If using a 2.4Ghz to 900Mhz transmitter and receiver they will go through walls and trees but the distance is reduced. 5Ghz doesn't go through walls or trees well at all so must have a clear line of sight between antennas.
IP (Internet Protocol) Cameras work much the same as their analogue counterparts accept they don't all need to be wired back to the recorder with special video cable they just need to be connected to a Computer Network with standard network cable along with a Network Video Recorder (NVR). IP Cameras can have higher definition than analogue cameras and NVR's can be viewed remotely using the Internet (not just a camera) by a PC or another NVR if supported. So you can in fact have a network of NVRs in different areas around the country connected back to one using the Internet.
Wireless IP Cameras (WiFi Cameras)
A lot of IP cameras have WiFi built in so they can connect to a home or office WiFi router that is also connected to an NVR. These work fine for shorter distances (up to 30m) accept you still need to get power to the camera so need to run cable anyway unless you happen to have a power point near where you want to put the camera. WiFi is particularly handy if you have a camera on a pole near a front entry gate although if this is a long way from the building where the WiFi router is, to get a reliable connection an roof top WiFi link is necessary that consists of a couple of Outdoor WiFi Access Points, one on the roof of the building where the NVR is that is set up as a WiFi hot spot and the second on the pole where the camera at a 'roof top' height is that is setup as a WiFi client.
More than One WiFi Link
If you want a second WiFi link to another camera and the camera is in the same direction from the hot spot as the first then it can have its own Client WiFi Access Point and can share the Hot Spot. If the cameras are on the same pole then they can share the same Client Access Point although a Switch will be needed to split the network cable up, which is a standard low cost network device and can split a network cable into at least four. The switch would also need to be in a weather proof box places as close to the cameras as possible.
If the second camera is in a completely different direction to the first then the Hot Spot Access Point could have an Omni-directional antenna fitted that works in all directions but distance would be limited to 200m or so, which is still plenty for most applications. For this to work all Client Access points would need to be at a similar distance from the hot spot. If cameras in one direction are close and those in another direction a long way then a second Hot Spot Outdoor Access Point can be added and both use their built in directional antennas and they would need to be on different channels so they don't interfere with each other.
Number of Cameras per WiFi Hot Spot
This depends on a number of factors firstly the number of megapixels each camera is, secondly the amount of video compression is set (the more video is compressed the less data is streamed so more cameras can share a wireless link but picture quality is reduced) and thirdly how good the WiFi connection is. Generally though if using 1 mega pixel cameras with their video compression set as high as possible without loosing too much picture quality you can have up to 16 cameras working off each WiFi Hot Spot, although the Client Access Points would all have to be at a similar distance from the hot spot and the working distance settings on the Outdoor Access points set correctly for this to work well.
Choosing the Correct Outdoor WiFi Access Point
If there is a lot of WiFi traffic like you get in a gated community then its best to choose 5Ghz Outdoor WiFi Access points as this frequency isn't used much because it doesn't go through walls very well, which brings up the next point you need to have a clear line of sight with 5Ghz Access Points because they won't go through walls or trees all that well particularly when it rains as the water in the leaves blocks the WiFi.
If you're on acreage and the WiFi does need to go through trees then a 2.4Ghz Outdoor Access Point would be better because it will go through trees and bushes much better than 5Ghz and you don't normally get a lot of WiFi traffic on acreage. Your own WiFi won't be a problem as you can set the cameras WiFi link to a different channel.
WiFi won't go through the ground or metal fencing or walls so need to keep it high enough to avoid this.
Power to the Cameras, Access Points and Switches
If you have a camera on a pole next to a front entry gate then you could run a low voltage cable from the pole to the gate motor, which normally would have low voltage available for gate accessories. You would need to have a small voltage converter board (regulator) in a weather proof box on the pole to make sure the camera(s), access point and switch (if used) have the correct voltage and that it is stable. If you have 240VAC mains at the gate you could just use the power adapters that come with the cameras etc... and run some 1.3mm2 garden lighting cable for each or you can have two devices sharing each power adapter if they are the same voltage. If the gate motor is solar powered and is 12VDC then you could run power directly off the gate motors battery to the cameras etc... although you will need to add more solar panels and batteries to allow for the extra power being drawn from the system. If a solar gate motor is 24VDC you'll need to use a 24V to 12V or other voltage switch mode DC to DC converter as close to the cameras etc.. as possible to get the correct voltage.
If the cameras are on a lamp post that is powered by the property (not a street lamp powered by the city) then the cameras, access point and switch could be powered from the lamp post using the supplied power adapters, although there would need to be power on the post all the time so the lamp would need to have a built in daylight switch or timer that turns the lamp on and off. If the lamp only has power when the light is on then it will need to be changed around so there is power there all the time.
Another handy source of power is a pool or maintenance shed or garage that has power.
WiFi going Around Buildings or Hills
If you are using 5Ghz in a gated community and need to get around buildings or are on an acreage property and your driveway is down a hill from the house then you can use an Outdoor WiFi Access Point as a repeater by firstly adding an Omni-directional antenna and then placing it where it has line of sight (clear of buildings or hills) with both the Hot spot and Client Access points. If its a long distance then two Outdoor access points can be used one as a client from the Hot Spot and the second back to back with the first as another hot spot on a different channel. These two would use their built in direction antennas aimed at the appropriate Access Points they are repeating.
Compatibility between Cameras and NVRs
One issue with IP cameras in the past has been compatibility with the Camera and NVR so a standard called ONVIF has been established so if both the camera and NVR are ONVIF compliant then they will work together.
Is an NVR really necessary or can you just use a PC?
Cameras can be used without an NVR as they come with Apps so they can be viewed from a PC, Smartphone or Tablet and the video can even be recorded although this is only really practical with a PC with a large hard drive although from a practical point of view this needs to be on all the time and does slow the PC down making it useless for anything else so really it needs to be used for video surveillance and nothing else and Windows tends to want to upgrade every 5 minutes so restarts and stops recording video in the middle of the night so really an NVR is a much more reliable and economic solution as these have their own linux based operating system (not Windows) so are a lot more stable, use less power and are cheaper to buy than a PC. The App for a PC, tablet or smart phone is fine for viewing cameras and can be used to connect to the NVR remotely using the Internet so recorded video can be viewed.
Analogue verses IP Cameras
The attraction of analogue video surveillance cameras and recorders is they are simple you just plug them in and they go, although if you require cable longer than that provided then you need to make sure you get the correct type of cable and connectors to make up a longer video lead and you need to run a video cable for each camera back to the recorder. Also if you want high definition you need to make sure you match the HD cameras up with the correct HD DVR and they are limited to a maximum of 2 Mega pixel. Also if you want to go wireless you need a transmitter, receiver and antennas for each camera, there's no sharing and these normally only have 4 channels so you are limited to 4 wireless links that must either not be 2.4Ghx or are digitally encoded with anti-interference frequency hopping technology.
IP cameras however have the advantage that you only need one standard network cable to the NVR that can run to each camera in sequence or what ever arrangement uses the least amount of cable and the cable can be slit using a standard low cost network switch. Larger scale wireless high definition systems are also possible that can't be done easily with analogue. The draw back with IP cameras is you do need some knowledge of computer networking to get these working or have everything set up for you before hand so all you need to do is install everything and it will just work and fine tuning can all be done with a PC or laptop connected to the network.