Wireless technology is being applied to just about everything these days, and video surveillance takes good advantage of it. A wireless camera includes a built-in transmitter to send video over the air to a receiver instead of through a wire. Many people aren't aware that there are multiple types of wireless technology in use, each with unique advantages and disadvantages.
Most wireless cameras are technically cordless devices, meaning that though they transmit a radio signal, they still need to be plugged into a power source. Still, “wireless” is the commonly used industry term. Some cameras do have batteries, of course, making them truly wireless. But battery life is still an issue for professional or even semi-professional applications.
These devices work on a simple principle. The camera contains a wireless radio (RF) transmitter. This transmitter broadcasts the camera's video, which can be picked up by a receiver, which will be connected to a monitor or recording device. Some receivers have built-in storage, while others must be connected to a DVR.
Analog vs. Digital
There are two basic types of RF transmissions, analog and digital.
Analog devices send out a constant string of data when they transmit. The data can be picked up by any receiver that picks up signal in its frequency range.This means that anyone with a properly tuned receiver can pick up a transmitter. It also makes interference more likely. If there are multiple transmitters in the same area, the most powerful signal will knock out any others in range.
Digital wireless cameras work a little bit differently. They modulate their signal slightly, constantly cycling through frequencies in order to avoid interference. This also makes transmissions more secure. In order to pick up this video feed, a receiver needs to be paired with the camera. This means the camera and receiver are programmed to cycle through frequencies at the same rate.
Types of Wireless
Whether analog or digital, most commercially available electronic devices that broadcast do so in either the 2.4 GHz or 5.8 GHz ranges. 900 MHz and 1.2 GHz were common at one time, but have both been nearly completely phased out of use.
2.4 GHz and 5.8 GHz cameras are similar in function. Both contain a transmitter that sends a signal to a receiver, which can be connected to a monitor to view or a DVR to record.
- Available in digital and analog
- Has a maximum practical range of about 700 feet
- A single receiver can carry a maximum of 4 transmissions
- The frequency most cordless/wireless devices transmit on, so analog devices are very prone to interference
- Maximum range of about 2000 feet
- A single receiver can carry a maximum of 8 transmissions
- Used by fewer household devices, less prone to interference
- Analog signals can still be picked up by outside receivers
WiFi cameras are wireless IP cameras. They allow multiple devices to be networked together and access a local area network through a wireless router. Each device talks to the router, which can send information back and forth to other networked devices as well as to and from the internet. A typical WiFi router has a range of about 150-300 feet and can (for practical purposes) connect as many devices as they have bandwidth to support. Typically, routers are not included with these cameras and must be purchased separately.
WiFi cameras are so popular because they allow remote access to a video feed from outside the network. Set up can be more complicated than traditional wireless cameras and usually requires the user to have a PC available to set up the camera.
Cellular cameras contain a cellular transmitter and connect to a cellular network to send video. In function, they can be very similar to WiFi cameras. This is the newest of the wireless technologies, and reliability can vary widely, largely based on network conditions.
These also tend to be very costly. Not only is equipment expensive, but it also requires a cellular data plan in order to transmit video. These costs can vary by cellular carrier, and a lack of cellular coverage can render the devices inoperable. As costs drop, expect to see this type of camera become more and more popular.
Can I Make a Wired Camera into a Wireless Camera?
Yes. There are simple kits available consisting of a transmitter to connect to an existing camera and a receiver that can be connected to any analog camera.
Can the Range of a Wireless Camera be Increased?
Yes. There are devices called repeaters that can be used to increase wireless range. They work on a simple premise, receiving a camera’s signal and retransmitting it. This can effectively double the range of a wireless camera, but using multiple repeaters is not advised, as each one will degrade video quality exponentially.
Maximum camera ranges are always calculated based on line of sight (LOS). This means the transmitter and receiver have no obstructions between them. Though a transmitter can send data through walls, windows, and even thin metal, those obstacles will weaken the signal and shorten the device’s transmission range.See also: