Understanding Digital and Analog Wireless Technology

The following guide will help you learn the basics of wireless technology and why the digital wireless technology used in Lorex wireless cameras and video monitors is superior to the older analog wireless technology.

The following terms are used throughout this guide:

Transmitter: A transmitter is a device that sends radio frequency signals to a receiver, such as a camera.
Receiver: A receiver is a device that receives radio frequency signals sent by a transmitter. For example, a receiver for a wireless camera receives video image signals from the camera and outputs them to a built-in or external display.
Analog Wireless Analog wireless is the technology used in older Lorex wireless cameras. Analog wireless is the transmission of audio and video signals using radio frequencies. Typically, analog wireless has a transmission range of around 300 feet (91 meters) in open space; however, walls, doors, and furniture will reduce this range.

Pros of Analog Wireless: Cost effective: the cost of individual cameras is low. Multiple receivers per camera: the signal from the camera can be picked up by many receivers, so you can have receivers in different locations.
Cons of Analog Wireless: Susceptible to interference from household appliances, such as cordless phones and microwaves. Interference may affect the quality of images from the camera. No signal strength indicator: there is no visual alert (like the bars on a cellular phone) indicating the strength of your signal. Susceptible to interception: because analog wireless uses a consistent frequency, it is possible for the signals to be picked up by other receivers. One-way communication only: it is not possible for the receiver to send signals back to the camera.
Types of Analog Wireless Analog wireless is available in three frequencies: 900MHz, 2.4GHz, and 5.8GHz. Currently, the majority of wireless security cameras operate on the 2.4GHz frequency. Most household routers, cordless phones, and microwaves operate on the 2.4GHz frequency and may cause interference.
Analog Interference Interference is most common when two analog wireless devices compete for same frequency. Examples of analog wireless interference can be in the form of strong static interference, large horizontal lines on the video screen rolling upward, an increased noise level, or wobbly video.
Digital Wireless Digital wireless is the transmission of audio and video analog signals encoded as digital packets over high bandwidth radio frequencies. Current Lorex wireless cameras use digital wireless technologies to transmit video and audio signals.
Pros of Digital Wireless: Interference-free: image is not affected by competing wireless signals; no static Secure signal: neighbors cannot pick up the signal; no one can listen in Signal strength indicator High-quality video and audio Increased range of transmission: typically up to 500 feet (152m) with line of sight Two-way communication between camera and receiver: along with video/audio, you an also send commands and functions, such as turning the light on the camera on/off. Can connect multiple receivers to a recording or viewing device: signals from cameras will not interfere or overlap with one another* * Make sure to leave distance between multiple receivers when connecting to a recording or viewing device. A maximum of 4 wireless cameras is recommended in any given installation.
Cons of Digital Wireless Cannot connect a single camera to multiple receivers. While some receivers can support multiple cameras, cameras must be paired to a single receiver.

FHSS: The Technology Behind Digital Wireless

Digital wireless features FHSS technology (Frequency Hopping Spread Spectrum). FHSS uses a channel hopping sequence based on an algorithm generated by the receiver. As a result, the digital wireless signal is highly secure and resistant to jamming and interference.

The 2.4GHz (2.400-2.480GHz) band is divided into sections or paths of 2MHz per section, and each second, the transmission signal hops hundreds of times in a specified sequence within this frequency range. The overall bandwidth required for frequency hopping is much wider than 2MHz; however, because transmission occurs only on a small section of this bandwidth at any given time, the signal being transmitted does not suffer from greatly reduced signal degradation and also avoids paths blocked by other devices that act as sources of competing signals. The strength of the signal being transmitted is set to be from 13.5-16dBm, which is much higher than the analog transmission signal allowed by authorities around the globe.

When an image is captured by a digital wireless camera, it is instantly converted from an analog to a digital signal and is packaged into small packets. With each successful transmission via the 2MHz paths discussed above, the packets of information containing images are delivered to the receiver and decoded into analog information. The information can then be displayed on devices that are connected to the wireless receiver (RX).

A device pairing process is required to synchronize the transmitter (TX, Camera) and the receiver (RX). This allows the transmitter and receiver to be on the same frequency and use the same algorithm for frequency hopping. This ensures that only the paired transmitter and receiver can maintain communication signal by hopping to the same frequency paths at the exact same time. As a result, the chance that other devices within the same frequency range are on the same frequency, at the same time and in the same order is
vastly reduced.

NOTE: Products that ship within the same packaging are already paired. Any additional devices you purchase separately, such as accessory cameras, will need to be paired to the original receiver. Please see your system’s instruction manual for information on pairing additional devices.

Interference Free

One of the major benefits of digital wireless is that the digital signal is free from interference from external devices. You will not experience the kind of static interference you would using analog wireless technology.

Digital wireless devices operate on public frequencies, and may be affected by competing wireless signals. For digital wireless cameras, this may cause a drop in frame-rate. The digital wireless signal typically operates at a certain FPS (Frames-Per-Second) level, which is the number of times in a second the image from the camera will update. In most cases, the drop in frame rate will not be noticeable

If you place cameras too closely together, or place digital wireless receivers too closely together, you may notice a drop in frame rate. For best results, always keep a distance of at least 6.5 feet (2 meters) between cameras; if connecting multiple digital wireless receivers to a recording or viewing device, make sure to leave as much space as possible between receivers.

Last Updated: 4/26/2012