Infrared remote controlSince the 1970's, most wireless remote controls for home theater equipment have relied upon infrared signals. While relatively easy and inexpensive to produce, infrared signals have some drawbacks:
- Most infrared remote controls are "one-way" -- that is, they only send signals to the equipment and cannot receive information back from them.
- Infrared signals cannot travel through walls or other opaque objects. Often this limitation is referred to as the "line of sight" problem: your equipment must have an unobstructed view of the remote control in order for the system to work. (RedEye mini customers will still need to use “line of sight” to control their devices)
- Infrared signals have relatively poor range -- usually between 25 and 50 feet (7.5 to 15 meters). In addition, sunlight contains large amounts of infrared light can degrade the effective range of an infrared remote.
- Infrared signals are "low bandwidth" -- meaning that they cannot send large amounts of information quickly. As a result, they are good for turning the TV off or on, but forget about streaming audio or video.
Radio frequency remote controlRadio frequency remotes also use light waves to send signals, but they use higher frequency microwaves, which gives them certain advantages. Chief among these are the ability to travel through walls, longer range, and wider bandwidth. Although much less common than infrared remotes, radio frequency remote controls have become more popular recently as they have become more affordable. For example, both the Sony Playstation 3 and the Nintendo Wii use radio frequency (Bluetooth) remote controls. RedEye and RedEye Pro systems use both infrared (IR) and radio frequency (RF) signals. The RedEye sends out IR signals to control your home theater equipment. However, in order to overcome the limitations of IR, it communicates with your iOS device using RF signals — specifically, a Wi-Fi network. This combination of IR and RF gives you the best of both worlds: compatibility with a wide array of equipment over IR, and the ability to control your equipment from any room in your house over RF. The RedEye mini functions using only infrared (IR) signals and offers a range of up to about 30 feet, depending on the sensitivity of the equipment you are controlling.
Contact ClosureA contact is basically electronics jargon for a switch. When a contact is closed, the switch is on (current is flowing). When it is open, it is off (current stops). The light switch, the most familiar of control devices, is a simple contact closure apparatus. RedEye Pro provides two types of contact closure. One type is the contact closure sensor – a device which determines when a switch is flipped. For example, this could be tied to a garage door opener, a magnetic strike plate, or something more sophisticated such as a light or humidity sensor. The other type is a contact closure relay – a switch that turns on or off another piece of equipment, such as a pump or a sprinkler system.
Serial (RS-232) controlRedEye Pro is able to interface with devices that use serial communications, specifically the RS-232 standard. RS-232 has been around since the 1960ʼs, when it was developed for the telecommunications industry and used primarily in modems. It generally provides “point-to-point” communication – i.e., a direct connection between two devices. From a control perspective, RS-232 control provides two distinct advantages:
- Communication is bi-directional. Not only does this allow feedback to the controller – whether the power is off or on, what the current volume level is, etc – but it also enables error handling so that we can know a command was transmitted successfully.
- Data throughput can be much faster. Infrared signals have relatively low bandwidth – with the ability to transmit up to a handful of commands per second – but modern serial communications can move significant amounts of data. Sending images or audio files may not be ideal, but doing so is theoretically possible, at least.
Internet Protocol (IP) ControlAlthough it is more sophisticated than control via infrared or contact closure, the RS-232 standard dates back to the 1962 and was originally developed for modems and teletype machines. Since that time, electronic communications have come to be based predominantly on Internet Protocol. It follows that many devices today provide a control mechanism using IP. IP control is similar to RS-232 in that it is bidirectional, but it also has certain advantages. Specifically:
- IP is network-oriented. RS-232 is a point-to-point protocol – that is, it connects two machines together directly. By contrast, IP defines a mechanism by which a large number of machines can be interconnected without having to run a physical connection between each pair. For RedEye, the implication is that you can add a virtually unlimited number of IP devices to your system, without ever running out of ports. And since both RedEye and RedEye Pro are attached to your (IP) network already, it means that you can have the bi-directional capabilities we introduced with RedEye Pro in the more inexpensive and compact RedEye package.
- Data throughput is even faster. While we measure RS-232 speeds in thousands of bits per second (kbps), today’s typical Internet speeds are millions of bits per second (Mbps) or even billions of bits per second (Gbps).
- More and more devices use IP. Smart TVs, connected Blu-Ray players, streaming media servers, UPnP and DLNA devices – the trend is toward IP control. Infrared control will stay with us because it is inexpensive and simple, but the wave of the future for more advanced control is Internet Protocol.