Does your home entertainment system look anything like the below photo? Do you have a TV in your bedroom that you have to reach at odd-angles from your bed to control with your line-of-sight IR remote control? Am I the only one that's amazed that we're in the 21st century and reliant on a near 30-year old, one-way, line-of-sight-limited technology to control our bleeding edge consumer electronics products like our multi-thousand dollar plasma big-screen TVs and other entertainment systems? I don't think I am—and that's why you're still reading.
| Figure 1 - http://www.flickr.com/photos/videocrab/3229365143/sizes/l/#cc_license
The alternative to infrared remote control technologies is RF-based remote controls. RF-based remote controls overcome three major limitations of infrared technologies: line-of-sight and range; one-way communications; and high power consumption. Let's take a look at each of these limitations and attempt to better understand why the primary interface to our home entertainment, the remote control, continues to be based on a 1980s era technology and how this will change, especially with the introduction of the RF4CE consortium and standards.
Line-of-Sight and Range
The most apparent limitation we all deal with on a regular basis with our infrared remote controls is the need for a line-of-sight connection. This connection is fragile in that it is broken if the receiver is accidentally pushed back into the entertainment center enough to cover the optical IR receiver. Even if you just want to turn the TV off, you have to walk right up to the receiver with the remote to toggle the power. What happens in these same scenarios when the remote is no longer restricted by line-of-sight? You no longer have to care about where the receiver is or where the remote is in relation to the receiver.
Radio frequency technologies for remote controls, unlike Infrared, have physical characteristics that allow these control signals to penetrate line-of-sight obstructions such as walls, blankets, and home entertainment centers. Just as with a WiFi network connection, the beauty is that users are not tethered to a desk and can travel throughout the home while still maintaining a connection to the network. RF remotes work in much the same way. In addition, RF technologies allow for greater range then typical IR remotes (1~5m of range). RF technologies can easily reach 20-to-50m with the same operating characteristics of the IR remote control. And depending on the application, this range can easily be extended with a slight increase in power.
The next feature-limiting characteristic of IR remotes that RF technologies easily overcome is one-way communications. Most of us don't even realize this is a limitation of IR remotes primarily due to the fact that RF remotes are still not very common for home entertainment systems. Once the line-of-sight and range limitation has been addressed, users will quickly discover a need for the remote to provide feedback regarding the system being controlled. For example, say you want to find a particular song stored in your audio system. With a one-way system you must either remember exactly how many next-song button clicks to press from the current song playing or listen to opening of each song before clicking to the next. Ideally, users would prefer to scroll through their music, perhaps selecting the next song from an abbreviated list shown on the remote. Another feature enabled by bi-directional communications " a feature every family needs " is a pager function to locate the remote control. Rather than spending searching for a misplaced remote or operating the receiver manually, users could instead have the remote sound off to reveal its location. And this is just one of the new possibilities and innovations a bi-directional communication link can enable for controlling home entertainment system.
Let's now consider an example apart from the home entertainment system that would also benefit from these same RF remote control features—the garage remote control. How many times have you driven away from your garage thinking more about where you're headed, what your first meeting is at work, or whether you're going to be late just to realize that you don't remember if you shut the garage behind you. The most paranoid among us immediately turn around and return to the house just to realize that as a part of our normal day-to-day routines we have pushed the garage remote button just like we do every day as we backed away from the house. In contrast, imagine a remote that could display the status of the garage and whether it is shut or open? With a bi-directional communications feature, this could easily be accomplished. In addition, it serves as a differentiating feature for which many consumers might be willing to upgrade.
Typical IR remote controls require battery replacement at least once per year. Multiplying the number of home entertainment system remotes by the number of batteries in each remote (typically two AA/AAA batteries) and we're disposing on the order of millions of batteries each year. Further, due to the high power consumption of IR technologies, IR remotes require multiple large batteries, which impacts the minimum form factor. The lower power consumption of RF remote controls, on the other hand, can take advantage of smaller batteries such as the CR2032 coin-cell. The use of a smaller, single cell enables removes battery constraints, allowing for better hand-fitting, sleeker form factors. The table below compares a typical IR remote control's power consumption to that of a leading RF technology. In this table, it's clear to see that a low-power RF technology could easily and significantly increase the lifetime of the batteries in home entertainment remote controls. In addition, longer operating life also translates to fewer support calls and RMAs for the home entertainment system manufacturer due to failures in identifying problems with their systems ultimately being a result of failed power sources (i.e. drained batteries). For both the consumer and the manufacturer, a system with greater battery life such as RF remote controls is a huge win-win.
| Figure 2 - Power Consumption (RF vs. IR)
RF4CE: The Consortium Bringing Remotes into the 21st Century
Why, with all of the benefits that RF has over infrared, have we not seen this technology take off? Two reasons are usually cited: cost (including added design complexity) and the fact that IR is an incumbent standard. From a manufacturer's perspective in the consumer electronics market, price is king. The lower a manufacturer can drive their cost when building millions of a product, the less the manufacture has to charge to make a sustainable profit.
In response to this, the RF4CE consortium is working to establish a standard RF interface for consumer electronics products which, in turn, will commoditize the electronic components to meet this standard. This means, when it comes to the RF interface itself, few features other than compliance to the standard and measures of who can comply more effectively will truly separate the RF component offerings thus leading to the prime discriminator: price.
The second, and probably the most logical reason why RF has not taken off in the consumer electronics market is that IR is the de-facto standard for remote control communications. It's simple, relatively cheap, and everyone except for a small few of consumer electronics manufacturers utilize IR technologies for remote controls. An entire market of universal remote controls has evolved based on this and many of the same companies that design the core entertainment system devices develop devices for the universal remote control market. This alone has a spiral-effect of preventing RF from entering the remote control space. However, this changes as a large group of the world's major consumer electronics manufacturers and their suppliers continue to team together to form the RF4CE consortium to once and for all upgrade the world's home entertainment centers primary interface, the remote control.
In March of 2009, the ZigBee Alliance and the RF4CE Consortium jointly announced an agreement to deliver a standardized specification for RF-based remote controls—ZigBee RF4CE. In this way, major consumer electronics manufacturers have made a clear statement that RF for remote controls is necessary, can be achieved at reasonable cost and effect, and, through a public partnership, can be standardized to continue minimizing the number of remote controls we have in front of our couches. RF for remote controls will quickly become a simple add-on component thanks to both the ZigBee RF4CE standards development and its supporting manufacturers.
About the Author
Jim Davis is Global Marketing Manager for wireless products at Cypress Semiconductor Corp., based in San Jose, California. He joined Cypress in January 2008 and prior to that served for 8 years in the United States Air Force as a communications officer. He has a bachelor's degree in computer science from United States Air Force Academy and a master's degree in software engineering from the University of Maryland.