Dr. Adler recently passed away, on February 17, 2007, at the age of 93. His crowning achievement, the wireless TV remote control, dubbed the "Space Command" was first brought to market by Zenith in 1956.  It used ultrasonic technology and was later replaced in the market by remote controls using infrared technology, the technology used by a vast majority of remotes sold today.

Although he didn't invent the first wireless remote, that distinction belongs to Eugene Polley, inventor of the "Flashmatic," and also a Zenith engineer, Adler's design was a vast improvement over the "Flashmatic" and produced the first viable consumer remote control.  Polley's "Flashmatic" used a directional flashlight as the transmitter, which sounded great until direct sunlight could cause the television to change channels, power off, or do any number of unwanted actions.  Adler's design instead used sound to control the set.  Early designs included aluminum rods that would be struck by tiny hammers in response to a button push, much like a tuning fork.  These sound waves were used to control the television.  He later modified the design to use ultrasonic sound waves and that became the basis for remote controls from 1960 until they were replaced by IR devices in the 1980s.

An IR remote control uses pulses of light that is not visible by humans. These pulses translate to ones and zeros. A specific sequence of ones and zeros represent a command like changing channels and switching inputs. While the earlier TVs had limited remote functionality today's IR remotes can recreate thousands of commands. That is very important as more devices in the home theater have IR capability you need a large number of command sequences so you don't inadvertently turn something on or off. In the old days a remote had three buttons, on/off, channel up, and channel down. But that was OK as you could cycle through all the channels with about 5 button presses. There was no input switching, FF, or RW, functions needed. On the TV side an IR receiver recognizes the sequence as a command and responds as needed.

Some IR remotes work better than others. That's a function of the strength of the Remote LED. If your remote has a strong LED or even multiple LEDs you do not have to aim it directly at the device. The signal fills the room and the receiver has no problem seeing the command. In fact way back in the day, before DVRs, if you wanted to record onto VHS off your satellite receiver you either had to set both the receiver and VCR to come on at the same time or you could add your VCR model number to your Satellite receiver and have the satellite receiver blast the room with IR commands. Since the satellite receiver was not powered by a battery it could fill the room with VCR commands.

A typical IR Remote has a range of about 30 feet and as well know IR won't penetrate walls or closed electronics cabinets. If you need to use a remote behind walls you can use an Radio Frequency (RF) remote. RF will go through walls. Your cordless telephone is an RF device. But the issue with RF is that most devices in your home theater will not respond to the command. So to make it work a device needs to be put in the space with the equipment to translate the RF command into an IR command. Harmony Remote makes a device that works with both RF and IR (Harmony 890 Buy Now).

You may be asking why doesn't ambient light interfere with the IR remote. This was an issue with early prototypes. To get around that your TV, or other device with an IR remote,  looks for an IR signal that has a wavelength 980 nanometers. They Infra red eye on your TV is blind to any other wavelength but because sunlight has light at that frequency something else must be done to make the remote work. Engineers came up with a solution to modulate the signal to something that is not present in sunlight. Thus your TV, DVR, or receiver will only respond to something at light with a 980nonometer wavelength modulated to a specific frequency.