Remote control

A remote control is usually called an electronic hand-held device that can be operated via the short to medium distances ( about 6 to 20 m) equipment or machinery. For control over greater distances, the term radio remote control is in use.

• 7.1 Universal Remote Control
• 7.2 Interactive remote control

History

The TV remote control was developed in 1948 in the U.S.. She was then connected via a cable to the TV and could not enlarge or reduce the image. 1950 Zenith Radio Corporation also brought a wired remote control called " Lazy Bones" ( English for " slackers " ) out, which could change the programs.

Five years later, the Wireless Remote Flash -Matic. She had an idea of Zenith employee Eugene Polley and worked with a visible beam of light was directed to one of four light-sensitive sensors in the corners of the TV. It was also often the mere daylight turn on the TV. A year later, in 1956, ultrasound technology replaced the light method. The Austrian Robert Adler, a developer of Zenith, built the model of " Space Commander ". It worked without batteries by a hammer - similar to the piano - on a staff suggested that generated the ultrasonic sounds. Shortly afterwards, from the same manufacturer, the model " Cadet " (1958 ), and later "Vector " (1960).

In Germany the first "magic switch" remote control appeared called, in 1956 by the company Tonfunk. With it, the radio device could be wireless and off. In 1959, there were remote controls with multiple features for televisions.

Types

One can distinguish remotes after the transfer medium:

• Wired remote control Wire connection with mechanical action ( Bowden, Air switch, tethered flight )
• Wire connection with electrical effect, for example, for missile control (see for example MILAN ), remote control on the steering wheel for the car radio, older remote controls for televisions (cable remote control)

• Sound and ultrasound ( as telephone beeper for remote answering machines, ultrasonic remote control for TV earlier )
• Radio waves ( for example, for remote unlocking of cars, garage door opener, wireless switches, Bluetooth with modern entertainment devices)
• Infrared (IR) radiation ( among other electronic devices such as TV )

Radio remote controls are in contrast to IR remote controls do not rely on optical sight to the receiver and thus act even through walls and ceilings. There could be ( wireless phone, video transmission, etc.) and a microwave oven may cause interference with the use of other radio applications.

There are also universal remote controls that can operate a variety of devices from different brands.

Distinction between

Devices with higher coverage are usually referred to as a remote control. They operate using radio waves.

Devices with only a few functions are called hand-held transmitter.

Modes of transmission

Initially, the signals have been passed only through a cable, whereas modern remote controls are wireless in general. The transmission method used, for example, radio waves can be used, this is sometimes a permit from the national telecommunications authorities ( in Germany, the Federal Network Agency ) is required. No permit is required are transfers using infrared, inductive transmission with a transmission frequency of 10 kHz, for example, for opening garage doors and ultrasonic remote control - it is hardly used today. Ultrasonic remote controls - such as inductive Remote Controls - susceptible to interference from the environment. In addition, animals can hear ultrasound and startled when actuated.

Most remote controls today use infrared (light emitting diode at a wavelength of 950 nm as a transmitter ). To improve the noise immunity, the radiation at a frequency of 20 to 70 kHz is modulated. The modulation of the signal reduces the power consumption of the transmitter, making the transmission without interference from ambient light. With infrared remote controls direct visual contact with the device to be controlled is not absolutely necessary, since IR signals are reflected from many surfaces.

Recent developments use radio frequencies to 2.4 GHz. Among other things, devices via mobile phone or computer via remote apps can be remotely controlled via Bluetooth or LAN / WLAN. This method does not require visual contact.

Infrared remote control

IR modulation

IR remote controls transmit a signal in the invisible infrared range. The radiation source often used infrared LEDs. The signal is switched at a frequency of 40 kHz and. Thus, the noise immunity of the receiver increases: A bandpass filter passes only those frequencies and blocks random noise from. By modulating this transmit signal information is transmitted to the receiver.

The left image shows an IR carrier signal of 38 kHz. The signal sequence (english burst ) has a transmission time of about 560 microseconds, which are about 21 trains of waves of the carrier signal. Through deferred broadcast of the signal sequences, data can be transmitted. The bursts and the intervals between them, encode the information to be transmitted to the receiver. The carrier signal is not visible in the right image due to the low resolution.

Encoding is performed by different methods by varying the burst and pause duration ( pulse telegram ). The audio file is an example of how an IR signal would listen. In the first block sound pulses encode with a length of 500 or 1600 microseconds duration, separated by about 500 microseconds long pauses that information. Share The following crackles with the receiver that the remote control is pressed for more and the information of the first block to be repeated. Here are two additional sequences that convey the information of other holding the remote control buttons. The repeat signal is identical. The subtle differences in the information block are acoustically not be identified.

Spread the procedure RC-5 and RC -6, which go back to the company Philips. You use a carrier of 36 kHz. The bursts and pauses have a duration of 889 microseconds, respectively. The coding is a Manchester code as a basis. This step breaks and bursts of simple and double maximum duration. A signal packet transmits 14 bits, so that every second a transmit command is at least ten times repeated broadcast.

Technical Realization

Handset

In the hand-held device, or the remote control, there is a battery, a control circuit, key pad and a gallium arsenide light-emitting diode. The control circuit ( almost always as an integrated circuit (IC ) is performed ) is generated for each key a specific code, and supplies the resulting modulated carrier frequency (eg 36 kHz ) to the light emitting diode. Often, a driver transistor is interposed for reinforcement. The modulation frequency is generated by an oscillator, which is usually operating with a ceramic resonator.

Receiver

The receiver, such as in the television receiver consists of a photodiode, a selectively operating at 36 kHz controlled amplifier (AGC ), and a demodulator which supplies the digital coded signal to the control circuit of the device. Before the photodiode sits an impermeable to visible light blocking filter to, for example, of energy saving lamps to avoid disturbances.

While such receivers were built earlier from discrete components, are available as IC, containing all of these features since the 1990s. Most IC and photodiode are integrated in a colored plastic housing which filters out visible light.

Applications

IR remote controls are used for household appliances, and especially in the field of consumer electronics.

Radio remote controls, see, among others, to open / close garage doors or for locking and unlocking of automobiles ( since the 1990s ) use.

Special shapes

Universal Remote Control

Universal remotes are remotes that can control various devices. It is necessary to distinguish between adaptive remote controls that can be trained using the original remote control and programmable remote controls that can be set by means of a numerical code on the user-friendly devices. Universal remote controls can also both numerical codes for the most popular brand cell phones and learning function for unusual control signals.

Universal remote controls can control multiple devices: Generally, for by so-called device keys operation to a specific device - and can thus control all devices with a single remote control. To reflect the equipment often manufacturer specific code must be entered into the remote control.

The better alternative is to program a ( well-maintained ) database on the Internet ( online connection required), plus an additional learning feature that also may not be functioning commands can be taught correctly.

The more expensive of the universal remotes additionally offer so-called "action -driven activities ", ie first all devices used in the home theater be entered using the manufacturer's instructions and model from a list on the manufacturer's website, then transfer the commands on the remote, then logically linked to one another for different actions. For example, driving on a button next to the displayed in the display "Beamer TV" the screen down, the projector will turn on, the correct video input on the projector is selected, the A / V receiver will turn on and the correct audio input is set. Then turn on the DVD player, the light is dimmed and the movie starts.

In the above scenario, the throughput stated universal remote also controls devices that are addressed via radio, such as electric screen or light via radio outlets. There are commercially affordable converter of infrared to radio, a good find instructions below in the links.

The most widely used have action-controlled universal remotes naturally in home theaters with their usually larger equipment fleet.

Interactive remote control

A special form of the universal remote control represented the " Betty ", an advertised as an interactive remote control unit of Swisscom Fixnet. This came in 2006 on the Swiss and early 2007 on the German market. The remote control bot, accompanying the program some TV stations, on the display games, background information and advertising. Profits were paid out as a bonus.

Collected data were transferred via telephone by means of a built-in modem. The design of the system allowed the providers to monitor the viewing and usage patterns of the viewer.

Only 100,000 Bettys 1,000,000 customers until July 25, 2007 discontinued - After the launch were in Germany instead of the planned 500,000. Betty was discontinued in late 2007 in Switzerland and in Germany. The Betty became an ordinary universal remote control.

An alternative operating system for Betty boop the firmware, named after the cartoon character Betty Boop. So she works as a universal remote for the d- box2, Xbox and other devices.

Gallery

Ultrasonic remote control brand " Grundig ", around 1976

Ultrasonic remote control brand "ITT Schaub Lorenz ", around 1976

Infrared remote control a Philips TV, built in 1978

Wrist Watch with TV and video recorder remote control

Universal switch TV-B -Gone for commercial television, 2008