Garage door remote control
Garage door handheld transmitters are used for radio remote control of garage doors . They make it possible to send a command from a distance using a radio signal. The radio command is received by a receiver, which then triggers a predetermined action.
General
There are around 500 types of hand-held transmitters for controlling garage doors in Europe . Many models are not compatible with each other. In addition to color, shape, buttons and battery, there are technical differences in operating frequency, modulation and coding. Only compatible radio systems can work together. For the procurement of spare parts or reorders, it is therefore necessary to precisely determine the existing radio system (type) of your own garage door drive.
Operating frequency and modulation
The control command from the hand transmitter to the radio receiver is transmitted via a modulated radio signal. The following frequencies are mainly used in Germany.
| Frequency (MHz) | modulation |
|---|---|
| 26.975 | AT THE |
| 26,995 | AT THE |
| 27.015 | AT THE |
| 40.685 | AM + FM |
| 433.92 | AM + FM |
| 434.42 | FM |
| 868.3 | AM + FM |
| 868.865 | FM |
The two different types of modulation are understood as follows:
- AM = amplitude modulation , i.e. H. the hand-held transmitter is switched on and off electronically in the rhythm of the coding. The height of the amplitude, i.e. the deflection, is changed.
- FM = frequency modulation , i.e. H. the operating frequency of the hand-held transmitter is changed slightly electronically in the rhythm of the coding. The frequency of the amplitude in a certain time unit is changed.
Encodings
Coding is required so that a hand-held transmitter only controls the associated radio receiver or devices . This is to prevent third-party garage door transmitters from operating a radio receiver, thus preventing unauthorized access.
The following coding systems are common:
- 12-bit linear code, usually adjustable via coding switch in the hand-held transmitter
- 18-bit linear code, partially adjustable via coding switch in the hand-held transmitter or permanently set by the manufacturer.
- Rolling code, rolling code, Keeloq , Somloq etc .; Changing or rolling code, permanently programmed by the manufacturer without a coding switch in the hand-held transmitter.
Learning and malfunctions
There is usually a so-called "learn button" on the receiver. After pressing it, it is ready to teach-in the hand-held transmitter. Usually an LED indicates readiness to learn.
Interference occurs when the range is too short or the distance between transmitter and receiver is not free of obstacles. If sources of interference such as computers, baby monitors, wireless headphones, etc. transmit on the same frequency, communication can be interrupted. In the case of car models with a heated windshield , the fine wires for the anti-fogging protection can lead to a reduced range.
Individual evidence
- ↑ Learning process: video . As of January 13, 2020.