840. How do remote garage door openers work? — JD, Greenville, SC
The communication from the remote to the opener is done with radio waves. When you push the button on the remote, it produces a brief burst of radio waves at a specific frequency and with a selected pattern of pulses. A radio receiver in the opener is continuously looking for a transmission at that same frequency and with that same pattern of pulses. While other garage door openers may use radio waves of the same frequency, it's extremely unlikely that they will make use of the same pattern of pulses. This pattern of pulses is the security code that prevents unauthorized opening of your garage door. These security codes have grown longer and more sophisticated over the years. Early garage door openers had no security code at all and could be opened by almost any radio transmission at the right frequency. You could drive around neighborhoods with a remote and open garage doors right and left. But now the security codes are complicated enough that opening someone else's garage door is almost impossible.