Duty Cycle (Transmission Time Ratio)
In the RF context, duty cycle is the ratio of the total time a transmitter may stay on air within a given time window. Looked at over an hourly window, a ratio of 1 percent means a total of 36 seconds and a ratio of 10 percent means 360 seconds of transmission. The aim is to prevent a single device from continuously occupying the shared band.
This limit is not a device feature but a channel access rule laid down for the benefit of everyone sharing the band. It feeds directly into remote control design:
- There is no continuous transmission: even if the button is held down, the transmitter does not transmit without interruption; it sends short packets at certain intervals.
- Budget calculation: the packet air time and the repetition interval are chosen so as to fit within the hourly budget.
- Receiver side: since the packets arrive intermittently, the signal loss timeout is set longer than the normal repetition interval but below the safe limit.
Which ratio applies in which band varies by region and sub-band; different conditions may also be defined for systems that transmit after listening to the channel. For this reason the conditions applying to a product should be read from its declaration of conformity. The practical conclusion is this: a wireless remote control link is intermittent by design, and that is why safety is built on timeout logic.
Context in which this term is used: Wireless remote control installation: pairing, relay, safety