SRD Duty Cycle Limit
A rule that limits the proportion of the total time a device may transmit within a given time interval. In the 433.050 - 434.790 MHz band the limit is applied as 10 percent, in the 868.0 - 868.6 MHz range as 1 percent, and in the 868.7 - 869.2 MHz range as 0.1 percent.
The aim is to prevent the many devices sharing the same band from drowning each other out. The 10 percent limit means transmission is possible for at most six minutes of the hour; 1 percent corresponds to 36 seconds per hour.
For a remote control, what this means is clear:
- The transmitter only transmits while a button is pressed; it is silent when idle. This behaviour preserves the duty cycle budget.
- Because the budget can be used up quickly during long, uninterrupted movements, designs send the frames intermittently.
- The limit directly affects the choice of sub-band: higher permitted power is not always better, because it may come with a narrower transmission budget.
The practical field consequence is that range and response time drop when many remote controls operate in the same area. This is not a pairing conflict but channel occupancy; every set has its own ID code and a neighbouring remote control's command is not accepted.
The context in which this term is used: Wireless Crane Remote Control Selection Guide