We are designing a 868MHz keyfob, which is transmitting in a band with a 1% duty-cycle limit.

According to the ETSI EN 300 220-1 standard section 5.4, the duty-cycle should be measured for a period of 1 hour. In normal use, the keyfob will transmit well below 1% duty-cycle. But if some user activates the keyfob rapidly for a long period, the 1% duty-cycle will be violated.

Section 5.4.2 of the standard states that the representative period should be the most active in normal use, so does this mean, that we do not need to make some algorithm, that would block transmissions, if a user activates the keyfob more than intended. ?

  • \$\begingroup\$ What prevents you from transmitting for 1ms and then be silent for 99ms? \$\endgroup\$
    – PlasmaHH
    Nov 15, 2017 at 8:39
  • \$\begingroup\$ We are transmitting for 1 sec, this is due to reliability of the keyfob. But I think this is minor important for the question, it is more a principal question. \$\endgroup\$
    – JakobJ
    Nov 15, 2017 at 8:44
  • \$\begingroup\$ You will have to prove that after that 1 sec, the keyfob doesn't transmit for 99 seconds, regardless of the user's actions. \$\endgroup\$
    – Lior Bilia
    Nov 15, 2017 at 12:04
  • \$\begingroup\$ I think there should be some limit on the repetition of the transmission of signals. I tried to search but couldn't figure out. So, in that case you need to take care of that in the firmware that idle time should not be less than standard definition. \$\endgroup\$
    – Vishal P
    Nov 15, 2017 at 12:17
  • \$\begingroup\$ But the standard states "normal use", I was hoping that this could be interpret as "a user would normally never press the keyfob more than 36 times pr. hour". \$\endgroup\$
    – JakobJ
    Nov 15, 2017 at 12:24


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