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Troubleshooting
9.2
Duty cycle
The wireless DHC accessories operate in the following fre-
quency bands:
•
868,000~868,600 MHz
•
869,400~869,650 MHz
In order to safeguard operation of all devices working in this
range, it is legally required to limit the transmission time of
devices. Limiting the transmission time minimizes the risk
of interference.
The 'duty cycle' is the maximum transmission time. It is
the ratio of the time that a device is actively transmitting
in comparison to the measurement period (1 hour), and is
expressed as a percentage of 1 hour.
If the total amount of allowed transmission time is reached,
the DHC accessory will stop transmitting until the time limit
is reached.
For example, when a device has a duty cycle limit of 1%, it
is only allowed to transmit 36 seconds in 1 hour. After this, it
will stop transmitting until the 1 hour limit is reached.
DHC accessories fully comply to this limitation and use 2
frequency bands with a duty cycle of respectively 1 % and
10%.
During normal operation of the DHC accessories, this limit
is not usually reached. However it is possible that the limit
is reached during start-up or during a fresh installation of a
system. In this case, the LED of the accessory lights up red.
It may be non-responsive for a short period (max. 1 hour),
until the time restriction for transmission has expired. After
30
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