User's Manual

PTP 250 User Guide Wireless operation
phn-2182_002v000
May 2011
1-19
Radar avoidance
In regions where protection of radars is part of the local regulations, the PTP 250 must
detect interference from radar-like systems and avoid co-channel operation with these
systems.
To meet this requirement, the PTP 250 implements the following features:
ETSI regulations
The regulations have radar detection requirements for both master and slave devices.
The requirements for a master device are:
• The device can only transmit on available channels, of which there are none at
initial power up. The radar detection algorithm will always scan a usable channel
for 60 seconds (channel availability check) for radar interference before making
the channel an available channel.
• As a result of this compulsory channel scan, there is a service outage of at least
60 seconds every time radar is detected, and the installation time is extended by
at least 60 seconds even if no radar is detected on the channel.
• When operating on a channel, the spectrum monitoring algorithm implements a
radar detection function (in-service monitoring) which looks for impulsive
interference on the operating channel. If impulsive interference is detected,
spectrum management will mark the current operating channel as having
detected radar (unavailable channel) and initiate a channel hop to an available
channel. The previous operating channel will remain in the unavailable state for
30 minutes after the impulsive interference pulse was detected.
• After the 30 minutes have expired the channel will be returned to the usable
channel
pool.
• There is a secondary requirement for bands requiring radar avoidance.
Regulators have mandated that products provide an approximately even loading
of the spectrum across all devices. In general, this prevents operation with fixed
frequency allocations. However, ETSI regulations do allow frequency planning of
networks (as that has the effect of spreading the load across the spectrum).
NOTE
The Master device will not initiate any transmissions on channels which
overlap the band 5600-5650 MHz as the radar detection requirements are
more severe.