User's Manual

5 Radio Link Planning and Regulations
58
5.3 Operational Restrictions
5.3.1 Radar Avoidance
Radar Avoidance requires that equipment used in the region:
• Detects interference from other systems and avoids co-channel operation with these
systems, notably radar systems.
• Provide on aggregate a uniform loading of the spectrum across all devices, that is, Fixed
Frequency operation is not allowed.
Radar avoidance is not applicable to the PTP 25600 product or the PTP 45600 product.
To address the primary aims, the Spectrum Management algorithm implements a radar
detection function which looks for impulsive interference on the operating channel only. 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
thirty minutes after the last impulsive interference pulse was detected. After the thirty minutes
have expired the channel will be returned to the usable channel pool.
The equipment 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
for radar interference before making the channel an available channel. This compulsory
channel scan will mean that there is a 60 seconds service outage every time radar is detected
and that the installation time is extended by 60 seconds even if there is found to be no radar
on the channel.
NOTE: On system installation or start-up this extends the initial scan time of the Master unit
by 60 seconds. To address the “provide aggregate uniform loading of the spectrum across all
devices” requirement, the channel selection algorithm will choose a channel at random from a
list of useable channels. The channel selection algorithm is initiated at link initialization and
when radar interference is detected.