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Chapter 1: Product description
Dynamic spectrum optimization
The PTP 650 series uses an interference mitigation technique known as Dynamic Spectrum
Optimization (DSO). Both the Master and Slave continually monitor for interference on all channels
and then select the best frequency of operation. This is a dynamic process where the PTP 650 can
continually move channels in response to changes in interference. Two modes of operation are
available:
•
First mode: the two link directions are forced to select the same frequency, determined by the
Master.
•
Second mode: the frequency of operation can be determined independently for each direction.
This mode is not permitted in radar regions.
Radar avoidance
In regions where protection of radars is part of the local regulations, the PTP 650 must detect
interference from radar-like systems and avoid co-channel operation with these systems.
To meet this requirement, the PTP 650 implements the following features:
•
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 at least 60 seconds service outage every
time radar is detected and that the installation time is extended by at least 60 seconds even if
no radar is found.
•
When operating on a channel, the spectrum management algorithm implements a radar
detection function 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
thirty minutes after the impulsive interference pulse was detected.
•
After the thirty 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 a uniform 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 same effect of
spreading the load across the spectrum).
•
The FCC does allow channels to be barred if there is actually interference on them.
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Wireless operation
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