Motorola PTP 500 User's Guide download pdf (Page 67)

PTP 300 and PTP 500 Series User Guide Wireless operation

phn-1115_006v000

Sep 2010

1-27

Radar avoidance

In regions where protection of radars is part of the local regulations, the PTP 300 and

PTP 500 must detect interference from radar-like systems and avoid co-channel

operation with these systems.

To meet this requirement, the PTP 300 and PTP 500 implement the following features:

• 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 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 there is found to be no radar on the channel

• 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.

NOTE

Fixed frequency allocation is not recommended in radar avoidance regions,

as any radar detection would cause a system outage of at least 30 minutes.

1 ... 66 67 68 ... 447

No comments

Motorola PTP 500 User's Guide Page 67