Specifications

System Overview Tsunami MP.11 5012-SUR Installation and Management
Basic Configuration Information
29
• DFS is not a configurable parameter; it is always enabled and cannot be disabled.
• You cannot manually select the device’s operating channel; you must let the unit select the channel. However, you can
specify a particular “preferred” channel that you want to scan first whenever the DFS process starts. You may also
make channels unavailable by manually “blacklist” them and prevent those channels to be scanned, as well as display
the Channel Blacklist Table.
With 5012-SUR units, Dynamic Frequency Selection (DFS) is enabled automatically based upon the country you select.
You can tell DFS is in use because the frequency selection field displays only the DFS-selected frequency. DFS scans all
available frequencies, starting with the DFS preferred channel and skipping blacklisted channels, to select the operating
frequency automatically.
A country selection with DFS enabled causes the Base Station to come up in scan mode. It scans the available
frequencies and channels to avoid radar and selects a channel with the least interference.
NOTE: Scanning is performed only on the frequencies allowed in the regulatory domain of the country selected when it is
required for radar detection and avoidance.
To comply with your country’s regulations, change the DFS selection to specify your country. You can do this by logging
into the unit, clicking Configure > System. There is a drop-down box labeled Country with all available countries from
which to select. Choose your country, configure the unit as required, and reboot
for the settings to take effect.
The SU also comes up in scan mode to scan all available frequencies to find a BSU with which it can register. Scanning
may take several minutes. After establishing a wireless link, the wireless LED stops flashing and continues to shine
green.
NOTE: Because DFS may need to scan for radar on multiple channels, you must allow a sufficient amount of time for the
units to start up. This is considerably longer than when the unit is not using DFS. This is expected behavior.
Startup time is within four minutes if no radar is detected, but up to one minute is added for every selected
channel that results in radar detection.
DFS is required for two purposes:
1. Radar avoidance both at startup and while operational. To meet these requirements, the BSU scans available
frequencies at startup for the presence of a radar signal on all available frequencies. If a radar signal is detected on
any DFS enabled channel, the system will blacklist the channel for a period of 30 minutes in accordance to EN301-
893. Once fully operational on a frequency, the BSU actively monitors the occupied frequency for radar interference. If
radar interference is detected, the BSU blacklists the channel, logs a message and rescans to find a new frequency
free of radar interference.
Radar detection is performed only by the BSU and not by the SU. When an SU is set to a country in which DFS is
used, it scans all available channels upon startup looking for a BSU that best matches its connection criteria (such as
Base Station System Name, Network Name, and Shared Secret). The SU connects to the BSU automatically on
whatever frequency the BSU has selected. Because of this procedure, it is best to set up the BSU and have it fully
operational before installing the SU, although this is not required. If a BSU rescans because of radar interference, the
SU loses its wireless link. The SU waits 30 seconds (when the Mobility feature is enabled, the SU starts scanning for
a BSU instantly rather than waiting 30 seconds); if it finds that it could not receive the BSU in this amount of time, it
rescans the available frequencies for an active BSU.
2. Guarantee the efficient use of available frequencies by all devices in a certain area. To meet this requirement, the
BSU scans each available frequency upon startup and selects a frequency based upon the least amount of noise and
interference detected. This lets multiple devices operate in the same area with limited interference. This procedure is
done only at startup; if another non-radar device comes up on the same frequency, the BSU does not detect this or
rescan because of it. It is expected that other devices using these frequencies also are in compliance with country
regulations, so this should not happen.
Transmit Power Control
Transmit Power Control is a manual configuration selection to reduce the unit’s output power. The maximum output
power level for the operating frequency can be found in the event log of the unit’s embedded software.