Site survey troubleshooting – Banner SureCross DX80 Wireless Networks User Manual

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Result

Description

Yellow

Packets received at a good signal strength. A good signal is between
−90 and −100 dBm at the receiver.

Red

Packets received at a weak signal strength. A weak signal is less than
−100 dBm at the receiver.

Missed

Packets not received on the first transmission and requiring a retry.

Judging if the reliability of a network’s signal meets the needs of the application is not simply a matter of green, yellow, and red packets
received. In normal operating mode, when data packets are not received, the transmitter re-sends the packet until all data is received.
For slow monitoring applications such as a tank farm, where data is required in terms of seconds or minutes, receiving most of the data in
the ‘red’ range, indicating a weak but reliable signal, transmits enough data for accurate monitoring. Nodes positioned near the outside
range of the radio signal may have 90% of the data packets received in the red zone, again indicating a weak, but reliable signal.
A good rule of thumb is to keep the missed packets average to less than 40%. When the network misses more than 40% of the data
packets, the signal is usually too unreliable or obstacles may be interfering with the signal. When Site Survey reports the missed packets
are 40% or higher, improve the radio system performance by:

• Mounting the network’s antennas higher,
• Using higher gain antennas, or
• Adding data radios to the network.

Mounting the devices’ antennas higher allows the radio signal to clear obstacles in the area and improves the line of sight between
SureCross® devices. Higher gain antennas focus the energy of the radio signal in a specific direction and extend the signal’s range.
Using data radios is another option to consider when trying to extend the range of a radio network. For more information on data radios,
please refer to Banner’s white paper on range extension on

www.bannerengineering.com/surecross

Site Survey Troubleshooting

Some tips and tricks about improving radio signal reception may improve the site survey results.

Problem

Solution

Marginal Site Survey (RSSI) Re-
sults

If the distance between devices is greater than about 5,000 meters (3 miles) line-of-sight *OR*
objects, such as trees or man-made obstructions, interfere with the path, and the MISSED packet
count exceeds 40 per 100 packets, consider the following steps:

• Raise the DX80 units to a higher elevation, either by physically moving the devices or instal-

ling the antenna(s) remotely at a higher position.

• Use high-gain antenna(s) such as Yagi and/or Omni (see Accessories).
• Decrease the distance between devices.
• Use data radios to extend the position of the Gateway relative to the host system.

Conducting a Site Survey and Interpreting the Results