January 6, 2003

Locus Radios Offer High Reliability and Security in Distribution Automation Systems.

For transmission distances greater than 100 feet, wireless modems are actually more cost effective than cable and fiber-optic in many applications. The wireless advantage grows when ease of maintenance, network complexity, transmission distance, and network reconfiguration are factored in. Often used for SCADA communications, wireless modem technology has undergone some remarkable advances. The new Locus OS2400 Series Radios operate in the license-free 2.4 GHz ISM band, and are ideal for use in international markets where the 900 MHz band is licensed, or in domestic markets where the 902-924 MHz band is overcrowded with traffic from pagers, cell-phones, and other unlicensed radio products.

Designed to operate in high interference environments, the Locus radios combine advanced frequency hopping spread spectrum, digital signal processing technology, sharp sensitivity, and antenna diversity to provide exceptional interference rejection, and reliably communicate critical system data. Networks can be setup for point-to-point, broadcast, or point-to-multipoint modes. The output signal power is user configurable, and 32 data channels allow multiple networks to operate in the same area.

Data entering the radio is grouped into packets for routing over the network. A device address is parsed from the data, and a Network Address table is used to determine the destination Radio Address assigned to that device address. When the beginning of a DNP message sequence is recognized, the device address and message length are both parsed from the data. The message is complete once the number of characters determined from the message length is received.

Diagnosing and repairing a cable problem can be time consuming and expensive. A malfunctioning wireless modem can be immediately identified using the Microsoft Windows® based diagnostics supplied with the modems. The faulty component can be quickly replaced, which greatly minimizes network downtime.

The Locus OS2400 Series Radio can be configured as a master, remote or repeater radio. Industrial wireless modems can typically support up to 2000 radios in a network, and many layers of repeaters to cover distances of hundreds of miles. Physical structures that could block radio waves, such as metal walls, no longer represent barriers to reliable wireless operation — a repeater radio appropriately positioned will allow the signal to go around the impasse. High gain, directional antennas such as Yagis or parabolics can be used for long distance communications.

Secure communication is important in a Distribution Automation system. Industrial modems have been specifically designed to prevent undesired access to data and to other manufacturers’ radios, and it is virtually impossible for a would-be intruder to access raw or encrypted data from these devices. In addition, any spread spectrum modem transmits in a predefined pattern that requires not only the receiving and transmitting modems to know the pattern, but also to be synchronized.

The distribution automation specialists at S&C can integrate the right combination of comm options for the lowest initial system cost and the strongest communication system performance.