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Multiple Address (MAS) Radio

A Multiple Address (MAS) Radio link is a preferred communication medium for supervisory control and data acquisition (SCADA) and distribution automation (DA) radio communications. A typical MAS radio system consists of a master station and several remote stations. The master station connects to a data acquisition controller either directly, via dedicated wireline, or wireless link. Each remote radio station connects to such a data collection unit as Remote Terminal Unit (RTU), Programmable Logic Controller (PLC) or Intelligent Electronic Device (IED). The MAS Radio is a single channel system that the master unit uses to communicate with multiple remote radio station units. The master unit is always ready to transmit and receive to prevent delays due to transmitter keying. Each remote unit with a unique address is always in the listening mode until polled and is than ready to transmit. For a large service area many, master units are needed to cover groups of remote units. Each link covers typically 15 km which can be extended by using repeaters. Data rate is up to 4.8 kbps, can be increased to 9.6 kbps but the coverage reduces. Federal Communications Commission (FCC) allows channel bandwidth of 12.5 kHz which limits the expansion and upgrade capability of the MAS Radio System.

According to [1], main features of technology include
- Technology : Radio
- Frequency : 895 to 960 MHz transmit/receive frequency pair
- Bandwidth : 25kHz for existing frequencies, 12.5kHz for new frequencies
- Operation : Requires line-of-sight, point-to-multipoint for master and remote radios
- Capacity : Can be expanded by using more master radios, but will be limited by how fast remotes can be polled and system scan period allowed
- Coverage : Each link is typically 15km
- Data rate : Up to 4.8kbps, can be increased to 9.6Kbps but coverage will be reduced
- No. of channels : Minimum separation between adjacent channels is 25kHz for previous frequency allocations and 12.5KHz for new frequency allocations
- Modulation : Frequency shift keying (FSK)
- Power : 5W master, 1W remote
- Regulatory : Frequency licensing required


MAS radio is the preferred communication means used widely by utilities for SCADA and DA systems. In addition, MAS radio is also widely used for data communications in railroad monitoring, oil and gas pipeline monitoring, and water and wastewater monitoring systems.

Key Technology Area: 
Integrated Communications

Sample Vendors:

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