Specifications

30 Rockwell Automation Publication AG-SG001G-EN-P - April 2015
Chapter 2 Choosing a Telemetry Network
Disadvantages
• Repeaters are needed to extend transmissions over distances greater than
15 miles.
• Most radio link frequencies are allocated and regulated by the FCC. In
urban areas, fewer data-transmission frequencies are available.
• The signal from 900 MHz and higher transmitters can experience
distortion and interference, and can be affected by poor weather
conditions.
• The narrow bandwidth carries only one channel.
• You incur an initial expense for equipment; less expensive than microwave
or satellite.
Equipment Required
• Tra n s m i t te r s
• Receivers
• Antennas
• Repeaters are needed to transmit greater distances and over hills and
mountains
Geosynchronous Satellite
Geosynchronous satellites use a high-frequency (GHz) radio transmission to
route transmissions between sites. The satellite's orbit is synchronous with the
earth's orbit (geosynchronous); therefore, the satellite remains in the same
position with respect to the earth. Satellites receive signals from and send signals
to parabolic dish antennas.
Advantages/Capabilities
• The transmissions can link sites almost anywhere on Earth.
• A constant connection exists.
• You incur a monthly service fee.
• You can lease circuits from a telephone company
• Rates can be competitive with leased lines, depending on the total distance,
remote station locations, and amount of data being transmitted.
• The media offers high reliability and data integrity.
• You do not need to ‘group’ remote sites because the communication media
usually is accessible.
Earth