Due to the remote location of some stations, an Internet connection may not be available. However, if a station has a line of sight to another station or location that does have reliable Internet access, the best option can be to establish a radio telemetry link from the station without an Internet connection to another site where an Internet connection is available. It is also advantageous to combine multiple stations via radio link into one network with a common Internet connection, cutting down on the number of Internet connections that need to be maintained and paid for. In the PBO GPS Network UNAVCO utilized Intuicom 900MHz spread spectrum radios for the majority of installations. These radios are compact, very rugged, have relatively low power consumption, are easy to use and have exceptional long range transmission characteristics.
Radio networks can be set up two different configurations. These are Point-to-Point and Point-to-Multipoint. A point-to-point network consists of a radio located at an Internet gateway, linked to a single remote end point station. A Point-to-Multipoint network consists of one gateway radio located at the Internet connection, linked to end point radios located at the remote GPS stations. Sometimes if there is not direct line of sight between a station and a gateway it is necessary to install a repeater radio in a location that has line of sight to both. In these cases it is often preferable to set up a series of point to point links, as this tends to be more reliable and allows for faster data transfer between stations.
The following table outlines the published specifications for some of the common types of radios used by UNAVCO.
|Manufacturer||Model||Radio Frequency||Useful Range||Power Consumption||Serial Capability (Y/N)|
|Intuicom||EB-1||900 - 928 MHz||60 miles LOS||6 W max||N|
|Intuicom||EB-3plus||902 - 928 MHz||60 miles LOS||6 W max||Y|
|Intuicom||EB-6plus||902 - 928 MHz||40 miles LOS||6 W max||Y|
|Intuicom||EB-58||5.8 GHz||60 miles LOS||7 W+||N|
This network links AC12 Chernabura, AC28 Nagai Island and AB06 Sand Point via an Intuicom EB-1 Point to Multipoint radio network to a common Hughes VSAT internet connection at C154 in Sand Point, AK that is co-located with GPS station AB06. The gateway radio is located at VSAT at Sand point; there are end point radios at AC28 and AC12. A repeater radio located a C153 relays the links from AC28 and AC12 over the topography that obstructs line of sight between these two stations and C154.
AB25 Tatalina Radio Repeater — AC Powered site with an aluminum enclosure and an externally mounted radome covered yagi (recommended to for all external applications where possible).
AV24 Unimak Volcano GPS Station — A typical data telemetry radio installation inside a standard PBO hut. The EB3plus radio in this location is mounted to an aluminum back panel; it is wired to the antenna that is attached to a mast installed in the center of the hut.
For more information about radio communication technologies, please see the UNAVCO Knowledge Base on Radio Modem Summary.
Last modified: Friday, 01-Apr-2016 23:53:08 UTC