We all are familiar with the VSAT (Very Small Aperture Terminal) network, which encompasses a hub and multiple, identical remote stations. VSAT licenses in Ku-band have been used for a long time and provide what is popularly called “blanket license” authority.
Interestingly, there is an equivalent concept in C-band, the C-band Small Aperture Terminal (CSAT). This article appears on the 10th anniversary of the implementation of CSAT regulations in the United States and examines the advantages and disadvantages of CSAT licenses.
Comparable to VSAT licenses, CSAT licenses provide a so-called “blanket” authority to operate multiple, identical remotes controlled by one or more master stations. Yet, this is where the similarities end. Despite the decade-long existence of the CSAT concept, CSAT licenses still lack the popularity that VSAT licenses have enjoyed for so long. Here is why:
Location Restrictions and Frequency Coordination
VSAT terminals may be moved at will without the need to report geographical location or modify the license. This is possible because conventional Ku-band is allocated exclusively to fixed satellite services.
In contrast, conventional C-band is shared on a primary basis between satellite and fixed microwave services. Therefore, every CSAT remote terminal must undergo frequency coordination for a given set of geographic coordinates. Any change in location requires a new frequency coordination as well as a modification of the CSAT license.
Spectrum Allocation and Number of Satellites
CSAT networks are limited to 20 MHz of spectrum for the uplink and 20 MHz for the downlink per satellite. There can be up to three satellites per license, and the frequencies can be different for each satellite. This totals a maximum of 120 MHz of combined spectrum for a CSAT license. In other words, a CSAT license is limited to 12 percent of the 1,000 MHz of spectrum available in conventional C-band.
Compare this with Ku-band VSAT licenses and regular C-band licenses that have access to the entire Ku-band spectrum and full satellite arc. Put in this light, this spectrum ceiling places CSAT networks at a significant disadvantage with regard to the ability to expand the number of remotes.
Terminal Reporting
Licensees of CSAT networks have an obligation to file an annual report with the U.S. Federal Communications Commission (FCC) detailing all operational Earth stations in the system. This report also must contain a list of all stations deactivated during the year. The FCC then issues a public notice reporting the stations that were deactivated that year.
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