DGPS MAX

1.5.1.2 WAAS Signal InformationWAAS and other SBAS transmit correction data on the samefrequency as GPS, allowing the use of the same receiver equipmentused for GPS. Another advantage of having WAAS transmit on thesame frequency as GPS is that only one antenna element is required.In the case of the CDA-2MAX antenna, a second antenna element isrequired internally for the beacon sensor within the DGPS MAXreceiver. Further, the internal GPS / WAAS antenna has beendesigned for reception of OmniSTAR signals, which also broadcast inthe L-band. More about the CDA-2MAX antenna is provided inSection 1.8.1.5.1.3 WAAS ReceptionSince WAAS broadcasts in the L-band, the signal requires a line ofsight in the same manner as GPS to maintain signal acquisition.Currently, two commercial satellites are transmitting WAAS data forpublic use, and one each is located above both the Pacific and Atlanticoceans. Due to their location away over the oceans, these satellitesmay appear lower on the horizon, depending on your geographicposition on land. When using WAAS correction data, the DGPS MAXis able to provide you with the azimuth and elevation of both satellitesto aid in determining their position with respect to the CDA-2MAXantenna. More about this feature is described in Section 5.10.1.1.5.1.4 WAAS CoverageFigure 1-3 depicts the current WAAS coverage as provided by thecurrently leased Inmarsat Atlantic Ocean Region - West (AOR-W) andPacific Ocean Region (POR) geostationary satellites. This figureapproximates the coverage of these satellites by depicting coveragewithin the white shaded region. Within the white shaded coveragearea, at least one of the two satellites is available by line of sight.Within the overlap area, both satellites may be accessible.DGPS MAX Reference Manual 10