The Integrated GPS and Occultation Receiver (IGOR) is manufactured by Broad Reach Engineering and is based on the heritage of the JPL (Jet Propulsion Laboratory) Black Jack receiver. Since KOMPSAT-5 uses 1553B bus as a main interface, the KOMPSAT-5 IGOR has been modified to include a 1553B interface. An internal solid state recorder (SSR) was added in the IGOR for storing receiver output data during the mission. Since KOMPSAT-5 carries a SAR device, IGOR uses four external filters between each of the GPS antennas and IGOR in order to avoid interferences from the SAR devices. Figure 2 shows an engineering model of the KOMPSAT-5 IGOR receiver. One of the filter/preamp assemblies is on the top of the receiver frame. The KOMPSAT-5 IGOR has two POD antennas and two occultation antennas. Figure 3 shows the KOMPSAT-5 POD and occultation antennas. The POD antenna is a patch type omnidirectional antenna attached on the - Z plane of the KOMPSAT-5.The occultation antenna is a patched array type antenna to optimize the performance for an occultation science. The occultation antennas are installed in the velocity and anti-velocity direction for observing rising and setting occultations. The normal operation mode of KOMPSAT-5 is a 33.7° tilted right looking mode. For the occultation antennas, the tilt angle is compensated by using appropriate brackets. Figures 4 and 5 show the configuration of the KOMPSAT-5 POD and occultation antennas, respectively. Table 1 summarizes the characteristics of the KOMPSAT-5 IGOR.
Table 1 KOMPSAT-5 IGOR characteristics
Internal memory Bus interface POD antenna Occultation antenna External signal filter RF port
128 MB solid state recorder MIL-STD 1553B bus/RS422 Two patch type antennas Two patched array antennas Four Filter/Preamp assemblies Four RF ports, 12 channels per port
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