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<br />stored longer. In the case of a failure in either the Direct Readout Ground <br />Station or the central computer, the data will not be lost but will be on-line <br />on the backup system. A modem-linked computer port will allow direct access <br />by the DWR to the data. As the two systems are identical, the.re will be no <br />problems with data format. As soon as the DWR systems come back on-line, the <br />data will be transferred by computer-to-computer dump. The backup should be <br />operational by early 1988. <br /> <br />Repositioning of the GOES spacecraft and various GOES operating malfunc- <br />tions resulted in having to redirect the remote Vagi antennas and the system's <br />receive dish on several occasions. GOES-WEST (GOES-3) was utilized by the DWR <br />until November, 1986, when the. spacecraft went into an ell iptical orbit and <br />could not be stabilized due to lack of on-board propellant. TheDWR receive <br />dish, operating without an automated tracking system, lost line-of-sight <br />communications with the spacecraft approximately 40% of each day. Trans- <br />missions were switched over to GOES-CENTRAL (GOES-6). GOES-WEST, positioned <br />at 136.W equatorial, requires antenna orientation of 207.W (magnetic) and an <br />elevation of 36.. GOES-CENTRAL, positioned at 107.W equatorial, requires <br />antenna orientation of 168.W (magnetic) and an elevation of 4S.. Since it was <br />evident that switching transmission operations between GOES-WEST and <br />GOES-CENTRAL would be necessary in the future, the remote Vagi antennas were <br />oriented to a point between the spacecraft. As the Vagi antenna transmits a <br />wave length beam with an effective field-of-view of 42., this orientation <br />would allow for transmissions to be received by both spacecraft. <br /> <br />The launch of GOES-7 on February 26, 1987, resulted in GOES-7 being moved <br />to the EAST position at 7S.W equatorial, GOES-S (GOES-EAST) was moved to the <br />CENTRAL position, and GOES-6 (CENTRAL) was moved to the WEST position. GOES-6 <br />repositioning began on March 2S, 1987, and was completed on April 21, 1987. <br />Movement of the spacecraft was approximately 1. per day. As the DWR receive <br />dish has a field-of-viewwith GOES of about 2., the dish had to be redirected <br />every two days. This is accomplished by physically moving the dish on an <br />a-ring and centering on the strongest readable signal. <br /> <br />DCS operation .has secondary priority according to NOAA-NESDIS operating <br />guidelines for GOES. The GOES weather imaging has the number one priority. <br />As a consequence, the spacecraft are frequently moved to facilitate the moni- <br />toring of major weather events, i.e. hurricanes. <br /> <br />The GOES spacecraft undergo an eclipse period each spring and fall, where <br />the on-board solar panels are not able to function. For a period up to two <br />hours per day, NOAA-NESDIS deactivates the DCS due to insufficient power. The <br />periods run February 26 to April 12 and August 31 to October lS, occurring <br />between 2330-0130 MST. There is minimal impact on DWR DCP transmissions as <br />less than 20% of the DCP's are scheduled to transmit in the self-timed mode <br />during this period. To compensate, redundant data sets (current 4 hours and <br />previous 4 hours of data) are transmitted at each self-timed transmission. <br /> <br />NOAA-NESDIS runs tests on all DCS channels to check the integrity of the <br />system. Test address ISC94F4E is utilized. This transmits over regularly <br />scheduled transmissions and causes loss of such transmissions. It is not a <br />significant problem as it affects less than 1% of the transmissions on a given <br />day. <br /> <br />-14~ <br />