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322 C. Meinig et al.Figure 5: Histogram of station sites, deployment durations, and percentage of data return for the year1997–2001.
ITS 2001 Proceedings, NHTMP Review Session, Paper R-24 323Table 1: Performance of the DART array responding to scheduledtransmission and random events.Events 1997 1998 1999 2000 2001Scheduled TransmissionsScheduled/received 0/0 0/0 0/0 4/4 *tsunami test transmissionsRandom TransmissionsTsunami 0 0 0 0 0Earthquake 0 0 2a,b 2c,d 1eFalse Trigger 0 0 0 0 0* Scheduled for July and October 2001a = D123 station 10/19/99b = D157 station 12/9/99c = D130 station 6/2/00d = D130 station 8/10/00e = D157 station 1/10/01In summary, the DART array has gone through two phases of development,“R&D” and “Prototype” array. Many engineering improvement weremade during the “R&D” phase to boost reliability and decrease costs. Theprototype DART array has performed very well with: 1) high data returns;2) excellent response to scheduled and random events; and 3) no false alarmsduring the 5-year development period.4. Data DropoutThe most significant cause of data dropouts from the 1997 and 1998 R&Ddeployments was poor acoustic communications with the seafloor BPR. Toa large measure, this has been corrected through hardware, software, andpackaging changes of the acoustic modems.The D157 station correctly triggered on a January 2001 earthquake, butfailed to return to the low-power “tide” mode after the expected periodof time. The buoy remained in the high power “trigger” mode for over 2months until all battery power was consumed. The buoy has recently beenrecovered and the cause of this failure is now under investigation. Someadditional isolated causes for data losses are listed below: GOES satellite: Dropouts have occurred during times of high solarflare activity. GOES transmitter: Commercial product failures; changed vendors. Isolated cable and connector problems. Tower failures: During the harsh winter of 1998, two surface buoytowers were destroyed, severing the satellite link. Aluminum towerconstruction and weld inspection was improved and the problem hasnot reoccurred.
Page 4 and 5: 320 C. Meinig et al.Figure 3: DART
Page 8: 324 C. Meinig et al.5. Future WorkI

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