Tests

The ADCP comparison took place during a transit from the shipyard in Tampa, Florida, to Endeavor's home port, Narragansett, Rhode Island (Figure 1), February 17-23, 2001. The ship track included both shallow coastal regions and deep water. Much of the track was along the Gulf Stream; two sections across the Stream were made near the end of the cruise. More ship time for testing had been planned, but was eliminated owing to delays in the shipyard.

Figure 1: R/V Endeavor cruise track and tests (Table 1), Tampa, Florida to Narragansett, RI. Velocity vectors are samples from 40 m taken every 50 minutes. NB data prior to February 20 (2001 decimal day 50.68; test 14) were corrupted and are not shown.

Although we would like to be able to show meteorological data from the cruise, we don't have any. Measurements of pitch and roll are used as an indication of good versus bad weather.

Three types of tests were performed. First, the OS and NB were operated separately and simultaneously, with and without triggering, to check for interference. Second, the ship's speed was varied to compare the OSN, OSB, and NB in terms of data return, depth range, and accuracy. Third, during most of the cruise, when the ship was underway at full speed, the test consisted of simply gathering data with several reasonable configurations, in order to get as broad a comparison as possible among the three instruments. Thirty-one such comparisons were made (Table 1).

Table 1: Test sequences. Start and end times are in 2001 decimal days, where zero is the beginning of the year. The trig column has N to indicate no ping triggering (synchronization between instruments) and YN to indicate that triggering was used during only half of the test; all other tests used triggering. BT column entries of Y denote bottom tracking was turned on; all NB data from tests with OS BT on and ping triggering were subject to interference from the OS BT pings. Depth bin numbers are nominal vertical pulse and sampling intervals in meters; parentheses in the NB bin column show where data were corrupted by the incorrect switch setting on the Peripherals 2 board. In the notes, AT1, AT2, and AT3 mark the three acoustic interference tests, comparing data with synchronized versus unsynchronized pinging. A full Gulf Stream (GS) crossing occurred during test 27. Except during tests 22 (speed test) and 13 (5 kts), the ship was underway at normal cruising speeds up to 11 kts, depending on weather.

	decimal day			OS	OSB	OSN	NB	NB
test	start	end	trig	BT	bin	bin	bin	BT	note
1	47.62	48.46		Y	4		(4)	Y
2	48.47	48.72		Y		8	(8)	Y
3	48.81	48.89	YN		8	8	(8)		AT1
4	48.91	48.94		Y	8		(8)	Y
5	48.95	49.46		Y		8	(8)	Y
6	49.47	49.55		Y	8		(8)
7	49.56	49.63		Y		8	(8)
8	49.63	49.70		Y	8	8	(8)
9	49.71	49.77		Y	8	16	(16)
10	49.86	49.95	N	Y		16	(8)
11	49.97	50.07		Y		16	(8)
12	50.08	50.57		Y	8	8	(8)
13	50.58	50.67				8	(8)		5 kts
14	50.68	50.73				8	8
15	50.77	50.89	YN		8	8	8		AT2
16	50.90	50.94		Y		8	8
17	50.95	50.98		Y	8		8
18	50.99	51.04		Y	8	8	8
19	51.05	51.52		Y		8	8
20	51.53	51.58				16	16
21	51.59	51.63			16		16
22	51.64	51.74			8	16	8		speed test
23	51.76	51.87	YN		16	16	8		AT3
24	51.89	51.98			8		8
25	51.98	52.04			8		8
26	52.05	52.11				8	8
27	52.11	52.65			8	16	8
27	52.11	52.65			8	16	8		GS
28	52.66	52.87		Y	8	16	8
29	52.87	52.88			4	8	8	Y
30	52.89	52.98		Y	4	8	8	Y
31	52.99	53.41		Y	4		8	Y