Range and resolution

As expected, in narrowband mode the OS-75 was able to profile about twice as deep as the NB-150 (Table 2; Figure 5. The greatest NB range was about 400 m, versus about 800 m for the OSN. More typical ranges were 350 m and 700 m, respectively. Under good conditions, The OSB range was about 85% of the OSN range. The range of all instruments and modes was reduced in rough weather, particularly as the ship's pitching increased. The percentage of good velocity estimates (based on editing in each instrument and data acquisition system) was most dramatically reduced in the OSB over the entire potential profiling range. Both OSN and OSB maintained their highest percent good in their top bins, but NB percent good was reduced in the top few bins and in the deeper bins.

Table 2: Depth ranges during representative tests, using 5-minute averaged data, requiring at least 30% good data.

Figure 5: Ship motion and depth range of the three virtual instruments. The top panel shows 5-minute maximum absolute values of roll (red circles) and pitch (black plus signs), together with ship's speed (green). The lower three panels show the percentage of good velocity estimates as a function of time and depth for the NB, OSB, and OSN virtual instruments.