The maximum sampling rate for current profiling (ADCP) or bottom tacking (BT) depends on a variety of factors, including the configured BT range and the use of an altimeter(ALT).
If you are operating the instrument at a depth of 50m, the maximum sampling rate achievable is 4Hz. This ensures that the BT pings separates each ALT and ADCP ping, as illustrated below:
Spec | 4Hz | ADCP=1 | ALT=1 | |||||
Type | BT | ALT | ADCP | BT | ALT | ADCP | BT | ALT |
Counter | 1 | 2 | 3 | 4 | 1 | 2 | 3 | 4 |
Time | 1 | 2 | ||||||
Answer: at max range, 1.3Hz
If the instrument is operated within a limited range of 25m, a higher sampling rate of up to 8Hz can be achieved.
Spec | 8Hz | ADCP=1 | ALT=1 | |||||||||||||
Type | BT | ALT | ADCP | BT | ALT | ADCP | BT | ALT | ADCP | BT | ALT | ADCP | BT | ALT | ADCP | BT |
Counter | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
Time | 1 | 2 | ||||||||||||||
Answer: 2.6Hz
If the instrument is still operated at 8Hz, but you change the ALT sampling rate to 2, the sequence would change to:
Spec | 8Hz | ADCP=1 | ALT=2 | |||||||||||||
Type | BT | ADCP | BT | ADCP | ALT | BT | ADCP | BT | ADCP | ALT | BT | ADCP | BT | ADCP | ALT | BT |
Counter | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
Time | 1 | 2 | ||||||||||||||
The reason for this is that the unit doesn't define specific "seconds" but operates continuously, resulting in an irregular sample rate.
Updated