## 2 Development of the Profiler
### Cyclogram of the Winchi Profiler's Operation  
The profiling schedule and control parameters, e.g., motor power rate, can be configured using Bluetooth before deployment, e.g., boarding a boat. In water, the device is operated using the MCU, and it repeats all operations multiple times, including sinking and rising. However, certain parameters can be configured remotely using a GSM link. The parameters are GSM communication timeout, LED flashing, duration of the pressure measurement in parking mode, and threshold height of the sea surface wave, which would be unsafe for profiling. A high-level description of the instructions to complete the profiler mission is defined step by step. Figure 9: GPS/GSM module of the profiler—Winchi: (1)—pressure-proof housing, (2)—end cap made of acrylic, (3)—cap nut, (4)—GSM antenna (spiral), (5)—light reflector (white plastic caved cover), (6)—LED flashlights (only 2 pieces of the total 8 pieces are shown), (7)—air–sea interface sensor, (8)—data I/O and power connector, and (9)—mounting clamp. The antenna of the GNSS navigation receiver is located behind the light reflector (not shown). 1. Program the device to operate: set the mission parameters. Upload the mission schedule. Set a timeout prior to the initiation of the mission (up to 30 min (by default)). 2. Start mission: Initiate automatic operation modes. Switch on the LED beacon. The wire is released to ascend to consider the starting position at the sea surface. Then, the external sensors are turned off. 3. Profiling cycle 1. Keep the profiler floating on the sea surface--turn on the SurffHold function. When the device submerges for more than 15 s owing to wave action or current, SurffHold switches on the motor to spool more wiring to ensure that the air-sea interface sensor remains above the waterline. As soon as the air-sea interface sensor rises above the waterline or the wire tension drops below a predefined threshold, SurffHold cuts off the motor power. 2. Navigate--Acquire a GPS position. 3. Communicate--Transmit the telemetry and measurement data and receive control commands. Turn off SurffHold after the communication is accomplished or timed out. 4. Count the profiling cycles--If the predefined maximum number of cycles is reached, the device switches to the user direct control mode with the transmission of telemetry every 15 min. Otherwise, a new cycle is initiated. 5. Descend--Switch on the external sensors and motor to wind the wire. 6. Save energy--Turn off the LED beacon while descending below a depth of 2 m. 7. Park--Turn off the sensors after descending to the predefined parking depth. 8. Sleep--Set the MCU to sleep mode. The external pressure is measured every 5 min. If the device depth is less than 2 m, cancel the automatic operation mode, set the error code to WireBreak, switch to the user direct control mode, acquire the GPS position, and transmit the alarm data every 15 min. 9. Wake up--Begin the measurement of the external pressure (the sampling is done every 0.1 s (by default)). Collect data on the pressure fluctuations (for 1 min (by default)) and estimate the surface wave height. If the wave height exceeds the threshold height of the sea surface wave (0.8 m by default), then the MCU program moves to step 3 h of this cyclogram, i.e., it turns to another sleep period. 10. Ascend--Switch on the sensors. The system conditions are checked. Switch on the motor to spool the wire 11. Display--Turn on the LED beacon above a depth of 2 m (the activation of the LED beacon can be canceled remotely using a user command during the next communication session). 12. Surfacing--Slow down the motor at a depth of 1.5 m. Check the air-sea interface sensor every 0.2 s. The MCU program has initiated at the beginning of the profiling cycle. 13. End of the mission--The device stays on the sea surface or can submerge to the specified depth for a user-defined period of time based on a user command received via the GSM link. Figure 10 shows a chart of the profiling cycle track.