## 4 Conclusions and Future Work  
This work introduces a new design of waves in ice instrument. This instrument is able to perform measurements of sea ice drift using a GNSS module and to measure waves in ice up to a high degree of accuracy (the noise threshold corresponds to a significant wave height of around 0.1 cm for waves with period 16 s, as demonstrated in the laboratory experiments), using an inexpensive 9-degrees-of-freedom sensor and extensive signal processing and noise reduction techniques. In addition, this instrument costs only around slightly under 650 USD in electronics components (including taxes), raw materials, and assembly time, which is around 10 times less expensive to build than the closest, least-expensive commercial alternative we know about (the Sofar Spotter buoy), while being both more sensitive and much better adapted to working in the polar night, when solar input is not available. Battery autonomy using a couple of Lithium D-cells is around 4.5 months, and this can be easily increased by adding more cells if needed. Assembly time has been cut down to no more than typically half an hour per instrument when building a small series of these, thanks to the use of highly integrated open-source development boards, and requires no advanced electronics skills. The code is provided as open source together with the full design blueprints and assembly instructions. Binary precompiled firmware versions are provided for rapid upload to the electronics boards. Additional sensors can easily be added to the instruments. Two-way communications are implemented through highly optimized binary protocols and take place over Iridium, which enables global coverage. All data measurements take place at a fixed time thanks to the real-time clock available on board to allow easy time synchronization, and data are buffered on board the instrument to avoid data loss in case of temporary failure in establishing an iridium communication. Figure 9: (**Top**): drift pattern of Floatenstein (colored continuous black line) and satellite measurement transects (colored points) over which wave characteristics are measured by the satellites. (**Bottom**): comparison of the Significant Wave Height (SWH) (i) reported by Floatenstein (continuous black line) and (ii) from satellite measurements on the corresponding measurement transects. This set of characteristics is, as a whole, and to the best of our knowledge, unrivaled by any commercial or open-source instrument. These drastic improvements in cost and power efficiency, compared even with previous open-source instruments such as the one described in [PERSON] et al. (2018), are made possible by the use of a cutting edge smartwatch processor, which can handle all of the logging and data processing workloads. This is, to the best of our knowledge, the fist time that such an instrument has been built without the need for an expensive, data-hungry, embedded microcomputer, and the first time the full logging, data processing, and communication workload is controlled from a single, power-efficient, low-cost microcontroller. In addition, this design is both modular and adapted to not only measurements of sea ice drift and waves in ice but also for open ocean measurements, as we have shown in the validation section. We validated the design and signal processing code through a number of test campaigns in the laboratory, in the open water, and on sea ice. Results indicate agreement within typically 5% with state of the art reference instruments and measurement methods and confirm the robustness of the design as well as its power efficiency. In particular, the low power consumption of the instrument (which is always challenging to get right, as any error in the code or hardware design can easily increase the sleep power by a few milliamps, which, while it sounds little, drains battery over time) is confirmed during a deployment in the Arctic, and the accuracy of the wave measurements and wave data processing code are confirmed in several test cases.