## 4 Results  
### System Performance  
The system tested at AAOT performed very well and demonstrated its capability of making automated measurements following a predefined protocol and interval. After installation and configuration, there were no blocking issues while the system worked autonomously, and no intervention was required during the six days of operation while the system performed as expected. Since the system was still in a prototype phase when tested on the AAOT, some functionality is yet to be tested or demonstrated in a real-world scenario. The system was powered from the mains grid and, as the platform was visited daily, there was no need for 3G/4G data transmission. Most measurement sites will require one or both of these functions as mains power or cabled internet may not be available. With the defined measurement protocol and a measurement interval of 20 min, it became obvious that the system speed needed improvements. The measurement protocol described in Section 2.4 took about 12 min to finish, depending on sun azimuth (since this affects required movements and how many measurements are skipped because they fall within the \"no-go\" zone). Post-FICE optimization of the control libraries for the pan/tilt head since resulted in faster movements. Additional speed can be gained in the control of the instruments, as well as by implementing multi-threading. Before each measurement cycle, some of the devices need time to start up and/or calibrate. The pan/tilt head, for example, needs to run a calibration routine to find the center point of both axes, and the IP camera needs time to boot and warm up. Implementation of multithreading would allow us to do both at the same time. Shorter measurement cycles result in more low-power standby time in between measurement cycles and lower power consumption, thus achieving better overall efficiency. Some existing systems such as the CIMEL SeaPRISM hardware rely on the sun to calibrate the system azimuth during installation. While a high accuracy can be achieved with this method, it is only usable on sunny days. An electronic compass that achieves the required accuracy on metal structures, and that has a low power consumption, a marine-grade enclosure, and low cost is yet to be found. The current mode of operation for aligning the system zenith is achieved by placing a spirit level on the top bracket. This allows alignment as accurate as the used spirit level. After this is done, a digital inclinometer is placed on top of the instruments to verify their absolute inclination for different angles. Azimuth calibration is similar to the CIMEL system; the user can order the head to rotate toward the sun, after which the shadows cast by the top bracket serve as a reference while manually performing the alignment. The images taken as part of each measurement cycle showed an unexpected interest from the local wildlife. Even though the system was (almost) continuously moving, birds seemed not to be deterred but showed a rather close interest in the new technology, both contaminating data by blocking the instrument field of view completely or subtly (Figure 5) and by potentially contaminating the instrument itself by fecal deposits. Major blocking of a radiometer field of view will be easily identified as bad data because the spectral signature will be different from the expected water, sky, and full sky irradiance targets. However, partial blocking of the instrument field of view (Figure 5b) may contaminate data in a way that cannot be automatically detected and rejected. Discussion with experts on bird life suggests that typical visible or audible \"scarecrow\" devices are not effective deterrents and the best approach is the use of spikes to prevent comfortable resting spots. We, therefore, strapped cable ties around the moving parts (Figure 4c), leaving the ends uncut as deterrent spikes, being careful to avoid the irradiance sensor field of view.