## 2 Materials and Methods
### Field Implementation on Sheep
#### 2.3.2 Animals and Experimental Protocol  
Seven 1-year old Merino ewes (average body weight of 36.9 \(\pm\) 5.9 kg) were used in this experiment. The animals were selected randomly from a research flock located at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Chiswick Research Station (Armidale, NSW, Australia) and had no previous experience with wearing GPS-devices. Two days before data collection commenced, dog harnesses (Comfy Harness, size 8, 84-120 cm, Company of Animals, Surrey, UK) were placed on the sheep to habituate them to the equipment. On the day of the study, an RTK rover was fitted to the dog harness and secured using plastic netting and cable ties. The harness was then fitted onto the backs of the sheep (see Figure 4a). For ease of checking, each sheep was numbered with coloured sheep wool marker (Heiniger Shearing Supplies, Briba Lake, WA, Australia) that matched different coloured antennas on the RTK rovers. Animals were placed into a paddock approximately 100 m \(\times\) 70 m in size. The sheep had been kept in the same paddock as a  
Figure 3: The areas where the accuracy performance of the device was first tested including (**a**) the initial test with the rover driven in a car (movement track indicated by the red dotted line), and (**b**) the second test with 6 rovers carried by experimenters (movement tracks indicated by coloured lines) where ‘GNSS lock’ indicates the starting position and the star indicates the position of the base station. Note: The multiple lines indicating 6 tracks can be seen during the initial GNSS lock up as well as in the “foliage attenuation” area, but the accuracy of the results negates clear visual separation of the 6 tracks during optimal operation. group for four weeks prior to the study so were familiar with each other. The paddock was estimated to have approximately 2500 kg DM/ha of pasture available, and water available at the NE and SW corners of the paddock. The study was conducted across four consecutive days from 11 to 14 February 2020 (summer season). During the study period, two days (second and third day) experienced some intermittent rain and the weather was cloudy on the other two days. The mean minimum, overall, and maximum temperatures across 24 h periods over the test days were: mean \(\pm\) SEM min: 21.25 \(\pm\) 0.12 \({}^{\circ}\)C, avg: 24.62 \(\pm\) 0.49 \({}^{\circ}\)C, max: 28.00 \(\pm\) 0.54 \({}^{\circ}\)C based on weather data collected directly at the Chiswick site. On each of the four study days, the devices were attached to the animals in the morning and then removed at the end of each day after 5 h of testing. The device continually recorded the GNSS location data throughout the daytime for 5 h per day with a sampling rate of one second. The GNSS receivers were removed from the sheep each evening. Sheep were kept in a small yard overnight with free access to water but not food to encourage grazing during the day. Sheep were checked twice daily during each day of testing to ensure the devices remained in position. On the last day, RTK rover D slipped to the side so all animals were brought into the yards at 10:30 a.m. to fix it before being placed back into the test paddock at 10:39 a.m. In addition, animals were video-recorded using a hand-held video recorder (Sony Handyam, HDR-XR260E, Sony Electronics Inc., Tokyo, Japan) twice per day for an hour each time; one hour in the morning soon after the animals were released into the paddock (8:00-9:00 a.m. except for the first day which was 11:20 a.m.-12:20 p.m. due to a late starting time) and one hour in the afternoon (2:00-3:00 p.m. for the first day and 1:00-2:00 p.m. for the remainder) for ground proofing of the data collected from the RTK Rovers. On the first day of the experiment, the reference base station was fixed in the middle of the paddock (Figure 4b) and the location determined from GNSS averaging. The range of the 433 MHz communication radio was measured to ensure that the signal covered the test paddock.