Page 141 - A bird’s-eye view of recreation - Rogier Pouwels
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Appendix 1 Dataset of GPS tracks (Chapter 2)
The original dataset was collected as part of the PROGRESS research project in the New Forest during spring and summer of 2004 at 41 car parks (Gallagher et al. 2007). Both models of the GPS devices used, the eTrex and eTrex Venture, were manufactured by Garmin and have 12 receiver channels. The nominal position accuracy is 15 m for the eTrex and 5 m for eTrex Venture. However, Rodríguez-Pérez et al. (2007) showed a decrease in accuracy in areas with a forest canopy for comparable device models. The positional accuracy is affected by stem density due to the lowering of the signal to noise ratio and the signal interception caused by electromagnetic waves penetrating through stems and canopies. At each car park, the GPS devices were turned on before data collection to ensure that the current almanac was stored and an accurate position was acquired. At the time of data collection, no selective availability was in operation. The devices have a storage capability for 2048 data points and were set to the ‘Auto’ record method for recording the tracks. This method records the tracks at a variable rate to create an optimum representation of the track. After participants returned, their device was connected to a laptop. A lightweight application, using the Garmin transfer protocol, read the data points into a database.
Table 1 shows the number of days the car parks were monitored and the number of tracks collected from each car park. Table 2 shows monitoring was conducted less frequently on Sundays. Sharp et al. (2008) showed that residents in the New Forest tend to use different car parks than visitors living outside the area. Combining the dataset with information from Sharp et al. (2008) indicates that visitors with dogs are mainly local residents (Fig. 1). The dataset used contains 14 columns of information (Table 3).
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