Processing data from a portable processing device

A computer-implemented method of processing data from a portable processing device to determine when the portable processing device has begun a journey, the method comprising:

• receiving data generated by the portable processing device defining a sequence of positions and, for each respective position, an accuracy of the position;
• for each of a plurality of positions in the sequence, processing the data defining the position and the accuracy of the position as well as the data defining a preceding position in the sequence and the accuracy of the preceding position, to determine whether the position is more than a first threshold distance from the preceding position;
• processing data defining a time-ordered set of the positions for which it was determined that the position is more than the first threshold distance from the preceding position, to determine whether a distance between the position at the latest time in the time-ordered set and any position at an earlier time in the time-ordered set is greater than a second threshold distance;
• and
• when it is determined that the distance between the position at the latest time in the time-ordered set and any position at the earlier time in the time-ordered set is greater than the second threshold distance, it is determined that the portable processing device has begun a journey;
• wherein the processing to determine whether the position is more than the first threshold distance from the preceding position comprises:
• (a) calculating a position difference between the position and the preceding position;
• (b) calculating an accuracy difference between the accuracy of the position and the accuracy of the preceding position;
• and
• (c) comparing the position difference and the accuracy difference to determine whether the position is more than the first threshold distance from the preceding position, wherein the processing to determine whether the position is more than the first threshold distance from the preceding position comprises determining whether:
• |x2−x1|>(a2−a1)k
• where x2 is the position, x1 is the preceding position, a2 is the accuracy of the position, a1 is the accuracy of the preceding position, and k is a constant, and a2 and a1 comprising values that decrease as the accuracy increases.

A computer-implemented method of processing data from a portable processing device to determine when the portable processing device has ended a journey, the method comprising:

• receiving data generated by the portable processing device defining a sequence of positions and, for each respective position, an accuracy of the position;
• for each of a plurality of positions in the sequence, processing the data defining the position and the accuracy of the position as well as the data defining a preceding position in the sequence and the accuracy of the preceding position, to determine whether the position is more than a first threshold distance from the preceding position;
• for the positions for which it is determined that the position is more than the first threshold distance from the preceding position in the sequence, generating a time-ordered set of positions;
• processing data defining the time-ordered set of positions to determine whether a distance between the position at the latest time in the time-ordered set and any position at an earlier time in the time-ordered set is greater than a second threshold distance;
• and
• when it is determined that the distance between the position at the latest time in the time-ordered set and each position at the earlier time in the time-ordered set is not greater than the second threshold distance, it is determined that the portable processing device has ended a journey;
• wherein the processing to determine whether the position is more than the first threshold distance from the preceding position comprises:
• (a) calculating a position difference between the position and the preceding position;
• (b) calculating an accuracy difference between the accuracy of the position and the accuracy of the preceding position;
• and
• (c) comparing the position difference and the accuracy difference to determine whether the position is more than the first threshold distance from the preceding position, wherein the processing to determine whether the position is more than first threshold distance from the preceding position comprises determining whether:
• |x2−x1|>(a2−a1)k
• where x2 is the position, x1 is the preceding position, a2 is the accuracy of the position, a1 is the accuracy of the preceding position, and k is a constant, and a2 and a1 comprising values that decrease as the accuracy increases.