Determining Movement in an Opposite Direction

One or more computer-readable non-transitory storage media embodying software that is operable when executed to:

• access a first portion of a magnetic recording, wherein:
• the magnetic recording corresponds to a trajectory of a device;
• the magnetic recording comprises a series of magnetic values that represents a set of magnetic measurements along the trajectory;
• and
• the first portion corresponds to a first portion of the trajectory;
• access a second portion of the magnetic recording, wherein the second portion corresponds to a second portion of the trajectory;
• compare the first portion of the magnetic recording with the second portion of the magnetic recording;
• based on the comparison, determine that the series of magnetic values in the first portion of the magnetic recording is substantially repeated in reverse order in the second portion of the magnetic recording;
• and
• based on the determination that the second portion of the magnetic recording substantially repeats the first portion of the magnetic recording in reverse order, determine that the device moved in an opposite direction during the second portion of the trajectory relative to movement of the device during the first portion of the trajectory.

A system comprising:

• one or more processors;
• and
• one or more computer-readable non-transitory storage media coupled to one or more of the processors and comprising instructions operable when executed by one or more of the processors to cause the system to:
• access a first portion of a magnetic recording, wherein:
• the magnetic recording corresponds to a trajectory of a device;
• the magnetic recording comprises a series of magnetic values that represents a set of magnetic measurements along the trajectory;
• and
• the first portion corresponds to a first portion of the trajectory;
• access a second portion of the magnetic recording, wherein the second portion corresponds to a second portion of the trajectory;
• compare the first portion of the magnetic recording with the second portion of the magnetic recording;
• based on the comparison, determine that the series of magnetic values in the first portion of the magnetic recording is substantially repeated in reverse order in the second portion of the magnetic recording;
• and
• based on the determination that the second portion of the magnetic recording substantially repeats the first portion of the magnetic recording in reverse order, determine that the device moved in an opposite direction during the second portion of the trajectory relative to movement of the device during the first portion of the trajectory.

A system comprising:

• means for accessing a first portion of a magnetic recording, wherein:
• the magnetic recording corresponds to a trajectory of a device;
• the magnetic recording comprises a series of magnetic values that represents a set of magnetic measurements along the trajectory;
• and
• the first portion corresponds to a first portion of the trajectory;
• means for accessing a second portion of the magnetic recording, wherein the second portion corresponds to a second portion of the trajectory;
• means for comparing the first portion of the magnetic recording with the second portion of the magnetic recording;
• means for, based on the comparison, determining that the series of magnetic values in the first portion of the magnetic recording is substantially repeated in reverse order in the second portion of the magnetic recording;
• and
• means for, based on the determination that the second portion of the magnetic recording substantially repeats the first portion of the magnetic recording in reverse order, determining that the device moved in an opposite direction during the second portion of the trajectory relative to movement of the device during the first portion of the trajectory.