Sensor device with persistent low power beacon

An apparatus comprising:

• a sensor configured to generate sensor data, the sensor data being a measurement of
• athletic performance;
• a controller;
• a transmitter configured to transmit the sensor data to a second device;
• a battery;
• and
• a memory storing instructions, wherein the controller is configured to process the instructions to cause the apparatus at least to perform:
• operating in a first operational mode in which the sensor and the transmitter are used at least occasionally to obtain and transmit the sensor data to the second device;
• determining that the battery has reached a low power threshold that is a function of power consumed by the transmitter to transmit a beacon signal for a predetermined number of times;
• and
• in response to determining that the battery has reached the low power threshold,
• operating in a second operational mode where the sensor is not used but wherein the transmitter
• at least occasionally transmits the beacon signal to the second device;
• wherein, when the apparatus is in the second operational mode, the apparatus is configured to detect stimulus or user input, and
• wherein the transmission of the beacon signal occurs periodically for a period of time subsequent to detection of the stimulus or to detection of the user input.

A memory storing instructions that, when processed by a

• controller, are configured to cause an apparatus at least to perform:
• operating the apparatus in a first operational mode in which a sensor and a transmitter are used at least occasionally to obtain and transmit sensor data to a second device, the sensor data being a measurement of athletic performance;
• determining that a battery of the apparatus has reached a low power threshold that is a
• function of power consumed by the transmitter to transmit a beacon signal for a predetermined
• number of times;
• and
• in response to determining that the battery has reached the low power threshold,
• operating the apparatus in a second operational mode where the sensor is prevented from
• operating but the transmitter at least occasionally transmits the beacon signal to the second
• device;
• wherein the transmission of the beacon signal occurs periodically for a period of time subsequent to detection of a stimulus by a transducer or to detection of user input.