Intelligent data network with power management capabilities

A combination comprising a second, ambulatory device and a first device, the second device being capable of engaging in two-way communication with at least a first device, the second device comprising:

• second circuitry configured to render the second device operable as at least one of a wristwatch, a cellular telephone, a personal data assistant, and a portable music device;
• a second transmitter;
• a second receiver;
• and
• at least one second controller coupled to the second transmitter and the second receiver, the at least one second controller being configured to power on the second transmitter to transmit second messages to the first device during finite time periods following reception by the second receiver of respective first messages from the first device, and being further configured to power down the second transmitter after transmission of each of the second messages from the second device to the first device;
• wherein the at least one second controller is configured to power down the second receiver during at least some time periods that are identified based upon information included in at least some of the first messages communicated from the first device to the second device, which information indicates when the first device expects to send at least one subsequent first message to the second device;
• and
• wherein the first device comprises:
• a first transmitter;
• a first receiver;
• and
• at least one first controller coupled to the first transmitter and the first receiver, the at least one first controller being configured to power on the first receiver to listen for second messages from the second device during finite time periods following use of the first transmitter to transmit respective first messages to the second device, the at least one first controller being further configured to power down the first receiver after each of the finite time periods following use of the transmitter to transmit respective first messages to the second device;
• and wherein:
• the at least one second controller is configured such that at least some of the second messages communicated from the second device to the first device include information identifying time periods during which the second device expects to receive first messages from the first device, and is further configured to power down the second receiver during at least some time periods during which the second device does not expect to receive first messages from the first device;
• and
• the at least one first controller is configured to cause the first transmitter to transmit at least some of the first messages from the first device to the second device during the identified time periods during which the second device expects to receive first messages from the first device.