Patent ID: 7738964

Claim:
A telemetry system, comprising: an implantable device and an external device, each having an RF transmitter and receiver and a wakeup timer; wherein one of the implantable or external devices is configured to operate as a master device while the other device is configured to operate as a slave device; wherein the master device is programmed to power up its RF transmitter and receiver for a specified master time window and to wirelessly transmit a digital key to the slave device at wakeup intervals defined by the master device wakeup timer and listen for a wireless response; wherein the slave device is programmed to power up its RF receiver for a specified slave time window, which is synchronized to the master time window, to listen for a digital key transmitted by the master device at wakeup intervals defined by the slave device wakeup timer and to power up its RF transmitter to wirelessly transmit a response to the master device if the digital key is received; and wherein the master and slave devices are programmed such that a wireless RF communications session is established between the master and slave devices when the response is received by the master device, wherein the master time window is adjusted based on the time of the response.