Patent ID: 7664553

Claim:
A telemetry system for enabling radio-frequency (RF) communications between an implantable medical device and an external device, comprising: an antenna, an RF transmitter, an RE receiver, and a controller incorporated into each of the implantable and external devices; a wakeup timer incorporated into the implantable device; wherein the RF transmitter and receiver of the implantable device are interfaced to the controller in the implantable device to enable the RF transmitter and receiver of the implantable device to be powered up or down; wherein the external device is programmed to transmit a data segment containing a repeating sequence of special wakeup characters and a device ID in order to establish a communications session with the implantable device; wherein the implantable device is programmed to operate its transmitter and receiver according to a timed duty cycle by being programmed to power up its transmitter and receiver for a specified time window at periodic intervals defined by the wakeup timer and wait for receipt of one of the special wakeup characters transmitted by the external device; wherein the implantable device is programmed to suspend operation of the timed duty cycle and wakeup timer, maintain its transmitter and receiver in a powered-up state upon receipt of a special character prior to receipt of the device ID and prior to establishment of a communications session and for as long as consecutive special wakeup characters continue to be received, transmit an acknowledge signal to the external device if the device ID matches its own ID, and wait a specified period of time for a response from the external device; and, wherein the external device and the implantable device are programmed to establish a communications session when a response to the acknowledge signal is received by the implantable device.