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Abstract

A data link and protocol for a subcutaneous, tissue stimulating device. While stimulation is taking place, under control of pulses whose durations in a data frame determine the stimulation pulse widths, data is actually transmitted and processed for determining the parameters of the next stimulation. Thus transmission of data occurs simultaneously with stimulation. Data is represented by sequences which have more 1s than 0s, with each 1 being represent by a number of successive RF cycles and a single 0 by the absence of a number of RF cycles. In this way a duty cycle of 75% can be achieved so that required power is transferred to the implant. Variations in link condition, e.g., degree of ringing, are accommodated by means of offset tuning the transcutaneous transmit and receive coils. This ensures that the oscillating signal in the receive circuit that persists during the transmission of a 0 becomes out-of-phase with the RF transmission that is received for the next 1. The signal induced in the receive coil with the transmission of a new 1 cancels the out-of-phase ringing in the receive coil due to the earlier transmission, thereby causing the oscillation's amplitude to fall below a detection level to ensure the detection of an earlier transmitted 0 during the time that the next 1 is transmitted. A bit decoder is implemented that unambiguously recovers the number of 1s over a prescribed range of link transmission conditions.

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First Claim