An inductive through-the-head OOK communication platform for assistive listening devices

This paper proposes an inductive transmitter with associated rsppiver for unidirectional through-the-head communicatisp. The system is intended for use in assistive listening devices. It complies with ITU regulation 5.115 by employing a carrier frequency of 3.175 MHz. A Hartley oscillator serves as transmitter to realize both OOK bit modulation and data transmission. Its counterpart, a four-stage common source JFET amplifier, detects and amplifies transmitted signals. Small, self-twisted solenoid coils are operated as transducer elements. Measurements demonstrate the reliable functionality of the point-to-point network over a distance of 20 cm with a data rate of 100 kBit/s. Operation is possible with a standard 1.5 V battery cell, whereby low currents are measured on our discrete benchtop prototype [transmitter: 0.8 mA; receiver 1.7 mA].