Abstract: An implantable, readable miniature transponder has an antenna coupled to a microchip integrated circuit. The integrated circuit has unique identifying information stored in the chip. The integrated circuit microchip also has control logic, a muscle stimulator, an EMG amplifier and a data transmitter. The integrated circuit is connected to the antenna and to muscle electrodes that have EMG sensors. When an external reader illuminates the transponder the control logic alerts the implanted subject and inhibits any data from being sent to the reader. Through a series of predetermined voluntary muscle contractions the subject sends a signal to the control logic to either allow or deny the reader access to the identifying information.

Abstract: A system providing an inductive power and data link between an external transmitter and miniature internal receiver is presented. The system is suited to applications where the receiver must be of a small size and the system must consume very little power, such as an implanted biomedical device. The system is also compatible with systems where bi-directional communications are required. The novel transmitter and receiver form an improved forward data telemetry system. The transmitter consists of a Class-E converter with its optimum operating frequency being synchronously, instantaneously and efficiently altered in accordance with the data to be transmitted, thereby producing an FSK modulated magnetic field of substantially constant amplitude. The constant amplitude output allows for the continuous, data-independent transfer of power to the miniature receiver and its associated electronics.

Abstract: An apparatus and method for forming a RAM data memory that generates predictable noise/interference components that are coherent with each write cycle and essentially independent of the data content of the RAM data memory. The RAM data memory is comprised of a plurality of cells, each representing a data bit, which are selectively addressable as memory bytes formed of multiple bits. Each cell is formed of two sets of cross-coupled transistors. By causing each set of cross-coupled transistors to be set to a common voltage level at the beginning of a write cycle before setting one set of transistors to a low level and the one set of transistors to be set to a high level (thus representing a desired data bit value), the associated noise/interference components of the power drain are data independent. Furthermore, the data-independent noise occurs at frequencies at or above the write cycle rate.

Abstract: A protected, transformerless power converter for converting an AC mains power source to a low voltage DC power source is presented. The AC input voltage is rectified to supply pulsating DC voltage to a pass element resistor. An electronic switch located between the pass element resistor and an output filter capacitor interrupts the current flowing into the output filter capacitor. The output filter capacitor averages the pulse current drawn from the AC input line to provide a constant DC output voltage to a load. The instantaneous AC input voltage, the average value of the AC input voltage, and the output voltage are used to calculate the optimal times of conduction of the electronic switch. Controlling the time of conduction in this manner maximizes the power efficiency of the converter and protects the supply from an output overload or short circuit condition over a wide range of AC input voltages.

Abstract: A transponder system including a transponder and an interrogator having a transmission coil for producing a high-intensity electromagnetic field for inductively powering the transponder and two receiver coils for receiving a low-intensity electromagnetic field reradiated by the transponder. The transmission coil includes one or more conductive windings circumscribing a substantially polygonal volume of space. The receiver coils are diametrically disposed opposite one another within the volume space of the transmitter and are electrically connected to each other in a differential circuit relationship, the output of which is at a minimum when the two receiver coils receive approximately equal quantities of energy and is at a maximum when one of the receiver coils receives more electromagnetic energy from the transponder than the other receiver coil. The transponder uses a coil to derive both a power source and a clock pulse from the high-intensity field for powering and driving an identification circuit.

Abstract: A transponder system including a transponder and an interrogator having a transmission coil for producing a high-intensity electromagnetic field for inductively powering the transponder and two receiver coils for receiving a low-intensity electromagnetic field reradiated by the transponder. The transmission coil includes one or more conductive windings circumscribing a substantially polygonal volume of space. The receiver coils are diametrically disposed opposite one another within the volume space of the transmitter and are electrically connected to each other in a differential circuit relationship, the output of which is at a minimum when the two receiver coils receive approximately equal quantities of energy and is at a maximum when one of the receiver coils receives more electromagnetic energy from the transponder than the other receiver coil. The transponder uses a coil to derive both a power source and a clock pulse from the high-intensity field for powering and driving an identification circuit.

Abstract: A coil assembly for use in an inductively powered transponder including a primary coil and a secondary coil wrapped around the same coil forming ferrite rod. The primary coil's leads are left floating while the secondary coil's leads are connected to the integrated identification circuit of the transponder. There are approximately three times as many turns to the primary coil as there are turns to the secondary coil. The primary coil is configured to self resonate at the operating frequency of the identification circuit when brought within range of an interrogator's magnetic field, thereby creating a voltage across the primary coil having a high source impedance.

Abstract: An electromagnetic transmission and detection apparatus comprising a transmission coil (20) for producing a high intensity electromagnetic field including one or more conductive windings (24) circumscribing a substantially polygonal volume of space having a central axis, and first and second receiver coils (22) disposed within the polygonal volume of space for receiving a low-intensity electromagnetic field transmitted from an external source. The receiver coils (22) are co-planar with the transmitter coil (20) and are disposed within the polygonal volume of the transmitter coil at positions which are polygonally, diametrical opposed to one another. The receiver coils (22) are electrically connected to each other in a differential circuit relationship such that the magnitude of electrical signals induced in the receiver coils (22) by uniform electromagnetic energy are substantially equal and opposite to one another.

Abstract: A portable musical instrument and associated therewith a radio frequency transmitter for broadcasting to a remote receiver and audio amplifier the sounds generated by the instrument. The user-operated controls vary the sound level sent by the transmitter, vary the mixing of sound levels from pickup groups such as neck and bridge groups of an electrical guitar, and provide control signals for controlling a sound processing unit such as a reverberator associated with the audio power amplifier system. The immediate status of the gain and fader settings is relayed as an ultrasonic modulation on the portable transmitter to actuate unique display conditions in a delay element actuated from the fixed receiver to provide to the user an indication of the status of his settings. Low battery conditions in the transmitter battery unit cause unique signal conditions to be sent to the receiver, resulting in a readily visible warning display configuration. The currently selected mode, e.g.

Abstract: A compressor comprises a variable gain path and a feedback path. The variable gain path includes a modulator which, in response to an input signal and a feedback signal, outputs a train of pulses whose widths and heights are modulated. Also in the variable gain path, a demodulator converts the pulse train into a compressor output. Feedback is derived from the variable gain path.