Abstract: A status monitoring system for evaluating the condition of an electrode implanted in the body of a mammal. The system comprises a modulator for modulating interrogation signals on an electrode of an implanted device, and a monitor for analyzing modulated interrogation signals being reflected by the electrode. The monitor comprises a transmitter for transmitting interrogation signals, a receiver for receiving and processing the signals reflected by the electrode, and a microprocessor for controlling the transmitter and the receiver. The microprocessor producing electrode condition data from the signals processed by the receiver. The invention further comprises a communication system in communication with the monitoring device for transmitting the electrode condition data to a remote location. The interrogation signals are transmitted by the transmitter onto the electrode. The interrogation signals are modulated on the electrode by combining with a modulation signal generated by the modulator.

Abstract: A telemetry system includes a remote monitoring station, a repeater worn externally by a patient and a quasi-passive transponder attached to a device implanted in the patient. The remote monitoring station communicates to the repeater to initiate an interrogation routine between the repeater and the transponder to extract patient condition information from the implanted device. When the repeater receives the condition information, it relays it to the remote monitoring station. The transponder is specially designed to operate with an extremely low level of power, less than 1 nW/baud, and to be compatible for attachment to existing implanted devices. The transponder can operate at a very high data rate, including a rate of about 100 kbps.

Abstract: A wide dynamic range optical link using a double sideband suppressed carrier linearizer, the link comprising a laser source for producing a lightwave carrier output at a predetermined power level and wavelength, a double sideband suppressed carrier optical modulator having the lightwave carrier as a first input and an RF information-bearing signal as a second input, said double sideband suppressed carrier modulator comprising a signal splitter for dividing the lightwave carrier into primary and secondary carriers, a Mach-Zehnder optical modulator producing a modulated signal comprising information sidebands and a primary carrier component, a feedback controlled phase shifter in which the secondary carrier is shifted 180 degrees from the primary carrier phase, a signal combiner into which are input the modulated signal and the phase shifted secondary carrier, the combination of said signals causing the controlled suppression of the carrier component in the output of the signal combiner.

Abstract: A variable sensitivity compensation network for a Mach-Zender optical modulator comprising first and second pilot signal sources f.sub.1 and f.sub.2, a signal coupler for combining the pilot signals with an RF information signal for modulating a bias-controlled Mach-Zender optical modulator, a variable sensitivity feedback loop comprising an optical detector for detecting the pilot signals from the modulator output, a bandpass filter for selecting the sum frequency f.sub.1 and f.sub.2, a voltage variable attenuator for adjusting the sensitivity of the loop, a logarithmic compression circuit for compressing the f.sub.1 and f.sub.2 signal level from the variable attenuator, means for measuring the signal level, means for controlling the variable attenuator and means for producing an analog bias signal for controlling the operating point of the Mach-Zender modulator. The measuring and controlling means include a microprocessor.

Abstract: A radio frequency pulse multiplier for producing coherent multiples of radio frequency (rf) pulses comprising an input terminal for receiving rf pulses, a signal divider for providing a plurality of pulses in response to an input pulse, the output of the signal divider coupled to a plurality of signal paths, each respective path comprising a time delay element providing a selectable delay to a respective pulse, a signal combiner for combining the plurality of pulses on a single output, and an output terminal. The output of the multiplier comprises pulses delayed by amounts equal to the preselected delays in the respective signal paths of the multiplier. The multiplier may comprise signal conditioning elements for conditioning the rf pulses within the multiplier.

Abstract: A dual-polarization fiber optic communications link comprising a dual polarization light source for emitting a monochromatic lightwave having two polarizations, a polarization splitting coupler for separating the polarizations of the lightwave into a carrier signal and a standard signal, an optical modulator employing the carrier signal and an information signal to produce a double-sideband suppressed carrier signal with the polarization of the carrier, an optical signal combiner for combining the double-sideband suppressed carrier having one polarization with the lightwave standard having a different polarization, said combination occurring substantially without interaction between the respective signals, and the combined signals being coupled to a fiber optic transmission medium. The communications link permits greater modulation dynamic range than conventional amplitude-modulated optical communications links.