Abstract: An electrical to audible signal measurement apparatus comprises an absolute value converter, a voltage to frequency converter, a polarity detector, and a waveform changer. The absolute value converter is capable of converting a bipolar input signal into a unipolar signal. The voltage to frequency converter is connected to the absolute value converter and is capable of generating a frequency signal proportional to the unipolar signal. The polarity detector is capable of identifying a polarity of the bipolar input signal to form an identified polarity. The waveform changer is connected to the voltage to frequency converter and polarity detector and is capable of generating a number of different waveforms in an audio frequency range in response to receiving the frequency signal from the voltage to frequency converter and in response to the identified polarity.

Abstract: A method and apparatus for sending timing information using an optical signal. A first electrical signal comprising a pseudorandom binary sequence is generated. The first electrical signal comprising the pseudorandom binary sequence is modulated with a second electrical signal to form a modulated electrical signal. The second electrical signal includes timing data in a format used for global positioning systems. An optical carrier signal is modulated with the modulated electrical signal to form the optical signal using an optical transmitter.

Abstract: A method and apparatus for sensing radio frequency signals. A radio frequency strength sensing apparatus converts a sensed radio frequency signal to an audible tone. The apparatus comprises a radio frequency detector, a voltage to frequency converter, and a speaker system. The radio frequency detector is capable of detecting radio frequency signals over a selected frequency range with different signal strengths and capable of outputting a logarithmic voltage that varies with signal amplitude change. The voltage-to-frequency converter is connected to the radio frequency detector and is capable of producing an electrical signal waveform in the audio frequency range to generate the audible tone. The speaker system is connected to the voltage-to-frequency converter circuit, wherein the speaker system outputs the audible tone, with pitch of the tone related to the strength of the radio frequency signal.

Abstract: A bidirectional fiber-optic transceiver with lower optical loss than previous beam-splitters or fiber couplers and a method of implementing the same. Preferably, the transceivers can operate in both directions using a single-wavelength of electromagnetic radiation.

Abstract: An electrical to audible signal measurement apparatus comprises an absolute value converter, a voltage to frequency converter, a polarity detector, and a waveform changer. The absolute value converter is capable of converting a bipolar input signal into a unipolar signal. The voltage to frequency converter is connected to the absolute value converter and is capable of generating a frequency signal proportional to the unipolar signal. The polarity detector is capable of identifying a polarity of the bipolar input signal to form an identified polarity. The waveform changer is connected to the voltage to frequency converter and polarity detector and is capable of generating a number of different waveforms in an audio frequency range in response to receiving the frequency signal from the voltage to frequency converter and in response to the identified polarity.

Abstract: A method and apparatus for sensing radio frequency signals. A radio frequency strength sensing apparatus converts a sensed radio frequency signal to an audible tone. The apparatus comprises a radio frequency detector, a voltage to frequency converter, and a speaker system. The radio frequency detector is capable of detecting radio frequency signals over a selected frequency range with different signal strengths and capable of outputting a logarithmic voltage that varies with signal amplitude change. The voltage-to-frequency converter is connected to the radio frequency detector and is capable of producing an electrical signal waveform in the audio frequency range to generate the audible tone. The speaker system is connected to the voltage-to-frequency converter circuit, wherein the speaker system outputs the audible tone, with pitch of the tone related to the strength of the radio frequency signal.

Abstract: Bi-directional optical signal transmission apparatus and methods are disclosed. In one embodiment, an optical detector is configured to receive an optical signal from an end of an optical fiber. An optical element is located at the detector surface and is configured to receive and direct a laser beam. A laser beam is directed by the optical element through the end into the optical fiber substantially parallel with the principal axis.

Abstract: A method for introducing errors into a digital fiber optic communication link so that small analog changes in optical transmission efficiency can be determined by changes in the audible error rate. The method comprises providing a transmitter with a test channel that provides a pseudorandom encoded optical transmission through coupled fiber optic cables. The signal is sent through the cables and received by a receiver which introduces and measures errors. The received signal is split and processed by a clock recovery circuit and a lowpass filter. The clock recovery circuit obtains the optimal sampling point. The lowpass filter filters the data and provides a timing adjustment relative to the recovered clock signal. The clock retimes the filtered data with a sampling comparator. The variable timing introduces errors allowing optical transmission efficiency measurements. A bit error rate tester produces audible sounds whose frequency content is related to the bit error rate.

Abstract: A system for image data communication in military aircraft between a graphics processor computer, referred to as the computer node, and weapons carried on wing pylons, referred to as remote nodes, includes a hub connected via fiber pairs to the computer node and to the remote nodes. The hub includes a number of port bypass switches connected in a bypass loop so that each port bypass switch conveys data between the computer node and the hub or between the remote node and the hub when in a first state, and each port bypass switch conveys data within the bypass loop in the hub, i.e. bypassing its node, when in a second state.

Abstract: A method for introducing errors into a digital fiber optic communication link so that small analog changes in optical transmission efficiency can be determined by changes in the audible error rate. The method comprises providing a transmitter with a test channel that provides a pseudorandom encoded optical transmission through coupled fiber optic cables. The signal is sent through the cables and received by a receiver which introduces and measures errors. The received signal is split and processed by a clock recovery circuit and a lowpass filter. The clock recovery circuit obtains the optimal sampling point. The lowpass filter filters the data and provides a timing adjustment relative to the recovered clock signal. The clock retimes the filtered data with a sampling comparator. The variable timing introduces errors allowing optical transmission efficiency measurements. A bit error rate tester produces audible sounds whose frequency content is related to the bit error rate.

Abstract: A fluid-motion-powered modulated reflector apparatus is provided that modulates the frequency of a reflected radiation signal. Passing the apparatus through a fluid such as air causes rotational velocity of a chopping wheel or, in some instances, a polarizing filter rotatably connected to propeller blades. The radiation signal is modulated by the blocking effect of a chopping wheel or a fixed polarizing filter and a rotating polarizing filter. The apparatus also can include a frequency selector to control the rotational velocity of the chopping wheel or rotatable polarizing filter. A fluid-motion-powered modulated reflector system may include an array of fluid-motion-powered modulated reflectors, each differently modulated by a frequency selector to allow a position sensor, such as a duo-lateral photodiode position sensing detector, and position determining system, to locate and determine the position of each individual retroreflector simultaneously.

Abstract: A photodetector circuit having a power supply and an avalanche photodiode coupled electrically thereto. The power supply includes a first portion, which supplies a substantially constant current, and a second portion, which supplies a substantially constant voltage. At low to moderate optical input signal levels, the substantially constant current that is applied to the avalanche photodiode generates a biasing potential that provides a signal gain, the magnitude of which varies depending upon the optical input signal level. A bias filter between the power supply and the avalanche photodiode slows changes in bias voltage so that the instantaneous photocurrent follows the modulation on the input optical signal. With constant average current bias, the bias potential automatically adjusts with temperature and sample variations to give the same average current flow.

Abstract: A system transmits Digital Video Interface (DVI) signals over a single optical fiber between a video graphics-generating source and a video display device. The system accepts input signals from a conventional DVI transmitter for transmitting video-encoded digital signals to a coarse wavelength division multiplexed (CWDM) optical transmitter. The CWDM optical transmitter produces an optical signal comprised of a multiplexed plurality of optical signals having different wavelengths and outputs this multiplexed optical signal to a single optical fiber. The signal is transmitted over the single optical fiber to a CWDM optical receiver which demultiplexes the signals into a parallel plurality of video encoded optical signals which are each separately received in a corresponding plurality of optical receivers to reproduce the original electrical signals of the DVI transmitter.

Abstract: A photodetector circuit having a power supply and an avalanche photodiode coupled electrically thereto. The power supply includes a first power supply portion, which supplies a substantially constant current, and a second power supply portion, which supplies a substantially constant voltage. At relatively low to moderate optical input signal levels, the substantially constant current that is applied to the avalanche photodiode generates a biasing potential that provides a signal gain, the magnitude of which varies depending upon the optical input signal level. A bias filter between the power supply and the avalanche photodiode slows changes in bias voltage so that the instantaneous photocurrent follows the modulation on the input optical signal. With constant average current bias, the bias potential automatically adjusts with temperature and sample variations to give the same average current flow.

Abstract: An apparatus and method are provided for controllably phase shifting the optical signals emitted by at least one of a plurality of optical fibers by positioning the end portion of the optical fiber that emits the optical signals to be phase shifted relative to the optical signals emitted by the other optical fibers. The apparatus includes a plurality of optical fibers for supporting the propagation of optical signals from a first end to an opposed second end from which the optical signals are emitted. The apparatus also includes at least one micromanipulator, typically operating under the direction of a controller, for controllably positioning the second end of a respective optical fiber relative to the second ends of the other optical fibers, thereby shifting the phase of the optical signals emitted by the respective optical fibers. Typically, the optical signals have a predetermined direction of propagation following emission by an optical fiber.

Abstract: The collimation apparatus includes a plurality of optical fibers for providing respective primary optical signals. The collimation apparatus also includes a plurality of collimating lenses. Each collimating lens collimates the primary optical signals provided by a respective optical fiber. The collimation apparatus further includes a common reflector for reflecting the collimated optical signals back to the respective collimating lens. These reflections produce a return optical signal from each collimated optical signal. The collimation apparatus also includes at least one detector for receiving the return optical signals and a plurality of actuators for iteratively positioning the optical fibers based on the magnitude of the detected signals.

Abstract: A system and method for monitoring messages containing command, status, and data words transmitted on a high speed, serial, asynchronous AS1773 fiber-optic data bus employing Manchester encoding includes a fiber-optical receiver connected to the data bus and adapted to receive and convert optical signals into message words containing either a command, a status, or a data word. The system also preferably includes a memory device having a number of storage locations adapted to receive and store the message words, which is organized in an optimal fashion to allow the system to monitor high speed data buses. Preferably, a logic device is operationally coupled to the fiber-optical receiver and adapted to serially receive and process each message word. The logic device controls the transfer of each message word into one of the memory locations of the message buffer.

Abstract: A stand-alone test device for testing remote terminals intended for use on a command-response data bus which includes a single-purpose electrical waveform generator for generating a coded electrical waveform which is representative of a transmit command sequence which includes an address of a remote terminal under test, an electrical-to-optical converter (e.g., an LED driver and LED) responsive to the coded electrical waveform for producing a first coded optical waveform corresponding to the coded electrical waveform, and an optical transmission line (e.g., an optical fiber) having a first end coupled to the coded optical waveform and a second end coupled to an optical input of the remote terminal under test. The remote terminal under test is responsive to the coded optical waveform for producing an optical output indicative of the operational status of the remote terminal under test. The stand-alone test device further includes an optical-to-electrical converter (e.g.

Abstract: An optical fiber monitoring method and apparatus is described for monitoring the signal loss within an optical fiber during installation of the optical fiber. The apparatus contains a jig for advancing the optical fiber along a predetermined path, a light source for transmitting light signals along the optical fiber, and a light sensor for detecting the light signals. The detected light signals are converted to an audible signal having a frequency which varies in relation to the detected signal. An audio transducer then outputs the audible signal. Since the frequency of the audio signal is a measure of the signal loss along the optical fiber and, therefore, is a measure of the amount by which the optical fiber is bent during the installation process, the audible signal can be monitored in an "eyes-free" manner to detect excessive bending of the optical fiber in order to prevent damage to the optical fiber during installation.

Abstract: An avalanche photodiode array comprising a plurality of photosensitive regions in a light sensitive body with each photosensitive region having a semiconductor junction. Between said photosensitive regions, there are a plurality of low response regions separating the photosensitive regions. A plurality of wedged shaped regions having a reflective coating on their surface are placed on the light sensitive body to cover the low response regions and to reflect incident light rays towards a photosensitive region; such incident light rays typically arriving at the photosensitive regions at angles of grazing incidence. Back reflector regions having a reflective coating on their surface are positioned about the periphery of the light entry surface to reflect light incident thereon to a photosensitive region.