Abstract: A surface acoustic wave (SAW) filter device configured as a tapped time delay is mounted on a plastic card. The SAW filter acts as a nondestructive storage medium for an identification code in an access control system. The identification code is imbedded in the SAW device by selectively connecting certain taps to the filter output terminals. The identification code is read out of the SAW filter device and decoded for verification of the code. To read the code a sweep frequency oscillator excites the filter to launch an acoustic wave. The filter ouput mixes with the input sweep signal and the lower sideband (f.sub.b -f.sub.a) is extracted to obtain a discrete line spectra each line representing the connected tap of the filter. The line spectra signal is mixed with another version of the input sweep signal to obtain a time-based amplitude response of the discrete line spectra. This analog signal is converted to a digital signal which corresponds to the binary code of the connections to the SAW filter.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or repeater, or for retransmitting test pulses on the next cable to the next repeater for causing it it perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: In a DC switching regulator circuit, a circuit to demagnetize the transformer during OFF periods to extend the duty cycle range of the regulator. The regulator uses a transformer in series with an FET switch device to cause the primary transformer current to be switched ON and OFF in response to the power needs of an electrical load connected to the secondary circuit. A first diode, connected to the junction of the primary winding and a series switch, conducts the demagnetizing energy out of the primary circuit into a shunt connected storage capacitor. A second FET switch, operating out of phase with the first switch, allows the storage capacitor to discharge through an inductor back to the unregulated input source. A shunt diode between the inductor and the second FET switch provides a path for the inductor to discharge through when the second switch opens the path between the storage capacitor and the inductor.

Abstract: A multilayer antenna aperture polarizer comprises a single continuous electrically conductive trace on a flexible thin dielectric strip, the trace being formed into a plurality of arrays of grid lines with adjacent arrays interconnected by shorting leads and with a ground lead connected to the last or end array. The strip and shorting leads are folded at the locations of the shorting leads to form a stack of plane parallel polarizer panels, each comprising an array on the strip, adjacent panels in the stack being spaced apart in a direction transversely of the planes of the panels by insulator spacers, respectively. The polarizer is inserted in front of the aperture of the antenna and the ground lead is electrically connected to the antenna frame for grounding the several arrays. The shorting and ground leads are located at the corners of the stack in the neutral or minimum field zone of the antenna.

Abstract: The output of an LF transmitter that operates at a prescribed frequency is coupled to an electrically conductive rodent shield on a buried optical fiber cable. The rodent shield operates as an elongated underground antenna that transversely radiates an electromagnetic field that preferably propagates beyond the surface of the ground. A receiver that is located on a piece of earth working equipment generates a warning signal when the equipment moves a receiving antenna such that it picks up signals of the prescribed frequency that are radiated by the buried optical fiber cable. Unique tone signals that can be modulated onto the prescribed signal are assigned to associated cable companies. A prescribed signal that is modulated with a single tone signal is only applied to optical fiber cables of the associated cable company to provide an equipment operator with the identity of the owner of the cable that he is near.

Abstract: A noise threshold estimating method for use in a high signal density environment defines a noise threshold level for a plurality of frequency divided channels such that X number of said channels will be defined as being active channels and the remaining channels as being inactive. Using a novel closed loop feedback technique to define a noise threshold level, the noise threshold estimator first compares the signal level of each incoming channel with an analog threshold voltage. A logic device counts the number of active channels and then scales that number according to a predetermined scaling function. The scaled binary number is added with the noise threshold level from the previous clocked interval to define a new noise threshold level. This binary noise threshold level is converted into an analog voltage and feedback to the feedback input of the noise comparison devices to be compared with the signal level of each incoming channel.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or repeater, or for retransmitting test pulses onto the next cable to the next repeater for causing it to perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: In satellite telephone communication equipment, the phase detector of a phase-lock loop compares the phase of a master oscillator signal from the loop oscillator with that of a pilot tone signal and produces an error control voltage which it combines with a constant sweep voltage that is stepped at a variable rate. When the loop is out of lock, a first count of the number of excursions of the beat or difference frequency signal from the phase detector that exceed a prescribed threshold level is generated, a second count is incremented for every n counts in the first count, and a constant amplitude step of the stepped sweep voltage is produced for each unique value of the second count. The steps in the sweep voltage occur at a variable rate that is related to the difference frequency of the beat signal. Since the difference between the oscillator and pilot frequencies decreases as the loop approaches lock, the rate at which the sweep voltage is stepped also decreases.

Abstract: A noise threshold estimator for use in a high signal density environment defines a noise threshold level for a plurality of frequency divided channels such that X number of said channels will be defined as being active channels and the remaining channels as being inactive. Using a novel closed loop feedback technique to define a noise threshold level, the noise threshold estimator first compares the signal level of each incoming channel with an analog threshold voltage. A logic device counts the number of active channels and then scales that number according to a predetermined scaling function. The scaled binary number is added with the noise threshold level from the previous clocked interval to define a new noise threshold level. This binary noise threshold level is converted into an analog voltage and fedback to the feedback input of the noise comparison devices to be compared with the signal level of each incoming channel.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or the repeater, or for retransmitting test pulses on the next cable to the next repeater for causing it it perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: A binary synchronous bit-sliced counter comprising a plurality of cascaded identical stages (slices). Each stage only requires for its operation a source of potential V.sub.dd, a carry-in signal input line, a clock signal input line, a reset signal input line and a carry-out signal output line. Cascading of the slices is implemented by connecting the carry-out signal output line of one slice to the carry-in signal input line of another slice and connecting the clock signal and reset signal input lines to all cascaded stages in parallel.

Abstract: A multimode perimeter intrusion detection system comprises at least one elongated electret tape mounted on a barrier, such as a fence or wall, along the perimeter of an area to be protected and operated simultaneously in both active and passive modes to detect intruders in proximity to, as well as in contact with, the barrier. The tape is directly mechanically coupled to the barrier above and parallel to the ground or floor and is electrically connected to a sound wave generator and to signal processing apparatus which detects signals produced on the tape by intruders and activates an alarm. In the active mode, the tape radiates sound waves, preferably in the ultrasonic range, outwardly from the barrier and receives doppler-shifted reflections from a person moving in the sound field for transmission to the signal processing apparatus.

Abstract: The exterior surfaces of a laser rod and pump lamp are covered with a highly reflective metal foil to prevent light leakage from the rod and lamp. The laser rod and pump lamp operate within a cavity inside a heat sink. Between the metal foil and the housing is a thermally conductive fluidic material selected to provide a tailored thermal impedance between the heat sink and the rod and pump to optimize the steady state temperatures of these components. The conductive fluid is not circulated but is contained to act as a simple heat conductor. The optically reflective and the heat transfer functions of the laser pumping operation are essentially separate from each other, enabling selection of materials for these respective functions to enhance performance of the laser and substantially simplify its construction.

Abstract: Laser apparatus with an electro-optic Q-switch assembly comprises a lasing medium which produces an unpolarized light beam when pumped, a polarizing beam splitter dividing the unpolarized beam into two orthogonally polarized parallel sub-beams, and a totally reflecting turning element which returns each sub-beam to the beam splitter along the path of the other sub-beam. A Q-switch is located in the path of one of the sub-beams. When the Q-switch is energized, the reflected polarization-shifted sub-beams are recombined at the splitter and pass through the lasing medium and adjacent partially-reflecting element as the output. When the Q-switch is deenergized, the sub-beams are dumped at the splitter which prevents the laser from oscillating.

Abstract: The exterior surfaces of a laser rod and pump lamp are covered with a highly reflective metal foil to prevent light leakage from the rod and lamp. The laser rod and pump lamp operate within a cavity inside a heat sink. Between the metal foil and the housing is a thermally conductive fluidic material selected to provide a tailored thermal impedance between the heat sink and the rod and pump to optimize the steady state temperatures of these components. The conductive fluid is not circulated but is contained to act as a simple heat conductor. The optically reflective and the heat transfer functions of the laser pumping operation are essentially separate from each other, enabling selection of materials for these respective functions to enhance performance of the laser and substantially simplify its construction.

Abstract: A microprocessor controller converts one or more sensor signals to a time multiplexed digital signal which is converted to an analog voltage signal by a digital-to-analog converter. A switching circuit, under the control of the microprocessor, selectively applies the analog signal to a plurality of current sources thereby setting the output current from each current source.

Abstract: An FDM subscriber carrier system with two pilots located adjacent the upper and lower ends of the high frequency band uses the detected pilot levels at a repeater to adjust the gain and slope amplifiers in both directions of transmission. A microprocessor, programmed to identify the cable transmission characteristics, uses status signals derived from the two detected pilots to produce control signals to adjust and optimize the gain and slope settings of line amplifiers.

Abstract: Drift of the standing wave pattern in an acoustic doppler intrusion detection system with radiating and receiving transducers in a confined space is compensated by changing the operating frequency of the carrier wave generator when the magnitude of the received carrier wave is less than a predetermined threshold level. The magnitude of the received carrier wave is continuously monitored and compared to the threshold level. The generator frequency is incrementally increased until the carrier wave magnitude is optimum. This invention comprehends the apparatus for and method of optimizing signal strength at the receiving transducer by this technique.

Abstract: An FDM subscriber carrier system with two pilots located adjacent the upper and lower ends of the high frequency band uses the detected pilot levels at a remote terminal to adjust the gain and slope amplifiers in both directions of transmission. A microprocessor, programmed to identify the cable transmission characteristics, uses status signals derived from the two detected pilots to produce control signals to adjust and optimize the gain and slope settings of line amplifiers.

Abstract: Laser apparatus having a very narrow (<1A) spectral output comprises a laser cavity having a metal vapor cell as one of the reflecting elements. This cell reflects the laser beam over a narrow wavelength region in the vicinity of one of the metal vapor's resonant absorption lines and achieves frequency locking to an atomic resonance line without any external frequency sensors or feedback loops.