Abstract: Digitized images of the propagated waveforms returned by Time-Domain (TD) sensors reveal the effects of bound water in soil samples, causing errors in the volumetric water content reported for samples due to soil type. Pattern analysis yields not only correct volumetric water content values but also the soil type from which the waveform was taken. Collection and analysis of waveforms from soils having precisely known properties yield computer-generated algorithms to improve the accuracy and number of reporting variables for integrated TD sensors. These algorithms can be deployed in the Cloud for external analysis, or can be incorporated within the sensor to report highly accurate readings of water content, conductivity and soil type under all conditions of these variables with no interpretive burden placed on the user of the sensor. Machine learning algorithms are intended to externally augment data measured by these sensors, or can be added to similar sensors.

Abstract: Soil water content and bulk electrical conductivity may be determined by time domain reflectometry at multiple depths in the soil such that the entire soil profile from the surface to a user-selected depth may be characterized. A short rise-time pulse is passed into an electrode and the reflected pulse is captured at multiple times. A waveform of reflection coefficient versus time is determined, which may be used to determine the pulse travel time, effective frequency and reflection coefficients at times necessary for the determination of the soil water content and bulk electrical conductivity.

Abstract: The described apparatus and methods use Time Domain Reflectometry (TDR) to determine the absolute volumetric moisture content of various media. The effects of dispersion caused by conductive and dielectric properties of the medium on the waveform are extrapolated by detecting the bulk propagation time and the slope of the distorted transition of the characteristic reflected waveform. Fast transitions are injected by a differential step function generator into a two-conductor waveguide, which is immersed in soil or other medium of interest. Unlike previous single-ended TDR systems, a differential digitizer senses the probes. Timing control between the two digitizers is critical. Use of an integrated fully differential system eliminates the need for a coaxial cable and an associated balancing transformer, or balun. This enables a two-conductor probe that is more easily inserted into soil, rather than requiring three conductors.

Abstract: An absolute moisture sensor is coupled to a controller circuit with the combination being integrated into a single device as a moisture-activated switch. The resultant switch is coupled in series with a power control line of a moisture-controlling device and can be placed within the medium for which moisture is to be controlled. In one typical use, the switch is buried in soil for control of valves that supply irrigation water. Since the moisture sensor is selected to provide an absolute reading of moisture, the switch programs itself when power from an external source is first applied. A communication protocol provides for readout of sensor values and allows for a remote reset of the controller.

Abstract: A combination of frequency and time division multiplexed signals communicates using bursts of higher frequency sinusoidal waves superimposed upon the alternating current in a two-wire power distribution network. A synchronization pattern precedes data, all bursts having the same frequency to overcome problems caused by varying reactances, and all bursts being confined within negative half-cycles of the AC power. Such networks minimize the amount of wire needed to connect large numbers of devices to a common controller while covering large distances, and requiring no particular connection pattern or terminations, whether near the surface, above ground, or in deep earth wells. In an irrigation system they accommodate at once solenoid valves and distributed environmental sensors. Landscape changes that would otherwise require new wiring to accommodate new irrigation zones are facilitated by merely tapping into the two-wire communications lines at the nearest accessible point.

Abstract: Narrow pulses transmitted wirelessly from a transmitting antenna to a receiving antenna are used to measure the electrical permittivity of the medium of interest between the two antennas. Timing signals are transmitted along a shielded transmission line coincident with the wireless transmission through the medium. The received waveform is digitized in the time domain and analyzed to determine the propagation time. The effects of dispersion caused by the conductive and dielectric properties of the medium on the transmitted waveform are overcome through analysis of the digitized waveform, resulting in an accurate measurement of the propagation time and thus the permittivity of the medium, from which volumetric moisture content may be derived.

Abstract: Methods and apparatuses are described for detecting volumetric moisture content and conductivity in various media based on a time-domain reflectometry (TDR) system wherein successive fast transitions are injected into a transmission line immersed in a medium of interest, and a characteristic received waveform is digitized and analyzed by continuously sampling multiple received waveforms at short time intervals. One method transmits a timing signal along a shielded transmission line while a coincident signal is transmitted through the medium of interest. Another method propagates the waveform along a transmission line, that may be either shorted or open-ended, and observes a reflected, rather than transmitted, waveform with a receiver connected to the same end of the transmission line as the transmitter.

Abstract: A combination of frequency and time division multiplexed signals communicates using bursts of higher frequency sinusoidal waves superimposed upon the alternating current in a two-wire power distribution network. A synchronization pattern precedes data, all bursts having the same frequency to overcome problems caused by varying reactances, and all bursts being confined within negative half-cycles of the AC power. Such networks minimize the amount of wire needed to connect large numbers of devices to a common controller while covering large distances, and requiring no particular connection pattern or terminations, whether near the surface, above ground, or in deep earth wells. In an irrigation system they accommodate at once solenoid valves and distributed environmental sensors. Landscape changes that would otherwise require new wiring to accommodate new irrigation zones are facilitated by merely tapping into the two-wire communications lines at the nearest accessible point.

Abstract: Methods and apparatuses are described for detecting volumetric moisture content and conductivity in various media based on a time-domain reflectometry (TDR) system wherein successive fast transitions are injected into a transmission line immersed in a medium of interest, and a characteristic received waveform is digitized and analyzed by continuously sampling multiple received waveforms at short time intervals. One method transmits a timing signal along a shielded transmission line while a coincident signal is transmitted through the medium of interest. Another method propagates the waveform along a transmission line, that may be either shorted or open-ended, and observes a reflected, rather than transmitted, waveform with a receiver connected to the same end of the transmission line as the transmitter.

Abstract: A disk drive having a pair of axially spaced disks has a rotary actuator/head assembly in which a single rigid actuator arm projects between the axially spaced disks. A gimbal spring is mounted to each surface of the opposite surfaces at one distal end of the rigid actuator arm. Each gimbal spring mounts a slider having a magnetic head, the individual magnetic heads confronting the respective disk surfaces. The proximal ends of respective cantilever load springs are mounted to opposite surfaces of the rigid arm and their distal ends engage and spring bias the respective sliders against the respective disk surfaces. A printed circuit coil on one or both surfaces of the other distal end of the rigid actuator arm is the armature of an axial gap actuator motor, having a permanent magnet stator.

Abstract: A disk drive in which the disk spindle motor for a rotatable recording/reproducing media has a printed circuit stator winding on a printed circuit board within the disk drive housing, fitted between axially spaced circular flanges of a bobbin-shaped motor rotor. Alternately poled, equally circumferential spaced, axial permanent magnet fields between the axially spaced circular flanges link radially disposed printed circuit winding sections. Electronic elements on the printed circuit board are linked internally of the housing with the magnetic head and the actuator motor winding which powers the actuator for moving the magnetic head to different radial locations on the rotatable media. Bi-polar energization of the stator winding of the disk spindle motor is under the control of a commutating circuit controlled by a Hall sensor linked by the axial permanent magnet fields.

Abstract: A phase lock circuit has a voltage tuned oscillator (VTO) which is tuned by a tuning circuit. The tuning circuit supplies tune-up and tune-down (in frequency) signals to phase lock the VTO with respect to a reference signal. The tuning circuit supplies the tune-up and tune-down signals based on the results of samples of the VTO output from a variable modulus counter (VMC) with respect to a reference signal. The reference signal and VMC are reset to a time reference by a reset generator during coarse tuning or phase locking.

Abstract: A plurality of communication stations is interconnected by conductors. Each station includes a transmitter and a receiver as well as control means. The transmitters transmit on any of several frequency bands, each such band being assigned to the receiver of a remote station. A signal generator interconnects the stations and generates intervalled pulse trains upon which the control means of the stations operate to impress coded control pulses. The stations include novel phase locking and phase detecting circuits.

Abstract: A plurality of communicating stations have transmitters, receivers and control means. The transmitters are tunable across a broad radio frequency spectrum and transmit an amplitude modulated selected carrier frequency. Each receiver is set to receive only one preselected amplitude modulated carrier frequency fixed and identified with each particular station. Stations may be regarded as telephones having signaling means and a chassis. The control means includes means to receive TDM control signals from and to supply TDM control signals to a remote common equipment unit. The control signals and amplitude modulated carriers are sent and received over common cabling. The common equipment unit includes processor means to process and generate control signals and means to interface with an external telephone system.