An apparatus for detecting and providing positional information as to an object in a field of view primarily for aiding blind persons comprising a frequency swept transmitting transducer and two receiving channels receiving reflected frequency swept incoming signals sampled in the channels respectively by encoders fed with time staggered switching pulses to generate a multiplex signal fed to a single variable gain amplifier, the output of which is decoded in the later portions of the two receivi...

An intruder detection system wherein vibrations generated by an intruder are detected apart from normal environmental noise and are utilized to set off an alarm. The system detects activity rate rather than total generated energy by measuring duration, frequency and amplitude of generated sound. Detected vibrations having a predetermined frequency range provide an input signal for both legs of a differential amplifier. The output signal of the differential amplifier is analyzed for presence of c...

A system for identifying the presence of physical surface patterns and/or areas in a surface which have different electrical conductivity characteristics from those of adjacent areas of the same surface. The system utilizes the optical characteristics of liquid crystal films having optically negative properties.

A detection system designed primarily for detecting intruders of fenced-in areas such as yards, compounds, factory areas and the like. In the preferred embodiment, a chain-link metal fence extends about the area being monitored. A conductive cable extends parallel to the fence either on its inner or outer side. The cable is spaced uniformly from the fence which functions as an electrical ground. The cable is selected with a dimension and is spaced at a distance such as to establish uniform chara...

A detection device comprising two spark-gap electrodes connected to a voltage pulse source having an amplitude greater than the striking voltage of the spark-gap, so that each pulse produces a spark between said electrodes. Such a detection device is characterized in that it comprises, connected to at least one of the electrodes, a detection circuit able to supply at its output a signal whose amplitude is representative of a definite condition of the atmosphere present between said electrodes, p...

A detector is disclosed for detecting the presence of substances that form ions in liquids, comprising a porous, non-conducting wicking material which is electrically connected to a power supply and a current or resistance detecting device.

A system for detecting objects or predetermined conditions at remote locations employs a control circuit coupled to a remote sensor circuit by two conductors to supply power to the sensor circuit during the positive half of each cycle. During the negative half of the cycle of operation, the remote sensor circuit develops an output signal indicating the presence or absence of an object or other detected condition and applies the signal to the control circuit via the same two conductors. The contr...

A system for detecting the presence of resonant circuit targets in a field of electromagnetic radiation. The system includes means for generating a burst of a predetermined single frequency and a detector enabled after the termination of transmission. The detector is sensitive to continued presence of the predetermined frequency indicative of resonant ringing of a target in the field. Time sharing of a common transmitter and detector is accomplished employing a time division multiplex arrangemen...

A tender patrols the spinning stations of a spinning frame and stops to service any station requiring attention. One reason for stopping the tender is because a strand normally spun into yarn has broken at a spinning station. In order to determine whether or not the strands are advancing normally at the spinning stations, the tender carries a transducer responsive to vibration of a feeler upon engaging the normally advancing strands to actuate an electronic switch which provides a signal permitt...

Damage detection apparatus for use on a normally vertical post supporting a remote signalling device including a radio transmitter, comprising an electric generator having output terminals connected to the transmitter, a source of mechanical energy, and means for applying mechanical energy from the source to cause operation of the generator and the transmitter when the orientation of the post departs from the vertical by a predetermined amount.