Abstract: Apparatus and methods are disclosed for analyzing particles, such as coarse particulates, fine particulates (e.g., diesel particulate matter), and combustion aerosols, using light-scattering sensors and/or ionization-type sensors. In one disclosed embodiment, a particle monitor includes an ionization module and a controller adapted to receive an output signal from the ionization module. The controller is operable to translate the output signal into the mass concentration of particulate matter within the ionization chamber. In another embodiment, a particle monitor includes a light-scattering sensor and an ionization sensor. The monitor is configured to measure separate mass concentrations of sub-micrometer particles and larger dust particles in an atmosphere having both types of particles.

Abstract: A hazardous area warning system with a non-directional magnetic field based proximity receiver for warning personnel of an attendant hazard. The receiver includes a x-axis receiver with an antenna directed in a x direction, a y-axis receiver with an antenna directed in a y direction and a z-axis receiver with an antenna directed in a z direction. The antennas may be a wire loop wrapped around a ferrite core. The output from each of the three receivers are combined in an adder. The combined result from the adder is representative of the distance between the receiver and a warning transmitter antenna. A comparator determines whether the received signal indicates an attendant hazard, i.e., the receiver is too close to the warning transmitter. The receiver wearer is warned of the attendant hazard, visually and/or tactilly, e.g., with warning lights and/or vibrations. An encoder encodes the signal indication and a transmitter transmits the encoded signal.

Abstract: A hazardous area warning system with a non-directional magnetic field based proximity receiver for warning personnel of an attendant hazard. The receiver includes a x-axis receiver with an antenna directed in a x direction, a y-axis receiver with an antenna directed in a y direction and a z-axis receiver with an antenna directed in a z direction. The antennas may be a wire loop wrapped around a ferrite core. The output from each of the three receivers are combined in an adder. The combined result from the adder is representative of the distance between the receiver and a warning transmitter antenna. A comparator determines whether the received signal indicates an attendant hazard, i.e., the receiver is too close to the warning transmitter. The receiver wearer is warned of the attendant hazard, visually and/or tactilly, e.g., with warning lights and/or vibrations. An encoder encodes the signal indication and a transmitter transmits the encoded signal.

Abstract: A warning system is provided for a mobile working machine to alert an individual of a potentially dangerous condition in the event the individual strays into a hazardous working zone of the machine. The warning system includes a transmitter mounted on the machine and operable to generate a uniform magnetic field projecting beyond an outer periphery of the machine in defining a hazardous working zone around the machine during operation thereof. A receiver, carried by the individual and activated by the magnetic field, provides an alarm signal to alert the individual when he enters the hazardous working zone of the machine.

Abstract: An encoding apparatus provides range or other data as determined by the setting of a control or selection knob therefor. The encoding apparatus is intended for use with an instrument providing an output voltage representative of data within a range, and providing output signals indicative of the setting for the range control or selection switch of the instrument. The encoding device is adapted to fit externally of the instrument chassis and is mounted between the range selecting knob and the chassis. The encoding apparatus is non-invasive, requiring no connection to or modification of the internal components of the measuring instrument.

Abstract: A battery powered paging and intercommunication system for application in a mine or other environment where it is necessary to conserve battery power comprises a plurality of transceivers electrically coupled to a common pair of signal lines. Each of the transceivers includes a push-to-talk switch for applying voice signals onto the lines as well as a push-to-page switch that amplifies received voice signals for reproduction through a loudspeaker. Each transceiver also includes dual tone multifrequency (DTMF) encoder and decoder circuitry for addressing a preselected transceiver on the lines for paging. A timer circuit within the transceiver limits the period of time the transceiver limits the period of time the transceiver is in the paging mode to reduce battery consumption. As a system check during paging, the called transceiver generates "beep-back" signals on the lines indicating to the calling transceiver that it is receiving paging signals.