Abstract: A method of dialing digits using dual tone multifrequency (DTMF) signals comprised of generating a digit from a DTMF generator comprised of a first pair of signals forming a DTMF signal, one signal of the first pair of signals being in a low frequency band and one signal of the first pair of signals being in a high frequency band, and applying the DTMF signal to a telephone line connected to a central office, detecting the first pair of signals in an auxiliary circuit and immediately applying a third signal in either of the low or high bands to the telephone line at the same time as the first pair of signals, and detecting the presence of the pair of signals and the third signal at the central office and preventing processing of the DTMF signal at the central office as a result thereof.

Abstract: The invention provides a method and apparatus for diagnosing the mechanical condition of a machine. The method of the invention includes the following steps: sensing reference vibrational characteristics of a machine in the time domain; creating a reference signature from the reference vibrational characteristics; saving the reference signature; sensing test vibrational characteristics of the same machine in the time domain; creating a test signature from the test vibrational characteristics; automatically computing a measured distance between at least one point of the reference signature and at least one corresponding point on the test signature; automatically comparing the measured distance against a threshold value to determine if the machine is operating normally or abnormally; and providing a signal when the comparison indicates abnormal operation. An apparatus is also disclosed for implementing the method of the invention.

Abstract: A key telephone system for use with at least two telephone lines that extend between a central office and two or more telephone stations. Each station is capable of responding to a manually-actuated hold select switch by establishing a hold condition on one of the lines and by connecting a line terminating impedance across the line that is to be held. Each station is further capable of monitoring the state of each line, and indicating the state of each line, without applying any indicating signals to the telephone lines. Each station furthermore determines threshold voltages for on-hook, off-hook and hold line states and determines line state by comparison of line voltage with such threshold voltages.

Abstract: The present invention relates to an apparatus for the controlled heating of an ultra small volume. The invention provides a means of heating, measuring, and controlling the temperature in such ultra small volume. The present apparatus includes a heat-sensor portion comprised of an electrical resistance. Heat is generated in the heat-sensor portion by a flow of electrical current through such electrical resistance. The temperature in the heat-sensor portion is determined by measuring the electrical resistance of the circuit that includes the heat-sensor element. The apparatus is comprised of a thin-walled microcapillary tube filled internally with an electrically conductive material and coated externally with a dissimilar electrically conductive material. The external electrically conductive coating on the microcapillary tube is suitable a noble metal such as gold.