Abstract: A paging system transmits consecutively numbered page messages to receivers. Receivers detect missing page messages by interrogation of received page message numbers, and a missing page message is indicated by a gap in received page message numbers. However, page messages may be separated by long time intervals and a gap in received message numbers can not be detected until a subsequent page message is received. To more immediately detect a missing page message, a sequence message generated by the paging system provides a last transmitted page message number to receivers during otherwise unused portions of the transmission bandwidth. The receivers can thereby detect missing page messages without waiting until receiving a subsequent page message and without depleting the transmission bandwidth resource.

Abstract: A wide area paging system is disclosed in which paging messages input to the system in one local area can be broadcast to a receiver in any other local area without necessarily broadcasting the message in all areas. A local area clearinghouse in each area stores resident subscriber data including current location and receiver serial number. This data is used to transfer messages over a data network to the correct clearing-house. The system uses a TDM data protocol. The data is encoded and transmitted at a very high rate (e.g., 19,000 baud) in short packets (256 bits/13 milliseconds) via stereo FM sidebands. Receivers are assigned to receive sequentially numbered time slots matching a portion of their address. The addresses of intended receivers are included in the data packets. Battery-powered receivers are deactivated between packets and reactivated in accordance with the sequential time slot number scheme to receive an incoming packet.

Abstract: A paging system using synchronized transmission protocol and remote pagers active during monitor intervals to receive data transmitted during corresponding message intervals is provided with adaptive on-off radio receiver control for reducing monitor interval duration to conserve battery power and for centering message intervals within corresponding monitor intervals to increase message reliability. The adaptive on-off control is a function of a recent history of timing errors and thereby accounts for environmental conditions.

Abstract: A paging system and method utilize a trunk interface module which is capable of recognizing unique identification numbers, which comprise the telephone number which a caller dials to reach a particular paging receiver. The relative-digit-independent truck interface module is located between the telephone company central switch and the computer in the central clearing house and is capable of recognizing and relaying a set of at least seven digits, which comprise the unique receiver's identification number, wherein the values of the digit and the identification number are completely random, i.e., the digits are not necessarily representative of telephone numbers/identification numbers, in a particular telephone exchange. The system also includes a separate inward dialing portion which does not use the interface module and which requires the manual entry of receiver identification numbers.

Abstract: An electronic circuit, such as the type which may be found in a watch pager receiver, which contains both analog and digital circuitry, includes harmonic noise minimization circuitry. The minimization circuitry is constructed using standard cell designs which are optimized for particular clock operations. Select circuit components are optimized to produce minimal harmonics, to operate at the predetermined frequency and include resistance means to provide an output of a second known level which is characterized by an optimized output signal having a ramped wave configuration. The optimized output signal is of adequate strength to provide an input to a downstream component.

Abstract: The present invention provides a technique and system for modifying the modulation of the 66.5 kHz subcarrier in such a way that its spectrum will not overlap that required by the 57 kHz subcarrier, while at the same time maintaining compatibility with existing subcarrier receivers. A special signal is created whose spectral shape is asymmetrical with respect to the 66.5 kHz subcarrier. In the frequency domain, the lowest frequency part of the symmetrical spectrum is cut off, flipped about the carrier frequency and then added to the highest frequency part of the spectrum. This technique and system takes advantage of the fact that the receiver, with which the system is designed to operate, uses a sampling process which products frequency aliasing.

Abstract: A wristwatch paging receiver is provided with an antenna matching network that automatically retunes the network at the beginning of a listening interval. During the retuning operation, a control signal is applied to a variable tuning element in the matching network, such as a varactor diode, and is swept from a minimum value to a maximum value. This sweeping is desirably performed in discrete voltage steps that correspond to unit increments of varactor capacitance. A feedback signal from the receiver, such as an AGC signal, is monitored during this operation to note which varactor bias signal yields the maximum AGC signal. After the sweep is concluded, the apparatus applies to the varactor the bias voltage that yielded the maximum AGC signal during the sweeping operation. This bias voltage is maintained through the end of the listening interval. At the beginning of the next listening interval, the process may be repeated.

Abstract: An illegal-sheet-material detecting apparatus, which is adapted to detect whether the property of each of the passing sheet materials is legal or not in a sheet manufacturing machine, provided with a comparison circuit for detecting the lag of the same detection value of the n th+ first sheet material with respect to the detection value showing the property such as thickness, size or the like of the optional portion of the n th sheet material memorized in the memory circuit as an electric signal. When the lag detected by the comparison circuit has exceeded a predetermined range, the counting operation of the sheet material is caused to stop thereby to use the detection value of the n th sheet material as a reference value for comparing it with the n th+ first sheet detection value.

Abstract: A mechanical seal for sealing a slurry liquid between a casing and a rotary shaft comprises a fixed seat ring; a rotatable slide ring in the casing and abutting against the seat ring to form a sealing face therebetween; a helical spring in the casing and surrounding the rotary shaft, and biassing the rotatable slide ring toward the seat ring; and a rotatable ring on the rotary shaft and rotatable with the rotary shaft and holding the spring at a predetermined position relative to the rotary shaft, the spring being interposed between the rotatable slide ring and the rotatable ring. A small space is provided between the casing and the rotatable ring and the rotatable ring has a helical projection on the outer surface thereof. The helical projection of the rotatable ring and the helical spring are directed such that upon rotation thereof a force is produced in a direction away from the sealing face and toward the interior of the casing.

Abstract: A sealing device for a rotary shaft is provided with a spiral member having a determined pitch and a determined thickness on a rotating portion and/or a stationary portion corresponding to the rotating portion. The spiral member may be provided via a shaft sleeve, or may be directly attached on a rotating portion and/or a stationary portion corresponding to the rotating portion. The spiral member may be in advance shaped in a spiral form, or may be a string-like flexible member which may be shaped in a spiral form.

Abstract: A mechanical seal has a seal ring whose sealing face is divided into an inner part and an outer part by a circular groove through which sealing liquid is fed. The inner part of the sealing face is concave in the axial direction thereof.