Abstract: An automatic dispensing machine of substantially flat goods is provided which detects the over-dispensing of goods while accommodating for varying thickness of the substantially flat goods. The automatic dispensing machine includes a table which supports goods such as cards, a suctioning device which pulls the cards, a transporting device which transports the cards after they are pulled by the suctioning device, a position-control device which controls the distance between the uppermost card and the suctioning device. The position-control device is configured to increase the distance between the uppermost card and the suctioning device based on a dispensing signal. The distance between the uppermost card and the suctioning device is then decreased until a predetermined distance is reached.

Abstract: A radio paging network transmits non-paging data, such as facsimile images, to lap top computer receivers by formatting the data into a series of packets and interleaving these packets, on a space available basis, into the paging signal.

Abstract: In a time keeping system providing time of day by radio signal to remote time keeping devices, the transmitted time of day is provided in association with a given time zone identification. The time keeping devices receiving the time of day reference and the time zone identification include a time zone preference identification. By comparing the time zone preference and the time zone identification transmitted, the time keeping device can, when necessary, offset the received time of day value according to user preference for display relative to a preferred time zone.

Abstract: A digital filter is designed by characterizing a desired filter passband in the frequency domain, transforming this representation into the time domain, selecting weighting coefficients at periodically spaced intervals from this transformed function, and weighting the coefficients with a Gaussian windowing function. This function may take the form:.sub.e -.vertline.( 2 n-N)/A.vertline..sup.Pwhere:A=N(-ln.epsilon.).sup.-1/P; .epsilon.<1.epsilon.=Window value desired at n= 0 and n=N (reduction ratio);N=(number of F.I.R. taps)- 1; andP=an arbitrary power.

Abstract: A radio paging network transmits non-paging data, such as facsimile images, to lap top computer receivers by formatting the data into a series of packets and interleaving these packets, on a space available basis, into the paging signal.

Abstract: A paging system using synchronized transmission protocol and 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. The adaptive on-off control is a function of recent timing errors and thereby accounts for environmental conditions.

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: A method for searching for a station carrying paging data without unduly draining the paging receiver battery. If a station to which the receiver is presently tuned becomes unreliable, the pager scans among channels listed in a local channel list. If no paging data is received on these channels, the scanning among the local list channels may optionally proceed for a further interval at a slower rate. After it appears that paging data will not be found on channels listed in the local list, the pager begins a full spectrum search at a slow rate until it again finds a channel carrying paging data. By this arrangement, battery power is expended at a rate roughly in accordance with the likelihood of finding a paging station.

Abstract: A radio receiver for use with a time slot paging system which receives intermittent data includes a direct coupled zero IF receiver circuit with at least one automatic gain control (AGC) amplifier stage. DC offset errors are removed from the AGC amplifier stages by a timed zero adjustment circuit that is switched into the AGC circuit just prior to the receipt of data. The resulting zero IF circuit may be miniaturized in monolithic form making it ideal for use in a wristwatch sized pager.

Abstract: The present invention provides an antenna or preselector tuning method and circuit that tunes an antenna or preselector in a very short period of time. The circuit of the present invention does not rely on measuring the magnitude of the signal strength at the output of the receiver as do many prior art antenna tuning techniques. With the present invention a radio frequency (RF) oscillator set to the desired receiver frequency generates an excitation signal which is lightly coupled to the antenna tuned circuit through a network. A phase detector then compares the phase of signal established in the antenna tuned circuit with the phase of the excitation signal to produce an "error" signal indicative of the phase shift of the excitation signal as it passes through the network. Using this "error" signal and locked loop (PLL) techniques, an antenna tuning voltage is created that results in a zero phase shift through the network.

Abstract: An AFC switch circuit is controlled by an select input logic signal for providing a selected output signal to control the local oscillator in a miniature FM receiver. The output signal has a voltage equal to either an AFC signal voltage for AFC operation of the receiver, or a reference voltage for synthesized operation of the receiver. The AFC switch circuitry employs bipolar transistors in current mirror configurations to minimize voltage offset and to enhance isolation between the unselected input and the output while operating on a power supply voltage less than 3 volts.

Abstract: Data flow control is achieved by use of variable length flags delimiting information packets whereby longer flags result in less information flow and shorter flags result in greater information flow. A single channel carries message data as well as status and command data in information packets delimited by the variable length flags. The channel runs continuously such as to provide a constant flow of status and command data, yet includes flow control for preventing overflow and underflow of message data at the receiving end of the channel.

Abstract: Real time synchronization of radio signal data is achieved by a feedback loop between a clearinghouse generating data and a radio station transmitting data. Transmission time is adjusted in response to detected timing errors by selectively inserting padding data between certain data packets to shift data packet position within a data stream transmitted at a predetermined transmission rate. Data flow control is achieved by use of variable length flags delimiting data packets whereby longer flags result in less data flow and shorter flags result in greater data flow.

Abstract: A frequency agile data receiver checks are needed, according to a first protocol, among a plurality of channels to find a channel carrying data. A control activated by the user interrupts this first protocol and institutes a second protocol different than the first. Applied to a paging receiver, the first protocol may sequentially tune the receiver to a plurality of previously identified channels to locate a channel on which paging data is satisfactorily received. The second protocol may sequentially tune to all possible channels to locate such a channel. By this arrangement, a person who knowingly moves to a new locality (e.g., flies to another city) can instruct the paging receiver to abandon a previously identified list of candidate channels and to begin a spectrum-wide scan to locate a new satisfactory paging channels.

Abstract: A page receiver is provided a list of alternative paging channels to which it can tune if the paging channel presently being received becomes unreliable. This list, and other lists used by paging receivers in the other geographical areas, are disseminated by linked paging transmitters that broadcast identical paging signals throughtout a large geographical area. When a paging receiver finds a channel carrying paging data, it identifies which of the plurality of transmitted lists is appropriate for its use by finding the list that references the channel to which the receiver is presently tuned. The channels referenced in the identified list are then stored in a memory and may be tuned if the existing paging signal is lost. Data is desirably transmitted with the local channel lists to permit each paging receiver to locate the list relevant to its geographical area without examining each of the transmitted lists.

Abstract: A paging system where messages are numbered before they are transmitted. The paging receivers in the system compare both the number and the text information in each message which is received to the message number and the text information in the most recently received previous message. The comparison is used to determine if the same message was previously received and if the any messages were missed. The receiver includes an icon which is turned on to indicate if a message has been received. The icon is set to a blinking state if a message is received and if there is a break is the sequence of message numbers indicating that a message has been missed.

Abstract: The present invention provides a pager system which integrates a plurality of transmitters which operate at different frequencies. Some of the transmitters transmit paging messages using FM subcarrier signals (termed FM-SCA signals) and some transmit messages using a modulated carrier (termed RCC signals). The receiver includes two front ends. One front end receives and demodulates FM-SCA signals and one front end receives and demodulates RCC signals. Each paging message is transmitted on both FM-SCA transmitters and on RCC transmitters. The signals on each of the transmitters are slightly off set in time. When an assigned time slot occurs, one receiver turns on and attempts to receive a message, if it does not receive an appropriate signal, it tunes to another station that is in a stored list of stations. If the next station has an RCC flag associated therewith the RCC receiver rather than the FM-SCA receiver is operated. The entire process is controlled by a microprocessor which is a part of the system.

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 clearinghouse. 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 local telephone/radio paging system includes a local paging system, a telephone, and a memory for indicating which telephone numbers are within the local area. When a telephone number is dialed, if the person dialed does not answer, the telephone switching equipment checks the memory to determine whether the dialed number is within the local paging area. If so, a local paging transmitter is activated, paging the person assigned to the unanswered phone. Such a paging transmitter may be included in each phone, or a single central local transmitter may be employed. The paging receivers desirably include alphanumeric displays and indicate the number of the telephone that originated the unanswered call, so that the person carrying the paging receiver may call back immediately.

Abstract: A radio paging network transmits non-paging data, such as facsimile images, to lap top computer receivers by formatting the data into a series of packets and interleaving these packets, on a space available basis, into the paging signal.