Abstract:
A charger for charging a battery at a first predetermined rate and automatically terminating said charge rate when the battery temperature rises, in response to the charging current, to a point indicating full charge. The battery has a thermistor mounted therein which changes resistance as the battery temperature changes. The charger includes a charging circuit and silicon controlled rectifier in series with the battery. A sensing circuit, coupled to the thermistor, senses a thermistor resistance indicative of less than a full charge and changes from a first to a second state. If the thermistor resistance indicates a full charge, the sensing circuit changes from the second to the first state. A switch circuit connected to the sensing circuit and the rectifier gate electrode is responsive to changes from the first to the second state to trigger the rectifier into conduction and allow charging of the battery at the predetermined rate. A latch circuit connected to the sensing circuit and rectifier gate electrode operates in response to the sensing circuit changing from the second to the first state to inhibit further conduction of the silicon controlled rectifier. The latch circuit is deenergized, allowing further conduction of the silicon controlled rectifier, by removal of the battery from the battery charger.
Abstract:
A fax selective call receiver system (10) featuring compression of a fax message with an optimal one of a plurality of compression code-books (50). At least a portion (44) of a source document (26) is compressed with each of a plurality of code-books (50), and the smallest resulting data file is selected as the optimal compressed file. The compressed data file is transmitted to a selective call receiver (40) together with an index identifying the optimal code-book. The selective call receiver (40) stores each of the plurality of code-books and accesses the particular code-book for decompressing the data file on the basis of the received index. In an alternative embodiment, the fax message is divided into composing segments (SI1, SI2 and SI3), and each segment is compressed with each code-book to determine the optimal code-book for each segment.
Abstract:
A method of transmitting and receiving encoded data generated from input data comprising readable text characters (102) in a communication system having an optical character recognition element (206) and a graphic encoding element (208), the communication system also having a transmitter (114) and a receiver (116), comprises accepting (602) the input data comprising the readable text characters (102) by a facsimile input (202). The method further comprises encoding (620, 622) as character code format data the readable text characters (102) received that are recognizable by the optical character recognition element (206), and encoding (610, 612, 614) as graphic code format data the readable text characters (102) received that are not recognizable by the optical character recognition element (206). The method further comprises assembling (632) the character code format data and the graphic code formate data into an output data stream, the output data stream including information that describes original sizes and positions relative to one another of the readable text characters (102).
Abstract:
A communication system has a base station having memory for storing information within a plurality of information files relating to a plurality of information services. A receiver receives an information service request for requesting information within at least one of the plurality of information files from a selective call receiver. A transmitter transmits the information requested from within the at least one information service file to the selective call receiver. The selective call receiver includes a generator for generating the information service request and a transmitter transmitting the information service request. The selective call receiver receives the information transmitted from the base station in response to the information service request and a display displays the received information.
Abstract:
An acknowledge back (ack-back) paging system is provided which includes a central station which transmits a group of message signals to a group of ack-back pagers which are addressed as a group. The users of the group of addressed ack-back pagers indicate a response to their respective pagers thus providing ack-back data. The pagers in the group of addressed ack-back pagers then simultaneously transmit back to the central station their ack-back data on different frequency sub-bands, a different frequency sub-band being allocated to each of the pagers in the group.
Abstract:
A communication system has a base station having memory for storing information within a plurality of information files relating to a plurality of information services. A receiver receives an information service request for requesting information within at least one of the plurality of information files from a selective call receiver. A transmitter transmits the information requested from within the at least one information service file to the selective call receiver. The selective call receiver includes a generator for generating the information service request and a transmitter transmitting the information service request. The selective call receiver receives the information transmitted from the base station in response to the information service request and a display displays the received information.
Abstract:
A paging system is provided for transferring information to a paging receiver (12), including a central controller (20) having a paging controller (22) for receiving the information, an encoder (24) coupled to the paging controller for generating a selective call paging signal designating the paging receiver. The paging receiver receives and decodes the selective call paging signal generating a coded acknowledgment signal indicating whether the selected paging receiver is in a normal or a deferred operating mode, and transmits this signal back to the paging controller. When the coded acknowledgment signal indicates the paging receiver is in the normal operating mode or memory is available, the information is transmitted to the paging receiver. When the coded acknowledgment signal indicates the paging receiver is in the deferred paging operating mode, and the paging receiver memory is full, the information is stored in the central controller for transmission at a later time.
Abstract:
A paging system has a signal for transmitting a variable amount of messages to paging receivers. The signal has a synchronization signal (100), an address field (104), an information and a boundary signal indicative of the boundary between the address field and the information field. Each message has an address which is included within the address field and may have message information which is included in the information field. The information field includes two portions, a first portion (106) having a plurality of packets for holding a predetermined amount of information and a second portion (108) for holding a variable amount of information. If the message information is greater than the predetermined amount, it is stored in the second portion of information field and a vector signal indicating the location of the message information is stored in the first information field.
Abstract:
2050892 9100655 PCTABS00003 This invention relates to selective call receivers (11), such as paging receivers, for receiving modulated data signals having a variable bit rate. A band pass filter (26), particularly an I. F. filter, is provided having an adjustable bandwidth. The bandwidth of the filter is adjusted in accordance with a code in the received signal which indicates the bit rate.