Nec Corporation

Nippon Electric Co., Ltd.

Yoshio Ichikawa

Takashi Ohyagi

Yukio Sato

Kazuyuki Tsunoda

Masaaki Akahori

Daisuke Ishii

Shinjiro Umetsu

Koichi Nagata

Yoshikazu Takayama

Kazumori Yamada

Yohichiro Minami

Derek Dawkins

A global radio paging system in which a plurality of radio frequency carriers having the same frequency are synchronously modulated in a plurality of base stations corresponding in number to the radio frequency carriers with the same digital paging signal and transmitted, respectively. A paging controller which receives paging calls through a public switched telephone network stores preliminarily the maximum value of a sum of a paging request signal transmission time in a transmission line and a time required to process the paging request signal in each of the base stations and a high precision time signal is produced on the basis of a reference signal from a GPS (Global Positioning System) satellite. A transmission time assigning code is attached to the paging request signal, which assigns a time instance which is delayed from a current time determined by the high precision time signal by the maximum value of the sum of the transmission time and the processing tame as a transmission start time. In each of the base stations, a high precision time signal is produced on the basis of the reference time signal from the GPS satellite and the paging request signal supplied through the transmission line is processed on the basis of the high precision time signal to convert a format into the digital paging signal to thereby realize a synchronous modulation of the carriers.

Radio paging system having a plurality of transmitter stations

In a pager receiver for receiving first through N-th pager signals successively at a first predetermined period (T1) and comprising a battery saving switch and a receiving circuit connected to the switch and enabled while the switch is in an on state, a controller puts the switch in the on state repeatedly at a second predetermined period (T2) to make the receiving circuit receive at least a portion of a preamble signal (PA) and whole of a synchronization (SS) and an address (AS) signals of the first pager signal (RS1) and detect an address signal end of the first pager signal. The controller keeps the switch in the on state to make the receiving circuit receive at least a part of the preamble signal and whole of the synchronization and the address signals of each of the second (RS2) through the N-th pager signals and detect the address signal end of each of the second through the N-th pager signals. The controller puts the switch in the off state from detection of the address signal end of each signal of the first through the N-th pager signals until lapse of a preselected duration (D3) from reception of the synchronization signal of the each signal.

Transmission and reception of pager signals without useless sampling

This improved paging system not only detects an omission of a message reception, but also acquires an unreceived message. When a normal paging request call is made from a public telephone network, the paging control unit adds to the received request a message counter including the called subscriber's number and then transmits an encoded paging signal which includes the received request. Further, a control unit stores the message data in a storage unit corresponding to a value of the counter of the called subscriber's number. The called pager detects an omission of a message reception through the received message counter value by comparing it with the message counter value of the last received message signal. A displayed message indicates an omission as well as the value of the omitted message. Thus, a call can be made through a public telephone network to request a repeated transmission. When the message counter value is specified, the paging control unit retrieves the message data stored in the message data storage unit corresponding to the specified value and transmits the data from the transmitter.

Paging system and its operating method with repeated transmission

A paging system comprises a predetermined number of radio paging terminals each producing a subscriber identification number, a service zone signal, and a frequency signal respectively corresponding to a subscriber number, a paging processor for allocating subscriber identification numbers received from the radio paging terminals respectively to a predetermined number of paging service zones and a predetermined number of time slots in accordance with the service zone signals and frequency signals, and a predetermined number of transmitter for radiating paging signals provided in each of the paging service zones so that at least two paging signals having different frequencies which are obtained by modulating at least two of the subscriber identification numbers are radiated in two adjacent paging service zones at one of the time slots.

Apparatus for allocating subscriber identification numbers to plural

A single-frequency signal communications system such as a paging network includes plural communication groups, each of which includes one master station and plural slave stations. The master stations of at least adjacent groups are within each others' reception zones. To avoid signal collision problems, each master station refrains from initiating transmission of a data signal unitl it has failed to detect the carrier signal of any other master station for a time period T. The designated slave station acknowledges receipt of the data signal by transmitting an acknowledgment signal within a period t after receiving the data signal. The time period T is greater than the time period t in order to avoid master station-slave station signal collision problems.

Radio communication system having means for avoiding signal collision

A radio paging system for transmitting address signals and messages, as well as information common to a plurality of receivers, and a receiver applicable to such a system. The radio paging system includes: an encoder which produces a first code, followed by a string of address codes each of which is followed by message codes, and a second code followed by a string of information codes, a transmitter for transmitting a string of codes produced by the encoder; and a receiver which upon detection of the first code produces an alert signal and displays the message codes when the address code agrees with an address code stored in memory, and which, upon detection of the second code, displays the information codes which follow.

Radio paging system capable of transmitting common information and

A pager receiver for a radio calling signal carrying a call number and/or a message comprises a processing unit for producing a drive and an information signal to produce ordinary tone or tones related to the call number and to provide ordinary visual displays representative of the message, respectively. A processed signal is produced by the processing unit to provide extraordinary tones peculiar to a message-absent call, a message-present call, and a repeat call for repeatedly displaying a prior message. The processed signal also appears to provide extraordinary visual displays unique to the message-absent call. When the pager receiver has a plurality of preassigned call numbers, the processed signal is produced to provide such extraordinary displays inherent to each of the respective preassigned call numbers. In addition to the extraordinary displays of the preassigned call number, a plurality of messages are successively stored in a memory in a predetermined order to be successively displayed one by one. On reception of the repeat call, the predetermined order may be changed to keep the message related to the repeat call from being erasing from the memory even when the memory is full of message.

Pager receiver for giving at least one of extraordinary tones and

A testable pager including a receiver for demodulating a sequence of signals, and a manually operated switch. A controller receives the outputs of the receiver and the switch. The controller thereby switches on a power supply for the receiver for a set period after the start of the signal sequence. When the sequence includes a test code, the power supply stays on and a first test is performed. Actuations of the switch cause further tests to be made.

Paging receiver having a plurality of test modes

A radio paging receiver for receiving a carrier wave modulated paging signal which includes a preamble, an address code and a message, is composed of at least a receiver section, a waveform shaping circuit, a memory section, a control section, a speaker with driving sectionto sound an alert signal and a display section. The memory section stores a predetermined number of received messages, which are counted as they are received by a counter in the control section. The display section under the control of the control section, produces a three part display, the first part being an indication of the age of the displayed message relative to the other messages stored in memory, the second part the call type, when a dual call service is implemented, and the last part one of the messages stored in memory. If a message is being displayed as a new message is received, the previous message continues to be displayed, while the new message is stored in memory if memory space is available. In addition, the receiver operates to change the first part of the display to inform the subscriber that a new message has been received.

Display pager having memory overflow indication and concurrent message

A paging system in which an address code is transmitted at a lower transmission rate than message code and a discrimination code defines the boundary between the address and the message. The receiver includes a low pass filter with a cut-off frequency switchable between the reception rate for the address and the reception rate for the message in response to the discrimination code.

Digital paging system having bit rate switching means and digital paging

In a radio communication apparatus comprising a P-ROM (32), a loudspeaker (34), and/or a display unit (36) and carrying out a receiving operation of selectively receiving a call signal specific to the apparatus by the use of an identification number read out of the P-ROM, a predetermined signal to be produced after the call signal is defined to inhibit or disable the receiving operation carried out after reception of the predetermined signal. The loudspeaker may be driven under control of a reception controller (31) to continuously produce an audible signal when the predetermined signal is received. The display unit may also be driven to provide visual displays representative of particular messages conveyed by the predetermined signal. The particular messages may be 'lost' and 'theft' codes and a telephone number.

Radio communication apparatus disabled on reception of a predetermined

A radio paging receiver of the type having a display unit includes a plurality of storage cells respectively for storing received message words therein, and a data processing unit which is arranged to detect a match between a received address word and a subscriber's address word and proceed to sequentially store the received message words into the storage cells. A numeral indicating the degree of freshness of the received message word is generated and displayed simultaneously with the message word in response to to the operation of a reset key. An indication is given that a message word will follow if the length of message words is greater than the capacity of the display unit. A symbol is subsequently given with the display of the next message word to indicate that the message word being displayed is a continuation from the previous one if said total is greater than the number of digits.

Display radio paging receiver for variable length messages

A radio paging receiver which generates an alert tone and a message display on receipt of a selective calling signal, includes a manually operated non-lock type switch which generates first and second control signals. The first control signal stops the generation of the alert tone while the second control signal initiates a time-out period after which the displayed message is turned off. Depressing the switch produces the first control signal while its release produces the second control signal.

Radio paging receiver having display control means

A battery saving circuit for use in a portable radio communication apparatus adapted to receive a communication signal which includes a preamble and identification codes. The apparatus includes a receiver section, a waveform shaper section, a decoder section and a power supply. The battery saving circuit, forming a portion of the decoder section, periodically generates a first control signal which causes the power supply to be electrically connected to the receiver and waveform shaper sections. A second control signal is generated to disconnect the receiver and waveform shaper sections from the power supply when, during an assigned time period, the preamble code is not detected. A third control signal is generated to maintain electrical connection between the power supply and the receiver and waveform shaper sections for a selected period of time after the preamble is detected.

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Tokyo, Japan

Yoshio Ichikawa