Abstract: A transmission signal frame format includes an address field and a message field. The address field includes a plurality of addresses associated with the subscriber's receivers to be called, respectively. The message field includes a plurality of messages corresponding to the addresses, respectively. A message includes a transmitting sequence number which is coincident with the transmitting order of the address corresponding to this message. A selective calling receiver, receiving a frame, sequentially searches the address field for the ID address of its own while incrementing a receiving sequence count at each the address. When the ID address is found, the receiver stores the receiving sequence count at that time. The receiver selects its own message data from the message field when the transmitting sequence number of a message is coincident with the receiving sequence count.

Abstract: After bit synchronization and frame synchronization are established in accordance with a transmission signal from a transmission office, reception RX is stopped until a reception timing assigned to a group of a portable radio unit comes. A receiving operation is performed again at the reception timing assigned to the group of the unit. If the ID code of the received signal coincides with the ID of the unit, an informing operation is performed. At the same time, transmission TX is performed. A transmitting operation is performed during a transmission signal stop period TXOF upon completion of transmission of data corresponding to all the eight groups. The transmission timing of the portable radio unit is based on the fact that frame synchronization is established in the reception RX, so that transmission TX is performed at a timing assigned to the group of the unit in the reception RX.

Abstract: A decision circuit compares an input voltage with a reference voltage and judges whether the input voltage is at least equal to the reference voltage. A controller in the decision circuit detects whether the input voltage or reference voltage is at least equal to the setting voltage. When both the input voltage and the reference voltage are lower than a setting voltage, which represents an operating voltage of the decision circuit, a first bias-supply circuit adds a predetermined bias voltage to the input voltage and supplies a level-shifted input voltage to the decision circuit. Similarly, a second bias-supply circuit adds the predetermined bias voltage to the reference voltage and supplies a level-shifted reference voltage to the decision circuit. Therefore, the decision circuit compares the level-shifted input voltage with the level-shifted reference voltage.

Abstract: A paging receiver having a display and an alerting device which alerts the user to an incoming call by producing tones in any one of a plurality of different patterns. The paging receiver allows the user to replace any of the patterns with a desired pattern by operating a setting device. The desired pattern is written to an EEPROM (Electrically Erasable Programmable Read Only Memory) built in the paging receiver.

Abstract: An FSK receiver includes an amplifier, a local oscillation circuit, a mixer circuit, a limiter circuit, a demodulation circuit, a current detecting circuit, and a control circuit. The amplifier amplifies a received wave frequency-modulated with a binary digital signal. The local oscillation circuit outputs a local oscillation frequency signal. The mixer circuit mixes an amplified output from the amplifier with the local oscillation frequency signal. The limiter circuit receives a baseband signal component output from the mixer circuit to limit an amplitude. The demodulator samples the binary signal from the limiter circuit with a sampling signal generated by the received wave. The current detecting circuit detects a current flowing in the mixer circuit. The control circuit controls the gain of the amplifier in accordance with an output from the current detecting circuit.

Abstract: In an FSK receiver of double superheterodyne type for receiving an FSK modulated wave and comprising a PLL local oscillator (10) for ensuring a phase-locked loop to produce a first local oscillation signal and a demodulating section (12) for demodulating the FSK modulated wave into a demodulated signal using the first local oscillation signal and a second local oscillation signal, a control signal producing circuit (14) produces a control signal when the demodulated signal has a mean value indicative of a deviation from a phase lock in the phase-locked loop. Connected to the demodulating section, a synchronizing circuit (16) establishes bit and frame synchronization on the basis of a binary digital signal obtained by deciding the demodulated signal to produce a synchronization detection signal when the bit and frame synchronization is established.

Abstract: In a receiver for use in demodulating a modulated wave modulated by a digital data signal arranged within a preselected channel to produce a reproduced data signal by the use of a local frequency signal of a local frequency, a VCO and a PLL circuit are intermittently put into active states with reference to an offset frequency between a channel frequency and the local frequency. The PLL circuit is put into the active state for a time interval determined by the offset frequency before reception of the preselected channel while the VCO is put into the active state during the active state of the PLL circuit and during reception of the preselected channel. A duration of the active state in the PLL circuit becomes long when the offset frequency does not fall within a predetermined range determined by predetermined offset frequencies and, otherwise, the duration of the active state in the PLL circuit becomes short.

Abstract: A phase locked loop PLL circuitry for use in a radio pager. A power source applies a voltage to a charge pump circuit. A power supply control circuit controls the application of the voltage.

Abstract: An FSK receiver includes first and second channel paths to which the received FSK signals are applied. Each channel path includes a mixer circuit, a low-pass filter connected to the mixer circuit, and a limiting amplifier connected to the low-pass filter. A voltage-controlled oscillator generates a local carrier and a phase shifter applies its output to the mixer circuits with a 90.degree. phase difference therebetween. A frequency detector is coupled to one of the limiting amplifiers for generating a signal representative of the deviation frequency minus the offset frequency of the received FSK signal. An average circuit detects an average value of the signal from the frequency detector. A comparator circuit detects whether the frequency representative signal lies in or outside of the neighborhood of the average value.

Abstract: A pager includes a display mounted on the front side of a pager housing. On the back side of the housing is mounted a clip which is used for carrying the pager on the user's belt. The display displays a received message and inverts the displayed message in response to a switch signal. The inverted message is reflected at a foldable mirror to produce a noninverted message that the user can see from the upper side of the housing. A switch produces the switch signal to invert the displayed message with the unfolding movement of the foldable mirror.

Abstract: In a pager receiver operable in response to an incoming signal including a specific call number signal preassigned to the pager receiver, a directory number signal of a calling subscriber follows the specific call number signal. The directory number signal is detected by a directory number detector (17) after detection of the specific call number signal and is converted into a corresponding dial tone signal by a dial tone generator (21). The dial tone signal is automatically sent through a telephone set to the calling subscriber in response to closure of a switch (19). Thus, the pager receiver may be of a tone-only type and can call back unspecific persons even when the directory number signal is not displayed on a display unit. A particular symbol may be included in the directory number signal so as to distinguish the directory number signal from a usual message signal.