Abstract: A mixer separates IF components IF1, IF2 of the same frequency which are images of different frequency RF signals RF1, RF2 beating with a given LO signal. The LO signal is applied to a FET active power divider and applied to the drains of a pair of balanced FET mixing elements. The FETs for the active power divider are built from the same device structure as the FETs for the mixing elements sharing drain nodes. The RF signals are passed through a quadrature phase shifter and applied to the gates of the FET mixing elements. The mixed signals appear at the drains of FET mixing elements are applied to opposing ports of a second quadrature hybrid at whose output ports the separated IF output signals IF1, IF2 appear.

Abstract: A method, and apparatus for accomplishing the method, that causes the power of a narrow bandwidth signal to be spread to a wider bandwidth. The method operates by modulating the power of the spectral components that are located close to a carrier frequency. This reduces the DC component of a base band signal and correspondingly reduces the charging of a AC coupling capacitors in the base band circuitry. As a result, receiver recovery time is increased, and a more accurate signal strength estimate is made by a mobile telephone. In one embodiment of the invention a local oscillator signal (LO1) for an IF stage is first offset from a nominal frequency for an RF channel to be measured, and is then subsequently made equal to the nominal frequency. The variation in LO1 introduces phase noise which results in the modulation of the base band signal.

Abstract: When remote control data has been input during calling in analog mode, a mobile radio communication apparatus according to the invention outputs a predetermined first voice frequency signal indicative of the remote control data and transmitting the signal to a radio link, and outputs the first voice frequency signal. Further, when remote control data has been input during calling in digital mode, the mobile radio communication apparatus outputs message data indicative of the remote control data and transmitting the message data to a radio link, generates a second voice frequency signal corresponding to the input remote control data and also the first voice frequency signal, and outputs the second voice frequency signal before the message data is transmitted.

Abstract: A radio frequency millimeter-wave signal antenna and mixer system includes a dielectric substrate having a generally planar upper surface, and a ground-plane layer of conductive material disposed below the upper surface. This ground plane layer includes a plurality of spaced-apart low conductivity sections or windows to allow passage therethrough of radio frequency signals received at a surface of the substrate. A plurality of antennae are disposed on the upper surface of the substrate, with each antenna being positioned over a respective one of the windows in the ground-plane layer. A plurality of mixers are also disposed on the upper surface of the substrate, each adjacent a respective antenna for receiving radio frequency signals therefrom and for producing intermediate frequency signals.

Abstract: A dual-mode radiotelephone terminal includes a .pi./4-shift DQPSK modulator (11). A dual-mode modulation is achieved by mixing an output of a transmitter oscillator (16) with an output of an offset oscillator (18) to form an injection signal (LO) at a final transmitter frequency, the injection signal being further modulated with a quadrature modulator in a digital mode of operation. In an analog mode of operation the transmitter oscillator or the offset oscillator is frequency modulated and the quadrature modulator is disabled, thereby passing the frequency modulated injection signal without substantial attenuation. The LO signal is regenerated and also phase shifted with a circuit (35) having a frequency multiplier (30) and a frequency divider (34). The circuit outputs two local oscillator (LO) signals (LOA and LOB), each of which directly drives an associated quadrature mixer (36, 38) of the modulator.

Abstract: A portable paging system communicates a paging message including a first portion having at least a selective call address (406) and a first activation code (407), and a second portion having a first segment (409) of an audio portion, to a selective call receiver (300). In the portable paging system, an input device (104) prompts an originator to request an extension of the second portion of the paging message, the extension including at least a second segment (410) of the audio portion. Upon receiving an affirmative talk time extension request from the originator, and if extending the second portion of the paging message does not exceed a predetermined number of extension requests or a predetermined total broadcast time allocated for the second portion of the paging message, a paging terminal controller (210) extends the second portion of the paging message.

Abstract: In a radio paging receiver operable in response to a radio signal which includes a preamble signal, a call number signal, and a display information signal to decode the call number signal and the display information signal in synchronism with a sequence of internal clock pulses produced from a clock synchronization circuit, the internal clock pulses are also produced from the clock synchronization circuit during a time interval except for the preamble signal with reference to electric field intensity and a phase or a frequency difference between the internal clock pulse sequence and a sequence of digital signal derived from the radio signal. Specifically, the internal clock pulse sequence is produced again when the electric field intensity and the phase or the frequency difference become large so as to keep synchronization of the internal clock pulse sequence during reception of the radio signal.

Abstract: A quadrant generator for generating a pair of pulse trains maintained in perfect phase quadrant with one another. The quadrature generator includes a feedback control loop for altering the duty cycle of an oscillating signal applied to a master-slave flip-flop pair configured to generate a pair of pulse trains maintained in a relative phase relationship. The feedback control loop controls the duty cycle of the oscillating signal applied to the master-slave flip-flop pair which, in turn, is determinative of the phase relationship between the pulse train pair generated by the master-slave flip-flop pair. When the pulse trains generated by the flip-flop pair are beyond phase quadrature, a control signal generated by the feedback control loop alters the duty cycle of the oscillating signal applied to the flip-flop pair to alter the phase relationship between the pulse trains of the pulse train pair.

Abstract: A call control method for a radio system, wherein a half-duplex type mobile station (MS1, MS2) is commanded so as to clear a call on the radio channel of a base station (BS), by transmitting a disconnect signal to the mobile station (MS1, MS2) over the radio channel, the mobile station leaving the radio channel upon receiving the disconnect signal. In order to ensure that the disconnect signal is received by the mobile station, the field intensity received by the base station (BS) on the radio channel is measured immediately after the transmission of the disconnect signal, and the radio channel is released for the next call only when the measured field intensity falls below a predetermined threshold value.

Abstract: The invention provides a fading simulator method and a fading simulator by which the attenuation ratio is not varied and the fading characteristic of a wide band can be realized stably even when the notch frequency sweeps. A fading simulator is interposed between a transmitter and a receiver, and a signal from the transmitter is inputted to first and second path artificial circuits of the fading simulator. In the first path artificial circuit, the attenuation amount of a first variable attenuator is controlled to control the amplitude of the signal passing therethrough, and the signal is delayed by a first delay circuit.

Abstract: In a radio communications system, a selectively enabled time- and/or frequency-diverse signaling scheme is employed to improve signal quality. In particular, a method of exchanging a message between communication devices using a communications resource might include the step of transmitting a first portion of the message on a first frequency within the communications resource. After determining the quality of the communications resource to be unfavorable, a second portion of the message might be transmitted on the first frequency, and also re-transmitted on a second frequency and/or at a separate time.