Motorola Corporation

Other

Walter J Grandfield

Walter L Davis

James G Mittel

Gary L Pace

Leonard E Nelson

James Ian Jaffee

George A Drapac

George W Smoot

Vance H Peterson

Victoria A Leonardo

Wei Len Tan

A direct conversion receiver (200) is capable of recovering a filtered baseband signal (295) from a radio signal (201) modulated with a baseband signal (202). The direct conversion receiver (200) comprises a radio frequency mixer (205) for converting the radio signal (201) to the baseband signal (202), a lowpass amplifier (210) DC coupled to the radio frequency mixer (205), that amplifies the baseband signal (202) and substantially attenuates components of the baseband signal above a high corner frequency, and a DC offset compensation section (225) DC coupled to the lowpass amplifier (210), that provides a DC offset compensation and a controlled highpass filtering of the baseband signal. A low corner frequency of the DC offset compensation section is smoothly varied from a predetermined maximum value to a predetermined minimum value during a low frequency, low energy portion of the signaling protocol.

Radio having a fast adapting direct conversion receiver

A selective call receiver (100) includes a radio frequency amplifier (202) having an output power level that is controllable. A radio frequency level sensor (500) generates a sensor output signal in response to an input signal level received at the radio frequency amplifier (202). The receiver also includes a RSSI signal (208) that indicates a relative strength of an on-channel signal received at the radio frequency amplifier and recovered by the selective call receiver. The amplifier output power level adjustment circuit that operates to adjust a power gain of the radio frequency amplifier (202) in an unconditionally stable feed-forward manner based on the sensor output signal and the RSSI signal, such that the output power level remains substantially constant when the input signal level sensed by the radio frequency level sensor (500) substantially reaches or exceeds a first predetermined signal overload level or the received on-channel signal substantially reaches or exceeds a second predetermined signal level.

Feed-forward RSSI assisted radio frequency amplifier power control

A selective call receiver (100) includes a radio frequency amplifier (202) having an output power level that is controllable. A radio frequency level sensor (500) generates a sensor output signal in response to an input signal level received at the radio frequency amplifier (202). The sensor output signal is conditioned by a filter (401, 402) to generate a control signal representing an effective value of the input signal level received at the radio frequency amplifier (202). The control signal is then coupled to an amplifier output power level adjustment circuit (403) that operates to adjust a power gain of the radio frequency amplifier (202) in an unconditionally stable feed-forward manner such that the output power level remains substantially constant when the input signal level sensed by the radio frequency level sensor (500) substantially reaches or exceeds a predetermined signal overload level.

Differential feed-forward amplifier power control for a radio receiver

A selective call receiver (100) includes a radio frequency amplifier (202) having an output power level that is controllable in an unconditionally stable manner. The selective call receiver (100) includes a loading diode (403) coupled to an output of the radio frequency amplifier (202) and a feed-forward load control (201) coupled to an input of the radio frequency amplifier (202). The feed-forward load control (201) detects an input signal strength and regulates conduction of a current through the loading diode (403). In response to the input signal strength substantially reaching or exceeding a predetermined activation threshold corresponding with a predetermined input signal strength and a maximum output power level, the feed-forward load control (201) adjusts the current causing an impedance of the loading diode (403) to vary in a manner that causes the output power level to remain substantially constant.

Diode loaded feed-forward radio frequency amplifier power control

A stacked double balanced mixer (220) includes a double balanced mixer (320) and a first cross coupled differential mixer (330). The double balanced mixer (320) includes two input transistors (321, 322) and four cross coupled output transistors (323-326). The first cross coupled differential mixer (330) includes four cross coupled input/output transistors (331-334) and a second mixer output (227, 228). The four cross coupled input/output transistors (331-334) have first output terminal pairs DC coupled in series to second output terminal pairs of the four cross coupled output transistors (323-326). The stacked double balanced mixer (220) generates, at the second mixer output (227,228), a second IF differential output signal having a second IF frequency at a difference of a radio frequency of a differential input signal and the sum of first and second LO frequencies, respectively, of first and second LO signals.

Stacked double balanced mixer circuit

A heterodyne stage of a receiver which includes a conventional mixer circuit and local oscillator circuit further includes a differential amplifier circuit which measures the amplitude of the injection signal generated by the local oscillator circuit and controls it precisely to a desired reference level by adjusting the current bias supply to the local oscillator circuit within a banded range to ensure start-up of the local oscillator upon energization and to protect against loss of injection signal under all operating conditions. The differential amplifier circuit provides for a precise amplitude reference setting and sufficient closed-loop gain for controlling the amplitude of the injection signal with a minimum of error between the measured and reference values.

Heterodyne stage having precise closed-loop control of the amplitude of

A pager receiver includes at least one lock-out circuit, an out-of range circuit, and a single timer coupled to the lock-out and out-of range circuits and responsive to timing signals generated by the pager for generating an initiated one of either the lock-out timer interval or out-of range time interval. Each lock-out circuit of the pager receiver corresponds to an address function programmed therein and is activated by the function detect signal generated in response to the initial decoding of the corresponding address function to initiate the generation of the lock-out time interval by the single timer and to inhibit the corresponding alert annunciation from responding to subsequently generated function detect signals corresponding thereto for the duration of the lock-out time interval. The single timer is also initiated to generate the out-of-range time interval at the generation of each sync pulse timing signal by the pager receiver, but only in the absence of an activated lock-out circuit. Accordingly, the single timer is disabled from initiating the generation of the out-of-range time interval for the duration of an initiated lock-out time interval. Still further, the single timer may be reinitiated to generate the lock-out time interval during the generation of a lock-out time interval by an activated lock-out circuit corresponding to an uninhibited alert annunciation.

Pager receiver having a common timer circuit for both sequential

A constant propagation delay current reference is provided having an external source providing a reference frequency signal. A phase lock loop is provided which is responsive to the reference frequency signal and to an operating frequency signal to provide a current reference signal at the output of the loop. The current reference signal is provided to a current to frequency converter which generates the operating frequency signal. A current mirror, also coupled to the phase lock loop output provides an output current proportional to the current reference signal which is suitable for providing the injector current for I.sup.2 L devices. The output current tracks the process, voltage and temperature variations of the integrated circuit, allowing the injector currents to be optimized for maintaining constant propagation delay in the circuits being powered.

Constant propagation delay current reference

Apparatus and method is disclosed for automatically, or by selective response, call forwarding a message to one or more system pagers which have an acknowledge back capability. In one embodiment, disclosed apparatus automatically forwards a message to another system pager upon the initially called pager failing to acknowledge back within a predetermined time period. Such other pager is determined from a set paging hierarchy included within the paging terminal apparatus itself. In another embodiment, wherein the system pagers have multiple acknowledge back response capability, a called pager can request the received message be additionally call forwarded to one or more other system pagers in accordance with the particular acknowledge back response chosen by the called pager user.

Paging terminal apparatus with page forwarding capability and

A paging system is provided having page transmission means responsive to a message origination device for transmitting selective call paging signals and messages. A query signal is also transmitted a predetermined minimum time period from the corresponding paging signal. A plurality of transceivers are provided responsive to the selective call paging signals and messages, and further responsive to the query signals for enabling the generating and transmitting of a response signal. Receivers are provided for receiving the transmitted response signals. The received response signals are then delivered to the message origination device from which the original message originated.

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Lake Worth, FL, United States of America

Walter J Grandfield