An RF receiver having a coupling capacitor connected between the back end of the receiver and the input to a data limiter circuit, a battery saver strobe feature which periodically turns the receiver ON and OFF and a precharge circuit for precharging the coupling capacitor. The receiver further includes a reference voltage stabilization circuit which prevents a received signal from reaching the output of the back end of the receiver during the precharging of the coupling capacitor in order to minimize the voltage offsets from the desired unmodulated carrier frequency reference voltage which results in erroneous data being decoded by the decoder portion of the RF receiver.
There is disclosed a circuit for stabilizing the bias of a paging receiver. An oscillation control signal of first period is generated at the time when a voltage source is connected to the RF components. An oscillation means generates a signal of the center frequency of a received modulated signal in response to the oscillation control signal. A demodulation means demodulates the signal of the center frequency so as to generate a signal of second voltage that is received by a waveform reshaping means to stabilize the bias into the level of the second voltage. The RF receiver converts the received RF modulated signal into a signal offset by a frequency deviation from the center frequency during second period after the termination of the first period. The demodulation means generates a demodulated signal of first or third voltage according to the logical state of the received modulated signal. The waveform reshaping means compares the received demodulated signal with the bias so as to generate a digital signal of a constant duty ratio.
Frequency control in a miniature receiver is effected by a synthesizer that is operated briefly to provide a tuning voltage to a voltage controlled local oscillator. A capacitor is shunted across the output of the synthesizer and is charged to the level of the tuning voltage. After the capacitor is charged, the synthesizer is deenergized and the diminishing voltage provided to the oscillator by the discharging capacitor is correspondingly supplemented by an AFC voltage that tracks drift of the received signal in the IF passband. The deenergizing of the synthesizer eliminates synthesizer noise and reduces the receiver's power consumption.
A low power digital receiver (10) is provided that contemporaneously selects the lowest possible sampling signal frequency (34) (from a plurality of available sampling signals), and received signal level (28) to properly digitize (32) and recover a desired signal. Digitization is performed after the first IF using broadband stages (28, 30, and 32) that are temporarily enabled (44) to rapidly digitize the first IF signal. This, together with the low sampling rate, minimizes the power consumption of the receiver (10) thereby permitting portable and mobile digital receiver embodiments.
4910752 - Low power digital receiver - Owned by Motorola, Inc. (Schaumburg, IL) [*] Notice:The portion of the term of this patent subsequent to March 7, 2006 has been disclaimed.
A low power digital receiver (10) is provided that contemporaneously selects the lowest possible sampling signal frequency (34) (from a plurality of available sampling signals), and received signal level (28) to properly digitize (32) and recover a desired signal. Digitization is performed after the first IF using broadband stages (28, 30, and 32) that are temporarily enabled (44) to rapidly digitize the first IF signal. This, together with the low sampling rate, minimizes the power consumption of the receiver (10) thereby permitting portable and mobile digital receiver embodiments.
In a police radar warning receiver with a self-contained battery source of supply, battery life may be prolonged by duty cycling the RF front end circuitry of the receiver and, especially, the swept oscillator thereof at a duty cycle rate not greater than 25% with the circuitry being energized not more than once every approximately one-half second.
