Abstract: An adaptive noise suppression system includes an input A/D converter, an analyzer, a filter, and a output D/A converter. The analyzer includes both feed-forward and feedback signal paths that allow it to compute a filtering coefficient, which is input to the filter. In these paths, feed-forward signal are processed by a signal to noise ratio estimator, a normalized coherence estimator, and a coherence mask. Also, feedback signals are processed by a auditory mask estimator. These two signal paths are coupled together via a noise suppression filter estimator. A method according to the present invention includes active signal processing to preserve speech-like signals and suppress incoherent noise signals. After a signal is processed in the feed-forward and feedback paths, the noise suppression filter estimator then outputs a filtering coefficient signal to the filter for filtering the noise out of the speech and noise digital signal.

Abstract: SAW devices such as interdigital transducers (IDTs) have been widely used in RADAR applications and as filters. An IDT produces a SAW when excited by a single electrical pulse and can be fabricated to embody a code, which code provides for a passive autocorrelation of a SAW input to the IDT and thereby lends itself to further application as a signal generator in a communication device. However, conventional SAW expanders and compressors typically have insertion losses greater than 20 dB, which can have a profound effect on an RF link budget in a communication system. Insertion losses are drastically reduced by using a single phase unidirectional transducer (SPUDT-type) instead of a conventional IDT as a SAW expander/compressor. A SPUDT-type reflects SAW components which are lost in conventional IDT designs so that a stronger SAW is directed toward a transmission element. In a receiver, a SPUDT-type directs a stronger SAW toward a compressor IDT.

Abstract: A system and method for pushing information from a host system to a mobile data communication device upon sensing a triggering event is disclosed. A redirector program operating at the host system enables a user to continuously redirect certain user-selected data items from the host system to the user's mobile data communication device upon detecting that one or more user-defined triggering events has occurred. The redirector program operates in connection with event generating applications and repackaging systems at the host system to configure and detect a particular user-defined event, and then to repackage the user-selected data items in an electronic wrapper prior to pushing the data items to the mobile device.

Abstract: A system and method for pushing information, such as calendar event messages, from a host system to a mobile data communication device upon sensing a triggering event is disclosed. A redirector program operating at the host system enables a user to continuously redirect calendar event messages, such as meeting reminders and notices, from the host system to the user's mobile data communication device upon detecting that one or more user-defined triggering events has occurred. The redirector program operates in connection with event generating applications and repackaging systems at the host system to configure and detect a particular user-defined event, and then to repackage the calendar event messages in an electronic wrapper prior to pushing the data items to the mobile device. An optimized data structure for storing the calendar event messages is also provided.

Abstract: A PLL-based frequency synthesizer is provided that includes a phase detector, a loop filter, a VCO, a sampler and filter system, and a frequency divider. This architecture reduces the high division ratio (N) necessary in a classical PLL-based frequency synthesizer while maintaining low phase-noise. This is achieved through sub-sampling the VCO output signal in the feedback path. The sampler is placed in the feedback loop following the VCO and is clocked at a low frequency (sub-sampling). The output of the sampler is the beat frequency between the VCO frequency and the sampling clock (in addition to harmonics that are filtered-out by a low-pass filter (LPF)). The LPF in the feedback loop attenuates any tones resulting from the sampling operation. A frequency divider is then used to bring down the feedback signal to the frequency of the phase detector input.

Abstract: A system and method for pushing information from a host system to a mobile data communication device upon sensing a triggering event is disclosed. A redirector program operating at the host system enables a user to continuously redirect certain user-selected data items from the host system to the user's mobile data communication device upon detecting that one or more user-defined triggering events has occurred. The redirector program operates in connection with event generating applications and repackaging systems at the host system to configure and detect a particular user-defined event, and then to repackage the user-selected data items in an electronic wrapper prior to pushing the data items to the mobile device. The system includes attachment processing components for identifying one or more attachment displayers in the vicinity of the mobile data communication device and then routing an attachment from the host system directly to a selected attachment displayer.

Abstract: A boot-strapped current switch is provided that includes a biasing network, a control signal, a transistor, a control switch and a boot-strapping circuit. The biasing network generates a substantially constant voltage on a biasing network output. The transistor has a control terminal, a first current-carrying terminal, and a second current-carrying terminal, wherein the first current-carrying terminal generates the output current of the current mirror, and the second current-carrying terminal is coupled to a first potential. The control switch is coupled between the biasing network output and the control terminal of the transistor, and is also coupled to the control signal. The control switch couples the first biasing network output to the control terminal of the transistor when the control signal is in a first state. The boot-strapping circuit is coupled between the control terminal of the transistor and a second potential, and is also coupled to the control signal.

Abstract: A system includes a recharging device to which an electronic hand-held device powered by a battery can be connected. A controller associated with the recharging device performs a method of intemal-device battery cell detection, i.e., distinguishing between NiMH/NiCd and other types of cells in the battery, before recharging the battery. A method determines the cell chemistry without any modifications to the battery and/or without any user input by performing tests on the battery. The tests include a Battery Voltage Test, an Internal Resistance Test, and a Timed Voltage Test. The testing is performed through a combination of hardware and software in the charging cradle. By performing the tests in a preferred order, detected alkaline, lithium, rechargeable alkaline, and carbon-zinc cells, damaged NiMH and NiCd cells, and close to fully charged NiMH and NiCd cells cause termination of a recharging operation before damage to the device or battery is sustained—without requiring input from a user.

Abstract: A battery disconnect system is provided for a device having a battery and load. The battery disconnect system includes a switch that is operative to connect the battery to the load when the switch is in a closed state. The switch is also operative to disconnect the battery from the load when the switch is in an open state. The battery disconnect system also includes a switch controller that is coupled to the switch. The switch controller is operative to cause the switch to enter the closed state in response to receipt of a first signal from a first external source. The switch controller is also operative to cause the switch to enter the open state in response to receipt of a second signal from a second external source.

Abstract: A closed-loop voltage-to-frequency (V/F) converter includes a voltage-controlled-oscillator (VCO) placed in a feedback voltage-locked loop (VLL). This converter achieves both wide bandwidth (for good phase-noise suppression) and good spurious rejection. The closed-loop V/F converter may be further configured in a larger phase-locked loop (PLL) to achieve accurate channel selection that is independent of temperature and process variations.

Abstract: A differential SAW filter having a cascaded structure includes including an input SAW stage and an output SAW stage. The two SAW stages are configured so that the distance of travel of the surface acoustic waves from a single unbalanced input of the input stage to the dual balanced outputs of the output stage is electrically equidistant, thus resulting in a balanced differential output. The input stage includes a single unbalanced input coupled to a pair of outer IDTs, which both launch a surface acoustic wave to a single input stage inner IDT. The input stage inner IDT connects to the input IDT of the output SAW stage, which launches a surface acoustic wave to a pair of identical, but inverted output IDTs that form the differential, balanced output signals.