Abstract: A battery (105) includes a battery housing (340) having a latching mechanism (301) for attaching to a radiotelephone body (102). The latching mechanism (301) includes a button portion (405), a first torsion plate (403), a second torsion plate (404), and a catch (401). The battery housing (340) further includes an inner surface (400), a first rib (630), and a second rib (632). The first and second ribs (630, 632) extend upwardly from the inner surface (400) and attach respectively to the first and second torsion plates (403, 404), thereby supporting the latching mechanism (301) at a distance above the inner surface (400). The first and second torsion plates (403, 404), while providing a torsional twisting movement for detaching the battery (105) from the radiotelephone body (102), provide a strong deflection resistance for the latching mechanism (301).

Abstract: A method for protecting information bits wherein input data bits, at least some of which are to be protected, are sorted based upon information determined from a subset of the input data bits. An error control coding technique is applied to at least some of the sorted bits. In the preferred embodiment, an input data stream of voice coder bits is separated into arrays of bits. A first array (302) comprises voice coder bits needing error protection, with the bits arranged in order of importance determined by voicing mode. The second array (303) comprises bits that will not be error protected. The bits from the first array are provided to the input of an encoder (304), then the encoded bits are combined (305) with the bits from the second array (303) to form a bit stream.

Abstract: A tuning circuit (202) uses a precision current reference (Iref) along with an analog-to-digital converter (218) to produce a digital output (228) to represent variations of internal resistance values. The precision current reference (Iref) is fed to an internal tuning resistor (R210) in order to provide an analog voltage signal to the analog-to-digital converter (218). The analog voltage signal changes in accordance with the variations in the tuning resistor value over process and temperature. The digital output (228) controls programmable capacitor arrays (C220, C222) which are included in the tuning circuit (202) as well as in an active RC filter (208) whose bandwidth is controlled by the programmable capacitor arrays (C220, C222) and internal resistors (R212, R214, R216).

Abstract: A flap housing (14) for a foldable radiotelephone handset (10) has a hinge pin (72) with an actuator (96) for the radiotelephone activation switch (44) and a detent catch (88) integrated with the flap housing body (60). The actuator (96) engages the switch (44) to deactivate the handset (10) when the flap housing (14) is in a closed position. The detent catch (88) engages a detent stop (110) on the front housing (30) of the radiotelephone (10) when the flap housing (14) is in an open position.

Abstract: An operational transconductance amplifier (500) includes an input stage (502) having a first and second amplifiers (504, 508) driving class-AB, push-pull amplifiers (506, 510). The input stage (502) receives a differential input signal at first and second amplifier inputs (528, 540). The push-pull amplifiers (506, 510) establish differential currents in a transconductance-setting resistor (512), thereby eliminating the need for static current sources. The biasing levels established by the first and second amplifiers (504, 508) to drive the push-pull amplifiers (506, 510) also control a current source (514). Currents from the current source (514) are summed and provided to amplifier outputs (594, 596).

Abstract: A radiotelephone (101) has a memory, a display (127) and a keypad (117) with at least one key (121) to produce at least a first function key signal and a second function key signal, and a plurality of data keys (119). First, a first function key creates a first function key signal, turning on the radiotelephone (209); second, a phone number is selected (215). Third, the first function key creates a second function key signal from said first function key, activating the radiotelephone to call the phone number (207). Fourth, a second function key creates a third function key signal disconnecting the radiotelephone from said call (211). Fifth, the second function key creates a fourth function key signal turning off the radiotelephone (213).

Abstract: A programmable voltage controlled attenuator (100) meets the dynamic range and gain requirements for various communication protocols using a single bias generator circuit (104). A control voltage input, Vcnt, and a slope select input provide the dynamic range and attenuation for a voltage controlled attenuator (VCA) (102).

Abstract: A handset (100) has first and second modes of operation controlled by a moveable flap (104). The first mode of operation provides two way voice communication when the moveable flap (104) is in a closed position. The second mode of operation provides a personal organizer when the flap (104) is in a open position.

Abstract: The radio frequency (RF) shielding method uses RF shield clips. The RF shield clips have a base and two walls. The base is shaped to form two stabilizing legs for providing vertical stability. The two walls extend upward from the base, each wall has a portion flanged outward for accepting a portion of a RF shield. Each of the walls has multiple inwardly protruding domes for providing point contact to the RF shield.

Abstract: A digital speech coding method uses an Rth-order filter to model the frequency response of multiple filters, thereby, providing a filter which offers the control of multiple filters without the complexity of multiple filters. The Rth-order filter can be used as a spectral noise weighting filter or a combination of a short-term predictor filter and a spectral noise weighting filter, referred to as the spectrally noise weighted synthesis filter, depending on which embodiment is employed. In general, the method models the frequency response of L Pth-order filters by a single Rth-order filter, where the order R<L.times.P. Thus, this method increases the control of a speech coder filter without a corresponding increase in the complexity of the speech coder.

Abstract: A portable radio (104) initiates a communication link using a synchronous protocol format. A base station (102) generates a synchronization pattern (200) which includes a marker. The marker (202) includes a generic code that invites portables to make link requests. The portable radio (104) synchronizes to the marker (202) and recognizes the generic code that indicates base availability. The portable radio (104) sends a link request in response to the generic code to initiate the communication link, and the base station (102) grants a link in order to establish the communication link.

Abstract: Electronic devices using microprocessors requiring additional external memory can have security protection for the microprocessors while in an expanded mode of operation. A microprocessor having a security access circuit allows executable code to be stored in a peripheral storage device, such as external EPROM, while maintaining protection to the microprocessor EEPROM by monitoring if an instruction code is generated from an internal memory source or an external memory source.

Abstract: A diversity handset (100) used in a personal communication system includes a flap (104), a first antenna (108) and second antenna (110). The second antenna (110) consists of two portions, the first portion being a direct feed portion (202) printed onto a substrate (206), and the second portion consisting of a parasitic radiator (116) located within the flap (104). The first and second portions (202) and (116) of the second antenna (110) are inductively coupled together between the flap (104) and the substrate (206). Diversity is maintained with the flap (104) open or closed as well as with the flap removed from the handset (100).