Abstract: In order that ink leakage be reduced from a compressed foam storage ink container for an inkjet printer cartridge, at least one of the walls of the container is provided relief pockets having air spaces free of the compressed foam. At least one vent channel communicates between relief pockets and ambient air pressure to provide pressure equilibrium.

Abstract: An inkjet printer printhead is coupled to an ink source and has a plurality of ink firing chambers dimensionally defined by a barrier layer disposed between a substrate and an orifice plate. Two ink feed channels are coupled to one ink firing chamber and are dimensionally defined, in part, by the barrier layer. One of these ink feed channels has a smoothly converging wide dimension inlet at the ink source and a narrow dimension outlet at the ink firing chamber. The other ink feed channel also has a converging wide dimension inlet at the ink source and a narrow dimension outlet at the ink firing chamber but has an "S" shaped wall contour to make it asymmetrical to the first ink feed channel. An island of the barrier layer separates one ink feed channel from the other ink feed channel serving the ink firing chamber. This island has an essentially flat wall surface disposed toward the ink firing chamber.

Abstract: A printhead includes a substrate with an ink feed aperture extending from a first surface to a second surface and a plurality of heater resistors disposed on it. Primitive groupings of the resistors are coupled to associated group power sources. An ink barrier layer is deposited on the substrate to create ink firing chambers for each resistor. One wall of the ink barrier has a constricted opening through which ink is supplied from the ink feed aperture. A plurality of transistors are disposed in the substrate with each transistor output coupled to an associated one of the resistors and each input coupled to one of a plurality of addressing signal lines. The number of addressing signal lines is equal to the number of resistors in a primitive grouping.

Abstract: Mobility is provided for wireless local loop radiotelephone systems by providing the home access network of a subscriber unit with a home access number. Upon registration of the subscriber unit with its home access network, the home access number is transmitted to the subscriber unit for storage there. When the subscriber unit moves to a visited access network and registers there, the subscriber unit transmits the home access number to the visited access network, which uses the home access number to contact the home access network. Since all call originations and terminations by and to the subscriber unit occur via the individual subscriber line appearance at the PSTN, a minimum of special network elements are required for subscriber unit mobility when the home access number is stored at the subscriber unit.

Abstract: An error detection system for a discrete receiver. Sequences of bits together forming frames of information comprise the signal received by the discrete receiver. The signal is decoded by a convolutional decoder and is re-encoded by an encoder. Successive portions of nonoverlapping sets of adjacently positioned bits of the re-encoded signal formed by the encoder are compared with corresponding bits of a signal representative of the signal received by the receiver. When excessive numbers of the successive portions of the signals which are compared include bit dissimilarities, a bad frame indication is generated.

Abstract: Data transfer apparatus (211,213) for a radiotelephone peripheral using a time multiplexed data bus for communication with a bus master of the radiotelephone couples peripheral devices external to the radiotelephone and other user information inputting devices, such as a handset for a cellular mobile radiotelephone, to the radiotelephone's central processor and speech processor. The data transfer apparatus generates time slots in frame formats in which the information is sent over the data bus. The entire message, information bits and the header, sent in a time slot from a peripheral device to the bus master is used to determine bus contention. Bus contention resolution during the start-up of data bus operation sets the priority with respect to other data transfer apparati with which a peripheral device's data transfer apparatus is able to access the bus during normal operation.

Abstract: An apparatus and method for issuing busy call-backs (146) on the voice channel to busied communication units (209,211) on a trunked radio communication system (200) is disclosed. This is accomplished, in part, by issuing a busy signal (104), via a control resource (203), to a communication unit when a requested communication resource is unavailable. Additionally, the radio communication unit (209,211) is capable of receiving the busy signal via the control resource (213) and participating in a second communication while in a busied state. The resource controller (201) is capable of allowing the busied communication unit (209,211) to participate in a second communication on a second communication resource (215) and issuing the call-back signal during the second communication.

Abstract: A radio receiver having a variable bandwidth received channel filter (113,115) to reduce interference is disclosed. A interference is detected by comparing received signal strength and received signal BER. The bandwidth of the filter (113,115) is narrowed to improve BER when a received signal strength is greater than a threshhold value and BER is worse than a threshhold value.

Abstract: A radiotelephone system verifies the carrier/interference (C/I) of a selected target channel before handoff. The subscriber (125), communicating to a source base-station (130) on a source channel, measures the received signal strength indication (RSSI) of a target channel at a target base-station (135) when the channel is keyed (transmitting) and dekeyed (not transmitting). The subscriber (125) transfers the measurements to a source base-station (130) which determines the ratio of the RSSI with the keyed channel (C) to the RSSI with the dekeyed channel (I). If the ratio is greater than a predetermined threshold, the source base-station (130) transfers the subscriber (125) from the source channel to the target channel at the target base-station (135).

Abstract: A call box (201) provides vandal-resistant operation by using a concealed magnetic switch and magnet (179) and specially locked compartments (101 and 103) in a heavy duty structure. The concealed magnetic switch determines the position of a handset (119) within the call box (201). When the handset (119) is removed from its resting position, a radio (129) within the call box (201) responds when a pushbutton (127) within the call box (201) is pressed. When the pushbutton (127) is pressed, telephone service is provided via a radio (129) to a preprogrammed phone number, such as the highway patrol for a call box (201) located on a highway, to handle situations such as a malfunctioning vehicle.

Abstract: A digital radiotelephone system requiring a transfer of communication from a source base-site (200) in a source cell (100) to a selected one target base-site in a target cell. A source base-site (200) in the source cell (100) provides a first and a second threshold and measures the received signal strength of a mobile unit (225) communicating to the source base-site (200). When the measured signal strength at the source base-site (200) falls below the first threshold, the source base-site (200) initiates a handoff to target base-sites located by the mobile unit (225). The target base-sites measure the received signal strength of the mobile unit (225) and a target base-site is selected. The source base-site (200) is notified of the selected target base-site and hands off communication of the mobile unit (225) to the selected target base-site when the previously measured signal strength at the source base-site (200) falls below the second threshold.

Abstract: To compensate the audio distortion resulting from amplitude and phase imbalance in the quadrature oscillator (103) and mixers (105, 115) in zero-IF downconverters (203), a balancing action is required. An apparatus for distortion compensation compensates for the amplitude and phase imbalance to reduce audio distortion. This is accomplished by determining (309) two gain values, which are combined (217, 227, 229) with the in-phase and quadrature components of the zero-IF downconverter (203) to compensate for the imbalance.

Abstract: A dielectric layered sequentially processed circuit board is disclosed. A first photodefinable resin containing an electroless plating catalyst is disposed on a substrate and portions of the substrate are exposed through the first resin. A second photodefinable resin absent the electroless plating catalyst is disposed on the first resin, and portions coincident with the exposed portions of the substrate as well as portions of the first resin are exposed through the second resin. A conductive material is deposited on the exposed portions of the substrate and the exposed portions of the first resin.

Abstract: A dual mode cellular cordless portable radiotelephone preferentially selects the cordless base station over the cellular system when in range of the cordless base station. When the cordless cellular portable is operating in the cellular mode, the radio channel associated with the cordless base station is sampled for a predetermined time. When a signal on the sampled cordless base station channel is detected, the cordless portable moves to the cordless mode and remains in the cordless mode for as long as the signal quality of the signal on the cordless base station channel exceeds a predetermined value.

Abstract: An equalization system for equalizing a corrupted signal is disclosed. The equalization system includes a complex matched filter (400) and a maximum likelihood sequence estimator (MLSE) (405) for removing the effects of phase shift, amplitude variations, intersymbol interference, etc. resulting from multi-pathing and noise contributed by the receiver front end. The system estimates a correlation signal C(t) (505) and synchronizes C(t) 505 to maximize its energy as seen on the taps of the complex matched filter (400). Taps having amplitude coefficients below a predetermined threshold are set to zero to produce a modified CIR estimate. The modified CIR estimate which has had the effects of noise virtually eliminated, is then used to construct the complex matched filter (400) and is also used as input to the MLSE (405) to produce a better equalized data signal.