Abstract: Briefly, according to the invention, a multi-loop synthesizer (100) for producing an output signal (114) having minimum spurious components is described. The multi-loop synthesizer (100) includes a first synthesizer loop (116) which has a divider stage (108) and an oscillator stage (106) for providing an oscillator output signal (118). The multi-loop synthesizer (100) also includes at least one additional synthesizer loop (121) which also has an output for providing a loop output signal (120). The multi-loop synthesizer (100) further includes an image balanced mixer (110) coupled to the divider stage (108) of the first synthesizer loop for mixing the oscillator output signal (118) of the first synthesizer loop (116) with the loop output (120) of the at least one additional synthesizer loop (121).

Abstract: A digital radio communication system includes a plurality of cells for providing two-way digital radio communication. Each of the cells utilizes communication frames having at least one inbound communication slot and at least one outbound communication slot. The frames of each cell are of uniform length. At least some of the cells have different bit rates than other cells. Information about the contiguous cells is provided to the radios operating within a cell. The radio includes a memory for storing information on adjacent cells and the radio can evaluate the signal of adjacent cells for determining an appropriate cell for hand-off purposes.

Abstract: A solder paste is formulated by combining a solder paste vehicle, a resin, and solder alloy particles. The solder paste vehicle is made by combining mono and polyfunctional alcoholic solvents with a fluxing agent. The solder particles are first reacted with a formate ion produced by formic acid, formaldehyde, paraformaldehyde, or mixtures thereof, in order to create a metal-formate complex that functions as an oxygen scavenger on the surface of the solder alloy particles.

Abstract: A loop antenna includes a circuit board having a ground plane layer. A formed loop is located on one side of the circuit board and a transmission line is located on the opposite side of the circuit board. Capacitors interconnect the ends of the formed loop and the transmission line. The transmission line is a microstrip formed by the ground plane layer in a microstrip portion.The circuit board includes RF circuitry that is located on the side of the circuit board opposite to the transmission line so that the ground plane shields the circuitry from the transmission line.

Abstract: The need for solder paste or wave soldering to assemble printed circuit boards and components is eliminated by applying (100) a layer of solder to the exposed metal pads, annular rings and plated through holes of the printed circuit board. Leadless components are placed into a layer of `tack` flux applied (110) to the printed circuit board (120). The printed circuit board is heated to reflow (130) leadless components, and the solder in the holes is melted (140). The leads of the leaded components are heated (150) and inserted (160) into the molten solder in the holes. The assembly is then cooled (170) to solidify the solder around the component.

Abstract: An integral electrical interconnection is made between two circuit carrying substrates (100 and 110). The first circuit carrying substrate (100) contains one or more protrusions (102) on the peripheral edge of the substrate (100) which couples to a series of one or more apertures (104) on the peripheral edge of a second circuit carrying substrate (110). Both the tabs and the apertures are covered with conductive materials (202 and 210) also connected to the circuit.

Abstract: A vehicular repeater interrupts the repeated audio and a timing signal that is transmitted to the portable. The timing signal is used by the portable to determine when the vehicular repeater will next interrupt the repeated information. Accordingly, the portable synchronizes its transmission of a signal to coincide with the next interruption. If no transmission is desired, the portable operates to mute the portable's speaker during the interruption to prevent noise bursts. Upon the initial recipt of a portable+s transmission signal, the vehicular repeater extends the interruption interval to verify the portable's transmission signal.

Abstract: A portable two-way radio includes a radio portion and a battery removably attached to the radio portion. The radio portion includes an opening that is accessible when the battery is removed. An electronic card is received by the radio portion through the opening. When reassembled, the battery retains the electronic card in the radio portion.

Abstract: A receiver 100 used for recovering modulation signals modulated on a carrier signal is disclosed. The receiver 100 includes a detector 204 and a decoder 206 for detecting the presence of a non-valid coded squelch signal and decoding such signal in the recovered modulation signal. The receiver 100 further includes a synchronizer 208 for synchronizing the detected non-valid coded signal. Receiver 100 is placed in a battery saver mode when a non-valid coded squelch signal is detected. The battery saver mode includes monitoring the recovered modulation signal for a change in the non-valid coded squelch signal. The battery saver mode is departed once a change in the non-valid coded squelch signal is detected.

Abstract: A radio communication system with on/off premise registration is provided. When a radio is registered with the system, incoming calls for the radio are directed to the radio via the system. When the radio is registered as off the system information is transmitted to the radio as via a wide area system. A voice mailbox is provided for storing messages when the radio is unavailable.

Abstract: A two-way radio includes a receiver having a squelch circuit for determining if a communication channel is available. A transmitter is provided for transmitting voice messages on the channel. When the communication channel is available, voice signals are directed from a microphone to the transmitter for transmission. When the communication channel is not available, the voice signals are automatically directed to a digitizer there they are digitized. The digitized voice signals are stored in a memory for later transmission when the channel becomes available.

Abstract: In conjunction with parallel connected transistors, a balancing network including a load-current sensing resistance in the emitter/collector path of each transistor and a shunt resistance connected between the sensing resistor and the base to control base current and a ring network of resistances connected to the bases to force equal distribution of base current.

Abstract: A communication device (10) measures and compares (16,18) the ambient sound level of its environment. When the current ambient sound level exceeds a given threshold (52) the communication device automatically transmits (38) an information signal (44). Optionally, the communication devices's volume is also adjusted (26).

Abstract: Solder pastes having vehicles including blends of low boiling point alcohols and relatively high boiling point alcohols are described which leave residues which may be cleaned using only water are described. The low boiling point alcohols have a boiling point range of between about 65.degree. and about 150.degree. C. whereas the high boiling point alcohols have a boiling point in rhe range of about 150.degree. to about 270.degree. C. The solder pastes also use water-soluble organic acids as fluxing agents such as compounds of the formula: ##STR1## where R is an electron withdrawing group such as fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl. Other suitable formic-acid fluxing agents include, but are not limited to, adipic acid, polyacrylic acid, methacrylic acid and polymethacrylic acid. The compounds clean oxides from the printed circuit boards (PCBs) under assembly and then volatilze leaving a residue to be cleaned away. The cleaning step involves rinsing with water.

Abstract: A method of producing a metallized pattern on a substrate includes the steps of providing a substrate having a high aspect ratio groove defining a desired metallization pattern and applying metallization to the substrate. The high aspect ratio groove is utilized to prevent metallization across the groove boundary thereby producing electrically isolated areas. The substrate can be a circuit board, hybrid module or other component carrying structure. Also the substrate can be a resonator or a stripline device in which the groove is used to electrially isolate a lead or wire extending from the substrate in the ground plane portion of the structure.

Abstract: A soldering process uses a plurality of individual heating elements (204) to solder a plurality of solder locations. The process consists of the steps of substantially simultaneously picking up a plurality of solder preforms (202); placing the plurality of solder preforms substantially simultaneously on different interconnection locations (214) found on a circuit board (212); and substantially simultaneously soldering the plurality of solder preforms (202) with a heating element fixture (200) which has a plurality of individual heating elements (204) which match the different interconnection locations (214) found on the circuit board (212).

Abstract: This radio communication system includes a plurality of remote base stations or callpoints. When an incoming call is to be directed to a cordless telephone, the identifying information for the cordless telephone, along with a call back number or ID is transmitted as by a paging signal by a PABX. Each of the base stations includes a paging receiver for receiving the information. If the base station has a line available it initiates a call to the cordless telephone. A base station that locates the cordless telephone would provide the connection for the call. By calling the PABX utilizing the call back ID, the base station can complete the call.

Abstract: A vented battery includes an aperture 108 in the battery housing 104 for venting built up gases inside of the vented battery 104. The aperture 108 is covered with a sintered metal vent 204. The sintered vent can be molded in the battery housing, staked to the housing, friction fitted into the aperture, or attached using other commonly known methods.In an alternate embodiment, a vented battery 200 has at least one battery contact 210 formed from sintered metal allowing for the venting of gases inside of housing 104. The battery contact 210 performs the dual function of allowing the battery 200 to be vented, and also act as electrical battery contacts which allow battery 200 to be connected to external devices.A communication device 300 includes a radio 302 that has a radio battery retainer 310, or other external housing member made from sintered metal thereby allowing for radio 302 to be vented.

Abstract: A fast locking phase locked loop includes a first integrator that provides a signal representing a function of the mathematical or ideal integral of the phase difference between an input signal and a feedback signal. A voltage controlled oscillator is coupled to the first integrator and provides a signal to a phase shifter that provides the phase shifted signal that represents a function of the phase of the signal from the VCO, and a function of the integral of the phase difference between the integrated signals.

Abstract: An improved frequency synthesizer 100 capable of producing true DC frequency modulation without the need to DC frequency modulate the reference oscillator. The synthesizer 100 includes a phase comparator 104 compares the reference signal 102 and the feedback signal 112. The output of said phase comparator 104 filtered and coupled to the main VCO 108. A balanced image mixer 200 mixes the two signals from the main VCO 108 and an offset VCO 300. The offset VCO 300 is a low frequency (e.g. 100 to 300 KHz) integrated offset VCO 308 whose center frequency is controlled accurately, by means of matching to a VCO 306 which is controlled by a feedback loop, and by using an image balanced mixer 200 to reduce the image response to substantially reduce or eliminate the filtering required at the mixer output. The configuration of the offset mixer within the synthesizer loop, any residual spurious content due to imperfect image balance or carrier feedthrough of the mixer is attenuated by the loop response.