Abstract: The present invention discloses a method and apparatus for optimizing the performance of a power amplifier circuit. In accordance therewith, one of the intermodulation products generated during a power amplifier's operation is selected. This selection is based upon the intermodulation product's amplitude. Next, the intermodulation product's amplitude is compared to a predetermined threshold. Based upon this comparison, various power amplifier circuit operating parameters are altered in order to improve the circuit's intermodulation performance or to maximize its operating capacity.

Abstract: An antenna selection technique is used in an RF communication system in which user modules (UM) communicate with at least one node. The UM's and nodes each have multiple antennae. The combination of each UM and node antenna is evaluated at the UM. Based on both signal quality and strength, the UM selects its antenna and the best node antenna for use.

Abstract: A method and apparatus for performing the asynchronous reconstruction of a digital data stream is disclosed. An input data stream having an input rate, such as digitized speech, is stored in a circular buffer. Within the buffer, read and write marker positions are determined. Upon subsequent retrieval of the data stream at an output rate, data is taken from the position of the read marker each time data is written to the position of the write marker. Of importance, the read and write marker positions are determined such that they provide a delay greater than the difference between the input rate and the output rate over the length of the buffer. The data stream processing is then modified by ignoring at least some of the data stream when the input rate is faster than the output rate, and repeating at least some of the data stream when the input rate is slower than the output rate. In this manner a method of digitized voice reconstruction without reliance upon network synchronizatin is achieved.

Abstract: A system and method of evaluating the radio coverage of a geographic area serviced by a digital cellular radiotelephone communication system is described which comprises a plurality of base stations each having a transmitter and a receiver and a plurality of mobile units having co-located transmitters and receivers for transmitting and receiving communication message signals between the base stations and a mobile unit. During operation, the position of at least one of the mobile units operating within the geographic area is located when a call is received by a base station. The base station monitors the signal quality of the call and collects information relevant to the actual performance of the communication system.

Abstract: Method and apparatus for facilitating communication of information in a system without the use of a baseband hopping unit, by sharing a common TDM bus between a plurality of radio communication units, processing units, and information links, where the processing units extract traffic channel information, packetize and/or unpacketize the information, and return same back to the common bus for retrieval by the information links or radio communication units.

Abstract: A feed forward distortion minimization circuit which receives an input signal and routes the input signal along two signal paths is disclosed. One path, the main signal path, includes a distortion generator such as, for example, a power amplifier, which generates an output signal having a distortion component. The other path, the feed forward signal path, includes a delay line responsive to the input signal for feeding the input signal forward, without distortion. The output signal from the distortion generator is combined with a fed forward input signal to form an error signal representative of the distortion component. A feedback circuit is employed to detect a DC current or RF voltage proportional to the error signal's signal strength and to adjust the amplitude and the phase of signals in the feed forward or main signal paths to reduce the carrier to distortion ratio of the error signal. Thereafter, the error signal is subtracted from the main signal path to cancel any distortion components therein.

Abstract: The present invention relates to a monolithic crystal filter having a passband of at least 30 Khz and a center frequency greater than 120 Mhz. This filter includes a piezoelectric substrate, a plurality of input electrodes conductively coupled together via a thin coupling bar, a plurality of output electrodes conductively coupled together via another thin coupling bar, and at least one common electrode disposed opposite to the plurality of input and output electrodes. The input and output electrodes are aligned on the substrate such that they electroacoustically couple along a crystallographic axes thereof. Multicoupling is provided along another crystallographic axes via the plurality of conductively coupled input and output electrodes, respectively. As a result of multicoupling, fifth overtone mode operation is now possible.

Abstract: The present invention discloses a method of simulating the state of a TYPE I Linear Feedback Shift Register (LFSR) with information available as a result of a TYPE II LFSR implementation. This is accomplished by clocking a TYPE II LFSR to produce an output sequence. This sequence, or at least a portion thereof, is then stored in a storage medium, such as, for example, a shift register. Cascading a TYPE II LFSR output sequence into a shift register of length N, where N is the number of stages employed by the TYPE II LFSR, is the exact equivalent of a TYPE I LFSR. Accordingly, the shift register's contents will contain data corresponding to the state of a TYPE I LFSR.

Abstract: The present invention discloses a device for positioning a multi-planar or multi-leaded surface mount electronic component on a printed circuit board (PCB) during reflow soldering. By design this non-conductive device made of thermoplastic resins comprises a fence, having a cavity, wherein the electronic component is positioned relative to printed circuit board foot print contacts. Attached to the bottom surface of the fence is a pair of collapsible slotted pegs. These pegs extend vertically downward from the fence and are adapted to provide a snap-fit insertion and retention mechanism whereby the fence is held in place by inserting the collapsible pegs into holes in a printed circuit board. Thereafter, a pair of cantilever beams which are attached to the fence sidewalls and extend into the fence cavity, make contact with the electronic component. As the fence is inserted into the printed circuit board, the cantilever beams press and hold the electronic component in place during reflow soldering.

Abstract: The present invention discloses a method of protecting a pseudorandom (PN) signal generated by a linear Feedback Shift Register (LFSR) from cryptographic attack. This is accomplished by first receiving a PN output signal generated by an LFSR, or by clocking an LFSR to produce a PN output signal. Thereafter, non-linearity is deterministically introduced into the PN signal to produce a deterministic bit pattern. According to the suggested embodiments, the introduction of non-linearity is accomplished by altering at least one bit of the PN signal sequence. Next, the deterministic bit pattern is substituted in place of the LFSR PN signal, thereby protecting the PN signal from cryptographic attack.

Abstract: The present invention discloses a laminated thermally conductive substrate for supporting microwave power amplifiers, having unique layering thicknesses with materials having similar thermal expansion characteristics, whereby the thermally conductive substrate experiences limited deflection during temperature cycling.

Abstract: The present invention discloses an apparatus that shields electronic equipment from electromagnetic interference. The apparatus is a partially enclosed box having a substantially enclosed cavity. Disposed within the cavity is electronic equipment that is either sensitive to or responsible for generating unwanted EMI radiation. Within each apparatus are cooling air openings. Within each opening is a heat sink device, dimensioned to provide a level of EMI filtering. The heat sink device has a dual function. First, as an EMI filter, it attenuates EMI radiation in the range of frequencies generated by or disruptive to the electronic equipment. Secondly, as a heat sink device, it transfers heat away from the apparatus. In this way, the apparatus of the present invention successfully provides an EMI filter that doubles as a heat sink.

Abstract: A modulation circuit is used in GMSK modulation system. The system includes I-channel and Q-channel ROM look-up tables, each preprogrammed for generating a representative digital waveform based on an input data stream and a clock signal. Each digital waveform is converted to an analog signal for subsequent radio frequency (RF) modulation. Each ROM is addressed by an interpolation counter controlled by a clock signal, by a data shift register receiving input data at a rate corresponding to the clock signal, and by an quadrant register, also receiving the input data, for specifying the phase of the data signal with respect to the clock signal. Additionally, a signal indicates a time at which synchronization to the system clock is required and such synchronization requires synchronizing at a non-integer bit interval time, and in response to that signal, the address of the ROMs is adjusted in order to modify the phase of the data signal so that it is consistent with the system clock requirement.