Abstract: An APCO 25 radio communication system 200 includes a repeater 101 arranged to receive signals from an inbound repeater link 103, thereby forming received signals. The repeater 101 is arranged to forward the received signals to a subscriber 121 via an outbound radio frequency path 113. The received signals include two types of packets, namely, packets 105 with correctable errors 107, and "erasure packets"109 with detectable-but-uncorrectable errors 111. The inbound repeater link is equipped with error correcting means 110 for correcting the correctable errors 107. The inbound repeater link is also equipped with error mitigating means 130 for mitigating the detectable-but-uncorrectable errors 111. The error mitigation is performed in accordance with the improved multi-band excitation ("IMBE") process.

Abstract: An RF power amplifier (100) includes a feedback loop with a loop phase, and is arranged for amplifying an RF signal (1). During an initial stabilizing mode (201), the amplifier is stabilized by applying a baseband reference signal (210) input via a reference input terminal to the feedback loop and adjusting the loop phase to an optimum value. Thereafter, during an amplifying mode (202), the RF signal is input via an RF input terminal and amplified while maintaining the loop phase at the optimum value. The feedback loop contains a baseband in-phase (I) path and a baseband quadrature (Q) path, and the baseband reference signal may be applied to the I path, the Q path, or both. The stabilizing and amplifying modes are fixed in duration and comprise a periodic cycle that is repeated. The input RF signal is substantially null during the stabilizing mode.

Abstract: A method of transmitting voice coding information is provided. First and second frames of voice coding information are provided. Each frame is then prioritized based on which bits need to be forward-error corrected, thus forming first and second prioritized frames. A six-bit CRC value is then computed based on the prioritized first and second frames. The six-bit CRC value is then split into first and second 3-bit CRC units. The first CRC unit is then combined with the first prioritized frame to form a modified first frame, and the second CRC unit is then combined with the second prioritized frame to form a modified second frame. The modified first and second frames are each then error correction coded to form first and second sets of symbols, respectively. The first and second set of symbols are then interleaved into a transmission unit, which is then transmitted.

Abstract: A radio communications apparatus employs a training routine for optimizing performance and has a modulator (64, 66) to modulate a radio channel with digital information, to provide baseband signals (I, Q) at a first data rate. A power amplifier (36) amplifies signals fed from the modulator. A feedback loop (40, 42, 44, 30) samples the output signals of the power amplifier and adjusts at least one of the amplitude and phase of the baseband signals to compensate for distortion introduced by the power amplifier. The data rate of the baseband signals is reduced during the training routine to reduce adjacent channel transmissions.

Abstract: A method for amplitude training for a power amplifier is described employing adaptively changing an input training signal of a feedback circuit.

Abstract: A monitoring computer (115) monitors a communication resource within a wireless communication system for transmissions by a communication unit. Upon detecting the transmission, which contains a unit identifier, the monitoring computer compares the unit identifier with stored system access information for the communication unit. When the unit identifier is not compatible with the stored system access information, the monitoring computer reprograms at least a portion of the system access information of the communication unit. In this manner, discrepancies in communication unit programming may be corrected.

Abstract: The method disclosed herein begins with a molded housing (13 or 31). In one embodiment (20) the molded housing (13) has a ground shield (14) that is formed by thermally spraying a metallic conductive material onto the housing (13). Electrical connections are then made to link an electronic circuit on a printed circuit board assembly (21) to the ground shield (14). In another embodiment (30), the molded housing (31) has a plurality of elements (such as an indented channel (32), extrusions (33), a slot connector (34), and a notch (35)) that are thermally sprayed in selected areas to form a plurality of connective elements required by the electronic circuit of the printed circuit board assembly.

Abstract: A transmitter that includes an amplifying element, an antenna, a gain stage, and a closed loop feedback may compensate for varying antenna loads without an isolator. This may be accomplished by determining the effects of the varying loading on overall loop gain. Knowing the effects, the transmitter adjusts the gain of the gain stage to maintain a constant overall loop gain, thus eliminating the need for an isolator.

Abstract: Modular equipment for data acquisition/control of a system comprises a central unit (CPU Board), a plurality of input/output modules and a bus coupled therebetween. The central unit has successive approximation generator means (2) for generating a plurality of unique system addresses. The plurality of input/output modules each acquire information from/administering control of said system, and each of said plurality of input/outout modules is located at one of said unique addresses. The bus comprises an interrupt control line (IRQ) for requesting an interrupt service, whereon one or more of said plurality of modules periodically places an interrupt service request. Identifcation means, responsive to said successive approximation generator means (2), identifies an address of a module from which an interrupt service request emanated.

Abstract: A method of communications between a master unit and a slave unit of a supervisory control and data acquisition system is provided. The communications protocol has at least two bytes of data where the first byte (100) is an address byte containing address information for addressing the slave unit and the second byte (101) is a control byte containing an expansion bit and two address/type variable bits to be interpreted by the slave according to a rule set. In the rule set, the meaning of certain control bits (107) is related to the state of an expansion bit (103). The expanion bit defines the presence or absence of a third byte (102).

Abstract: Communications may be established based on geographic location when a communication resource controller (101) transmits a communication message (119), which includes a message ID (120) and a communication payload (121), to a plurality of communication units (102, 103). Each of communication units (102, 103) upon receiving the communication message (119), compares its identification code (122) with the message ID (120). If a match occurs, the communication unit (102, 103) then determines its geographic location. Having obtained the geographic location, the unit then does a table look-up to determine, based on the message ID code, a geographic communication area (126). Having obtained this information, the unit then determines whether its present location is within the geographic communication area and if so, adjust its receiver to receive the communication payload (121).

Abstract: A modem (106) is arranged with a power control circuit (113) for controlling the power flow to the modem, based on the modem's data activity. After initial data activity is established (303), the power control circuit monitors the modem to determine when the data activity ceases. When the power control circuit determines that modem activity is no longer present (305), it releases a power-control relay (114), thus powering-down the modem (307). The power control circuit then continues to monitor the modem to determine when data activity returns. When the power control circuit determines that modem activity has returned (309), it operates the power-control relay, thus powering-up the modem (311). Normal data activity now continues (313).

Abstract: A data terminal (10) determines when to set a request to send ("RTS") signal (51) to a logical LOW state by determining when an internal counter (13) reaches a count value of zero. The counter is driven by the transmit clock signal (55) of an associated modem (70).

Abstract: A surface-mountable crystal resonator (100) is provided in the following manner. A first predetermined electrode pattern (105) and a second predetermined electrode pattern (201) are formed on a first major surface (104) and a second major surface (200), respectively, of a piezoelectric crystal substrate (101). Additionally, a first predetermined attachment electrode pattern (106), electrically coupled to the second predetermined attachment electrode pattern, and a second predetermined attachment electrode pattern (202), electrically coupled to the first predetermined attachment electrode pattern, are formed on a first attachment area (102) and a second attachment area (103), respectively. The first and second attachment areas include extensions (107) that, when mounted, allow a conductive adhesive (301), placed on a mounting substrate (300), to flow and establish electrical connections with the first and second predetermined attachment electrode patterns.