Abstract:
A transceiver system for interfacing digital modems with radio frequency signals is described. The system includes a modem interface connected to the antenna interface via a coax cable, and an antenna. Circuits for providing power regulation of the exchanged signals include power detection circuits and attenuators in the antenna interface as well as in the modem interface.
Abstract:
A method and apparatus for providing a mobile station user (8) with information about anticipated roaming charges. The visitor communication system (7) transmits a graded roaming signal to the mobile station user (8) indicative of the anticipated roaming costs. The graded roaming signal is determined by contractual agreements between the visitor communication system provider and user's service provider. This information is stored in a database at the user's home communication system (2) and is provided to the visitor communication system (7) upon request for authorization to provide service. The graded roaming signal is broadcast to the mobile station (8) and displayed to allow the mobile station user to estimate the cost of the service being provided.
Abstract:
A first remote vocoder (15) receives analog voice (170) and produces packetized vocoder data (190) which is transmitted over a wireless link (20). A first local vocoder (35) receives the packetized vocoder data (190) from the wireless link (20). The first local vocoder (35) converts the packetized data (190) to a multibit PCM output (120). The first local vocoder (35) also adds a detection code to one of the least significant bits (LSB) of the PCM output (210). The first local vocoder (35) passes the PCM signal (210) to the PSTN (40). The first local vocoder (210) also receives PCM input (120) over the PSTN (40). The first local vocoder (35) constantly monitors the least significant bit of the PCM input (120) for a detection code indicating that a second local vocoder (55) is connected at the receiving end. If the first local vocoder (35) detects the detection code from the second local vocoder (55), it begins to substitute packetized data and a redundancy check for a second one of the LSB's of the outgoing PCM (210). The first local vocoder (35) also begins to monitor the second one of the LSB's of the incoming PCM (120). If the redundancy check indicates that valid packetized data has been received, the first local vocoder (35) stops converting the PCM output (120) into packetized data and simply passes the packetized data on the second one of the LSB's to the first remote vocoder (15) as packets (100). If at any time the redundancy check fails and the detection code is not detected, the first local vocoder (35) returns to converting the incoming PCM (190) to packetized data. In this way, the tandem vocoding arrangement is avoided.
Abstract:
A dual-mode digital communication system for communicating an information signal during operation in frequency-modulated (FM) and multiple-access modes is disclosed herein. The digital communication system includes a dual-mode transmitter (14) for transmitting the information signal using an FM communication signal during FM mode operation, and for transmitting the information signal using a multiple-access communication signal during multiple-access mode operation. The communication system further includes a dual-mode receiver (16) for receiving the FM communication signal during FM mode operation, and for receiving the multiple-access communication signal during multiple-access mode operation. Incorporated within the dual-mode receiver (16) is a digital demodulator (96) for recovering the information signal from the received FM signal during operation in the FM mode, and for recovering the information signal from the received multiple-access signal during multiple-access mode operation.
Abstract:
A method and system for performing an intersystem handoff of communication with a mobile station (18) between base stations of first (A) and second (B) cellular systems. At the mobile station (18), a quantifiable parameter of a signal transmitted by a second base station of the second system is measured. When the measured value passes through a first predetermined level, the mobile station (18) communicates a signal quality message via a first base station of the first system to a first mobile switching control station. A channel request message is communicated from the first mobile switching station (MSCI) to a second mobile switching station (MSCII) within the second system. At the second base station, a quantifiable parameter of the signal received from the mobile station is also measured. The second base station establishes communication with the mobile station when the measured value passes through a predetermined level.
Abstract:
A modulator (109) for a spread spectrum telecommunication system not only receives local data (112) and processes it, but also receives input data from one or more other modulators (124), sums the input data with the local data, and provides the sum as data for a subsequent modulator or as final output for a transmit power amplifier (126). The modulator includes an input block (120) and an output block (122) and, depending on a control data signal (190), input data will be summed with the internally generated local data of the modulator before being provided to the output block (122). The output data can include parity data. The parity data can be used to check for faults that might be introduced, for example, by a faulty connection or broken hard-wired interconnect. If an error is detected, the summation function of the transmit modulator (127) can be automatically disabled.
Abstract:
A system and method for detecting fault conditions in a recording device (38) disposed within a vehicle (12) having one or more vehicle sensors (48) for monitoring one or more operational parameters of the vehicle (12). The recording device (38) is used to collect vehicle operation data produced by the sensors (48). One implementation of the fault detection technique involves the storing of a current time value at regular intervals during periods in which the recording device is provided with a source of main power. Time differences are determined between consecutive ones of the stored time values, and the time differences compared to a predetermined maximum value. A power loss fault condition is registered when at least one of the time differences exceeds the predetermined maximum value. An indication of the existence of the power loss fault condition may be communicated to a central control station (18) by the recording device (38).
Abstract:
A computationally efficient procedure for determining the set of quantization sensitivities for the line spectral pair (LSP) frequencies is performed by LSP quantizing system (10), which results in a computationally efficient error measure for use in vector quantization of the LSP frequencies. A new set of vectors are computed based upon the LSP values by a P and Q computation element (4). These vectors are then supplied to a bank of polynomial division computation elements (5a-5N) which provide the quotients to sensitivity autocorrelation elements (6a-6N). The sensitivities autocorrelations and a set of autocorrelations are used to generate a set of sensitivity cross-correlations by sensitivity cross-correlators (7a-7N). The computed sensitivity values are then used to quantize the LSP values.
Abstract:
A method and apparatus for matching the location of the forward link handoff boundary to the reverse link handoff boundary. A system constant is chosen which defines the product of the received power and the transmitted pilot power at every base station. The reverse link power level is measured at the base station and the forward link power level is compensated for the reverse link loading to maintain the constant product. Thereby the forward link handoff boundary to the reverse link handoff boundary are aligned to the same location.
Abstract:
The process of the present invention enables a mobile radiotelephone to operate at a 100 % duty cycle while providing closed loop power control. The base station measures the signal to noise ratio of the signal from the mobile and compares (305) that SNR with the SNR threshold values the base station has for each data rate the mobile is capable of transmitting. The base station then generates power control commands (310) to instruct the mobile to change its power depending on the outcome of the comparisons.