Abstract: The system and method determines whether the expected location of the pilot channel in the PN code sequence (i.e. the PN code phase offset) has been detected in an initial search window centered on the expected pilot PN code phase offset. If not, a new search window is defined which is advanced in the PN code sequence from the initial search window. If the actual location of the pilot channel in the PN code sequence is not detected in the new search window, a subsequent search window is defined which is retarded in the PN sequence from all previous search windows. This iterative "spiral" searching method is repeated with increasingly divergent alternating advanced and retarded search windows until either the actual location of the pilot channel in the PN code sequence is detected, or a predetermined maximum number of iterations has occurred.

Abstract: A system and method for acquiring a code division multiple access (CDMA) pilot signal having a pilot pseudonoise (PN) code offset in a CDMA communication system. A received signal is correlated with a first set of PN code offset hypotheses. If this first "full" search is unsuccessful in acquiring the CDMA pilot signal, the method includes waiting for a first period, and then correlating the received signal with a second set of PN code offset hypotheses which are a subset of said first set of PN code offset hypotheses and therefore requires less search time. If this "mini" search is unsuccessful in acquiring the CDMA pilot signal the method includes waiting for a second period and then quickly measuring the energy of the received signal. If the received energy exceeds a threshold, then a "mini" search is immediately performed. These alternating search techniques of full, mini, micro are repeated.

Abstract: A dual-mode communications processor disposed to be incorporated within a dual-mode communications device is disclosed herein. The dual-mode communications processor comprises a dual-mode voiceband signal processor having an input port for receiving digitized data. Within the dual-mode voiceband signal processor, first and second signal processing operations are performed upon the digitized data received during operation in first and second modes, respectively. These separate signal processing operations may advantageously be performed using common circuit elements within the dual-mode voiceband signal processor. In an exemplary embodiment the first signal processing operation is performed in accordance with a predefined vocoding algorithm, while the second signal processing operation involves the filtering of the digitized data as prescribed by FM cellular telephone standards.

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 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 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 is a digital demodulator 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 frequency synthesizer which uses a direct digital synthesizer (DDS) to generate a highly accurate periodic signal of a frequency selected from a plurality of reference frequencies. The DDS output signal is bandpass filtered utilizing a clean-up phase lock loop (PLL) to produce a spectrally pure reference signal and promote overall fast settling time. A second or primary phase lock loop, having a much faster settling time than the first PLL, adjusts the frequency of the reference signal generated by the clean-up PLL. In one embodiment, the DDS frequency synthesizer has a digital to analog (DAC) converter coupled to the clean-up PLL. Another embodiment uses a modified DDS (without a DAC or lookup table) and feeds the most significant bit (MSB) or overflow bit from the DAC accumulator into the "clean-up" PLL. In both embodiments, the resulting synthesizer has high spectral purity, fine frequency resolution and a fast settling time.

Abstract: The dual band code division multiple access radio of the present invention operates on multiple frequencies simultaneously on either transmit or receive. The transmit path operates by splitting the transmit intermediate frequency (IF) path (103) and mixing the IF to two different transmit frequencies using two frequency synthesizers (140 and 145). The receive path (104) has two RF channels (116 and 117) that are mixed with the frequencies generated by the synthesizers (140 and 145) and summed into one IF strip. Thus the radio of the present invention can perform a soft hand-off between frequencies while communicating with both base stations simultaneously. Additional mixing paths and synthesizers can be added if it is desired to communicate with more than two base stations simultaneously.

Abstract: A method and apparatus for selecting a communication system in a multi-mode subscriber station. In the exemplary embodiment, the subscriber station capable of operating in both CDMA and analog modes comprises a analog modulation and demodulation and processing element and a CDMA modulation and demodulation and processing element and a system determination element. System determination element examines exit parameters provided by the communication element exited and determines the next system upon which to attempt acquisition in accordance with a system preferences table, a CDMA channel table and a non-volatile memory element.

Abstract: A wireless remote telemetry system which uses low-cost remote communication devices operating on existing wireless communication systems in order to provide real-time reading and control of remote devices. In an embodiment applicable to utility service, consumption of electrical power among a population of customers is measured by a utility metering system having a wireless communication capability. The metering system comprises a remote metering unit which communicates with a central controller over existing wireless communication systems, such as cellular base stations, using existing communication standards. The remote metering unit transmits various messages over a shared random access channel to a central controller. The central controller transmits messages to the remote metering unit over a paging channel. The remote metering unit may operate in a half-duplex mode only. Furthermore, the remote metering unit may provide a gateway to advanced consumer services at the remote location.

Abstract: The process of the present invention adjusts the input gain by a predetermined amount. The receiver processing measures the gain change in the IF sisal power. If the change is less than the predetermined amount, the CDMA signal and jammers are below the noise floor and, therefore, the gain is increased. If the IF signal power change is equal to the predetermined amount, the CDMA signal is above the noise floor and the interference is minimal. Therefore, in this case, gain adjustment is not necessary, but increasing gain will improve sensitivity. If the IF signal power change is greater than the predetermined amount, the interference is evident and the gain is reduced to reduce the intermodulation products. This process is used until the receiver is operating at the best compromise between interference and noise figure.

Abstract: A method for adjusting the gain of a receive circuit, thereby improving a receiver's immunity to interference. The circuit has an LNA which amplifies the received signal. The receive signal power is controlled by enabling or disabling the LNA in response to the measured received signal power. The received power level is periodically compared to a threshold. When the received power level is greater than the threshold, the LNA is disabled. The LNA is re-enabled when the received power level is less than the threshold, and there are no significant intermodulation components detected. The intermodulation components are detected by briefly enabling the LNA and detecting the resultant change in the measured signal power. If the detected change is more than a predetermined amount, then there are significant intermodulation components present, and the LNA is not re-enabled. Otherwise, there are not significant intermodulation components present, and the LNA is re-enabled.

Abstract: The dual band code division multiple access radio of the present invention operates on multiple frequencies simultaneously on either transmit or receive. The transmit path operates by splitting the transmit intermediate frequency (IF) path (103) and mixing the IF to two different transmit frequencies using two frequency synthesizers (140 and 145). The receive path (104) has two RF channels (116 and 117) that are mixed with the frequencies generated by the synthesizers (140 and 145) and summed into one IF strip. Thus the radio of the present invention can perform a soft hand-off between frequencies while communicating with both base stations simultaneously. Additional mixing paths and synthesizers can be added if it is desired to communicate with more than two base stations simultaneously.

Abstract: The method and apparatus of the present invention improve the immunity to interference of a radio receiver. The power level of a received signal is detected. If the power level meets or exceeds a predetermined power threshold, the low noise amplifier is by-passed, thus increasing the intercept point of the receiver components.Alternative embodiments include the use of an RF power detector to control the front-end gain as a function of jammer power. In lieu of a switchable RF gain block, several methods of continuous gain control are proposed. Continuous gain control allows the interference suppression and sensitivity of the receiver to be adjusted at lower signal levels than the switchable gain block.

Abstract: A double helix antenna comprised of orthogonally-wound helix conductors is disclosed. The double helix antenna system includes a first helix conductor wound in a first direction about a vertical axis of the double helix antenna. A second helix conductor is wound in a second direction about the longitudinal axis. In a specific implementation, the first and second helix conductors are of different lengths, respectively corresponding to first and second frequency bands. Additionally, the first and second helix conductors are wound so as to be orthogonal at those horizontal planes within which the first and second helix conductors intersect or are otherwise minimally separated in the horizontal dimension. This orthogonal winding relationship between the helix conductors substantially reduces mutual coupling, thus enabling operation of separate helical antennas in close physical proximity. In a particular application, the double helix antenna system is incorporated within a portable communications device.

Abstract: In a digital communication system for communicating digital information, the digital communication system having a forward link and a reverse link, a system and method for communicating a data packet. The system comprises a communicating transceiver, from among a number of digital transceivers, for sending the data packet on a random access channel over the reverse link and for receiving the digital information from the forward link. The system also comprises a base station for receiving the data packet on the random access channel from the reverse link and for sending the digital information over the forward link. The digital transceivers share the random access channel. The digital transceivers have a bandwidth demand.

Abstract: A dual-band antenna system for use in a portable communications device is disclosed herein. The antenna system includes an antenna element for radiating electromagnetic energy within low-band and high-band wavelength ranges. In a preferred embodiment, a low-band isolator network, coupled to the antenna element, provides signal isolation between high-band and low-band signal paths during high-band operation. Similarly, a high-band isolator network provides signal isolation, during operation over the low-band range of wavelengths, between the high-band and low-band signal paths. During transmit and receive operation, low-band and high-band electromagnetic energy directed through the antenna is passed by the low-band and high-band isolator networks, respectively. Also included are low-band and high-band matching networks which couple the low-band and high-band isolator networks to low-band and high-band transceiver circuitry.

Abstract: A method and apparatus for negotiating service configuration in a digital communication system is disclosed. In an exemplary embodiment the service negotiation system is implemented in a wireless spread spectrum communication system. The service configuration comprises data rates, frame formats and types of services. Types of service may include speech encoding, facsimile or digital data services. Further described herein is a digital transmitter and receiver using the service negotiation system to provide service configuration mutually acceptable at both ends of a communication link.

Abstract: The present invention provides linear, digital automatic gain control (AGC) in a radio. A received signal is demodulated to provide I and Q digital baseband signals. A received signal strength indication is determined from these signals and the resulting digital signal is adjusted to provide a logarithmic response. This signal is then integrated to provide a digital receive AGC adjust signal. For the transmit AGC adjust, the digital receive AGC adjust signal is filtered and then summed with a scaled closed loop power control command. The closed loop power control commands are ignored if they would result in increasing the transmit gain beyond the amplifier's designed maximum output. The result of the sum operation converted from digital to analog for adjusting the amplifier. The outputs of the transmit and receive AGC amplifiers are linearized by transmit and receive linearizers, respectively, which pre-distort the digital AGC adjust signals prior to digital to analog conversion.

Abstract: An automatic gain control (AGC) and D.C. offset correction method and apparatus for controlling signal power of a received RF signal within a dual mode quadrature receiver is disclosed herein. In a preferred implementation the automatic gain control apparatus may be adjusted to provide a desired control response to various fading characteristics of a received FM, FSK, GMSK, QPSK, or BPSK signal. The AGC apparatus includes an adjustable gain amplifier having an input port for receiving an input signal, a control port for receiving a gain control signal, and an output port for providing an output signal. A quadrature downconverter coupled to the output port serves to translate the frequency of the output signal to a baseband frequency, thereby producing baseband signals. In a preferred implementation the downconverter is operative to map the carrier frequency of the output signal to a baseband frequency offset by a predetermined margin from D.C.

Abstract: The power control process of the present invention enables a base station communicating over a forward packet channel to a mobile radio to control the power of the mobile radio transmitting over a reverse packet channel to the base station. The base station maintains a maximum energy per bit to total interference spectral density ratio threshold for the reverse channel as well as a desired threshold that results in a low frame error rate. By comparing each radiotelephone's estimated energy per bit to total interference spectral density ratio to the desired and maximum thresholds, power control commands to increase or decrease the radiotelephone's transmit power are generated depending on the outcome of the comparison.