Abstract: A receiver tunable to a plurality of frequency channels includes a reference frequency generator, a downconverter, an analog-to-digital converter, and a processor. The reference frequency generator generates a reference frequency signal, and the downconverter downconverts received signals to provide intermediate frequency signals. Moreover, the downconverter is synchronized to the reference frequency signal. The analog-to-digital converter generates a plurality of complex numbers representative of the received signals including interference components responsive to the intermediate frequency signals wherein the analog-to-digital converter is synchronized to the reference frequency signal. The processor estimates an origin point for the plurality of complex numbers and subtracts the origin point from each of the complex numbers thereby producing interference-compensated complex numbers representative of the received signals with reduced internally generated interference.

Abstract: Multiple-mode cellular radiotelephones use a wide bandwidth receiving mode while scanning for signals in a narrow bandwidth receiving mode. Thus, when it is desired to scan the received frequency band to search for the presence of narrowband signals, the wider receiver bandwidth is first selected. When significant signal energy is identified in the wider bandwidth, a further scan using the narrowband mode may then be provided in order to locate the narrow bandwidth channel containing the strongest signal. In another embodiment, the signals that are received in the wider bandwidth mode are digitized to obtain complex signal samples. The complex signal samples are then processed to determine energy in each of a plurality of narrower bandwidths corresponding to channels in the narrower bandwidth cellular radiotelephone standards.

Abstract: A base station includes first and second antenna arrays for receiving first and second rotational polarizations, and a polarization diversity receiver connected to the first and second antenna arrays for processing respective first and second receive signals from a mobile station to generate an enhanced quality output receive signal based upon polarization diversity reception. Polarization isolation between the transmit and receive antenna elements may also provided by having a first plurality of transmit antenna elements for the second polarization mounted on a substrate carrying the first receive antenna elements. The second antenna array includes a second plurality of antenna elements of second polarization on a substrate carrying the second receive antenna elements.

Abstract: Two amplifiers that are driven using outphasing modulation are coupled to one another so that the amplifiers affect each other's effective load line. The two amplifiers can maintain efficiency over a wider dynamic range than in a conventional amplifier. Amplifiers according to the invention amplify an AC input signal of varying amplitude and varying phase using a DC power supply. A converter converts the AC input signal into a first signal having constant amplitude and a first phase angle and into a second signal having constant amplitude and a second phase angle. The first amplifier amplifies the first signal, and the second amplifier amplifies the second signal. A coupler couples the first and second amplifiers to one another and to a load impedance, such that voltages or currents in the first amplifier become linearly related to voltages or currents in the second amplifier.

Abstract: Techniques for providing a hearing aid compatible mode of transmission for a mobile station in a radio communication system are described. By adjusting a transmission envelope of a mobile station which transmits information in a burst fashion, harmonics which would normally be introduced into a hearing aid placed in close proximity with the mobile station are avoided. The modified transmission envelope provides a more gradual up and down-ramping of power to the transmitter to avoid introducing harmonics in the audio frequencies. This service can be provided at a system level in a manner which will avoid unnecessarily reducing system capacity by, for example, authenticating a user's identity, his or her subscription to this mode of operation, the mobile station's ability to modify the transmission envelope according to the present invention, and the user's desire to actually implement the hearing aid compatible mode of operation.

Abstract: Communication units used by a communications terminal are measured, and an economic efficiency associated with use of the terminal is determined from the measured communication units and a stored critical value of a tariff of a communications system that is stored in smart card that is coupled to the terminal. Measures to control communications unit usage by the terminal are initiated based on the determined economic efficiency. The measures to control usage may include providing an indication, e.g., a visual or audible indication, of the determined economic efficiency to a user of the terminal. According to one aspect, a first indication of economic efficiency is provided to the user, e.g., a first icon is displayed, if the measured communication units are less than the stored critical value, and a second indication of economic efficiency is provided to the user, e.g., a second icon is displayed, if the measured communication units are greater than the stored critical value.

Abstract: Wireless mobile terminals include a GPS Radio Frequency (RF) receiver and a wide bandwidth radiotelephone RF receiver having bandwidth that is at least half as wide as the GPS RF signal chip frequency. The wireless mobile terminals also include a shared Intermediate Frequency (IF) section that is responsive to both the GPS RF receiver and to the wide bandwidth radiotelephone RF receiver. A demodulator such as a CDMA despreader is responsive to the shared IF section. Thus, common circuitry may be provided except for the separate GPS RF receiver and wide bandwidth radiotelephone RF receiver. Low cost manufacturing and high efficiency operations may thereby be provided.

Abstract: Waveform synthesizers represent an input waveform as a sequence of numerical codes in a number base, each numerical code comprising a plurality of digits ordered by place significance. A plurality of bilateral amplifiers is provided, a respective one of which is associated with a respective one of the digits. The bilateral amplifiers consume current from the DC power supply and return current to the DC power supply based on the value of the associated digit, to thereby generate an output voltage level that is proportional to the value of the associated digit. The output voltage levels of the plurality of bilateral amplifiers are serially coupled to the load, with a weighting that is based upon the place significance of the associated digit. Waveform synthesizers that are so constructed are capable of theoretical efficiencies of 100% for any signal waveform. These waveform synthesizers may be used efficiently to amplify to a transmit power level or radio signal that varies in amplitude as well as phase.

Abstract: Power consumption of a radio communications device including a communications reference signal generator which produces a communications reference signal is controlled by selectively energizing the communications reference signal generator according to a time base which is compensated according to the communications reference signal. The communications reference signal generator may be selectively energized by generating a base timing signal, preferably from a lower frequency base timing signal generator, compensating the base timing signal according to the communications reference signal to produce a power timing signal, and selectively enabling power transfer between a power source and the communications reference signal generator according to the power timing signal.

Abstract: A transmitter receives information for transmission to a receiver over a communication channel. A cyclical redundancy checking (CRC) code circuit encodes the information with CRC code for error detection purposes. The CRC coded information is provided to a code switch. The code switch provides the CRC coded information to either a first code circuit or a second code circuit for forward error correction (FEC) coding. The first code circuit may, for example, encode the information using a FEC Code 1, such as convolutional coding, and the second code circuit may encode the information using a FEC Code 2, such as repetition coding. The code switch selects either the first or second code circuit based on detected characteristics of the channel. The channel characteristics may be obtained from a channel estimation circuit, may be obtained from an error feedback signal I.sub.3 from the receiver or may be obtained from a combination of both.

Abstract: A delay spread is created in a digital radio signal to reduce the coherence bandwidth and facilitate frequency hopping to reduce the effect of fading losses within an enclosed propagation environment The delay spread is introduced into the signal in several ways. One technique disclosed employs a transmitter with two separate antennas one of which transmits the digital signal and the other of which transmits the same signal after a phase delay has been introduced into the signal. The carrier frequency of the signals is hopped between at least two frequencies and the receiver processes the resulting signals. In another embodiment, a single transmit antenna is used but the signal is received by two different antennas with the output signal from one of those antennas being phase delayed before combining it with the other prior to processing by the receiver circuitry.

Abstract: A first control channel associated with a first cell is communicated in the first cell using a first time/frequency window. The first control channel and a traffic channel are communicated in a second cell using the first time/frequency window. The first control channel may be communicated in the second cell when the first time/frequency window is unassigned to a traffic channel in the second cell. The first time/frequency window may be assigned to a traffic channel in the second cell, and the first control channel may be communicated in the second cell when the traffic channel to which the first time/frequency window is assigned in the second cell is idle. The traffic channel to which the first time/frequency window is assigned in the second cell may be communicated over different carrier frequency bands to thereby frequency hop the traffic channel.

Abstract: A delay spread is created in a digital radio signal to reduce the coherence bandwidth and facilitate frequency hopping to reduce the effect of fading losses within an enclosed propagation environment. The delay spread is introduced into the signal in several ways. One technique disclosed employs a transmitter with two separate antennas one of which transmits the digital signal and the other of which transmits the same signal after a phase delay has been introduced into the signal. The carrier frequency of the signals is hopped between at least two frequencies and the receiver processes the resulting signals. In another embodiment, a single transmit antenna is used but the signal is received by two different antennas with the output signal from one of those antennas being phase delayed before combining it with the other prior to processing by the receiver circuitry.

Abstract: A frequency modulation (FM) radio transmitter, such as a cellular telephone, includes an automatic deviation control system to automatically compensate for varying sensitivity of the FM transmitter. The FM transmitter includes a phase lock loop including a controlled oscillator that produces a frequency modulated input signal on an output channel frequency in response to a control input that is applied thereto. A scaler is responsive to the input signal and to at least one scaling content, to scale the input signal based upon the at least one scaling constant and to provide the scaled input signal to the phase lock loop to produce the frequency modulated input signal on the channel frequency. An automatic deviation control system measures the control signal that is applied to the controlled oscillator when tuned to one of the plurality of output channel frequencies and updates at least one of the scaling constants based upon the measured control input, to thereby provide automatic deviation control.

Abstract: The sum of a plurality of logarithmic numbers is determined by expressing the logarithmic numbers as one of a predetermined values. For example, the numbers may be analog values which may be sampled by an 8-bit AtoD converter to be expressed as one of a possible 256 values. The number of occurrences for each of the values is accumulated in bins (counters) and the sum is determined by a summation of the logarithmic numbers based on processing of the counts rather than the logarithmic numbers themselves. Bin counts are reduced iteratively by replacing counts greater than 1 by incrementing the count of a proportionately higher value bin until only counts of 1 or zero remain. These counts are then combined to provide only a single counter with a non-zero count value which indicates the accumulated signal strength of the signal strength measurements. The invention may further be provided using single bit memory elements and byte processing with look-up tables.

Abstract: Waveform synthesizers represent an input waveform as a sequence of numerical codes in a number base, each numerical code comprising a plurality of digits ordered by place significance. A plurality of bilateral amplifiers is provided, a respective one of which is associated with a respective one of the digits. The bilateral amplifiers consume current from the DC power supply and return current to the DC power supply based on the value of the associated digit, to thereby generate an output voltage level that is proportional to the value of the associated digit. The output voltage levels of the plurality of bilateral amplifiers are serially coupled to the load, with a weighting that is based upon the place significance of the associated digit. Waveform synthesizers that are so constructed are capable of theoretical efficiencies of 100% for any signal waveform. These waveform synthesizers may be used efficiently to amplify to a transmit power level or radio signal that varies in amplitude as well as phase.

Abstract: A system and method for bidirectionally demodulating data symbols transmitted through a communication channel. The method includes sequentially receiving and storing a first plurality of known data symbols, a second plurality of unknown data symbols, and a third plurality of known data symbols. Thereafter, a first block of the unknown data symbols received nearer the first plurality of known data symbols is forward-demodulated. Likewise, a second block of the unknown data symbols received nearer the third plurality of known data symbols is backward-demodulated. The forward- and backward-demodulation of the unknown data symbols determines quality values (figure-of-merits based on at least one of signal power, noise power and a combination of signal power plus noise power) indicative of demodulation qualities of the unknown data symbols that are compared to produce a best direction indication.

Abstract: A method and apparatus for transmitting and receiving frequency hopped video signals is disclosed. A composite video signal is processed at a transmission end to remove line and frame synchronization codes and replace them with a frequency hopping synchronization code. The signal is then modulated with a frequency hopped carrier signal and transmitted to a receiver. The receiver detects the frequency hopping synchronization code to enable tuning of the receiver to the video signal. The detected frequency hopping synchronization codes are removed and replaced with the original line and frame synchronization code. The recreated video signal may be digitized and processed to detect and correct errors within the video signal by replacing lines or frames of the video signal with closely related lines or frames from another portion of the video signal.

Abstract: A communications system for transmitting selected information to a registered mobile terminal in response to the reporting of a vehicle identification associated with the registered mobile terminal to a database system. The communications system includes a database system having a memory with registered vehicle identifications and associated information. The database system is coupled to a radio system for receiving a reporting signal including a vehicle identification sent by a reporting mobile terminal. In response to the inputted reported vehicle identification, the database system identifies a registered vehicle identification corresponding to the reported vehicle identification and selects associated information corresponding to the identified registered vehicle identification. In the first preferred embodiment, the selected associated information includes a selected phone number and the database system sends the selected message to a registered mobile terminal associated with the vehicle identification.

Abstract: The invention relates to a method and an arrangement intended for radio communication systems and effective in digitalizing and subsequently processing numerically arbitrary radio signals. The signals are represented by composite (complex) vectors which have been subjected to disturbances in the system, such that information in the signals has been lost. This information is restored in its entirety when practising the present invention. For the purpose of solving this problem, the inventive digitalizing arrangement includes a multistage logarithmic amplifier chain (A) in which each stage is connected to a separate detector (D), the output signals of which are added in an adder. The adder output signals are then transmitted to a first A/D-converter (AD1) for digitalizing and converting the amplitude components of the signal.