Abstract: Techniques to correct for phase and amplitude mismatches in a radio device in order to maintain channel symmetry when communicating with another device using MIMO radio communication techniques. Correction for the amplitude and phase mismatches among the plurality of transmitters and plurality of receivers of a device may be made at baseband using digital logic (such as in the modem) in the receiver path, the transmitter path or both paths of that device. In a device, amplitude and phase offsets are determined among the plurality of radio transmitter and radio receiver paths by measuring phase and amplitude responses when supplying a signal to a transmitter in a first antenna path of the device and coupling the radio signal from a first antenna to a second antenna path of that device where the signal is downconverted by a receiver associated with the second antenna path, and similarly coupling a signal from the second antenna path to the first antenna path.

Abstract: Systems and methods to enable different types of radio communication devices to communicate using a common language in order to enable the devices to regulate their use of the spectrum. Each device participating in the ad hoc control channel (ACC) protocol transmits information using a common signal format that each of the other participant devices is capable of recognizing, in order to share information about how it uses the radio frequency band. Each device receives the information transmitted by other participant devices and based on that information, controls one or more of its operational parameters that impact usage of the radio frequency band. The ACC protocol enables devices of the same or different type to harmonize (instead of alienate) themselves with each other by allowing them to communicate about their usage of the radio frequency band using a common signaling framework.

Abstract: A spatial signal processing system and method are provided to optimize the received signal-to-noise ratio (SNR) at a first radio communication device based on the transmit filter at another radio communication device. Using an estimate of the channel derived from a signal received at one device from another device, an iterative process is provided to determine complex weights for one or more tapped delay-line transmit filters at each of two communication devices that optimize the received SNR.

Abstract: Systems and methods for optimizing the efficiency of each of a plurality of power amplifiers that amplify a corresponding one of a plurality of radio frequency signals for transmission by a corresponding one of a plurality of antennas. Using transmit beamforming, the power of each amplified signal output by the power amplifiers may not be the same for all the power amplifiers, and may vary with changes in the communication channel between the transmitting device and receiving device. Each of the plurality of power amplifiers is controlled to operate with one or more operating parameters that optimize the efficiency for an output power level of corresponding ones of the radio frequency signals. By adjusting one or more operating parameters of each power amplifier according to changing requirements (e.g., the destination device and channel conditions), the efficiency of each power amplifier can be optimized.

Abstract: Methods to optimize range of multicast signal communication in wireless communication applications that use range-enhanced techniques for directed signal communication. A multicast signal may be sent multiple times through each of a plurality of independent omnidirectional transmit antennas of a communication device to a plurality of other communication devices to improve packet error rate (PER) at a given range (i.e., SNR). More generally, the multicast message can be transmitted up to N times using up to N times using any set of N complex linearly independent N-dimensional transmit weight vectors v1, . . . , vN associated with N plurality of transmit antennas that meets the power constraint ?vi?2=1, i=0, . . . ,N?1, where the vector vi is used for the ith transmission of the multicast signal.

Abstract: A system and method for classifying signals occurring in a frequency band. One or more characteristics of one or more signals in the frequency band are detected using any suitable technology, such as a device that can generate characteristics of signal pulses detected in the frequency band. Data pertaining to the signal pulses is accumulated over time. The accumulated signal data is compared against reference data associated with known signals to classify the one or more signals in the frequency band based on the comparison. The accumulated data may include one or more characteristics selected from the group consisting of: pulse center frequency, pulse bandwidth, pulse duration, time between pulses and number of different active pulses, and wherein the reference data associated with each of a plurality of known signals comprises one or more characteristics selected from the group consisting of: pulse center frequency, pulse bandwidth, pulse duration and time between pulses.

Abstract: An equal gain composite beamforming technique which constrains that the power of the signal output by each antenna is the same, and is equal to the total power of the transmit signal divided by the number N of transmit antennas from which the signal is to be transmitted. By reducing output power requirements for each power amplifier, the silicon area of the power amplifiers are reduced by as much as N times (where N is equal to the number of transmit antennas) relative to a non-equal gain CBF.

Abstract: A MIMO radio transceiver to support processing of multiple signals for simultaneous transmission via corresponding ones of a plurality of antennas and to support receive processing of multiple signals detected by corresponding ones of the plurality of antennas. The radio transceiver provides, on a single semiconductor integrated circuit, a receiver circuit or path for each of a plurality of antennas and a transmit circuit or path for each of the plurality of antennas. Each receiver circuit downconverts the RF signal detected by its associated antenna to a baseband signal. Similarly, each transmit path upconverts a baseband signal to be transmitted by an assigned antenna.

Abstract: A spectrum analysis engine (SAGE) that comprises a spectrum analyzer component, a signal detector component, a universal signal synchronizer component and a snapshot buffer component. The spectrum analyzer component generates data representing a real-time spectrogram of a bandwidth of radio frequency (RF) spectrum. The signal detector detects signal pulses in the frequency band and outputs pulse event information entries output, which include the start time, duration, power, center frequency and bandwidth of each detected pulse. The signal detector also provides pulse trigger outputs which may be used to enable/disable the collection of information by the spectrum analyzer and the snapshot buffer components. The snapshot buffer collects a set of raw digital signal samples useful for signal classification and other purposes. The universal signal synchronizer synchronizes to periodic signal sources, useful for instituting schemes to avoid interference with those signals.

Abstract: A VCO having an automatic amplitude control circuit In the form of a sensing amplifier provided in the feedback loop to sense the oscillator amplitude and draw current away only when the positive peak voltage Is above a certain value. In general, any amplifier may be used in the feedback loop that outputs current proportional to a peak positive input (in a non-linear and asymmetric fashion with respect to the changing voltage). In one example, the amplifier in the feedback loop comprises first and second transistors that are set nominally in cut off and behave as class C amplifiers. The advantage of this amplifier transistor configuration is that the amplifier they form has a low load on the LC tank circuit and a high input impedance.

Abstract: A composite beamforming technique is provided wherein a first communication device has a plurality of antennas and the second communication has a plurality of antennas. When the first communication device transmits to the second communication device, the transmit signal is multiplied by a transmit weight vector for transmission by each the plurality of antennas and the transmit signals are received by the plurality of antennas at the second communication device. The second communication device determines the best receive weight vector for the its antennas, and from that vector, derives a suitable transmit weight vector for transmission on the plurality of antennas back to the first communication device. Several techniques are provided to determine the optimum transmit weight vector and receive weight vector for communication between the first and second communication devices so that there is effectively joint or composite beamforming between the communication devices.

Abstract: A wideband radio transceiver system that features a wideband RF section and a flexible and scalable baseband signal processing section. The transceiver system architecture has configurable baseband processing to process signals for multiple communication protocol standards, or multiple instances of the same communication protocol standard, that operate over the same frequency band. Optional additional features include a transmit carrier suppressor and transmit interference canceller to suppress the effects of a transmit signal on receive signal processing when signals are being transmitted and received simultaneously.

Abstract: A system and method for allowing a user to program characteristics of at least one light emitting diode (LED) in order to convey information about the operational status of an appliance, such as a printer. The user of the printer selects one of a plurality of display mode options for the LED for a particular operational status condition of the printer. For each display mode option, there is a range of parameters that can be programmed by the user. Display mode setting information for the particular operational status condition (and chosen parameters) is stored based on a selected display mode option. The display mode option may be tested for a particular set of parameters to allow the user to adjust the parameters to his/her liking. Moreover, a combination of display mode options may be programmed for an operational status condition.

Abstract: A system and method for controlling a stepper motor wherein the amount of memory space needed to store a phase table is minimized. The stepper motor controller comprises a memory sized to store data representing a plurality of states for current outputs to be supplied to a first winding of a stepper motor and from which are derived current outputs for the first winding and a second winding of the stepper motor. A finite state machine is coupled to the memory. The finite state machine comprises a first address register that stores an address for data in the memory for a present state of the first winding and a second register that stores an address for data in the memory for a present state of the second winding.

Abstract: A receiver circuit (10), and method for automatic frequency control of a receiver circuit (10) suitable for receiving a radio frequency (RF) signal, featuring determination of at least one parameter other than a frequency error of a signal which is mixed with the RF signal received by the receiver circuit; and adjusting the frequency of the signal which is mixed with the RF signal based on the frequency error if the at least one parameter satisfies a predetermined criterion.

Abstract: A modulation scheme (600) useful in a voice paging system in which both of two orthogonal modulation components (500 and 510) are used to carry two halves of a single voice message destined for a receiver, or two separate voice messages for a receiver. The single voice message is transmitted in half the time.

Abstract: A two-way messaging system (100) having a plurality of message subscriber units (500) and a base station (220) in each of a plurality of cells (210). The base station has a transmitter (224) for transmitting messages in an associated cell (210) and a receiver (228) associated therewith for receiving response signals from message subscriber units in a cell. A system controller (300) is coupled to each base station (220) and has a memory (320) for storing the customer paging area data for each message subscriber unit. The system controller (300) receives message requests and automatically updates the customer paging area data for each message subscriber unit (500) by tracking the mobility pattern of each message subscriber unit (500) in the messaging system coverage area (200).

Abstract: Error detection and correction of a received message, such as a digitized voice message is achieved by generating (318) interpolated vectors for each error vector corresponding to a codebook index in a sequence of codebook indexes representing parameters of portions of the message. A plurality of error corrected candidate vectors for the vector corresponding to the codebook index in error, are generated (322,324,326) by flipping one bit in a sequence of bits representing the codebook index in error. The error corrected candidate vector which has a minimal difference from its corresponding interpolated vector is used (338) to replace the error vector. In the case of digital voice, the vectors are spectral vectors which represent spectral information for a time sample of a voice message. An ordering property of vector components is exploited to detect errors in a received codebook index without parity bits.

Abstract: A method for determining whether a baud rate of a frequency modulated (FM) signal received by a receiver matches a predetermined baud rate. A parameter other than the baud rate is detected and used to confirm whether baud rate detection should be made, or whether if made, is reliable. The parameter is frequency deviation of the received FM signal, or other suitable parameters of the received FM signal.