A multiple description coder generates a number of different descriptions of a given portion of a signal in a wireless communication system, using multiple description scalar quantization (MDSQ) or another type of multiple description coding. The different descriptions of the given portion of the signal are then arranged into packets such that at least a first description of the given portion is placed in a first packet and a second description is placed in a second packet. Each of the packets are then transmitted using a frequency hopping modulator, and the hopping rate of the modulator is selected or otherwise configured based at least in part on the number of descriptions generated for the different portions of the signal. For example, in an embodiment in which two descriptions are generated for each portion of the signal, a first description for a current one of the portions of the signal is placed in a current packet along with a second one of the descriptions for a previous portion of the signal, and the frequency hopping rate of the modulator is doubled relative to a hopping rate used for single description transmission.

Communication units are each provided with a wireless communication control section, a timing pattern generating section for generating a specified timing pattern, an informing device control section for controlling an informing device in accordance with an arbitrary timing and a timing pattern analyzing section for analyzing the transmitted timing pattern. The communication unit generates a specified timing pattern in the timing pattern generating section, controls its own informing device in accordance with the timing pattern by the informing device control section and transmits the timing pattern from the wireless communication control section to the communication unit. The communication unit analyzes the timing pattern transmitted from the communication unit and controls its own informing device according to the analyzed timing pattern. This allows a person to reliably find his or her own unit to be searched even when a plural number of persons search different devices in an identical place.

A receiving device in a multi-carrier CDMA communication system. In the receiving device, a time compensation means has a time tracker for each of signals received on multi-carriers and generates a time delay compensation signal by combining time errors of the carriers received from the time trackers. A first PN sequence generator generates a first PN sequence whose time delay is compensated for by the time delay compensation signal. A plurality of PN despreaders PN-despread the signals received on the multi-carriers by the first PN sequence. A frequency compensation means detects pilot signals corresponding to the PN-despread signals, generates frequency error signals for the carriers by the detected pilot signals, and compensates for frequency errors of the signals received on the multi-carriers. A phase compensation means compensates for phases for the carriers using the PN-despread signals and the pilot signals. A multiplexer multiplexes the phase-compensated signals.

Described is a method and apparatus for obtaining accurate, timely information for event detection and prediction based on autonomous opportunism. The objective is to make the best possible use of all available resources at the time of acquisition, including historical data, multiple sensors, and multiresolution acquisition capabilities, under a given set of processing and communication bandwidth constraints. This method (and the corresponding apparatus) fuses multiple adaptively acquired data sources to prepare information for use by decision support models. The onboard data acquisition schedule is constructed to maximize the prediction accuracy of the decision models, which are designed to operate progressively, utilizing data representations consisting of multiple abstraction levels and multiple resolutions. Due to the progressive nature of these models, they can be executed onboard even with the use of substantially summarized (or compressed) datasets delivered from the ground or from other satellite platforms. Models are formulated to accept data with less than complete certainty, thus allowing real-time decisions to be made on locations where additional data is to be acquired based on predicted likelihood of the event of interest and uncertainties. Multi-abstraction-level multi-resolution data is expressed using standard-compliant representations, and progressively transmitted to the ground or other platforms. More detailed calculations can then be performed on the ground using all of the available real time and historical data.

A radio transmission telemetry system includes several transmitters intermittently transmitting short messages indicative associated sensors status and a receiver for collecting data from the sensors. Each transmitter changes time and frequency of transmissions according to a time-frequency pattern that is different for each transmitter. The receiver identifies each source of transmissions based on its unique variations of the transmission time and frequency, thus eliminating the necessity to include the transmitter ID code in each transmitted message. Thus, overhead in the transmissions is reduced. In addition, the sensor status and other supervisory information such as battery status are partitioned and included in the transmitted messages in portions and at different rates according to the state of the PN-generator for producing the time-frequency pattern. The receiver can determine what and when is included without additional control bits in the transmitted messages. Thus, overhead in the transmissions is further reduced.