A system and method for communicating information signals using spread spectrum communication techniques. PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance. With orthogonal PN codes, the cross-correlation is zero over a predetermined time interval, resulting in no interference between the orthogonal codes, provided only that the code time frames are time aligned with each other. In an exemplary embodiment, signals are communicated between a cell-site and mobile units using direct sequence spread spectrum communication signals. In the cell-to-mobile link, pilot, sync, paging and voice channels are defined. Information communicated on the cell-to-mobile link channels are, in general, encoded, interleaved, bi-phase shift key (BPSK) modulated with orthogonal covering of each BPSK symbol along with quadrature phase shift key (QPSK) spreading of the covered symbols. In the mobile-to-cell link, access and voice channels are defined. Information communicated on the mobile-to-cell link channels are, in general, encoded, interleaved, orthogonal signaling along with QPSK spreading.

System and method for generating signal waveforms in a CDMA cellular telephone system

A code division multiple access (CDMA) spread spectrum cellular communications system with both surface and satellite nodes and using forward error correction coding, to enhance effective gain and selectivity, is provided. The system network control center (12) directs the top level allocation of calls to regional resources in the system. The regional node control centers (14) are connected to the system network control center (12) and direct the allocation of calls to ground nodes. The ground nodes (16) under the control of one of the regional node control centers (14) receive calls over land lines, spread them, modulate them, and transmit them. Satellite node control centers (18) are also connected to the network control center (12), and uplink the spread, multiplexed calls to the designated satellite (20). User units (22) respond to signals of either satellite or ground node origin. A digital data interleaving feature reduces fading. User position is determined. An adaptative transmitter power control (188) compensates for signal strength variations. An intercell bus (90) in a satellitte node (20) connects together multiple cells.

Integrated cellular communications system

A technique for spread-spectrum communication which uses more than one mode and more than one frequency band. Selectable modes include narrowband mode and spread-spectrum mode, or cellular mode and microcellular mode. Selectable frequency bands include both licensed and unlicensed frequency bands, particularly frequency bands including the 902-928 MHz, 1850-1990 MHz, and 2.4-2.4835 GHz frequency bands. Spread-spectrum communication channels are 10 MHz or less in width. The frequency band onto which spread-spectrum signals are encoded may be changed upon a change in environment or other control trigger, such as establishment or de-establishment of communication with a private access network. A multi-band transmitter comprises a single frequency synthesizer and a frequency source (e.g., a local oscillator), coupled to a selectable band pass filter. A multi-band receiver capable of monitoring one or more frequency bands comprises bank of bandpass filters and a demodulator comprising a single frequency synthesizer and a frequency source.

Multi-band, multi-mode spread-spectrum communication system

Systems that monitor and control energy distribution manage energy distribution or use for Energy Service Providers and end-users. A system includes a publicly or privately accessible distributed network, a network access device, and a management device. The network access device communicates with the management device through the distributed network to control loads at a remote location. The method of monitoring and controlling energy distribution receives data at an on-line Site, processes an application program that evaluates load and market supply data, and initiates power curtailment requests or power curtailment events.

System and method for monitoring and controlling energy distribution

There is described an indicia reading terminal that can be operative to capture a succession of frames of image data and that can be operative so that a certain frame of the succession of frames is subject to quality evaluation processing where a result of the quality evaluation processing is responsive to one or more of an incidence and sharpness of edge representations of the frame of image data.

Indicia reading terminal including frame quality evaluation processing

A bidirectional data communications distribution network is established between the system operations center (SOC) and customer terminals of a load management and electrical energy distribution system. The distribution network comprises independent processor controlled, primary communications interface units (PCI) in communication with the SOC over telephone lines or other medium. Each PCI is in turn in communication with a plurality of independent processor controlled, secondary communications interface units (SCI) over electrical utility primary distribution power lines. Signals between PCIs and SCIs on the primary distribution power lines are code division multiplexed using direct sequence spread spectrum (DSSS) signal processing. Each SCI continuously polls a number of assigned customer load terminals on the low voltage side of the electrical energy distribution system, storing and calculating meter register readings and load status.

Distribution energy management system

A plurality of transmitters synchronized to a common clock each transmit a data signal spread by a common bipolar pseudo-random code having a different assigned code sequence shift. A receiver, synchronized to the clock, discriminates the signal transmitted by a predetermined transmitter from signals transmitted by the others by generating a first bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has a code sequence shift corresponding to that of the predetermined transmitter, and a second bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has an unassigned code sequence shift. The difference between the first and second bipolar pseudo-random code sequences, which is a trinary code sequence, is cross-correlated with the incoming signals. The cross-correlation despreads only the signal spread by the sequence having the predetermined code sequence shift. Each receiver includes a number of correlation detectors offset from each other by a fraction of a code chip together with decision circuitry to identify cross-correlation peaks for optimum synchronization. Analog and digital implementations of the correlation detectors are disclosed.

Correlation detectors for use in direct sequence spread spectrum signal receiver

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Distribution energy management system

Correlation detectors for use in direct sequence spread spectrum signal receiver