An automated meter reading server (15) having an open, distributed architecture that collects, loads, and manages system-wide data collected from energy meters (60) and routes the data automatically to upstream business systems. The automated meter reading server includes a repository (120) of metering data, and additionally provides timely access to information by including collection, storage, validation, estimation, editing, publishing and securing of meter consumption and interval data. The automated meter reading server obtains data from meters (60) equipped with modems via standard telephone lines or public RF networks. The data is converted from the format of the meter/communications infrastructure to a format usable by the automated meter reading server and the repository (120). The data is converted from the automated meter reading server compatible form to a format of a specific upstream business system prior to transmission.

Automated meter reading system

Coding techniques for a (e.g., OFDM) communication system capable of transmitting data on a number of “transmission channels” at different information bit rates based on the channels' achieved SNR. A base code is used in combination with common or variable puncturing to achieve different coding rates required by the transmission channels. The data (i.e., information bits) for a data transmission is encoded with the base code, and the coded bits for each channel (or group of channels with the similar transmission capabilities) are punctured to achieve the required coding rate. The coded bits may be interleaved (e.g., to combat fading and remove correlation between coded bits in each modulation symbol) prior to puncturing. The unpunctured coded bits are grouped into non-binary symbols and mapped to modulation symbols (e.g., using Gray mapping). The modulation symbol may be “pre-conditioned” and prior to transmission.

Coding scheme for a wireless communication system

Transmitter and receiver units for use in an OFDM communications system and configurable to support multiple types of services. The transmitter unit includes one or more encoders, a symbol mapping element, and a modulator. Each encoder receives and codes a respective channel data stream to generate a corresponding coded data stream. The symbol mapping element receives and maps data from the coded data streams to generate modulation symbol vectors, with each modulation symbol vector including a set of data values used to modulate a set of tones to generate an OFDM symbol. The modulator modulates the modulation symbol vectors to provide a modulated signal suitable for transmission. The data from each coded data stream is mapped to a respective set of one or more “circuits”. Each circuit can be defined to include a number of tones from a number of OFDM symbols, a number of tones from a single OFDM symbol, all tones from one or more OFDM symbols, or some other combination of tones. The circuits can have equal size or different sizes. Different circuits can be used for full rate data (e.g., active speech) and low rate data (e.g., silence periods).

Multiplexing of real time services and non-real time services for ofdm systems

A receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital autocorrelators. The sampling circuit provides digital samples of a received composite signal to each of the several receiver channel circuits. The synchronizing circuits are preferably non-coherent, in the sense that they track any phase shifts in the received signal and adjust the frequency and phase of a locally generated carrier reference signal accordingly, even in the presence of Doppler or ionospheric distortion. The autocorrelators in each channel form a delay lock loop (DLL) which correlates the digital samples of the composite signal with locally generated PRN code values to produce a plurality of (early, late), or (punctual, early-minus-late) correlation signals. Thus, during an initial acquisition mode, the delay spacing is relatively wide, on the order of approximately one PRN code chip time. However, once PRN code synchronism has been achieved, the code delay spacing is narrowed, to a fraction of a PRN code chip time. There are several advantages to this arrangement, especially in environments wherein multipath distortion in the received composite signal is of the same order of magnitude as a PRN code chip time.

Pseudorandom noise ranging receiver which compensates for multipath distortion by dynamically adjusting the time delay spacing between early and late correlators

An electronic meter incorporates a TCP/IP protocol suite and an HTTP server to provide two-way access to the meter data. Alternatively, the TCP/IP protocol suite may be incorporated into a gateway serving multiple meters connected through a power line or wireless two-way network. The gateway may incorporate an HTTP server for accessing data from multiple meters and for transmission of data to individual meters. Other aspects of the disclosed system include the use of a common gateway interface for remote access to meter data and to set meter parameters using HTML forms in HTTP browsers; remote reading and setting of multiple meter parameters using a TCP/IP protocol suite; a TCP/IP protocol suite implemented in designated nodes in a CEBus LAN with remote access through TCP/IP to routers and brouters and to individual meters on the LAN; and an SLIP-PPP enabled gateway for remote TCP/IP access through a serial interface to a single or multiple meter parameters.

Remote access to electronic meters using a tcp/ip protocol suite

A digital communication system (20) communicates using a polar amplitude phase shift keyed (P-APSK) phase point constellation (70, 70'). Pragmatic encoding and puncturing is accommodated. The pragmatic encoding uses the P-APSK constellation (70, 70') to simultaneously communicate both encoded and uncoded information bits. The P-APSK constellation (70, 70') has an even number of phase point rings (74, 76) and equal numbers of phase points (72) in pairs of the rings (74, 76). Encoded bits specify secondary modulation and uncoded bits specify primary modulation. The constellation (70, 70') is configured so that secondary modulation sub-constellations (78) include four phase points (72) arranged so that two of the four phase points (72) exhibit two phase angles at one magnitude and the other two of the four phase points exhibit phase angles that are at another magnitude. The difference between the phase angles at different magnitudes within a secondary sub-constellation (78) is constant.

Data communication system and method therefor

A digital communication system (20) communicates using a polar amplitude phase shift keyed (P-APSK) phase point constellation (70, 70', 70"). Pragmatic encoding is accommodated using the constellation (70, 70', 70") to simultaneously communicate both encoded and uncoded information bits (69, 51). The constellation (70, 70', 70") has an even number of phase point rings (74) and equal numbers of phase points (72) in ring pairs (75, 76, 77). Encoded information bits (69) specify secondary modulation and uncoded information bits (51) specify primary modulation. The constellation (70, 70', 70") is configured so secondary sub-constellations (78) include four phase points (72) arranged so that two of the four phase points (72) exhibit two phase angles at one magnitude and the other two of the four phase points (72) exhibit phase angles that are at another magnitude. The difference between the phase angles at different magnitudes within a secondary sub-constellation (78) is constant.

Pragmatic trellis-coded modulation system and method therefor

In despreading a received spread spectrum signal, spread by means of a linear feedback shift register, the signal is demodulated and filtered and then applied to a predictor for estimating the length, connection polynominal and contents in accordance with the Berlekamp-Massey iterative algorithm. The estimates are then applied to a local LFSR to produce a despreading random signal which is mixed with the received signal to remove the spreading factor. The instantaneous total energy of the output signal is measured and when the estimations are correct, the total energy will exceed a predetermined limit and a signal is supplied to the predictor to indicate that the estimates are correct.

Apparatus for despreading a spread spectrum signal produced by a linear feedback shift register (LFSR)

A communication system (10) includes a transmitter (20) having programmable signals (46, 58, 60, 80) which can be used to adjust transmitter-caused quadrature-phase signal imbalances. A receiver (18) of the system (10) is remotely located from the transmitter (20) and generates a signal quality statistic (102, 112) that is monitored in a slow-tracking feedback loop to formulate commands which indicate how to program the programmable signals (46, 58, 60, 80). This receiver (18) performs its signal quality statistic monitoring while a data stream (36) is being extracted from a received communication signal.

Communication system with end-to-end quadrature balance control

Symbols (18) of a burst (12) are sub-divided into symbol sections (20). Each symbol section (20) is sampled and converted into polar coordinates. A buffer bank (38) selectably delays the samples and replays a preamble (14). A demod bank (40) includes a coherent demod (58) and several differential demods (60). Each differential demod (60) processes its own stream of symbol sections (20). The differential demods (60) feed a preamble detector (66) and a symbol synchronization circuit (62). The symbol synchronization circuit (62) identifies the symbol section (20) which yields the smallest magnitude of frequency errors. This symbol section (20) is processed by the coherent demod (58) to acquire carrier phase and recover data. The coherent demod (58) is implemented in the phase domain so that only oscillation signal phase data need be generated in phase locked loops. Two phase locked loops (110, 112) operate in parallel but with initial reference phase offsets so that at least one of the two loops will not experience hang-up.

Bruce A. Cochran

Papers

Data communication system and method therefor

Pragmatic trellis-coded modulation system and method therefor

Apparatus for despreading a spread spectrum signal produced by a linear feedback shift register (LFSR)

Communication system with end-to-end quadrature balance control

Differential/coherent digital demodulator operating at multiple symbol points