Abstract: A digital signal processing apparatus for converting an analog signal to a digital signal and digitally processing the digital signal is disclosed. The apparatus includes a modulation part for performing pulse density modulation on the analog signal and outputting a pulse density modulation signal, a memory for storing a conversion program for converting the pulse density modulation signal to pulse code modulation data, and a CPU for receiving the pulse density modulation signal from the modulation part and converting the received pulse density modulation signal to pulse code modulation data according to the conversion program stored in the memory.

Abstract: In a device (10) for modulating Cartesian base band signals (I, Q) a first and second mapping unit (12, 14) each map signal samples of a corresponding Cartesian signal (I, Q) to intermediary signal sections having only two non-zero levels provided symmetrically around zero for forming two intermediary signals (S1, S2). A first and second processing unit (16, 18) each map each intermediary sections of an intermediary signal (S1, S2) to segments of a corresponding pulse train (S3, S4) through providing a positive pulse in one half of a segment if the corresponding signal section has a positive signal level and a positive pulse in another half of the segment if the corresponding signal section has a negative signal level. A delay unit (20) delays the pulses of one train in relation to the other and a combining unit (22) combines the trains for provision to a power amplifier (24).

Abstract: A model train and layout control system based on on-board sound and locomotive modules, new signaling methods, bi-directional communication, environmental sound, turnout control, train location methods, computer interaction and accessory control, by adding components to existing technology. AC power signal waveforms are variously altered to convey digital command words.

Abstract: In a communication apparatus which transmits parameters corresponding to a reception environment to a transmitting apparatus which switches the transmission rate based on the reception environment, reception quality calculated in the past is saved as a first reception quality, and past CPICH symbols used in calculating this first reception quality are saved. Channel compensation of the saved past CPICH symbols is performed using a current channel estimation value, and the channel-compensated CPICH symbols are used to calculate a second reception quality; the difference between this second reception quality and the first reception quality is used as a reception quality correction value to correct reception quality.

Abstract: A process is described to build physical layer frames with a modcode adapted to the signal quality of a destination terminal. Data packets assigned to the same modcode may be sent in the same frame, although packets associated with higher modcodes may be used to complete a frame before switching to the applicable higher modcode for construction of subsequent frames. After an interval, the order of progression is restarted with an out of order packet above a threshold age. Flow control filtering mechanisms and a variable reliability margin may be used to adapt dynamically to the current data traffic conditions.

Abstract: System and method are disclosed for synchronization of a transmitting device and a receiving device that communicate with each other via pulse modulation. The synchronization technique entails the transmitting device sending one or more quasi-periodic pulse sequences to the receiving device. A quasi-periodic pulse sequence is based on a substantially periodic pulse sequence, and may include some non-periodic pulses or not include some periodic pulses. The transmitting device may transmit frames each including a preamble that comprises one or more quasi-periodic pulse sequences, and a data payload that may comprise data. The receiving device receives the signal, generates samples of the signal, and detects the quasi-periodic pulse sequences in the received signal by analyzing samples based on a sample associated with a pulse and the period associated with the substantially periodic pulse sequence.

Abstract: A space-time coding method for a UWB transmission system comprising at least two radiated elements. The method codes a block of information symbols S=(a1, a2 . . . , ap,)) belonging to an M-PPM modulation or M-PPM-M?-PAM composite modulating alphabet with M being even, into a sequence of vectors (si,j, ?si,j), the components of a vector being intended to modulate a UWB pulse signal for a radiative element of said system and for a given transmission interval (Tƒ).

Abstract: A communications device includes a signal input for receiving signals such as a binary phase shift keyed (BPSK) communications signal having a repeated preamble bit or symbol pattern. A modem processes the communications signal and includes a demodulator and processor that generates an initial frequency offset estimate and phase error estimate by processing such as with a Fast Fourier Transform (FFT), that detects the repeated preamble pattern for a block of samples within the communications signal, correlates two halves of the block of samples with a plurality of different shifted sequences and determines a maximum correlation value for the shifted sequence that provides the maximum correlation value to establish a symbol timing estimate based on the known timing alignment of this shifted sequence. Radio circuitry is operative with the modem for processing communications data obtained from the communications signal.

Abstract: A communications device includes a signal input for receiving signals such as a binary phase shift keyed (BPSK) communications signal having a repeated preamble bit or symbol pattern. A modem processes the communications signal and includes a demodulator and processor that generates an initial frequency offset estimate and phase error estimate by processing a Fast Fourier Transform (FFT) that detects the repeated preamble pattern for a block of samples within the communications signal, correlates within a start of message correlator to search for a start of message sequence and correlates different phases of the repeated preamble pattern within training correlators for reducing false detections of the start of message. Radio circuitry is operative with the modem for processing communications data obtained from the communications signal.

Abstract: This invention relates to a space-time coding method for a UWB transmission system comprising two radiation elements. This method codes a block of information symbols (S=(a1,a2,a3,a4)) belonging to a PPM modulation constellation or a PPM-PAM composite modulation constellation with a number of time positions greater than or equal to 3, into a sequence of vectors (c10,c20,c11,c21), the components of a vector being intended to modulate a UWB pulse signal for a radiation element of said system and for a given transmission interval (Tf).

Abstract: A repeated preamble bit or symbol pattern such as for a binary phase shift keyed (BPSK) communications signal is received within a modem. An initial frequency offset and phase error estimate is generated by processing a Fast Fourier Transform (FFT) that detects the repeated preamble pattern for a block of samples within the communications signal. Two halves of the block of samples are correlated with a plurality of different BPSK shifted sequences to obtain a symbol timing alignment based on the shifted sequence providing the maximum correlation value. A frequency offset estimate is iteratively updated an N number of times using the shifted sequence providing the maximum correlation value to refine an acquisition estimate of the frequency offset and phase error of the received communications signal.

Abstract: A communication system comprising one or more transceiver units of a first type and one or more transceiver units of a second type capable of communicating with the transceiver units of the first type; each transceiver unit of the first type comprising: a frequency comparison unit for comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency; a feedback signal generator for generating a feedback signal dependent on the result of that comparison; and a transmitter for transmitting that signal to the transceiver unit of the second type; and each transceiver unit of the second type comprising: a local frequency reference unit on which the frequency of signals transmitted by it are dependent; and a frequency adjustment unit for receiving the feedback signal and adjusting the local frequency reference unit in dependence on the feedback signal.

Abstract: A method and apparatus is described for a time modulated signal. A cosine function is used as the basis for the signal with time intervals at the maximum and minimum values of the cosine function defining the encoded data. The received waveform is twice differentiated to provide a cosine function from which zero crossings are detected and the time intervals determined.

Abstract: Presently disclosed are a multichannel receiver and a method of operating it. The multichannel receiver includes a first channel circuit of N channel circuits. The first channel circuit includes a band pass (BP) filter and a gain control feedback circuit configured to adjust a signal provided by the BP filter with respect to a reference voltage.

Abstract: A power line communication method is provided, which divides the entire interval for transmitting power and data signals into a power transmission interval and a data transmission interval, and carries one or a plurality of data signals at the data transmission interval in the divided intervals.

Abstract: The present invention provides for a methods, system, and apparatus relating to data transmission. One method of the present invention includes representing data using at least one ultra wideband pulse, sending the at least one ultra wideband pulse over an electrically conductive guided media, and recovering the data from the at least one ultra wideband pulse. The present invention can be used in conjunction with telephony applications, cable TV applications, power line applications, fiber optic applications, and data bus applications.

Abstract: A method, system and type of database for transmitting data is disclosed in which the data is organized into a structured linear database. The structured linear database includes a routing header portion, a file allocation table, a data portion and a tailbit portion. The structured linear database may be transmitted over any type of network, such as a TM-UWB system or a fiber-optic system. Once the data to be transmitted is identified, a corresponding field is identified in the field allocation table giving the location of the data within the transmission. This field is then referenced by the user to access the specific type of data desired at the given location of the transmission. this process may be repeated enabling data to be stored on transmission lines and accessed at any point at any time providing an always on network.

Abstract: A method between terminals in a cooperative UWB pulse telecommunications system including a source terminal, a relay terminal, and a recipient terminal, the method including: transmitting, at the source terminal, a data symbol for the recipient terminal as a source signal constituted by a sequence of identical frames, the sequence corresponding to a symbol time, and each frame containing a pulse that is position-modulated by a PPM modulation alphabet; receiving, at the relay terminal, the source signal; detecting, at the relay terminal, a modulation position of a pulse in at least one frame of the source signal, referred to as the first position; transmitting, at the relay terminal, a relayed signal containing, in at least one predetermined subsequent frame of the symbol time, a pulse of which a position, referred to as a second position, is obtained from the first position by a permutation of the PPM modulation alphabet.

Abstract: This invention relates to a space-time coding process for a pulse type MIMO-UWB system using symbols belonging to a PPM modulation alphabet. Orthogonality of signals emitted by the different antennas is achieved by providing a mechanism for permutation of PPM symbol modulation positions and by imposing a constraint on the positions of said symbols. The space-time coding process according to the invention enables an incoherent type reception.

Abstract: The present invention presents a simple and novel channel estimation scheme for UWB communication systems. As disclosed herein, the present invention maximizes the extraction of information by incorporating a new generation of transmitted-reference (Tr) transceivers that utilize a single reference pulse(s) or a preamble of reference pulses to provide improved channel estimation while offering higher Bit Error Rate (BER) performance and data rates without diluting the transmitter power.

Abstract: A digital signal receiver including: a signal edge detector configured to receive a signal including a code and detect an edge of the signal; a reference point detector configured to detect a reference point for pulse width detection from a rising time point or falling time point of the edge detected by the signal edge detector; a pulse width detector configured to detect a pulse width from the rising time point or falling time point of the edge and the reference point; a sampling point determination module configured to generate a histogram of the pulse width and determines a sampling point of the code based on an analysis result of the histogram; and a sampling module configured to perform a sampling of the code based on the sampling point determined by the sampling point determination module.

Abstract: A method and transponder for wireless data transmission between a base station and a transponder is provided by means of inductive coupling, the transponder supports a first data transmission protocol type and/or a second data transmission protocol type. In the first data transmission protocol type, the data transmission is ended when a maximum value for the duration between successive field gaps is exceeded and in the second data transmission protocol type, after the initiation of the data transmission a reference duration is transmitted by the base station, by means of which the calibration value is determined in the transponder, whereby the calibration value is used for calibrating subsequently received durations. The reference duration is selected as greater than the maximum duration value.

Abstract: A communication system includes a modulating circuit to increase the amount of information to be transmitted, a transmitting apparatus capable of easily generating a desired waveform even for any very short wavelets, a receiving apparatus capable of easily separating wavelets even if the intervals thereof are narrow. The modulating circuit includes clock generating, transmission signal generating, control signal generating, delay and wavelet generating parts. The clock generating part generates a clock signal at predetermined time interval “Tp”. The transmission signal generating part generates a transmission signal at interval “Tp”. The control signal generating part outputs a control signal of a predetermined duration based on the clock signal. The delay part generates the control signal as a delay signal that has been delayed by a delay amount based on the transmission signal. The wavelet generating part generates a wavelet at the generation timing of the delay signal.

Abstract: An embodiment of a communication system can generate a composite signal that includes two or more different signals, where the signals represent different types of data. A data signal having one or more pulses that represent digital data of a first type is provided. A control signal that is a digital bit stream is provided. A composite signal is generated by multiplying a frequency of the data signal by a factor and modifying widths of pulses based on the bits of the control signal. The composite signal can be provided to a receiver device over a communication medium. The receiver device can determine the data signal and the control signal from the composite signal.

Abstract: A method of sending ultra-wide band signals via a plurality of sending antennas includes a phase for sending training sequences followed by a phase for sending data after which each antenna of the plurality of sending antennas sends a waveform using a Hermite pulse that is unique and orthogonal to the waveforms sent by the other antennas, and a device configured to perform the method.

Abstract: A novel data transmission method and apparatus is disclosed for communicating digital data using existing telephone wiring. According to the present invention, the digital data is represented by the time interval between two consecutive biphasic pulses. Biphasic pulses are used in the present invention because each biphasic pulse does not carry any dc component so DC component in the transmission line can be eliminated. In addition, additional data can be encoded in the amplitude or pulse width of each biphasic pulse so that higher data encoding ratio can be achieved.

Abstract: An identification method for a data Sk is disclosed which includes; a) construction of a chronological sequence {T1; . . . ; Ti; . . . ; TN} of times of arrival Ti of pulses or a block of successive pulses, b) calculation of a value of similarity between this sequence {T1; . . . ; Ti; . . . ; TN} and a predetermined chronological sequence {TREFk1; . . . ; TREFkj; . . . ; TREFkM} of times of arrival coding the data Sk for several time offsets Ol between the sequence {T1; . . . ; Ti; . . . ; TN} and the sequence {TREFk1; . . . ; TREFkj; . . . ; TREFkM}, c) identification of the data Sk in the series {T1; . . . ; Ti; . . . ; TN} if the calculated value of similarity for one of the time offsets Ol exceeds a predetermined threshold.

Abstract: A phase detector includes a plurality of phase detectors located in a phase correction loop, each phase detector configured to receive as input a radio frequency (RF) input signal and an RF reference signal, each of the plurality of phase detectors also configured to provide a signal representing a different phase offset based on the phase difference between the RE input signal and the RF reference signal; and a switch configured to receive an output of each of the plurality of phase detectors and configured to select the output representing the phase offset, that is closest to a phase of an output of an amplifier.

Abstract: A parallel channel timing recovery circuit. The parallel timing recovery circuit comprises multiple prefilters receiving parallel channel outputs and providing prefilter outputs. Multiple sampling filters receive the prefilter outputs and provide multiple discrete time signal samples. A self-timing circuit has multiple inputs receiving the multiple discrete time signal samples. The self-timing circuit provides a sampling control output to the sampling filters. The sampling control output is based on a composite of the multiple discrete time signal samples. Each of the sampling filters generates a discrete time signal sample based on the sampling control output and the prefilter outputs.

Abstract: The disclosed inventions relate to a method and apparatus for creating scramble signals. The disclosed inventions further relate to a method and apparatus for creating scramble signals from data signals. The disclosed inventions also relate to a method and apparatus for creating minimum-energy scramble signals. The disclosed inventions further relate to a method and apparatus for exploiting sleep and wake commands to achieve efficient data and scramble signals.

Abstract: A method is presented for determining an actual pulse position in a signal. This signal comprises a plurality of successive frames, wherein each frame has length L and contains one pulse with width W, a number of discrete possible pulse positions being considered within in each frame which is at least L/W. The method comprises the steps of a) sampling the signal at a sampling rate below L/W with a varying sampling phase such that the whole frame length L is covered, b) obtaining a set of samples with at least one at each of the possible pulse positions, c) correlating this set of samples with a set of one or more predetermined values and d) determining the actual pulse position from said correlation. The method provides a low-complex signal acquisition solution in a receiver and is particularly useful for low-complexity and low-power IR-UWB transceivers.

Abstract: Embodiments of the invention provide methods for optimizing the spectral efficiency of control channel transmissions carrying scheduling assignments from a serving Node B to user equipments. This is accomplished through the selection of the modulation and coding scheme with the highest spectral efficiency that can support transmission of a scheduling assignment to the corresponding user equipment with a reception performance satisfying a target error rate.

Abstract: A direct determination equalizer system (“DDES”) for compensating for the deterministic effects of a transmission channel and a data source is disclosed. The DDES may include an equalizer having equalizer-tap coefficients, a cross-correlator configured to receive the first sampled signal and an ideal signal and in response produce a cross-correlated signal, and a processor in signal communication with the equalizer and the cross-correlator. The equalizer is configured to receive a first sampled signal and in response produce an equalized output data signal sequence and the processor is configured to determine the equalizer-tap coefficients from the cross-correlated signal.

Abstract: A channel estimator and a related method for smoothing channel responses of a multi-carrier system. The channel estimator includes a channel response computing circuit for computing at least one of a target channel estimation and a reference channel estimation by utilizing a computing algorithm, wherein the target channel estimation and the reference channel estimation corresponds to a sub-carrier channel respectively.

Abstract: In one embodiment, a circuit is provided that includes: an impulse generator operable to provide a pulse train; a pulse position modulator having a splitting junction configured to receive the pulse train, the pulse position modulator including a plurality of n transmission lines, wherein n is an integer, the n transmission lines being selectably coupled in parallel between the splitting junction and a combining junction, the impulse generator driving each transmission line having a unique delay such that if the transmission line is selected, each pulse received at the splitting junction is uniquely delayed into a delayed pulse, whereby if all the transmission lines are selected, each pulse received at the splitting junction is uniquely delayed into a corresponding plurality of n delayed pulses; and a controller operable to select the transmission lines responsive to received words of n bits in length, each word arranged from a first bit to an nth bit, and wherein the transmission lines are arranged from a fi

Abstract: Systems and methods for the pulse edge modulation of digital carrier signals for communications systems which are useful in body implanted electronics. A digital carrier signal is generated and the carrier is pulse edge modulated with digital data. A pulse edge modulated signal is generated by either retarding or advancing each pulse edge of a carrier to be modulated relative to its original position in time, depending on the state of the digital bit to be modulated on that edge.

Abstract: Systems and methods for the demodulation of pulse edge modulated signals for communications systems which are useful in body implanted electronics. A pulse edge modulated signal is generated by retarding or advancing each pulse edge of a carrier to be modulated relative to its original position in time, depending on the state of the digital bit to be modulated on that edge. Each modulated edge of a pulse edge modulated signal is demodulated by determining the position in time of the modulated edge relative to the original respective position of the modulated edge prior to modulation.

Abstract: In one embodiment, a wafer scale radar antenna module (WSAM) is provided that includes: a substrate; a plurality of antennas adjacent the substrate; an RF feed network adjacent the substrate, the RF feed network coupling to a distributed plurality of amplifiers integrated with the substrate, wherein the RF feed network and the distributed plurality of amplifiers are configured to form a resonant network such that if a timing signal is injected into an input port of the RF feed network, the resonant network oscillates to provide a globally synchronized RF signal to a plurality of integrated antenna circuits, wherein each integrated antenna circuits includes a corresponding subset of antennas from the plurality of antennas, and wherein each integrated antenna circuit includes a pulse shaping circuit having a plurality of selectable delay paths, each pulse shaping circuit being configured to rectify and level shift a version of the globally synchronized signal through selected ones of the selectable delay paths

Abstract: A method and device for searching an algebraic codebook during encoding of a sound signal, wherein the algebraic codebook comprises a set of codevectors formed of a number of pulse positions and a number of pulses distributed over the pulse positions. In the algebraic codebook searching method and device, a reference signal for use in searching the algebraic codebook is calculated. In a first stage, a position of a first pulse is determined in relation with the reference signal and among the number of pulse positions. In each of a number of stages subsequent to the first stage, (a) an algebraic codebook gain is recomputed, (b) the reference signal is updated using the recomputed algebraic codebook gain and (c) a position of another pulse is determined in relation with the updated reference signal and among the number of pulse positions.

Abstract: In a transceiver that selectively transmits a modulated wave and a non-modulated wave to the outside, and receives a response signal from the outside, an S/N ratio during reception is improved. A transceiver, which selectively transmits a modulated wave and a non-modulated wave to the outside, and receives a response signal from the outside, includes an oscillator generating a predetermined carrier wave; a modulator modulating the carrier wave generated by the oscillator with a transmitted baseband signal to generate the modulated wave; a power amplifier amplifying the modulated wave being modulated by the modulator, or the non-modulated wave being not modulated by the modulator; and a circulator for sending output of the power amplifier to an antenna. When the non-modulated wave is transmitted from the antenna, switches are switched to a bypass circuit side such that the oscillator is directly connected to the power amplifier.

Abstract: This invention relates to a space-time coding method for a UWB transmission system including three or four radiative elements. It also relates to a method for transmitting a plurality of data symbols belonging to a PPM modulation constellation or a PPM-PAM composite modulation constellation using this space-time coding.

Abstract: A system and method for communicating information using Layer 1 from a powered device to power source equipment via Ethernet. In one embodiment, Layer 1 information such as power management, classification, temperature, and disconnect information is transmitted from a powered device to power source equipment using an AC signal that has a cycle defining a first time period during which the AC signal is turned on and a second time period during which the AC signal is turned off. A type of information being sent by the powered device can be determined based on characteristic on/off times of the AC signal cycle.

Abstract: In one embodiment, a circuit is provided that includes: an impulse generator operable to provide a pulse train; a pulse position modulator having a splitting junction configured to receive the pulse train, the pulse position modulator including a plurality of n transmission lines, wherein n is an integer, the n transmission lines being selectably coupled in parallel between the splitting junction and a combining junction, the impulse generator driving each transmission line having a unique delay such that if the transmission line is selected, each pulse received at the splitting junction is uniquely delayed into a delayed pulse, whereby if all the transmission lines are selected, each pulse received at the splitting junction is uniquely delayed into a corresponding plurality of n delayed pulses; and a controller operable to select the transmission lines responsive to received words of n bits in length, each word arranged from a first bit to an nth bit, and wherein the transmission lines are arranged from a fi

Abstract: A received pulse signal based on an on-off keying modulation scheme is alternately sampled by AD conversion sections operated by a clock signal whose frequency is one-half of a transmission rate. In the synchronization, amounts of delay in sampling timing adjustment sections are made different from each other, whereby phases of two different points in a symbol pulse are sampled. An amount of delay in a variable delay section is adjusted in accordance with a result of comparison of the sampled values, thereby achieving synchronization. At the time of demodulation, the amount of delay in the variable delay section is held, and the amounts of delay in the sampling timing adjustment sections are switched to the same value, and the symbol pulse is alternately sampled. The sampled values are subjected to threshold value determination, and the determination result is subjected to parallel-to-serial conversion, whereby a demodulation output is acquired.

Abstract: An ultra-wideband clear channel assessment system uses a double-window energy technique for energy detection, which indicates a clear or busy channel.

Abstract: A mobile channel estimation algorithm is disclosed, for use in a DVB-H coded OFDM demodulator. The mobile channel estimation algorithm estimates the mobile channel transfer function, overcoming many of the delay spread limitations without using time filtering and without having to collect many OFDM symbols. Once the channel estimate has been found for each symbol, equalization and inter-carrier-interference cancellation may be carried out relatively easily using known methods. The mobile channel estimation algorithm may be used in DVB-H as well as in other areas of OFDM.

Abstract: A time to digital converter having a hierarchical structure is provided. The time to digital converter includes: a plurality of delay stages for sequentially delaying a first signal for a specific delay time; a plurality of flip-flops for comparing delay signals of the first signal delayed by the delay stages with a second signal, and generating different outputs before and after a phase difference between the delay signals of the first signal and the second signal becomes smaller than a resolution of the phase detector; a selection signal generator for generating a selection signal for selecting a signal most similar to the second signal among the delay signals of the first signal from the outputs of the flip-flops; and a Multiplexer (MUX) for receiving the delay signals of the first signal and the selection signal, and outputting the signal most similar to the second signal among the delay signals of the first signal.

Abstract: A wireless communication system and a method for reducing a ranging time. The communication system includes a main synchronization block group which processes the transceived signal and determines whether the transceived signal is a signal desired by a transmitting device when a receiving device re-transmits the transceived signal to the transmitting device; a ranging block which measures a distance between the transmitting device and the receiving device using a ranging signal when the transceived signal is the desired signal of the transmitting device based on the determination of the main synchronization block group and when the transceived signal is the ranging signal; and a symbol synchronization block which detects a start point and an end point of a symbol forming the signal when the transceived signal from the receiving device is a data communication signal. Accordingly, the fast ranging is feasible and channel occupation time can be shortened.

Abstract: Systems and methods are described for transmitting and receiving spread spectrum signals using continuous waveforms. A method of transmitting a spread spectrum signal includes: generating a plurality of substantially continuous waveforms; summing the plurality of substantially continuous waveforms; modulating the summed plurality of substantially continuous waveforms to generate the spread spectrum signal; and transmitting the spread spectrum signal. A method of receiving a spread spectrum signal includes: generating a plurality of substantially continuous waveforms; summing the plurality of substantially continuous waveforms; modulating the summed plurality of substantially continuous waveforms with a code; mixing the modulated summed plurality of substantially continuous waveforms with the spread spectrum signal to produce a baseband signal; integrating the baseband signal; and detecting data.

Abstract: A transmitting controller is connected to a powerline and on command places a reference signal and a series of signal pulses in the powerline at a series of signal timing positions related to zero voltage crossing points so that the signals pulses are substantially in the powerline temporal quiet zone. The receiving controller is connected to the powerline and has a filter circuit therein which filters away the powerline AC signal and noise to leave the reference and signal pulses. The signal pulses are compared to the position of starting reference pulses to determine in which signal timing position the pulses have occurred. Digital data is communicated over the powerline in accordance with the nature placement of the data pulses related to the reference pulse positions. The timing zone for transmission and signals is preferably about 500 to about 1000 microseconds away from zero voltage crossing.