Abstract: A startup protocol is provided for use in a communications system having a communications line with a master transceiver at a first end and a slave transceiver at a second end, each transceiver having a noise reduction system, a timing recovery system and at least one equalizer all converging at startup of the system. The operation of the startup protocol is partitioned into stages. The first stage includes the step of converging the equalizer and the timing recovery system of the slave while converging the noise reduction system of the master. Upon completion of the first stage the protocol enters a second stage which includes the step of converging the equalizer and the timing recovery system of the master, converging the noise reduction system of the slave, freezing the timing recovery system of the slave, and resetting the noise reduction system of the master.

Abstract: A system for processing a data packet is disclosed and may include at least one processor that enables receiving of a data packet at a station on a network, the data packet having a preamble which includes a destination tag and a training sequence. The at least one processor may enable obtaining a channel model using the training sequence, and encoding each of one or more addresses that the station receives with the channel model to produce a result. The at least one processor may also enable comparing the result with the destination tag. The at least one processor may enable convolving of each of the one or more addresses that the station receives with the channel model to produce the result.

Abstract: A method and apparatus for equalizing digital data signals is disclosed. The method comprises the steps of demodulating and decoding an input signal having input data to produce a data output, remodulating the data output to produce a pseudo-training sequence including an idealized input signal, and generating equalizer parameters from the pseudo-training sequence. The apparatus comprises a demodulator for demodulating an input signal to produce a data output, a modulator, communicatively coupled to the demodulator, for remodulating the data output to produce a pseudo-training sequence including an idealized input signal, and a parameter generation module, communicatively coupled to the modulator for generating equalizer parameters from the pseudo-training sequence.

Abstract: Multicarrier receivers and methods for carrier frequency offset correction and channel estimation for receipt of simultaneous transmissions over a multi-user uplink are generally described herein. Other embodiments may be described and claimed.

Abstract: A method for demodulating a received digitally modulated signal subjected to multipath propagation impairment includes estimating the multipath propagation impairment of the received digitally modulated signal using a channel estimator, and estimating at least one symbol of the received digitally modulated signal using a symbol estimator. The at least one estimated symbol is adjusted based upon the estimated multipath propagation impairment to generate an estimate of the at least one symbol as impaired by the multipath propagation. At least one error signal is generated by comparing the estimate of the at least one symbol as impaired by the multipath propagation to the received digitally modulated signal. The at least one error signal is used for estimating remaining symbols to be demodulated and for refining the estimated multipath propagation impairment.

Abstract: Baseband (BB) input units input baseband received signals. An initial weight data setting unit sets weighting coefficients to be utilized in the interval of a training signal as initial weighting coefficients. A gap compensating unit compensates control weighting coefficients with a gap error signal and outputs the updated weighting coefficients acquired as a result of the compensation. A weight switching unit selects the initial weighting coefficients in the interval of the training signal and selects the updated weighting coefficients in the interval of the data signal. Then the weight switching unit outputs the selected initial weighting coefficients and updated weighting coefficients as the weighting coefficients. A synthesizing unit weights the baseband received signals with the weighting coefficients and then sums them up.

Abstract: Embodiments of the invention comprise a continuous-time equalizer for reducing ISI in data received from a communication channel, and methods and circuitry for tuning or calibrating that equalizer. Selected coefficients for a transfer function of the equalizer circuit are fixed, while other coefficients are tuned by an adaptive algorithm. The adaptive algorithm minimizes errors associated with the tunable coefficients based on one or more training signals sent by the transmitter and received by the equalizer circuit at the receiver. The training signals allow for a variety of error terms to be calculated, from which the tunable coefficients are updated so as to iteratively minimize the error terms and simultaneously tune the equalizer to more accurately compensate for the degrading effects of the channel.

Abstract: A method to reduce peak power consumption during adaptation for an IC with multiple serial link transceivers including the steps of (A) inactivating equalizer adaptation loops until a triggering event occurs, (B) when the triggering event occurs, determining whether the triggering event is a minor change or a major change, (C) when the triggering event is a minor change, spreading out activation of adaptation loops in time, and (D) when the triggering event is a major change, simultaneously activating all adaptation loops.

Abstract: A decision feedback equalizer (DFE) has an inter symbol interference (ISI) loop and inter chip interference (ICI) loop. A buffer at the input of the DFE loop receives a (CCK based data rate) signal coming into the DFE, retains a predetermined number of chips from each incoming symbol and assists to meet timing requirements by chip management. An outgoing rate for the chips from the buffer may depend on the incoming rate and may be higher than the incoming rate by a known factor. A method of designing a configuration for the DFE takes into consideration the timing delay in the loops. The operation within the DFE loop is pipelined, and any latency due to the pipelining is handled at a CCK demodulator. A method for designing the DFE architecture and an article comprising a storage medium with instructions thereon for executing the method, are also disclosed.

Abstract: A circuit and method is provided for reducing the effect of having potentially different sizes for an Inverse Discrete Fourier Transform (IDFT) at a transmitter and a Discrete Fourier Transform (DFT) at a receiver in a telecommunications system without requiring a change in the DFT's size. The method includes following steps. The first step includes determining whether the IDFT size is greater than, equal to, or less than the DFT size. The second step includes selecting a target impulse response length from a predefined set of impulse response lengths in accordance with a result the previous step. The third step includes training an equalizer at the receiver to the target impulse response length. The circuit comprises hardware and software for implementing the method.

Abstract: A method for designing a decision feedback equalizer (DFE) that handles packet based input data signals uses an inter symbol interference (ISI) removal loop and an inter chip interference (ICI) removal loop which is nested inside the ISI loop, for maximum interference removal and limited error propagation. The DFE may use a feed forward filter and a series connected chip-flow control buffer for receiving the input data signals. The DFE of the invention has application in 802.11 b PHY and 802.11 g PHY scenarios and any application involving a DFE with the need for minimum error propagation. Taught herein is a combined weighted DFE with erasure provision and interference removal in an optional two step mechanism. An article comprising a computer storage medium to execute the DFE design method is also disclosed.

Abstract: A method of initializing an equalizer of VSB DTV receiver and an equalizer using the same are provided. The method includes the steps of: obtaining a channel estimation value by estimating an impulse response of a channel from a received signal, initializing a backward filter by using the channel estimation value; generating an imaginary training signal by an arithmetical operation for the channel estimation value and a generated known training sequence; and initializing a forward filter by using the imaginary training signal.

Abstract: An offset calibration method is provided. Two input terminals of an equalizer are switched to a common voltage at a first time point, wherein the equalizer generates a first equalized signal and a second equalized signal according to the common voltage. It is determined whether a first offset voltage is present in the equalizer according to the first and second equalized signals generated from the common voltage. If the first offset voltage is determined to be present in the equalizer, a first compensation voltage is provided to the equalizer.

Abstract: A testing apparatus for testing a device under test is provided, wherein the testing apparatus includes: a comparator for receiving a signal output from the device under test and converting the signal into a logic signal by comparing the signal with a first reference voltage; a driver for amplifying a logic signal to be output to the device under test on the basis of a second reference voltage and outputting to the device under test; a comparator setting unit for determining the first reference voltage so as to compensate for a delay amount of a reception signal received from the device under test and setting the comparator to be the first reference voltage; and a driver setting unit for determining the second reference voltage on the basis of the reference voltage of the comparator and setting the driver to be the second reference voltage.

Abstract: The present invention provides a equalizer processing module operable to cancel interference associated with received radio frequency (RF) burst(s). This equalizer processing module includes a first equalizer processing branch and an optional second equalizer processing branch. The first equalizer processing branch is operable to be trained by applying a recursive DMI process such as a Levison algorithm, based upon known training sequences and equalize the received RF burst. This results in soft samples or decisions which in turn may be converted to data bits. The soft samples are processed with a de-interleaver and channel decoder, where the combination is operable to produce a decoded frame of data bits from the soft samples. This allows interfering signals to be cancelled and more accurate processing of the received RF bursts to occur.

Abstract: The present invention provides a multi-branch equalizer processing module operable to cancel interference associated with received radio frequency (RF) burst(s). This multi-branch equalizer processing module includes both a first equalizer processing branch and a second equalizer processing branch. The first equalizer processing branch is operable to be trained based upon known training sequences and equalize the received RF burst. This results in soft samples or decisions which in turn may be converted to data bits. The soft samples are processed with a de-interleaver and channel decoder, where the combination is operable to produce a decoded frame of data bits from the soft samples. A re-encoder may re-encode the decoded frame to produce re-encoded or at least partially re-encoded data bits. An interleaver then processes the at least partially re-encoded data bits to produce and at least partially re-encoded burst.

Abstract: An equalizer comprises a sampler, a filter, and a summer. The sampler samples a signal indicative of an input communication signal to determine digital decision output signals having a communication device data rate. The filter receives digital decision output signals from the sampler and generates equalization signals therefrom. The summer couples to the sampler and the filter and combines together the input communication signal with the equalization signals. Further, a plurality of clocks control timing associated with the sampler. These clocks have frequencies that are less than the predetermined data rate of the digital decision output signals.

Abstract: A method and appartus for converting FFE and FBE coefficients from a DOCSIS compatible cable modem termination system upstream equalizer into FFE only coefficients to be sent down to the cable modem which transmitted the training burst which resulted in convergence on the FFE and FBE coefficients. The method involves programming an FBE like conversion structure comprised of an FFE filter and an FBE filter whose outputs are summed with the FFE and FBE coefficients from the CMTS equalizer. The FFE coefficients are stored in the FFE filter of the conversion structure. The FBE coefficients are stored in an FBE filter of the conversion structure. Then, an input vector which simulates the Dirac function (an impulse) is input to the conversion structure to derive coefficients at its output which define the impulse response and transfer function of the conversion structure. These coefficients are the FFE only coefficients which may be used to select a subset of 24 for sending to the cable modem.

Abstract: A network interface is presented that receives packet data from a shared medium and accomplishes the signal processing required to convert the data packet to host computer formatted data separately from receiving the data packet. The network interface receives the data packet, converts the analog signal to a digitized signal, and stores the resulting sample packet in a storage queue. An off-line processor, which may be the host computer itself, performs the signal processing required to interpret the sample packet. In transmission, the off-line process converts host-formatted data to a digitized version of a transmission data packet and stores that in a transmission queue. A transmitter converts the transmission data packet format and transmits the data to the shared medium.

Abstract: Some embodiments store a training sequence in a communications system. The stored training sequence exhibits certain desirable characteristics when used by a peak to average power constrained modulation format. In one embodiment, a set of original ordered sequences is selected to have at least one desired property. A set of extended sequences is created from the original sequences by beginning with an element of an original sequence and cyclically appending elements of the original sequence in order to obtain a desired extended sequence length. Each extended sequence is modified using a corresponding modifying sequence, such that a training sequence can be generated from any one of the modified extended sequences. Each modifying sequence is selected so that the generated training sequence when modulated by a selected modulation format has the at least one desired property of the corresponding original ordered sequence.

Abstract: A system and method are provided for transmitting a rotating training sequence. A rotating training signal is generated in quadrature modulation transmitter. The rotating training signal includes training information sent via an in-phase (I) modulation path, as well as training information sent via a quadrature (Q) modulation path. The rotating training signal may be generated by initially sending training information via the I modulation path, and subsequently sending training information via the Q modulation path. The training information sent via the I modulation path may include a first symbol having a reference phase (e.g., 0 degrees or 180 degrees). Then, the training information sent via the Q modulation path would include a second symbol having a phase that is ±90 from the reference phase.

Abstract: The present invention relates to wireless communications and is particularly applicable to devices and modules for correcting errors introduced to a wireless signal after its transmission. An equalizer is provided which compensates for undesirable effects on received radio signals introduced by either signal processing or by the transmission medium. In operation, the equalizer multiples the complex received signal with a complex corrective signal that compensates for these effects. A tap corrective signal corrects for time-varying channel effects (i.e. channel distortions), a timing tracking signal corrects for carrier frequency offset errors, and a phase tracking signal corrects for sampling frequency offset errors.

Abstract: A system and method are provided for supplying a frequency-smoothed communications training signal. The method generates a frequency-smoothed unbiased training signal in a quadrature modulation transmitter. The frequency-smoothed unbiased training signal includes a plurality of pilot signal products, where each pilot signal product includes complex plane information represented by a reference frequency subcarrier, multiplying complex plane information represented by mirror frequency subcarrier. The sum of the plurality of pilot signal products is equal to zero. The method supplies the frequency-smoothed unbiased training signal so that it may be transmitted within a single symbol period. System and methods are also provided for using a frequency-smoothed training signal in the calculation of a receiver channel estimate.

Abstract: A multi-tap delay has a graphical user interface in which each delay tap is represented by a bar on a time line. The bars are oriented across the time line, the position of each bar on the time line specifying the amount of delay time of the represented delay tap. The length of each bar specifies the value of another parameter of the represented delay tap.

Abstract: An interference rejection algorithm for a radio receiver is presented. According to the present solution a signal comprising a training sequence and a data sequence is received at the radio receiver. A radio channel response may be estimated from the received training sequence, and interference parameters may be estimated from at least one of the received training sequence and the received data sequence, the estimation of the interference parameters comprising smoothing a frequency spectrum of at least one of the estimated channel response and the estimated interference parameters through averaging. Then, frequency domain interference suppression weights are calculated from the estimated channel response and the interference parameters, and weighting of the received data sequence is carried out with the calculated weights.

Abstract: An adaptive signal equalizer with a feedforward filter in which the feedback error signal and corresponding incoming data signal are dynamically aligned in time using signal interpolation, and further, to control the precursor/postcursor filter taps configuration, thereby producing more adaptive filter tap coefficient signals for significantly improved and robust signal equalization.

Abstract: A continuous time electronic dispersion compensation architecture using feed forward equalization and a non-linear decision feedback equalization forms an output signal by a linear combination of successively delayed versions of the input signal and the sliced output signal weighted by appropriate coefficients. A selected number of taps in the mixer used to generate a corresponding number of coefficients for use in the feed forward equalizer are held to a selected voltage to ensure that the coefficients associated with these two taps do not drift. This causes the other coefficients to converge to a unique minimum square error value. In one embodiment the selected voltage is the maximum system voltage.

Abstract: A method, circuit and system for altering the power consumption in communication links. A type of noise and an amount of jitter in a signal transmitted across a communication link is measured. Upon determining the contribution of the measured noise to the measured jitter in the signal, the measured noise is classified based on such contribution and the intensity of the measured jitter. The power consumption in a component(s) of the communication link may be adjusted based on the classification of the measured noise. For example, if the measured noise is classified as being a low amount of noise, then the power consumption of the component(s) may be reduced such as by lowering the voltage of the power supply and/or reducing the complexity of the circuitry. By reducing the power consumption when the communication link is not subject to the worst-case condition, a savings in power consumption may be made.

Abstract: An equalizer and an equalization method usable in a high definition television (HDTV) are provided. The equalizer may receive an input signal including a data signal and a training sequence and may compensate for distortion of the input signal in a high definition television. The equalizer may include an input signal reuse unit, a filter unit, and an error calculation unit. The error calculation unit may receive an equalizer output signal, may estimate the equalizer output signal at an estimate value, may generate the estimate value as a decision value, and may output a difference between the equalizer output signal and the decision value as the error signal.

Abstract: An equalizer is provided which is capable of making a filter factor to be set in the equalizer having an equalizing filter converge rapidly and a method is provided for setting an initial value for the rapid convergence of the filter factor. In the equalizer having a filter factor computing device to compute a filter factor for an equalizing filter, and a differential detecting circuit to generate a differential signal between a signal output from the equalizing filter and a common pilot diffusing code, an initial value for the filter factor computing device is generated and set by a multipath timing detecting circuit, a reverse diffusing section, and a channel estimating device being operated based on a received signal.

Abstract: A system for detecting transmission errors in a data transmission system includes a receiver for receiving a data packet transmitted thereto by a corresponding transmitter and transmitting the data packet to a destination device and an error detection device for receiving a plurality of protocol signals that control the operation of the transmitter and the receiver. The error detection device applies at least one predetermined rule to the protocol signals, wherein a violation of the at least one rule by the protocol signals indicates that an error in the transmission of the packet has occurred, and asserts an error signal when the at least one rule has been violated by the protocol signals. The system further includes a packet filtering device coupled to receive the error signal from the error detection device and the data packet from the receiver, wherein, upon receiving the asserted error signal, the packet filtering device terminates the transmission of the data packet to the destination device.

Abstract: System and method for canceling crosstalk in high-speed communications systems. An embodiment comprises precomputing channel pulse responses for a set of communications channels in a communications backplane, precomputing channel signal responses for the set of communications channels in the backplane with a training sequence, estimating noise coefficients using receiver training and the training sequence, storing noise coefficients for each communications channel in the set of communications channels, and canceling noise in a received transmission of a data sequence using the stored noise coefficients. The regularity of the communications backplane enables the precomputing of various values, which reduces computational requirements. Furthermore, it is often the case that a victim receiver has access to the digital data that is being transmitted by its dominant crosstalking transmitters, thereby simplifying noise cancellation.

Abstract: A training premable in multipoint-to-point communication using orthogonal frequency division multiplexing (OFDM) is provided. In one embodiment, a system comprises a host unit and a plurality of remote units using a multiple access scheme to communicate at the same time with the host unit using OFDM. The host unit sends an adjustment signal to at least one of the remote units instructing the at least one remote unit to adjust the timing of transmissions from the remote unit to improve orthogonality of an OFDM waveform received at the host unit. The host unit allocates orthogonal tones within the OFDM waveform to the plurality of remote units. At least one remote unit transmits a training sequence in at least one upstream OFDM signal to the host unit and the host unit uses the training sequence to assist in demodulating the upstream OFDM signal of the at least one remote unit.

Abstract: A decision feedback equalizer with dynamic feedback control for use in an adaptive signal equalizer. Timing within the decision feedback loop is dynamically controlled to optimize recovery of the data signal by the output signal slicer. The dynamic timing is controlled by a signal formed as a combination of feedback and feedforward signals. The feedback signal is an error signal related to a difference between pre-slicer and post-slicer signals. The feedforward signal is formed by differentiating and delaying the incoming data signal.

Abstract: Processing a received signal is disclosed. It is determined that a received signal does not satisfy a prescribed signal quality criterion. Based at least in part on the determination, an equalizer tap is not updated based on the received signal.

Abstract: A wireless communication system (100), method, and base station (112) are provided for optimizing performance of a base station receiver (120). The method includes selecting an interpolation matrix (216) specially tailored for particular channel characteristics from a pre-defined set of interpolation matrices (218), and using the selected interpolation matrix in the channel estimation, and applying the derived channel estimates for the data subcarriers to an equalizer (118) as a set of weights. The interpolation matrix (216) is selected by using the matrix corresponding to a received channel profile information, or by monitoring a performance metric (212) while using each interpolation matrix of a pre-defined set of matrices in the channel estimation and applying the derived channel estimates for the data subcarriers as a set of weights to the receiver equalizer (118) and selecting the matrix resulting in best performance.

Abstract: An initialization method for a network system is disclosed, which uses a channel estimation to predetermine coefficients of an FFE and an FBE. As such, convergence of the FFE, the FBE, a timing recovery, an echo canceller and a NEXT canceller is speeded up. Also, interaction of the cited devices and a divergence caused by the interaction are avoided. Therefore, system performance and stability are increased.

Abstract: In a method for performing equalization of a communication system, a predetermined signal can be transmitted from a transmitter unit to a receiver unit in a downchannel direction on a transmission line, for example as a pair of differential signals which simultaneously transition in opposite directions on respective signal conductors of the transmission line. At the receiver unit, an eye opening of the signal received from the transmission line can be analyzed to determine equalization information. Equalization information can be transmitted from the receiver unit to the transmitter unit in an upchannel direction on the transmission line and be received at the transmitter unit. Using received equalization information, a transmission characteristic of the transmitter unit can be adjusted.

Abstract: Training sequence interference in an equalizer-based receiver in a time-division duplex (TDD) communication system can be avoided without using interference cancellation, by providing to the equalizer both the desired data portion of the received signal, and a portion of the training sequence that is adjacent the desired data portion and has a length commensurate with the delay spread associated with the training sequence interference. The portion of the equalizer output that corresponds to the adjacent training sequence portion can be discarded while retaining the desired equalized data.

Abstract: A channel memory length selection method for wireless communication systems is provided. The method comprises estimating an initial channel impulse response (CIR) for the wireless communication system; determining a first refined CIR with a first group of taps and a second refined CIR with a second group of taps based upon the initial CIR, number of the second group of taps being less than number of the first group of taps; and selecting either the number of the first group of taps or the number of the second group of taps as the channel memory length according to an energy concentration criterion in regard to the first refined CIR and the second refined CIR.

Abstract: A method and apparatus to compensate for spectral attenuation are described wherein the spectral attenuation for a communications channel is determined, a first filter is created for the attenuation and the first filter compensates for the attenuation. The spectral attenuation for the communications channel is determined by a received L sequence signal that is used to model the spectral attenuation as a second filter. Other embodiments are described and claimed.

Abstract: A mobile station (MS) and method for estimating received signal strength of a radio signal from a neighboring cell in a cellular radio telecommunication network. The MS measures the received signal strength of the radio signal over a plurality of frames, and calculates an average received signal strength. During an idle frame, the MS receives a synchronization channel (SCH) signal, and determines a channel estimate for the SCH using a known extended training sequence. The extended training sequence is then modified with the channel estimate, and the modified extended training sequence is subtracted from the received SCH signal to obtain a residual signal. The MS calculates a residual energy of the residual signal, and subtracts the residual energy from the average received signal strength of the radio signal to obtain an estimated received signal strength of the radio signal from the neighboring cell.

Abstract: A method and device for determining at least one traffic parameter in a data transmission system including at least one transmitter and one receiver, wherein the receiver includes a modem with equalizer. The method includes determining at least one piece of data given by the equalizer, wherein the piece of data includes the equalization error Ei; and determining one or more traffic parameters in taking account of the data provided, the fixed quality of service QoS and a relationship linking the quality of service and the equalization error Ei.

Abstract: An signal communication device having an auto-configured equalizer. The signal communication device includes a scoping circuit, buffer circuit, select circuit and equalizing circuit. A test signal is transmitted to the signal communication device via a signal path. The scoping circuit generates a waveform trace of the test signal, the waveform trace indicating time interval between receipt of a transition in the test signal and receipt of a reflection of the transition. The buffer circuit stores a plurality of data values that correspond to data signals received via the signal path. The select circuit selects one of the plurality of data values from the buffer circuit based on the time interval indicated by the waveform trace. The equalizing circuit generates an equalizing signal based on the selected data value.

Abstract: A method and system for interactive channel equalization uses channel status information included in data packets. The system includes a first station adapted to transmit a first data packet including a channel status information segment over a radio communication channel as a first signal. A second station in the system includes a static pre-equalizer and an adaptive equalizer. The second station is adapted to receive the first signal and adaptively equalize the first signal using the adaptive equalizer and the channel status information to create a post hoc status estimate of the channel. The second station is further adapted to transmit a second data packet over the channel as a second signal, where the second signal is pre-equalized by the pre-equalizer using the post hoc status estimate of the channel. The method and system thus enable parameters of the channel equalization to be adjusted in real-time in response to varying channel conditions.

Abstract: The convergence time of a blind, adaptive equalizer is shortened by using a tracking generator. The tracking generator comprises a smoothing filter which receives and smoothes a tap coefficient error estimate derived from an output data stream. Thereafter, a fraction of the smoothed estimate is generated. It is the use of this function of the smoothes estimate which allows the convergence time to be shortened.

Abstract: A method and apparatus for parameter scanning for signal over-sampling. An embodiment of an apparatus includes an equalizer to equalize received data values, and a sampler to over-sample the equalized data. The apparatus includes an eye monitor to generate information regarding quality of signal eyes for the over-sampled data, and an equalization monitor to generate information regarding sufficiency of signal equalization. The apparatus further includes a scan engine to scan possible values of a plurality of parameters for the apparatus.

Abstract: A method for estimating channels of an OFDM signal. The method comprises the steps of deriving responses of pilot channels, deriving responses of first data channels by time and frequency domain combined linear interpolation among the responses of the pilot channels, deriving each response of boundary channels by frequency domain linear interpolation between the responses of the nearest pilot and first data channels, and deriving responses of second data channels by frequency domain extrapolation using the responses of the pilot and first data channels.

Abstract: In pulse width control equalization, attention is paid to the existence of the symmetry of anteroposterior signals and thereby the size of a table in which the adjustment amount of an edge position is stored is reduced to the power of one-half. Pattern jitters caused by inter-symbol interference are suppressed. The pulse time span of each symbol is adjusted to an optimum pulse width determined by a calculating formula or search in a table in response to a code sequence to be transmitted. In the configuration wherein a table is used, the table to store an edge position adjustment amount wherein the row of the exclusive OR of two symbols located at positions symmetrical to each other before and after a center symbol now ready to be sent in the code sequence is used as a search key is made.

Abstract: In order to generate a signal for canceling a chirped signal, a transmitter generates a cancellation signal along with the transmitted signal, using a single term variable complex gain multiplier adapted to cancel the chirped signal only at its instantaneous frequency, rather than attempting to cancel it with a complex FIR filter that works over the entire bandwidth of the chirped signal. The cancellation signal is varied in amplitude and phase as a function of the frequency of the chirped transmit signal for which it is intended to compensate. Since the signal that is to be cancelled is essentially sinusoidal but swept through a frequency range, the cancellation signal for the instantaneous transmit signal needs to be swept in both amplitude and phase in unison with the change in frequency of the transmit signal in order to accommodate gain and phase changes in the transmitted signal as a function of frequency.