Abstract: A radio frequency receiver includes an amplifier and a detector that produces a bias control signal based on a signal environment. A bias level of the amplifier is set according to the bias control signal. Bias levels other receiver circuits may have similarly adjusted bias levels, including buffers, IF oscillators, mixers, and converters. The invention can be used to increase range of linearity, intermodulation immunity and reduce power consumption by reducing the bias level under typical conditions and relying on the bias control to increase bias levels under adverse signal conditions. The invention has advantages where power is at a premium, particularly when a device is in standby mode, including mobile, portable and hand held pagers and wireless telephones and Internet connections. If standby mode operation in non-maximum signal environments dominates the usage of the receiver, then the invention can substantially increase battery life.

Abstract: Techniques to correct for phase and amplitude mismatches in a radio device in order to maintain channel symmetry when communicating with another device using MIMO radio communication techniques. Correction for the amplitude and phase mismatches among the plurality of transmitters and plurality of receivers of a device may be made at baseband using digital logic (such as in the modem) in the receiver path, the transmitter path or both paths of that device. In a device, amplitude and phase offsets are determined among the plurality of radio transmitter and radio receiver paths by measuring phase and amplitude responses when supplying a signal to a transmitter in a first antenna path of the device and coupling the radio signal from a first antenna to a second antenna path of that device where the signal is downconverted by a receiver associated with the second antenna path, and similarly coupling a signal from the second antenna path to the first antenna path.

Abstract: A method is provided for reducing a DC bias in a receiver. This method includes isolating a second circuit portion from a first circuit portion (535) and determining a second DC bias correction value for the second circuit portion that will eliminate a second DC bias at the isolated second circuit portion (540). The second circuit portion is then connected to the first circuit portion (550) and a bias-maximizing code word is generated at the first circuitry (505). A first DC bias correction value is then determined that will eliminate a first DC bias at the first circuit portion (555). The bias-maximizing code word is formed such that: a first integrated value of a first half of the bias-maximizing code word has a positive value, and a second integrated value of a second half of the bias-maximizing code word over half of the code word length has a negative value.

Abstract: According to a decision threshold voltage controlling method of feeding an optimum decision threshold voltage to a clock and data recovery circuit which converts an optical input signal into an electric signal, extracts a clock component from an input data signal amplified to a predetermined amplitude, and identifies 1 or 0 in the input data signal at a timing of the clock, three decision points are suitably controlled, by selectively performing a process of controlling the spaces of the three decision points, a process of moving the three decision points with their spaces kept as they are, and a process of changing an error pulse measurement time, depending on a measurement result of the error pulse.

Abstract: A receiver with baseline wander correction for correcting a received input signal. The receiver includes first and second biasing resistor networks configured to receive first and a second signal of the received input signal, and to produce a first correction signal and a second correction signal. A comparator is employed to compare the first and the second correction signals in order to produce a control signal. The receiver also has comparison logic and compensation control circuitry. The comparison logic generates a logic signal according to the first and the second correction signals. Finally, the compensation control circuitry produces a compensation signal and provides it to respective output terminals of the first and the second biasing resistor networks so as to correct respective DC values of the first and the second correction signals.

Abstract: Data of the packet header is digitalized by a slicer circuit of a floating slice level mode, which follows DC voltage fluctuation, and packet data other than the packet header is digitalized by a slicer circuit of a fixed slice level mode, which does not follow DC voltage fluctuation. A default slice level of the fixed slice level mode is created by using demodulated data in a packet header section so as to accurately carry out switching of slicing methods. Obtained is a data slicer capable of accurately carrying out digitalization with respect to a signal, which is demodulated after being received.

Abstract: A multilevel optical receiver can comprise a plurality of comparators that generally correspond with the number of levels in a multilevel data stream. Each comparator can be individually controlled and fed a decision threshold in order to decode a multilevel signal. The multilevel optical receiver can generate a statistical characterization of the received symbols in the form of a marginal cumulative distribution function (CDF) or probability density function (pdf). This characterization can be used to produce a set of ?-support estimates from which conditional pdfs are derived for each of the transmission symbols. These conditional pdfs may then be used to determine decision thresholds for decoding the received signal. The conditional pdfs may further be used to continuously estimate the fidelity or error rate of the received signal without the transmission of a testing sequence. The ?-supports may further be used to automatically control the gain on the receiver.

Abstract: A method for compensating a baseline wander of a transmission signal and related circuit are provided. The transmission signal includes a plurality of first pulses and a plurality of second pulses for representing digital data coded in the transmission signal. The method includes generating an accumulation result according to a number of the first pulses and a number of the second pulses for estimating the baseline wander of the transmission signal, and compensating the baseline wander of the transmission line according to the accumulation result.

Abstract: An Improved Signal Receiver Having Wide Band Amplification Capability is disclosed. Also disclosed is a receiver that is able to receive and reliably amplify infrared and/or other wireless signals having frequency bandwidths in excess of 40 MHz. The receiver of the present invention reduces the signal-to-noise ratio of the received signal to ?th of the prior systems. The preferred receiver eliminates both the shunting resistor and the feedback resistor on the input end by amplifing the signal in current form. Furthermore, the receiver includes transconductance amplification means for amplifying the current signal without the need for Cascode stages. Finally, the receiver includes staged amplification to amplify the current signal in stages prior to converting the signal into a voltage output.

Abstract: Clock recovery of a multi-level (ML) signal can be performed in a two-step process. First, the transitions within the ML signal can be detected by a novel transition detector (TD). And second, the output of the TD circuit can comprise a pseudo-non-return-to-zero (pNRZ) signal that can drive a conventional OOK clock recovery (CR) IC. The TD circuit can convert the edges of the ML signal into the pseudo-NRZ (pNRZ) signal. The TD circuit can capture as many transitions as possible to allow the conventional NRZ clock recovery (CR) chip to optimally perform. The TD circuit can differentiate the ML signal in order to detect the ML signal's transitions.

Abstract: A novel amplitude deviation correction circuit which corrects an amplitude deviation between an I signal and a Q signal is disclosed. An average amplitude deviation between an I signal amplified by a variable gain amplifier and a Q signal amplified by another variable gain amplifier is detected by an amplitude comparison circuit, and +1 volt or ?1 volt is outputted in response to a result of the detection. An integration circuit integrates the output of the amplitude comparison circuit and controls the gains of the variable gain amplifiers in response to a result of the integration.

Abstract: An improved decoding technique useful for hard decision decoding, such as quadrature phase shift keying (PSK) and quadrature amplitude modulation (QAM), as well as soft-decision techniques, such as Viterbi decoding and trellis decoding. The system in accordance with the present invention provides adaptive decision regions for hard-decision decoding techniques and adaptive metrics for soft-decision detection techniques in which the decision boundaries and reference constellations, respectively are optimized in order to minimize the bit error rate (BER). In particular, the decision boundaries and metrics are optimized based on the locations of the received constellation points.

Abstract: A multipath searching device includes a radio front-end for converting a received radio signal into a baseband signal and for outputting the baseband signal. A profile calculating unit is included for calculating and outputting the multipath profile of the baseband signal. A first detector determines whether or not the radio signal traveled along a multipath is having a short-delay path by comparing the peak value of the multipath profile with a profile value of a predetermined position time interval before or after the peak of the multipath profile. A path selector receives the multipath profile and the detection result of the first detector, generates time delay information for each path, and separates many paths along which the radio signal traveled. A receiving unit receives the time delay information of the paths, despreads the baseband signal, and combines despread signals.

Abstract: A method and apparatus for monitoring and adjusting an analog signal of an operating circuit. The apparatus includes a control circuit, an analog-to-digital converter, and a comparator. The control circuit has an analog generator for generating the analog signal and an adjusting circuit for adjusting the strength of the analog signal. The analog-to-digital converter receives the analog signal and converts the analog signal to a digital signal. The comparator then compares the value of the digital signal to a predetermined value and generates a comparator signal. The adjusting circuit then receives the comparator signal and adjusts the strength of the analog signal based upon the value of the comparator signal. The method includes generating the analog signal, converting the analog signal to a digital signal, comparing the value of the digital signal to a predetermined value and adjusting the strength of the analog signal.

Abstract: A communication system includes a forward link from a base station to multiple mobile units, the forward link having multiple shared channels (SHCH's), multiple shared control channels (SHCCH's), and multiple dedicated pointer control channels (DPTRCH's), and utilizes HARQ error control for error detection and error correction. The mobile unit, when listening to the DPTRCH, uses a SHCCH pointed to by the DPTRCH to demodulate and decode data on the SHCH. Throughput problems may arise in the system when the mobile unit combines and decodes the wrong SHCH data, that is, SHCH data that is intended for a different mobile unit, or may incorrectly decodes SHCH data that is intended for the mobile unit. In order to improve the data throughput of the system, the systems employs a flush test and an energy detector test to prevent improperly decoded data blocks from corrupting properly decoded data blocks.

Abstract: An amplitude modulated optical communication system and method are disclosed that achieve bandwidth compression by making use of an n level amplitude modulation scheme in one or more frequency bands. A soft decision decoder is disclosed that provides at least two soft slicing levels between each signal level in the multiple level transmission scheme to define an “uncertainty” region therebetween. The soft slicing levels are used to evaluate the reliability of a given bit assignment. In addition to assigning a digital value based on the received signal level, one or more soft bits are assigned indicating a “reliability” measure of the output code.

Abstract: Modified branch metrics for processing bit-soft decisions to account for phase noise impact on cluster variance (CV). The present invention is able to partition a modulation scheme's constellation into two or more regions, so that the bit-soft decision branch metrics may be adjusted based on the CV of the various constellation points. A confidence level may be attached to the various constellation points based on their particular CVs. There are a number of methods to ascertain the CV of the constellation's points, including finding characteristics of various components in a communication system (transmitter, communication channel and receiver), and any method may be used within various embodiments. The modification of the branch metrics/confidence level may be performed in a communication receiver; the communication receiver may be implemented in a communication system employing the vector orthogonal frequency division multiplexing (VOFDM) portion of the broadband wireless internet forum (BWIF).

Abstract: A pseudo-differential signaling system uses a plurality of signal lines and a single, common reference voltage. Signal line voltages are interpreted only in comparison to the reference line voltage. Within a receiving circuit, the reference line is buffered prior to its distribution to multiple comparators. The system utilizes an active buffer having a bandwidth that is significantly greater than the resonant input frequency of the receiving circuit. In an alternative embodiment, the signal lines are also buffered. In this embodiment, the buffers are implemented with transistor-based source-followers. The buffer associated with the reference line has a larger current capacity than the buffers associated with the signal lines. In yet another embodiment, a comparator produces a correction signal that is equal to the noise present on the signal lines. This noise is then subtracted from the signal voltages.

Abstract: In a line quality monitoring method of detecting a code error rate by identifying a received optical signal using different identification levels and executing bit comparison after identification, an amplitude of the signal and noise power contained in the signal are detected, and a difference between the different identification levels is controlled to be inversely proportional to the amplitude of the signal and to be proportional to the noise power of the signal. Alternatively, the amplitude of the signal is controlled to be constant and the difference between the different identification levels is controlled to be proportional to the noise power of the signal.

Abstract: A method of forming a constellation design, and a receiver having both a processor that generates the constellation design and having a comparator. The particular constellation design described herein reduces errors resulting from a noisy communication channel. The generated constellation design includes a minimum threshold and a maximum threshold representing a variable range for each of a plurality of possible message levels. The constellation design accounts for the interrelationship between signal strength and noise in the communication channel. The comparator identifies the transmitted message by comparing the received signal with the generated constellation design.

Abstract: A system and method for providing adaptive threshold selection for detecting a signal in the presence of interference or noise. The system and method thus enables a node, such as a mobile user terminal, in an ad-hoc communications network to reduce the number of false alarms it experiences in the detection of communications signals due to, for example, sudden noise bursts or reception of a high powered signal that overloads the automatic gain control (AGC) device of the receiver in the node. The system and method employ two correlation circuits which correlate the received signal with two reference sequences and output a correlated signal, a threshold generating circuit which generates a threshold value based on the estimation of the variance of the output of the first correlation circuit, and a comparison circuit which compares the correlated signal to the threshold value to determine whether the received signal includes a valid data signal, as opposed to only noise.

Abstract: An adaptive slicer threshold generation system includes a first moving average filter to determine a first average value of a first binary signal. A second moving average filter is included to determine a second average value of a second binary signal. A combiner combines the first average value of the first binary signal and the second average value of the second binary signal to generate a combined output.

Abstract: A receiving section for digital television broadcasting and a receiving section for analog television broadcasting are provided. When a digital television broadcasting program is selected, it is judged whether or not an analog television broadcasting program having the same contents as those of the selected digital television broadcasting program is being broadcast. In a case where the analog television broadcasting program having the same contents as those of the selected digital television broadcasting program is being broadcast, when the digital television broadcasting program cannot be received, the analog television broadcasting program having the same contents as those of the selected digital television broadcasting program is received and outputted.

Abstract: A system and method are provided for feed-forward/feedback non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; using three thresholds, estimating a first bit in the data stream; using two thresholds, determining a third bit value received subsequent to the first bit; comparing the first bit estimate to the third bit value; comparing the first bit estimate to a second bit value received prior to the first bit; and, in response to the comparisons, determining the value of the first bit. In some aspects of the method, the third bit value is determined in response to a prior third bit value determination. Determining a third bit value includes: distinguishing NRZ data stream inputs between fourth and fifth thresholds as a “0” if the prior third bit value was a “1”, and as a “1” if the prior third bit value was a “0”.

Abstract: A digital demodulation apparatus automatically controls gain based on a state of receiving a digital modulated signal. The digital demodulation apparatus amplifies a digital modulated signal wave received through the air with the gain automatically controlled so as to have a predetermined amplitude. In the digital demodulation apparatus, a receive level variation detector detects receive level variation, an amount of noise components of the received digital signal wave. A gain controller 15 controls the gain with a receive level variation adaptive control signal based on the detected receive level variation, the amount of noise components.

Abstract: A system and method are provided for temporally analyzing serial input data. The method comprises: establishing three thresholds; distinguishing present (first) high probability one bit value estimates; distinguishing present high probability zero bit value estimates; and, using a temporal analysis of bit values to distinguish indefinite present bit value estimates. Using a temporal analysis of bit values includes: distinguishing a present bit estimate below first threshold and above the third threshold as a zero if both the past (second) and the future (third) bits are one values and otherwise as a one; and, distinguishing a present bit value estimate above the second threshold and below the third threshold as a one if both the past and future bits are a zero value and otherwise as a zero.

Abstract: The invention discloses a process for re-transmitting single frequency signals and a single frequency signal repeater, where coupling occurs between the transmitting antenna and the receiving antenna, and where the process is of the type used in a single frequency signal repeater and comprises the steps of: [a] receiving a first radio frequency signal having a particular receiving power, [b] optionally converting said first radio frequency signal into a process signal, [c] filtering, amplification and automatically controlling the gain of said signal, [d] canceling said coupling between said transmitting antenna and said receiving antenna, [e] reconverting, as the case may be, said process signal into a second radio frequency signal, [f] amplifying the power of said second radio frequency signal, [g] output filtering, and [g] transmission.

Abstract: A system and method are provided for selecting an optimal threshold detection level for a single serial data input receiver. The method comprises: receiving a serial data stream of pseudorandom binary information; using a plurality of threshold detection levels, estimating bit values; comparing the differences between estimated bit values; and, adjusting the threshold levels to minimize the difference between comparisons of estimated bit values. In some aspects, comparing the differences between estimated bit values includes: counting a first number of differences between the first and third thresholds; counting a second number of differences between the second and third thresholds; and, adjusting the first and second thresholds until the first number equals the second number.

Abstract: A signal compensation circuit compensates for direct-current offset of an input signal by amplifying the input signal with an amplifier having a variable direct-current offset. A low-speed negative feedback loop charges and discharges a capacitor in an integrating circuit according to the direct-current component of the amplified signal. A high-speed negative feedback loop charges and discharges the same capacitor at a faster rate when the amplified signal goes outside an allowable amplitude range. The capacitor potential is used to control the direct-current offset of the amplifier. The allowable amplitude range is adjusted according to the amplitude of the amplified signal. High-speed compensation can thus be combined with a tolerance for runs of identical code levels in the input signal.

Abstract: A reception AGC circuit includes a high-speed power calculating circuit for calculating the power of an input signal at a short period, a normal power calculating circuit for calculating the power at a normal period, a circuit for receiving a power calculation result from the high-speed power calculating circuit or normal power calculating circuit to calculate a feedback amplification value, and addition amplification value setting units for self-station communication and peripheral station monitoring which receive the feedback amplification value through a switch and add the feedback amplification value to an amplifier in use.

Abstract: A system for detecting a burst in a wireless communications system. A signal strength indicator indicates the strength of an incoming signal representative of incoming packets. A signal strength change detector detects changes in the signal strength of the incoming signal. Signal strength detection logic determines if a change in signal strength of a predetermined magnitude has occurred. A pattern detector detects patterns of symbols, or symbol estimates, in the incoming signal to determine if a predetermined pattern of symbols is present. Burst detection logic signals detection of a burst if the signal strength detection logic determines that a change in signal strength of predetermined magnitude has occurred, and the pattern detector determines that a predetermined pattern of symbols is present.

Abstract: A radio frequency (RF) integrated circuit (IC) includes a local oscillation module, analog radio receiver, analog radio transmitter, digital receiver module, digital transmitter module, and digital optimization module. The local oscillation module is operably coupled to produce at least one local oscillation. The analog radio receiver is operably coupled to directly convert inbound RF signals into inbound low intermediate frequency signals based on the local oscillation. The digital receiver module is operably coupled to process the inbound low IF signals in accordance with one of a plurality of radio transceiving standards to produce inbound data. The digital transmitter is operably coupled to produce an outbound low intermediate frequency signal by processing outbound data in accordance with the one of the plurality of radio transceiving standards. The analog radio transmitter is operably coupled to directly convert the outbound low IF signals into outbound RF signals based on the local oscillation.

Abstract: There is provided a digital data transmission system that includes a first unit transmitting a first MLT3 signal, a second unit receiving the first MLT3 signal, and transformers. The second unit includes an equalizer receiving the first MLT3 signal and outputting a second MLT3 signal that is input to a recovery module for the transmitted digital data, and a device placed in feedback to the equalizer. The device receives the second MLT3 signal and outputs a third low frequency signal that is added to the first MLT3 signal. The device has a translation block for the up or down or no translation of the second MLT3 signal according to the low or high or intermediate value of such signal, and a low pass filter receiving the signal output from the translation block and outputting the third signal containing the low frequency component of the second MLT3 signal.

Abstract: A data reproducing apparatus and method for improving data detection performance by adjusting decision levels used in a data detector. The data reproducing apparatus includes an equalizer which equalizes an input digital signal, a data detector which detects data from the output of the equalizer based on decision levels, and a level decision unit which detects levels corresponding to the decision levels used in the data detector from the output of the equalizer and feeds back corrected decision levels, which adaptively vary with the output level of the equalizer, to the data detector. Accordingly, the detection performance of the data detector is improved.

Abstract: A system and method are provided for non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; establishing thresholds to distinguish a first bit estimate; comparing the first bit estimate in the NRZ data stream to a second bit value received prior to the first bit, and a third bit received subsequent to the first bit; in response to the comparisons, determining the value of the first bit; tracking the NRZ data stream inputs in response to sequential bit value combinations; maintaining long-term averages of the tracked NRZ data stream inputs; adjusting the thresholds in response to the long-term averages; and, offsetting the threshold adjustments to account for the asymmetric noise distribution. Two methods are used to offset the threshold adjustments to account for the asymmetric noise distribution: forward error correction (FEC) decoding and tracking the ratio of bit values.

Abstract: A balanced peak detector circuit adjusts differential voltage signals. In one embodiment, the peak detector uses competing current paths to provide a charging current to a storage capacitor. The charge on the storage capacitor is used to adjust either a transconductance or a transimpedance circuit. An offset current can be used to adjust the charge stored on the capacitor to change a peak-to-peak output voltage from the transimpedance circuit. In one embodiment, the offset current can be adjusted using an adjustable current source. A discharge circuit has been describe that allows a discharge of the capacitor to be controlled.

Abstract: A method for refining a DC-Offset estimate and removing of the DC-Offset includes the step of determining if any AM is present (602). If AM is determined to be present, it is next determined if the I and Q path DC-Offset estimates are closely matched, if they are, then only a single search using the average of the I and Q path estimates is used (608). If it determined however, that the two path estimates are not closely matched, than two searches are performed, one for each path (610). After this, the blocking signals are searched for up to a predetermined number and the DC-Offset vector is generated (612). Once the DC-Offset vector is generated, the DC-Offset is removed from the received signal (614). After which it is determined if the AM level is high (616), and if so, a transient correction routine is performed (618).

Abstract: A method for estimating and removing a time varying DC-offset includes the steps of dividing the received burst into blocks (902), then finding the maximum and minimum values in each block (904). Once the maximums and minimum values have been found, the upper and lower envelopes are determined (906). The DC-offset path is then calculated by taking the average of the upper and lower envelope (908). Once determined, the DC-offset path information is used in order to subtract the DC-offset from the desired signal.

Abstract: A fiber optic receiver that includes an opto-electronic transducer, an adjustable response preamplifier circuit, and a post-amplifier circuit is described. The opto-electronic transducer is configured to generate an electrical data signal in response to a received optical data signal. The adjustable response preamplifier circuit is coupled to the opto-electronic transducer and is operable to amplify an electrical data signal generated by the opto-electronic transducer. The post-amplifier circuit is coupled to an output of the preamplifier circuit and is configured to transmit a mode control signal to the preamplifier circuit in response to a received control signal. By transmitting the mode control signal from the post-amplifier to the preamplifier, the adjustable response amplifier may be placed in the preamplifier stage within a receiver optical sub-assembly (ROSA). As a result, the fiber optic receiver may accommodate multiple operating modes (e.g.

Abstract: In known telephone subscriber end stations a caller_ID IC detects a tone alerting signal TAS alerting that successive caller_ID information can be received for displaying on a display of the phone. The known station applies narrow frequency band filters to detect tones indicating the end of TAS. Such a detection is not flexible as it can only be used for a specific caller_ID signal protocol. A flexible detector is proposed which can easily be adapted to widely varying protocols and which can also be used for other purposes such as the detection of power drops in an FSK signal. The detector comprises means for determining a time-domain signal representing the signal energy of a signal on the subscriber line in a predetermined time interval.

Abstract: An Improved Signal Receiver Having Wide Band Amplification Capability is disclosed. Also disclosed is a receiver that is able to receive and reliably amplify infrared and/or other wireless signals having frequency bandwidths in excess of 40 MHz. The receiver of the present invention reduces the signal-to-noise ratio of the received signal to ?th of the prior systems. The preferred receiver eliminates both the shunting resistor and the feedback resistor on the input end by amplifying the signal in current form. Furthermore, the receiver includes transconductance amplification means for amplifying the current signal without the need for Cascode stages. Finally, the receiver includes staged amplification to amplify the current signal in stages prior to converting the signal into a voltage output.

Abstract: An apparatus and method for detecting a signal in an optical data network is disclosed. A peak power level and an average power level are measured for an optical input to an optical detector. A threshold power level is associated with each average power level that is sufficient to distinguish a data signal form optical noise at the average power level. A signal is detected if the measured peak power level exceeds the threshold power level appropriate for the average power level. In one embodiment, a threshold value of a ratio of the peak power level to the average power level is calculated and a signal is detected if the ratio of the measured peak power level to the average power exceeds the threshold value.

Abstract: A method that calculates a threshold for a signal according to a first bandwidth if the signal is greater than the threshold plus a first value or if the signal is less than the threshold minus the first value. The method also calculates the threshold for the signal according to a second bandwidth if the signal is not greater than the threshold plus the first value and if the signal is not less than the threshold minus the first value. The first bandwidth is greater than the second bandwidth. Various apparati that perform the method are also described.

Abstract: A method of automatically determining a peak level of a signal propagated on a carrier medium, such as for example POTS wiring, includes detecting a traversal of a noise threshold level by a data signal. The noise threshold level is determined relative to a noise floor. A determination is then made as to whether the data signal traverses a peak level within a predetermined time interval after the detection of the traversal of the noise threshold level. The peak level is then varied in accordance with the determination of whether the data signal traversed the peak level within the predetermined time interval. For example, should the data signal not traversed the peak level within the predetermined time interval, the peak level may be lowered. Alternatively, should the data signal traversed the peak level within the predetermined time interval, the peak level may be raised.

Abstract: A method of dynamically, and automatically, varying the sensitivity of a receiver coupled to receive signals on a carrier medium, such as for example POTS wiring, includes the step of detecting whether more than a predetermined number of noise events, such as for example traversals of a noise threshold level, occur within a predetermined time. If the predetermined number of noise events occur, the sensitivity of the receiver is automatically varied by a predetermined increment. For example, the noise threshold level may be raised by a predetermined voltage to vary the sensitivity of the receiver.

Abstract: A system and method of wireless communication determines received signal timing deviation which is used to generate a timing advance for adjusting User Equipment (UE) transmissions. An adaptive threshold for measuring the timing deviation is set based on the energy level of received UE signals. UE signal samples which exceed the threshold are evaluated to determine timing deviation.

Abstract: Methods and apparatus are provided for adjusting slicing parameters, such as a voltage threshold and a phase sampling point, used in recovering 1's and 0's from a signal so as to reduce a bit error rate (BER) of the signal. The BER is modelled as a second order polynomial of the slicing parameters. The BER is repeatedly determined from a Forward Error Correction corrected bits counter. For each BER measurement the model is updated, using for example a recursive least squares fit. New values of the slicing parameters are then determined by carrying out an iteration of an optimization, such as a Levenberg-Marquardt optimization, using the model. The new values of the slicing parameters are passed to a Clock and Data Recovery module. Various conditions are checked before updating the model or determining the new values of the slicing parameters, such as changes in signal power or high BERs which exceed the error correction capabilities of the forward error correction.

Abstract: A receiver employs non-linear threshold compensation to adjust input sample values from a single mode fiber to mitigate effects of polarization mode dispersion. A difference S between values for i) a decision for the current input sample and ii) a decision for the previous input sample is generated that indicates whether a transition between logic values occurred in the input data and the direction of transition (sign/phase). Two values are generated to determine a magnitude c of correction combined with the sign/phase (difference S) to generate a correction value. An error value e is generated as the magnitude of the difference between i) the decision for the input sample and ii) the input sample. A value d is calculated as the magnitude of the difference between i) the current input sample and ii) the previous input sample is also generated. The value d represents a relative “closeness” in value between two consecutive input samples.

Abstract: A receiver is adaptively calibrated by using a coherent reference signal. The reference signal is selected to be offset from a center frequency of the calibration signal such that the resultant product is offset from baseband by some small amount. The resultant product is used to determine a next value of the calibration parameters.

Abstract: Circuits for adjusting the duty cycle of a clock(s) signal include a negative feedback loop for applying an offset signal to the uncorrected clock signal(s). The offset signal, which corresponds to a duty cycle error of the corrected clock signal(s), adjusts the slicing level of the uncorrected clock signal(s) to cause the duty cycle error to converge toward a predetermined value, for example, zero. The techniques may be used to adjust the duty cycle error of differential clock signals as well as single-ended clock signals.