Abstract: A method is disclosed for establishing and adapting communication link parameters in xDSL transmission systems. The method determines a frequency allocation scheme that makes the delivery of both xDSL services and traditional telecommunications services possible, and uses information about service bit-rate requirements and the deployment characteristics of a given local loop to select an optimal combination of symbol rate and transmission modulation density that is capable of delivering desired xDSL services. The method includes the steps of establishing communication between xDSL termination units, and determining a maximum transmission modulation density that can be used for a plurality of predetermined symbol rates. One method of performing these steps is a symbol rate stepping method in which communication is initiated at a fraction of the final symbol rate, and the symbol rate is iteratively stepped up until the final symbol rate is reached.

Abstract: A tetrahedron modem phase modulates input serial binary data and demodulates input waveforms based on a four dimensional vector set. The phase modulation scheme has four possible state vectors (or symbols), that form a tetrahedron in four dimensional space. This symbol geometry improves the bit error rate performance over conventional PSK methods for a given signal to noise ratio. In addition the tetrahedron modem aids bit synchronization and eliminates phase ambiguity in the receiver. Lastly, the tetrahedron modulator outputs a constant envelope waveform, which may be subjected to non-linear devices and channels without fear of negative effects due to amplitude distortion.

Abstract: A training method provides an advantageous technique for estimating secondary propagation path parameters based on learning propagation path characteristics for a selected number of secondary propagation path signals. In a multipath environment, a received radio signal comprises multiple received signals, each received through a different signal propagation path. The strongest multipath signal is deemed the main path signal, while the remaining multipath signals are termed secondary path signals. In some types of direct-sequence, spread spectrum communications systems, significant secondary signals must be canceled from the received multipath signal to achieve desired receiver performance, while in other types of systems, such secondary signals may be used to enhance the signal-to-noise ratio of the received signal. In either case, the various multipath signals must be accurately characterized.

Abstract: An equalizer substantially eliminates a ghost of a received main signal by (i) applying coefficients b (where b may be equal to one) to the received main signal and the ghost in order to modulate the received main signal and the ghost so that the received main signal and the ghost are unequal, (ii) applying coefficients a to the modulated received main signal and ghost in order to substantially eliminate the ghost, and (iii) applying coefficients c as a window function to the substantially ghost-free received main signal in order to remove the modulation imposed on the received main signal by the coefficients b.

Abstract: A radio frequency identification (RFID) tag device having a pulse position modulation (PPM) decoder circuit which calculates a relative frequency relationship between an internal clock-oscillator of the RFID tag device and an external PPM source such as a RFID tag reader, and then synchronizes the RFID tag device PPM decoder circuit to the required precision for reliable PPM symbol decoding. The PPM decoder is synchronized by measuring the “counts per pulse” (CPP) from a calibration cycle having a plurality of pulses in a single symbol frame.

Abstract: A system and method for editing a bitstream is provided. A first segment is cut from a first bitstream and a second segment is cut from a second bitstream. In cutting the segments from the bitstreams, first and last GOPs in the segments can be cut between frames in the GOP. The number of frames of the broken GOP is then compared to a pre-determined threshold value. If the number of frames of the broken GOP is less than or equal to the threshold value, the broken GOP is combined with a neighboring GOP. Therefore, the newly created GOP is longer than the standard size regular GOP. However, if the number of frames in the broken GOP is greater than the threshold value, a new GOP is created with the frames of the broken GOP. Therefore, the newly created GOP is shorter than the standard size regular GOP.

Abstract: A video encoding scheme employs progressive fine-granularity layered coding to encode video data frames into multiple layers, including a base layer of comparatively low quality video and multiple enhancement layers of increasingly higher quality video. Some of the enhancement layers in a current frame are predicted from at least one same or lower quality layer in a reference frame, whereby the lower quality layer is not necessarily the base layer. Use of multiple reference layers of different quality results in occasional fluctuations in the encoded image data. The video encoding scheme efficiently eliminates such fluctuations by predicting higher quality data from the lower quality data encoded in the base layer and a low quality enhancement layer.

Abstract: Errors are detected in a motion-picture-experts group (MPEG) bitstream that has been corrupted by wireless transmission. Some 16×16 pixel macroblocks are divided into four smaller 8×8 blocks. A motion vector is encoded for each block. The Euclid distance is generated for each possible pair of the four motion vectors, and the maximum of these distances is compared to a threshold distance. When the maximum distance among the motion vectors in a macroblock exceeds the threshold, a bitstream error is signaled and error concealment is triggered. Since the four blocks within a macroblock usually stay close to each other in adjacent video frames, large jumps in the relative location of one block usually indicate a bitstream error. Squares of the distances can be generated and compared to reduce the computational load by eliminating square-root operations.

Abstract: A stream based bitrate transcoder for MPEG bitstreams that utilizes information extracted from MPEG bitstreams, such as picture-type, coding complexity, motion vector and MB-mode. Using this information, a stream-based bitrate conversion of rhythm is realized. DCT coefficients are dropped with regard to two components, specifically, picture/MB-level classification and motion reference calculation.

Abstract: A digital audio broadcasting (DAB) receiver designed for receiving a signal with 1536 active carriers generated by an inverse fast Fourier transform (FFT) with 2048 points, includes the usual RF stage (14), an IF filter (20), and a demodulator (22) providing baseband I and Q signals. This is followed by an anti-aliasing filter (28), a sampler (30), and an FFT (32). The FFT is a 4096-point FFT, and is thus twice as long as required, and gathers twice as many points during each symbol period. However this is found to substantially simplify the construction of the IF filter (20) and, more particularly, the anti-aliasing filter (28). For use with real signals rather than quadrature demodulated signals, an 8192-point FFT is employed.

Abstract: This invention provides an iterative process to maximum a posteriori (MAP) decoding. The iterative process uses an auxiliary function which is defined in terms of a complete data probability distribution. The auxiliary function is derived based on an expectation maximization (EM) algorithm. For a special case of trellis coded modulators, the auxiliary function may be iteratively evaluated by a combination of forward-backward and Viterbi algorithms. The iterative process converges monotonically and thus improves the performance of any decoding algorithm. The MAP decoding minimizes a probability of error. A direct approach to achieve this minimization results in complexity which grows exponentially with T, where T is the size of the input. The iterative process avoids this complexity by converging on the MAP solution through repeated maximization of the auxiliary function.

Abstract: A method of determining a quality metric for a message. The method comprises receiving (500) a message, constructing (502) a trellis array associated with the message, and determining (512) a quality metric for the message based on the trellis array. In one embodiment, the quality metric is derived from state information obtained from selected columns in the trellis array. The state information may include target states defining correct and/or incorrect transitions in the selected columns. The quality metric comprises in one embodiment a cumulative number of the occurrences of the target states in the selected columns.

Abstract: An ultra wide bandwidth, high speed, spread spectrum communications system uses short wavelets of electromagnetic energy to transmit information through objects such as walls or earth. The communication system uses baseband codes formed from time shifted and inverted wavelets to encode data on a RF signal. Typical wavelet pulse durations are on the order of 100 to 1000 picoseconds with a bandwidth of approximately 8 GHz to 1 GHz, respectively. The combination of short duration wavelets and encoding techniques are used to spread the signal energy over an ultra wide frequency band such that the energy is not concentrated in any particular narrow band (e.g. VHF: 30-300 MHz or UHF: 300-1000 MHz) and is not detected by conventional narrow band receivers so it does not interfere with those communication systems.

Abstract: A carrier reproduction circuit which can perform stable carrier reproduction even when reception takes place with low C/N values is provided. The reception phase of the demodulated known-pattern reception signal is detected with a frame synchronizing timing circuit (4), and based on the detected reception phase, either the phase difference table of absolute phase having one convergence point or the phase difference table of the phase rotated from the absolute phase by 180°, which are included in a carrier reproduction phase difference detecting circuit (8), is selected, and from the selected phase difference table the output based on the phase difference between the phase obtained from the signal point position of the reception signal and the phase convergence point is obtained, and thus carrier reproduction is implemented by undergoing the reproduced carrier frequency control via an AFC circuit (10) so that the phase obtained from the signal point position coincides with the phase convergence point.

Abstract: A digital demodulation apparatus for performing a stable oscillation operation has a simple circuit configuration. The digital demodulation apparatus includes a pulse width counter for measuring a cycle of a modulated signal to generate digital cycle information. A first digital filter equalizes the digital cycle information to generate averaged cycle information. A comparator compares the digital cycle information and the averaged cycle information to generate a bi-phase signal. A phase-locked loop generates a clock signal having a frequency according to the averaged cycle information and a phase being synchronized with the phase of the bi-phase signal.

Abstract: A parallel automatic synchronization system includes a variable delay devices for receiving and variably delaying N parallel transmitted channel data words over repetitive clock cycles in response to a synchronization latch clock and for synchronously clocking out the parallel data words by a local reference clock (FREF); sync logic devices for receiving repetitive control clocks corresponding to the transmitted channel data words, including a remote recovered clock (FFRM) and the local reference clock (FREF) and for generating the synchronization latch clock which determines the delay position of the variable delay of the delay devices; and output latch devices for clocking out the parallel data words from the variable delay devices with the local reference clock (FREF).

Abstract: An apparatus and method for synchronizing a derived bit clock with a transmit bit clock of a transmitted data signal is disclosed. The present invention uses a divide-only direct digital synthesizer and a fixed local oscillator. The synthesizer generates a derived bit clock by dividing the fixed, high frequency local oscillator. A transition detector identifies valid bit transitions in the unsynchronized data signal. At each valid transition, a control algorithm determines whether to adjust the frequency and/or phase of the derived data clock in order to maintain synchronization between the derived bit clock and the transmit bit clock. The unsynchronized data signal and the derived bit clock are processed by a reclock latch to generate a synchronized data signal.

Abstract: A method and apparatus for detecting the phase difference between an input data signal and a local clock signal is provided. An input data signal is frequency divided and then fed through a series connection of a pair of data latches. Signals provided at the input and outputs of the pair of the data latches are exclusively-ORed to provide a variable width pulse signal and a reference pulse signal that may be used in a phase-locked loop to align the local clock with the input data signal in a predetermined phase relationship. A re-timed data signal is provided by inputting the input data signal to a data latch clocked with an inverted phase-aligned clock signal.

Abstract: A phase lock loop circuit includes operation means (CPU) 15 for previously calculating divider control data 11 to obtain a division number corresponding to an output frequency, and a divider switching memory circuit 2 for writing the divider control data 11 and reading a division value 10 every time an output 9 of a variable divider 1 is generated, thereby controlling the variable divider 1.

Abstract: Methods and systems for automatic generation of an at-speed binary counter are described. The binary counter includes a slow counter that increments when a fast counter overflows to keep up with a fast clock. A framework to automatically generate a Hardware Description Language (HDL) for an at-speed binary counter is also described.

Abstract: Disclosed is a light transmitting apparatus between a rotor and a stator for transmitting data. The apparatus comprises a light-emitting element arranged in a position of a first reference radius of the rotor for emitting a light beam in accordance with the data to be transmitted, a photo-detecting element arranged in a position of a second reference radius on the stator 12 for detecting the beam, and a fan-shaped optical guide member positioned between the stator and the rotor, made of a transparent material, and fixed to the stator. The beam is reflected by a first reflecting surface formed in the arcuate portion of the member and, then, reflected by a second reflecting surface formed in the proximal end portion of the member so as to guide the beam to the photo-detecting element.

Abstract: One aspect of the present invention is a detector array for a computed tomographic imaging system having a z-direction corresponding to an image slice thickness direction and that is arc-shaped in a direction transverse to the z-direction. The detector array has a plurality of detector modules configured so that the detector array has active regions of differing thicknesses. This detector array embodiment provides an optimized detector array for certain imaging situations, for example, in cardiac imaging applications in which increased coverage is required only in a relatively small central portion of a field of view.

Abstract: An apparatus for use with a combined CT-PET system wherein a CT source and detector are mounted to a front end of a CT support and the support forms a parking space about a translation axis, a PET detector is mounted to a rear end of the support and a collimator support extends from the PET detector at least part way into the parking space, a collimator is mounted to the collimator support for movement between first and second positions inside the PET detector and outside the PET detector and at least partially within the parking space, respectively, a radiation blocking shield is mounted to the PET detector opposite the CT support to block radiation from that direction from being detected by the PET detector.

Abstract: Methods and systems for controlling critical dimension (CD) in a process system, including computing an exposure dose error based on at least one output of the process system, normalizing the computed exposure dose error based on a target exposure dose, and providing an exposure dose to the process system based on at least one normalized exposure dose error. The target exposure dose can be associated with a process system characteristic(s) and can be updated based on normalized computed exposure dose errors.

Abstract: To provide an X-ray fluorescence spectrometer of a simplified structure of a type in which a sample can be transported to an irradiating position where the sample is irradiated with primary X-rays and analysis can be achieved by positioning a target area to be measured of the sample. When an r drive means 37 drives an r drive shaft 43, a transporting function of transporting the sample 3 and a positioning function of positioning the target area in an r direction are performed. Also, a&thgr; drive shaft 53 of a &thgr; drive means 38 for performing the positioning function for positioning the target area in a &thgr; direction and the r drive shaft 43 of the r drive means 37 form a dual coaxial shaft assembly.

Abstract: There is provided an optical apparatus for radiation with a wavelength ≦160 nm. The apparatus comprises a mirror with a mirror surface, and a first device for generating elastic oscillations with different acoustic wavelengths on the mirror surface due to surface deformations. Radiation impinging on the mirror surface is diffracted in a predetermined range of angles (&agr;).

Abstract: The present invention measures the quality of a transmission channel by utilizing voice recognition technology in a novel manner.

Abstract: Digital answering machine that can receive not only voice but also fax information via a telephone line. In order to receive and send faxes with a computer, it is inventively provided to expand a digital answering machine such that incoming faxes are intermediately stored in a memory and can be transmitted to the computer via an interface after the computer is switched on.

Abstract: Remote access and configuration of a digital subscriber line (DSL) device using a telephone line. From a remote location, an operator can access the DSL device and receive data, including an operational parameter regarding the device, and upload an operational parameter or firmware, and thus, establish the operational configuration of the device. Also from a remote location, an operator can troubleshoot and provide technical support functions for the device.

Abstract: Apparatus and methods are provided for selectively providing telephone service that is either PSTN-based or Internet-based using a standard analog telephone circuit. In a first embodiment, the apparatus comprises a hardware module and associated software for coupling a personal computer or Internet appliance and a standard analog telephone. The apparatus includes a DTMF interface circuit, a subscriber line interface circuit, a ring detection circuit, and an interface circuit for interfacing with the PC or Internet appliance. The apparatus permits the analog telephone to be toggled between an Internet-based telephone mode and a PSTN-network mode by inputting a predetermined sequence of DTMF digits. In alternative embodiments, the apparatus comprises a processor, modem and optionally, analog telephone circuit, to provide a stand-alone or partially-integrated device capable of selectively switching between PSTN-based and Internet-based telephony services.

Abstract: Upon detecting an incoming call, a call screening system determines the CALLER ID information associated with the call and compares it to a database of allowable calling parties. If the calling party is to be allowed to ring through, the call screening system routes the incoming call to one or more communication devices associated with the calling party information in the allowable calling party database. In this manner, certain screened calls only ring through to a handset if authorized, while others are authorized to ring through to a fax machine, an answering machine, another handset, or a remote device connected between a remote handset and the local exchange. A single call screening device having several ports thus filters calls to multiple communications devices. Incoming call screening may be selectively different during different times of the day, for different calling parties, or for different communications devices connected to the call screening device.

Abstract: A digital audio transmitter system capable of transmitting high quality, wideband speech over a transmission channel with a limited bandwidth such as a traditional telephone line. The digital audio transmitter system includes a coder for coding an input audio signal to a digital signal having a transmission rate that does not exceed the maximum allowable transmission rate for traditional telephone lines and a decoder for decoding the digital signal to provide an output audio signal with an audio bandwidth of wideband speech. A coder and a decoder may be provided in a single device to allow two-way communication between multiple devices.

Abstract: A facsimile machine is capable of displaying a desired home page by one-touch operation. When button information obtained while the facsimile machine is in a standby state is a favorite-link button, a URL address corresponding to the button specifying information is retrieved from a memory unit, a HTTP request protocol is generated based on the URL address, and the generated HTTP request is transmitted to a server. After data in HTML is obtained from the server, the received data in HTML is displayed by the browser. Thus, the facsimile machine is capable of displaying the desired home page by one-touch operation.

Abstract: An apparatus for identifying multiple accounts belonging to a customer of a service provider using profiles indicating customer patterns of use of the service. The profiles distinguish the accounts of the service provider customers from each other. Those profiles that substantially match are considered to correspond to the same customer.

Abstract: A method and arrangement for providing prepaid calling card services to a calling party is disclosed. Near the end of value of a prepaid calling card account, the calling and called parties to a connection are split and the calling party is given the opportunity to increase the value of his or her prepaid calling card account. If the account is increased the call continues using the increased value. Alternatively, if the account is not increased the connection is dropped.

Abstract: A method of creating a call detail record is provided. An input signal is received. An account identification record is created in response to the input signal. An event jacket is created. The event jacket is associated with the account identification record. A command signal to store account identification information is received. A confirmation signal is received after the account identification information has been stored. Finally, a call detail leg jacket is created. The call detail leg jacket includes at least one record. Each record includes information relating to the stored account identification information.

Abstract: To prevent fraudsters from illicitly collecting the authorization number or authorization code, as well as personal identification number, of an unsuspecting authorized user of a public pay phone, the instant invention disables the keypad of the telephone so long as the pay phone is connected to an incoming call, unbeknownst to the authorized user who is attempting to dial out from that pay phone, and the user is detected to have lifted the handset of the pay phone to attempt to dial out. An alternative method of ensuring that the authorization code of an unsuspecting user is not misappropriated includes adding a circuit to the circuitry of the telephone to ensure that a true dial tone is provided when the user picks up the handset. If no true dial tone is detected, the keypad of the telephone remains disabled.

Abstract: A system and method to provide secure access across the untrusted public switched telephone network is described. The system and method can be initiated by a security policy defining actions to be taken based upon at least one attribute of the call.

Abstract: A method and a system for utilizing an interactive identity for an automated transaction are disclosed. User identification information is received. A pre-selected identity that is associated with the user identification information is retrieved. The pre-selected identity is utilized for interaction with a user for an automated transaction. The pre-selected identities can be stored in a database indexed by user identification information. In an exemplary embodiment of the present invention, selectable options for identities are provided to the user and the selected options form the basis for determination of a pre-selected identity for the user. The pre-selected identity can be one of an audio-based, a video-based, and a multimedia-based identity.

Abstract: In ordinary telephones, a communication partner is called without considering the location of the communication partner and whether or not the communication partner is busy. In the present invention, it is determined whether or not the communication partner is to be called at least based on information relating the position of a communication apparatus possessed by the communication partner.

Abstract: A method of operating an availability service in a telecommunication system interconnecting a legacy telephone system with at least one presence system, said legacy telephone system including a plurality of terminals (T1 . . . T10), at least some (T1,T2) of which are terminals of subscribers to said availability service, said method including: (a) continuously monitoring each subscriber terminal (T1,T2) for a change of a call status of said subscriber terminal from the presence of a call to the absence of a call; (b) generating a first or “high availability” signal when said call status of said subscriber terminal changes from said presence of a call into said absence of a call; (c) monitoring an interval of time beginning with said first signal; (d) generating a second or “availability unknown” signal after a predetermined time period &tgr; within said interval; and (e) making said availability signals accessible to any interconnected presence system.

Abstract: The present invention allows a single trigger, such as a Termination Attempt Trigger, to invoke multiple feature service logic programs (feature SLPs) through the use of a Feature Interaction Manager service logic program (FIM-SLP) installed at a service control point (SCP). A database, accessible by the service control point, contains subscriber information such as the type of services subscribed and the order in which the services are to be invoked. The Feature Interaction Manager service logic program invokes individual feature SLPs based on the information contained in the database that specify how the feature SLPs will interact. In one embodiment, the present invention allows multiple services to be deployed within a common service control point. In a different embodiment, the Feature Interaction Manager service logic program located in a first service control point can also invoke features SLPs that are located in other service control points.

Abstract: A method and an apparatus for protecting call privacy across telecommunication networks allow a calling party of a first telecommunication network to control the privacy of a telephone call to a called party of a second telecommunication network. This is achieved by selecting among a group of privacy options that represent varying degrees of privacy, assigning each of the selected privacy options to the call, and enforcing the selected privacy options within the second telecommunication network, thereby eliminating the need for external enforcement. The privacy options selected for the call limit the ability of a called party to manipulate the call. For example, the privacy options may prevent the called party from forwarding the call, transferring the call, conferencing the call, and/or listening to the call via a hands-free speaker phone.

Abstract: In a telephone system employing a PBX server to communicate with local telephones over a local area network, fallback adapters are provided to automatically respond to a power failure and also respond to the failure of the PBX server to automatically connect the telephones directly to a telephone line. This automatic connection enables the telephones to be used as analog phones and make and receive calls directly without using the PBX server. Power failure is detected by relays which default to a position to connect the telephones directly to the telephone line. The fallback detectors have controller logic which detects the presence of a ringing signal on the telephone line and the failure of the PBX to respond to the ringing signal. In addition, the fallback detectors detect the failure of the PBX to respond when a telephone is used to attempt to make an outgoing call or a call to another one of the local telephones.

Abstract: An arrangement (100) for monitoring contact-center (104-108) performance automates the monitoring process by using a database schema (250-270) that records (200-224) the contact center to be monitored, its skills, the locations where the skills are located (in the case of a distributed contact center), the objective or target value for a given skill attribute (such as average speed of answer, maximum delay, etc.), the acceptable deviation from the objective (tolerance), the maximum acceptable deviation between locations (in the case of a distributed contact center), the periodicity or frequency of the monitoring, and the comparison operator needed to determine how a given observed or actual value for the skill attribute is to be compared with its specified objective and tolerance. Monitoring is then effected (300-366) as follows.

Abstract: The present invention provides a method and system for processing and collecting, at a telephone network central office, information for a call directed to a call center prior to the call being received at the call center. A call is received for processing at a telephone network central office that is local to the call origination location. At the central office, a determination is made as to whether the destination number of the call is identified in a selected database. In response to the call destination number being identified in the selected database, the central office solicits the caller to provide requested information. An indication of the requested information received from the caller is included in a data packet associated with the telephone call before the call is transferred from the central office. The call, including the indication of the requested information, is routed to the call center.

Abstract: A communication apparatus 1 or 2 connected to a PBX 4 or 5 and an ATM network 3, is provided with a DTMF signal detecting portion 102 for detecting whether or not a DTMF signal is contained in a voice signal from the PBX 4 or 5, a DTMF signal monitoring portion 103, a DTMF cell generating portion 105 for coding and sending out a DTMF signal, a DTMF cell decomposing portion 110 for decoding a coded DTMF signal and a DTMF signal generating portion 113 for generating a DTMF signal on the basis of the information content of a decoded DTMF signal and sending out this DTMF signal to the PBX 4 or 5, and the transmission side communication apparatus 1 or 2 codes a DTMF signal in a specified form and transmits the DTMF signal and the reception side communication apparatus 1 or 2 decodes the coded DTMF signal and, on the basis of this content information, restores the DTMF signal in a DTMF signal generating portion 113.

Abstract: An apparatus and method for providing a ringing voltage to a communication device such as a telephone or a modem. Typically, communication devices are coupled to a ringing voltage providing telephone network, such as a Plain Old Telephone Service (POTS) network. The POTS network generally provides the necessary ringing voltages to the communication device. However, in other telephone networks, such as a PBX system, ringing voltages are not provided by the telephone network. The apparatus provides ringing voltages to the communication devices coupled to the non-ringing voltage providing telephone networks. The apparatus includes a switching regulator that provides the necessary ringing voltages to an indicator such as a bell or other output indicator.

Abstract: In a subscriber line interface circuit, a device applies to a line, associated with the line interface circuit, a substantially constant line current of a first predetermined value for line voltages up to a first voltage having an absolute value which, by a predetermined amount, is lower than the supply voltage of the line interface circuit. For line voltages between the first voltage and a second voltage having an absolute value which, by a predetermined amount, is higher than the first voltage, a line current which is inversely proportional to the line voltage and of a value between said first predetermined value and a second predetermined, lower value is applied to the line. For line voltages between the second voltage and a third voltage having an absolute value which, by a predetermined amount, is higher than the second voltage, a substantially constant line current of the second predetermined value is applied to the line.

Abstract: A known cross-talk adaptive noise cancellation apparatus uses two adaptive filters for suppressing the correlated noise in the main signal, which contains wanted voice and unwanted noise, by a reference signal, which contains unwanted noise and wanted voice via cross-talking. A noise canceler is provided in the present invention including some additional parts, such as a voice detection circuitry and a step size decision circuitry. The voice detection circuitry detects whether the wanted voice exists. The step size decision circuitry decides what the step sizes are used for the next update of the two adaptive filters.