Abstract: Embodiments of the invention comprise a new device and technique to realize an improved conversion of a high resolution signal to a lower resolution signal. This improvement is achieved by replacing an identity matrix with a diagonal matrix in a DCT domain. The diagonal matrix value B is set to be a value that corresponds to a minimized value and/or a threshold value. Successive results form invention are utilized to establish approximate equivalency, where the difference form the absolute true value is less than a predetermined threshold value.

Abstract: In one embodiment, a number of parameter values for an inductor, such as a spiral inductor, are received. Examples of the parameter values are Number of Turns, Spacing, Width, Xsize, and Ysize parameter values. From the received parameter values, a number of parasitic values for a subcircuit model of the inductor are determined. For example, parasitic resistor values and parasitic capacitor values of the inductor are determined. The parasitic resistor values and parasitic capacitor values are used in simulating the circuit comprising the inductor. An inductor layout is then generated that results in parasitic values that are the same as the parasitic values already used in simulating the circuit comprising the inductor. As such, the parasitic values of the inductor have already been taken into account in the initial circuit simulation and, there is no need to extract the internal parasitics of the inductor for further circuit simulations.

Abstract: In an electronic inductor circuit, an operational amplifier drives the base of the electronic inductor transistor, and receives negative feedback from the emitter of the transistor. The transistor and operational amplifier combine to form a voltage-controlled current source (VCCS) with respect to the loop current. A voltage divider connected across the rectified Tip and Ring voltage (or another node of the circuit at an equivalent voltage) provides a DC reference to the positive input of the operational amplifier, so that the line current automatically increases with an increase in line voltage. A capacitor couples the transmit signal driver to the positive input of the operational amplifier. This electronic inductor circuit can be driven using a low voltage supply and provides sufficient linearity for high-speed modem applications.

Abstract: A method for adjusting timing of a secondary system with respect to a reference system is disclosed. The secondary and reference systems include a secondary synchronization signal and a reference synchronization signal, which are used to detect a phase difference between the secondary synchronization signal and the reference synchronization signal. A filtered phase error is generated from the detected phase difference. In addition, a frequency difference is detected between the secondary synchronization signal and the reference synchronization signal, and an instantaneous frequency difference and a filtered frequency error are generated from the detected frequency difference. The filtered phase error and the filtered frequency error are accumulated, and the timing of the secondary system is controlled in accordance with the accumulated filtered phase error, the accumulated filtered frequency error, and the instantaneous frequency difference.

Abstract: A speech compression system capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech is disclosed. The speech compression system optimizes the bandwidth consumed by the bitstream by balancing the desired average bit rate with the perceptual quality of the reconstructed speech. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. The codecs are selectively activated based on a rate selection. In addition, the full and half-rate codecs are selectively activated based on a type classification. Each codec is selectively activated to encode and decode the speech signals at different bit rates emphasizing different aspects of the speech signal to enhance overall quality of the synthesized speech.

Abstract: A speech coding system that employs target signal reference shifting in code-excited linear prediction speech coding. The speech coding system performs modification of a target signal that is used to perform speech coding of a speech signal. The modified target signal that is generated from a preliminary target signal is then used to calculate an adaptive codebook gain that is used to perform speech coding of the speech signal. The speech coding performed in accordance with the present invention provides for a substantially reduced bit-rate of operation when compared to conventional speech coding methods that inherently require a significant amount of bandwidth to encode a fractional pitch lag delay during pitch prediction that is performed within conventional code-excited linear prediction speech coding systems.

Abstract: A system and method for performing power management in a communication system without losing data is disclosed. The G.Lite system is an exemplary system suitable for implementing the present invention because it includes at least one operational state and an idle state in which no data is transmitted. The G.Lite standard defines ATU states. The defined states are full on state L0, low power state L1 and idle state L3. In L0 state, the ADSL link is fully operational at full data rate. In L1 state, the ADSL link is fully operational at a lower data rate. In L3 state, no signal is transmitted. Because no signal is transmitted, no idle cells are transmitted. This will result in losing the cell delineation and ATM link connectivity. Therefore, when data is received for an ATU in L3 state, data cells may be lost.

Abstract: The frequency of use of video and other data is increasing. Additionally, video components are typically connected together. The video components may synchronize via a first in first out (“FIFO”) queue. Data may be written into the FIFO queue by a component with a first clock rate, and then the data may be read out of the FIFO queue by a component with a second clock rate. Because of the different clock rates, it is possible that there could be an underflow or overflow of data in the FIFO queue. Typically, when the timing between the components is far apart, the read and write pointers that point into the FIFO queue are realigned by using a reset control signal, which sets both pointers back to address zero of the FIFO queue. The present system provides an improved technique for synchronizing the read and write pointers. In particular, the present system provides a technique for aligning the read and write pointers of a FIFO queue at any time and at any random address.

Abstract: A method and apparatus for transmission of time critical data over a modem link is disclosed. Time critical data is intercepted by a modem at its host input-output port. The intercepted time critical data is injected directly at the top of the queue of data intended for transmission over the modem link. The injection of time critical data takes place at the input to the modulator in the form of specially identified frames, preferably of short duration. Time critical data is thus sent on a priority basis bypassing error correction circuits or routines, and bypassing data compression. At a receiving modem, time critical data is recognized in the demodulator as specially identified frames or packets. Such time critical data is recovered and immediately sent to the host without passing through the error correction process and without decompression.

Abstract: Disclosed is a frequency-locked loop (FLL), which attempts to bring about frequency and phase synchronization between two signals over the control bandwidth of the loop: a reference signal and a voltage-controlled oscillator (VCO) signal. For example, the FLL employs a reference signal generated by a crystal oscillator of frequency fREF and a VCO signal generated by the oscillations of an unquenched SRG resonator with tunable resonant frequency fRES. These signals are connected to the inputs of a phase/frequency detector (PFD) which produces output pulses in response to the relationship between fREF and fRES. These pulses are applied to a loop filter (LF) which creates a voltage using some kind of charge-storage element. This loop filter voltage is a so-called error voltage whose value is used to control the frequency of the resonator to bring the reference signal and VCO signal into phase synchrony.

Abstract: A speech compression system capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech is disclosed. The speech compression system optimizes the bandwidth consumed by the bitstream by balancing the desired average bit rate with the perceptual quality of the reconstructed speech. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. The codecs are selectively activated based on a rate selection. In addition, the full and half-rate codecs are selectively activated based on a type classification. Each codec is selectively activated to encode and decode the speech signals at different bit rates emphasizing different aspects of the speech signal to enhance overall quality of the synthesized speech.

Abstract: An initialization procedure for a digital modem system treats the presence of ADPCM as if it were a digital impairment such that the modem system can utilize effective compensation techniques to address the ADPCM. The modem system initially determines whether the current communication channel is a fully digital channel. Next, the modem system determines whether the channel includes any ADPCM elements. If ADPCM is detected, then a digital impairment learning routine is performed to obtain the ADPCM compression characteristics and data rate. The digital impairment learning routine may use a single probing sequence to obtain the ADPCM characteristics while identifying any concurrent digital impairments such as RBS, digital pads, and encoding law conversions. Once the digital channel is characterized, the modem system may condition its transmitters and receivers in an appropriate manner to obtain an increased data rate.

Abstract: A pulse code modulation modem system utilizes the same total average transmit power formula for designing signal point constellations and for verifying that the transmit power of the signal point constellations are within a designated maximum power limit. The transmit power of the signal point constellations designed by the client modem is also calculated by the server modem to verify that the transmit power limit imposed upon the server modem is not exceeded. In addition, the modem system is capable of designating a transmit power limit associated with one or more training signal points or a training sequence for use during a training mode.

Abstract: A DSL communication system including a DSL transmission unit at a central office (DTU-C) and a DSL transmission unit at a remote location (DTU-R) in communication over a communication link. DTU-C and DTU-R are capable of transmitting and receiving packets of data prior to synchronization or training. DTU-C transmits a discovery message to DTU-R and awaits receiving a discovery response message from DTU-R. After receiving the discovery response message, DTU-C transmits a probe message to DTU-R followed by a probe signal. DTU-R measures the line quality while receiving the probe signal. After receiving the probe signal, DTU-R transmits a probe signal to DTU-C, using which signal DTU-C measures the line quality. After transmitting the probe signal, DTU-R transmits a probe response message, including line quality measurements performed by DTU-R. DTU-C and DTU-R may negotiate a first data rate by transmitting data rate messages based on the line quality measurements.

Abstract: A multi-rate speech codec supports a plurality of encoding bit rate modes by adaptively selecting encoding bit rate modes to match communication channel restrictions. In higher bit rate encoding modes, an accurate representation of speech through CELP (code excited linear prediction) and other associated modeling parameters are generated for higher quality decoding and reproduction. To achieve high quality in lower bit rate encoding modes, the speech encoder departs from the strict waveform matching criteria of regular CELP coders and strives to identify significant perceptual features of the input signal. The encoder generates pluralities of codevectors from a single, normalized codevector by shifting or other rearrangement. As a result, searching speeds are enhanced, and the physical size of a codebook built from such codevectors is greatly reduced.

Abstract: A method for avoiding time-outs during facsimile transmissions over IP networks is disclosed. In the disclosed method, T.30 commands and responses are passed in V.21 channel 2 (“ch2”) modulation with HDLC framing. Normally, when a T.30 message is sent, the V.21 ch2 carrier starts, then there is one second of HDLC flags, followed by the contents of the message. In a method according to the present invention, the V.21 ch2 carrier and HDLC flags are started when a response is late from the remote facsimile machine. This step is preferably initiated on occasions when a time-out would otherwise be likely in view of the late response. If the response from the remote facsimile machine arrives during the one second HDLC flags, the message is sent to the remote facsimile normally. If the message has not been received by the end of the one second HDLC flags, this period is extended for an additional two seconds.

Abstract: An LO generation circuit generates an LO signal by doubling and quadrupling the frequency of a VCO signal. The frequency doubling and quadrupling provides high VCO-RF isolation as well as suppression of spurious noise signals in the LO output. The frequency doubler takes a quadrature signal input and utilizes mixer cores having double balanced transistor pairs to provide an output signal having doubled frequency but maintaining the phase balance of the input signal.

Abstract: An encoding system is presented for coding and processing an input signal on a frame-by-frame basis. The encoding system processes each frame in two subframes of a first half and a second half. In determining the pitch of a given frame, the encoding system determines the pitch of the first half of the subsequent in a look-ahead fashion, and uses the look-ahead pitch information to estimate and correct the pitch of the second half subframe of the given frame. The encoding system also determines the pitch of the first half subframe of the given frame to further estimate and correct the pitch of the second half subframe of the given frame. The look-ahead pitch may also be used as the pitch of the first half subframe of the subsequent frame. The encoding system further calculates a normalized correlation using the pitch of the look-ahead subframe and may use the normalized correlation to correct and estimate the pitch of the second half subframe of the first frame.

Abstract: A half-duplex facsimile modem system according to the present invention may exhibit a shorter startup time relative to conventional systems. The modem system exchanges capabilities information concurrently with the transmission of a conventional answer signal, thus obviating the need for performing a separate capabilities exchange procedure. In addition, the modem system is capable of determining a preferred training sequence duration based upon one or more characteristics of the current channel. The preferred training sequence duration is communicated from the answer modem to the calling modem such that the calling modem can format the training sequence in an appropriate manner. The resultant training sequence has a time duration that is variable in response to, e.g., the signal-to-noise ratio of the instant channel. These techniques can result in a significant reduction in the startup latency typically associated with conventional half-duplex facsimile modem systems.

Abstract: A communication system that includes a first modem and a second modem that establishes a communication link between the first modem and the second modem. The communication link has a first set of communication characteristics including a first communication channel or group of communication channels through which at least data is exchanged and a second communication channel through which no data is exchanged. Either the first modem or the second modem is configured to signal for a change, via the second communication channel, in the first set of communication characteristics.