Abstract: A plurality of passive distributed POTS filters (DPF) are associated with a respective plurality of POTS communications devices and decouple a POTS channel from a telephone connection, while permitting and not interfering with a second communications channel (e.g., DSL, ADSL, SDSL, RADSL, VADSL, etc.) on the telephone connection that is utilized by a modem. In architecture, the DPF system includes a plurality of POTS communications devices, such as telephones, and a plurality of the DPFs corresponding respectively with and connecting each of the POTS communications devices to the telephone connection. Each of the DPFs comprise an automatic control mechanism and a POTS filter. The automatic control mechanism is configured to isolate the POTS filter when a respective POTS communications device is on-hook. Each DPF is configured to permit POTS communications over a POTS channel on the telephone connection with the respective POTS communications device when the POTS communications device is off-hook.

Abstract: Digital data is encoded by partitioning a predetermined number of bits into two separate words. The first word is mapped into a first symbol constellation to produce a first data signal. The second word is mapped into a second symbol constellation that has a different number of symbols than the first symbol constellation to produce a second data signal. An additional signal is added to the first data signal to form a first combined signal. Another additional signal is added to the second data signal to form a second combined signal. The first and second combined signals are transmitted over a communication channel.

Abstract: A radio frequency (rf) receiver adapted to receive a number of different digitally modulated rf input signals such as quadrature amplitude modulated (QAM) and vestigial side band (VSB) rf input signals includes circuitry for down converting the rf input signals to an intermediate frequency (IF) range having a center frequency fc2 and a bandwidth of Bhz and converter circuitry for sampling the IF signals and then producing corresponding baseband signals. In a preferred embodiment, the intermediate frequency signals are applied to a sample and hold circuit which is sampled at a frequency fs and whose output is coupled via a low pass filter to an analog-to-digital converter whose output is then applied to a Hilbert filter for demodulating the sampled signals and producing baseband signals. In-phase (I) and quadrature (Q) signals are produced whose phase and amplitude are not a function of different components and their tolerance of different conduction paths, as in the prior art.

Abstract: A multiple line modem and method enable a user to automatically usurp a plurality of telephone lines for data transfer when the telephone is not in use and the ability to switch from multiple line data operation to one (or more) line data and one (or more) line telephone operation automatically when the telephone handset is lifted or an incoming call is detected signaling a request for voice service. The multiple line modem will automatically reestablish the data connection on the line(s) that was used for voice service when the voice service terminates. The multiple line modem allows end to end service that is transparent to the central office. When all lines are operating in data transfer mode, the aggregate data transfer rate is multiplied by the number of lines available for data transport. When one line(s) is operating in voice service mode, the other line(s) maintains data transfer operation at a reduced rate.

Abstract: A far-end modem transmits a "pilot tone" during the time that a near-end modem is training its echo canceler. Correspondingly, the near-end modem is modified to notch, or filter, out this pilot tone from the received signal. The filtered received signal is then used by the near-end modem to train its echo canceler.

Abstract: A fast response gain tracker operates to adjust the magnitude of an echo cancellation signal. The latter signal is developed from an echo canceler. The fast response gain tracker provides an adjusted echo cancellation signal that is subtracted from an echo-corrupted received signal to provide an echo-canceled signal. In particular, the fast response gain tracker correlates the echo-canceled signal with the echo cancellation signal from the echo canceler. If the gain of the gain tracker is correct the echo is canceled and there is zero correlation between the echo-canceled signal and the echo cancellation signal. However, if the echo level changes then a residual echo component appears in the echo-canceled signal, which now becomes correlated with the echo cancellation signal. In response, the magnitude of the gain tracker automatically adjusts the gain of the echo cancellation signal to match the change in echo level and thereby subsequently eliminates the residual echo.

Abstract: A compensation system is configured to improve the accuracy of digital signals that are communicated through a digital network by reducing loss from digital attenuation quantization (DAQ; digital pad quantization) and rob bit signaling (RBS). The combined DAQ/RBS compensation system can be employed within a transmitting modem connected to the digital network and is constructed as follows. In a first embodiment, a first adjustment mechanism combines a DAQ compensation quantity with each segment of the digital data, prior to transmission, in order to enhance accuracy of the received digital data. The value of the DAQ compensation quantity depends on feedback that is provided to the compensation system during a series of test transmissions.

Abstract: A processor of a cellular modem monitors for the presence of a residual echo signal during a full-duplex portion of a training sequence. In particular, the processor monitors an equalizer error signal during a full-duplex training phase that follows the half-duplex training phase for the echo canceler. If the processor detects a level of the error signal greater than a predefined threshold, the processor presumes the increase in the error signal is due to the presence of a residual echo signal and performs a predefined adjustment of the taps of the corresponding echo canceler of the cellular modem.

Abstract: Existing customer premises wiring can be used with high speed digital modems, such as RADSL modems by using POTS filters in line with each piece of PSTN equipment. Alternatively, an RADSL modem includes a line monitor which detects when a piece of PSTN equipment experiences a hook-switch transition. Upon that occurrence, the error detection circuitry in the RADSL modem is disabled for a time period sufficient to avoid the counting (with associated RADSL modem rate change) of any burst errors associated with the PSTN equipment going off-hook or on-hook.

Abstract: A system is provided for automatically selecting the mode of communication between a plurality of multi-mode modems. A calling modem and an answering modem are disposed for intercommunication across an established communication link of a telephone network. The calling modem transmits a continuous calling signal across the established link, and the answering modem detects the calling signal and analyzes the calling signal to determine the configuration of the calling modem. In response, the answering modem generates and transmits an answering signal across the established link. The calling modem detects and analyzes the answering signal to determine the configuration of the answering modem. Finally, the system determines whether the established link passes through a PSTN, and if so, transmits a 2100 hertz tone across the established link. Otherwise, the system proceeds directly to the a modem training sequence.

Abstract: A method and simultaneous voice/data transmission of signals through a single communications channel wherein the transmitted voice and data signal quality is greatly enhanced over current practice. A time-varying stream of coded voice and data signals is simultaneously transmitted and the sequence of transmitted data signals is determined only after receiving data signals for a predetermined period of time. The received signals are buffered and a received coded data signal sequence is compared to a predetermined plurality of permissible coded data signal sequences to correlate the received coded data signal sequence with the particular permissible coded signal sequence with which the data signal was coded prior to transmission. The correlated data signal sequence is then separated from the combined voice and data signal to recover the coded voice signal.

Abstract: A transmitting Mu-law modem creates a probe signal by modifying the 7th bit of each of a number of PCM samples during the "hand-shaking" phase of a data connection. Furthermore, the transmitting Mu-law modem only makes this modification on those PCM samples that fall into the range of segment 1 as defined in CCITT Recommendation G.711. Similarly, a receiving Mu-law modem searches for this known pattern. Upon detection of this pattern, the receiving Mu-law modem provides an acknowledgment signal and both modems subsequently switch to a digital-mode of operation. On the other hand, if, in fact, there is a least one analog link in the data connection, the probe signal becomes distorted and, since the receiving Mu-law modem does not detect the probe signal, handshaking is completed in the standard fashion.

Abstract: A cellular data gateway situated at a mobile telecommunications switching office (MSC) is provided for interconnecting an originating mobile modem of an analog cellular system to an answer modem of a public switched telephone network (PSTN) when one of the either the cellular side or the PSTN side of the connection is capable of a fast connection sequence. The cellular data gateway comprises a quick connect cellular modem connected to the MSC and configured for interfacing with the originating mobile modem. The cellular data gateway further includes a PSTN modem connected to the MSC and configured for interfacing with the answer modem of the PSTN. The cellular modem and the PSTN modem are interconnecting in the cellular data gateway as a back-to-back modem pair. As an important part of the invention, the cellular modem includes a mechanism for delaying the initiation of a fast connect sequence with the originating mobile modem until the PSTN modem has established a connection with the answer PSTN modem.

Abstract: A cellular modem pool provides call progress information to a calling party during call setup. In particular, the cellular modem pool includes a coupling means, which communicates any signals between the cellular-side of the cellular data connection and the PSTN-side of the cellular data connection during call setup. This allows the calling party to hear the call progress on the called party side of the data call. In addition, the cellular modem pool monitors the signals for a data signal provided by the called party, e.g., a predefined answer tone. Once the answer tone is detected, the cellular modem pool opens the connection provided by the coupling means and processes the respective signals on the cellular-side and the PSTN-side of the cellular modem pool.

Abstract: A noncooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codec, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network. The noncooperative feedback system is particularly suited for providing feedback to a compensation system for correcting distortion resulting from rob bit signaling (RBS), digital loss, or other types of digital signal degradation. The noncooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines different compensations with frames of digital data by way of an addition mechanism to produce modified digital data frames. The transmitter is configured to transmit the modified digital data frames into the digital network. A receiver (e.g., digital modem, analog modem, etc.

Abstract: A modified version of the operating communication program of a stored program controlled apparatus is downloaded by first downloading a segment of the new package of programs which contains the essential portion of the new programs. Control of the apparatus is then transferred to the new program segment. Thereafter, utilizing the downloaded essential portion of the new package of programs, the remainder of the new package of programs is downloaded.

Abstract: A slot token protocol for establishing and terminating data-links over a serial bus shared by multiple devices with low overhead, no supporting hardware, a low collision rate, and fast collision resolution. Of the devices sharing the serial bus, one device is designated as the master device with the remaining devices being designated as slave devices. The master device is responsible for controlling allocation of the serial bus between each of the slave devices so that only one slave device controls the bus at a time. The master device achieves this by requiring slave devices to submit bus requests before the requesting slave device is allocated control over the serial bus. In addition, a busy bus line may be included to reduce the likelihood of a data collision on the serial bus by connecting the master an slave devices with a bus busy line and allowing a slave device to signal to the other slave devices over the bus busy line that it intends to transmit a bus request.

Abstract: Using digital signal processing in a modem attached to a digital line, the modem sample rate for both transmit and receive signals is interpolated or decimated to the time slot rate of a digital channel connected to the modem by filters which are operated by a unified interpolation/decimation filter controller as a function of a modulo counter. For example, a modem signal is developed as if it were to be supplied to a codec. However, instead of being supplied to the codec, the signal is filtered using a low pass finite impulse response digital filter. The resulting filtered signal is sampled at the time slot rate and supplied in companded form as an output to the time slots of the digital line. Prior to operating the filter, the ratio of the time slot rate to the sample rate is determined. The ratio is expressed in a form that is a ratio of the smallest possible integers. The numerator of the resulting ratio is designated P and the denominator is designated I.

Abstract: A rob bit compensation system improves the accuracy of digital signals received from and transmitted to a digital network, such as a telephone network, that employs rob bit signaling (RBS) wherein the network periodically robs a bit for its own use. The system can be employed within a digital modem or a coder/decoder (codec), each of which is interconnected with the digital network that periodically robs a bit every nth frame, where n is, for example, 6 or 24. The system can be implemented in association with the receive subsystem of the digital modem or in the communications paths within the codec associated with receiving data from the digital network. The system includes a compensation control utilized to detect when a least significant bit (LSB) of a particular frame of data consistently exhibits a certain logic state, either a mark (logical 1) or a space (logical 0). When an LSB of a particular frame does consistently exhibit the certain logic state, then the particular frame is considered an RBS frame.

Abstract: A bus resolution system and method for resolving bus contention is used on a serial bus shared by multiple devices that broadcast data over the serial bus between the devices, giving rise to the possibility of data collisions. Of the devices sharing the serial bus, one device is designated as the master device with the remaining devices being designated as slave devices. The master device is responsible for controlling allocation of the serial bus between each of the slave devices so that only one slave device controls the bus at a time. Further, the master device is responsible for resolving bus collisions when multiple slave devices attempt to transmit at the same time and their data overlaps in time. Upon detecting a bus collision, the master device quickly and deterministically resolves the collision by identifying one of the colliding slave devices so that its data can be transmitted successfully.