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 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 synchronous clock regeneration system is implemented in a modem to enable the generation of a clock waveform at the same frequency as that of the transmitting device. The synchronous clock regeneration system receives an error signal indicating the timing difference in the receiving modem and the remote modem. The value in the error signal is added to a value in an offset integrator which integrates all of the error signals produced in a given transmission. The data is then relayed to a modulo subtractor which subtracts a predetermined value from the data if the value of the data is greater than the predetermined value. The data is then introduced to the offset integrator for integration and to a waveform generator. The waveform generator uses the data to offset a supply waveform an appropriate amount to match the frequency of the remote modem. As a result, the waveform generator produces a waveform that synchronously and smoothly tracks the clock waveform generated by the remote modem.

Abstract: A cooperative feedback system is provided for a compensation system associated with, for example, a transmitter or codes, for enabling the compensation system to improve the accuracy of digital signals transmitted to a digital network. The cooperative 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 cooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines 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 rob bit compensation system improves the accuracy of digital signals 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 rob bit compensation system can be employed within the transmit subsystem of a digital modem connected with the digital network that periodically robs a bit every nth frame, where n is, for example, 6, 12, or 24. The system may also be employed in association with the communications path within a coder/decoder (codec) that transmits data to the digital network. A feedback system advises the rob bit compensation system as to which frames of outgoing digital data are to have a bit robbed therefrom by the digital network. The feedback system causes a quantity to be mathematically combined with the digital data corresponding with each RBS frame in order to enhance accuracy of the RBS frames.

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 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: 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 cooperative 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 cooperative 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 cooperative feedback system includes a compensation selector in a transmitter (e.g., digital modem, analog modem, codec, etc.) that combines 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 rob bit compensation system improves the accuracy of digital signals 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 rob bit compensation system can be employed within the transmit subsystem of a digital modem connected with the digital network that periodically robs a bit every nth frame, where n is, for example, 6, 12, or 24. The system may also be employed in association with the communications path within a coder/decoder (codec) that transmits data to the digital network. A feedback system advises the rob bit compensation system as to which frames of outgoing digital data are to have a bit robbed therefrom by the digital network. The feedback system causes a quantity to be mathematically combined with the digital data corresponding with each RBS frame in order to enhance accuracy of the RBS frames.

Abstract: A echo-canceling modem uses pre-emphasis in both the transmitter and receiver sections. In particular, the receiver section of the modem processes a received signal with a pre-emphasis filter before performing echo cancellation on the received signal. The receiver pre-emphasis filter is identical to the transmitter pre-emphasis filter, i.e., the pre-emphasis added in the receiver is the same as the pre-emphasis added in the transmitter.