Abstract: An N:1 transcoder (12, 40) with a compression data path that includes uncompressed digroup circuits (92, 94, 96, 98, and 100) each receiving N incoming uncompressed signal and extracting a plurality of control, signaling, and voice/data traffic channels therefrom, a compressor (120) coupled to the uncompressed digroup circuits (92, 94, 96, 98, and 100) and compressing data in selected ones of the extracted voice/data channels, and a compressed data circuit (126) coupled to the compressor (120) for packing the compressed data into predetermined channels of one compressed signal, and further providing control, signaling, and performance monitoring information embedded therein.

Abstract: According to the teachings of the present invention, a data path interface (16) for receiving an incoming signal (14) and facilitating an interface to a digital signal processor (18) includes a synchronizer (62) for determining a signaling frame in a processed signal received from the digital signal processor (18). The data path interface (16) also includes an idle code detector (76) operable to detect an idle code in the incoming signal (14) by comparing the incoming signal (14) to at least one user-programmable idle code pattern. The data path interface (16) further including a least significant bit detector (78) operable to detect a loss of information in the incoming signal (14) by monitoring the status of the least significant bit of each channel to determine whether that bit is stuck at a particular value.

Abstract: An N:1 transcoder (12, 40) with a compression data path that includes uncompressed digroup circuits (92, 94, 96, 98, and 100) each receiving N incoming uncompressed signal and extracting a plurality of control, signaling, and voice/data traffic channels therefrom, a compressor (120) coupled to the uncompressed digroup circuits (92, 94, 96, 98, and 100) and compressing data in selected ones of the extracted voice/data channels, and a compressed data circuit (126) coupled to the compressor (120) for packing the compressed data into predetermined channels of one compressed signal, and further providing control, signaling, and performance monitoring information embedded therein.

Abstract: An N:1 transcoder (12, 40) with a compression data path that includes uncompressed digroup circuits (92, 94, 96, 98, and 100) each receiving N incoming uncompressed signal and extracting a plurality of control, signaling, and voice/data traffic channels therefrom, a compressor (120) coupled to the uncompressed digroup circuits (92, 94, 96, 98, and 100) and compressing data in selected ones of the extracted voice/data channels, and a compressed data circuit (126) coupled to the compressor (120) for packing the compressed data into predetermined channels of one compressed signal, and further providing control, signaling, and performance monitoring information embedded therein.

Abstract: A full duplex speakerphone for connection to a telephone system employs adaptive FIR filters for acoustic and electrical echo cancellation in a novel combination with analog gain controls responsive to incoming signal levels and a transmit level control responsive to the receive signal power level. The particular combination minimizes the amount of digital signal processing required to maintain full duplex operation by holding the signal dynamic range within predetermined limits.

Abstract: The length (or the number of taps) of an adaptive finite impulse response (AFIR) filter is continuously modified to produce optimal echo cancellation. In accordance with one illustrative embodiment, this modification is performed by increasing or decreasing the number of delayed samples which are used to generate an echo estimate. More specifically, the number of samples used to generate the echo estimate is determined by selecting a trial number of samples and operating the filter for a sufficient length of time to allow the tap weights in the filter to stabilize. The tap weights are then examined to determine whether the taps at the end on the filter contribute at least a first threshold amount to the echo estimate. If not, the number of samples used in the filter is reduced and the process repeated. If the taps at the end of the filter contribute more than a second threshold amount, the number of samples is increased and the process is repeated.

Abstract: In accordance with the present invention a plurality of input control data bits are added to a plurality of input telecommunications transmission channels in the form of an input control word wherein any of the individual data bits can be changed without adversely effecting the ability of the system to synchronize and recover the added control word from the multiplexed data stream at the receiving end. A service channel is thus provided. The synchronization circuit described by the present invention is particularly useful in telecommunications transmission of a large plurality of communication channels as is the case in fiber optic transmission wherein a single control word may be useful, for example, as an alarm with respect to one or more of the multiplex telecommunications channels. In a preferred embodiment of the invention, an 8 Kbit/sec control channel is described.

Abstract: Feedback equalization is employed for digital repeaters of transmission systems having twisted-wire pairs, in order to reduce intersymbol interference while minimizing near-end crosstalk gain. Previously the incoming signal was selectively amplified at the higher frequencies in order to negate intersymbol interference, with subsequent near-end crosstalk gain. According to the present invention the intersymbol interference element of an incoming signal is cancelled, prior to amplification in an adder by a compensation signal derived from the output signal of a regenerator and a retimer. An output stage serves to amplify and shape the resultant signal to a form suitable for transmission. The compensation signal comprises the inverted output of a filtering and scaling network.