Abstract: The amplitudes of a signal on the microphone input of a telephone and a signal on the line input of the telephone are compared with each other and with two thresholds. The comparisons are sampled and the samples control an up-down counter. The count in the counter is compared with two thresholds and the results of the comparisons are used to control at least two accumulators. A first accumulator counts consecutive comparisons having the same result and a second accumulator counts up or down in accordance with the comparisons. The counts in the first and second accumulators are logically analyzed to determine whether to receive or transmit. A plurality of samples defines a window, at the end of which the up-down counter is reset. The accumulators store data from a plurality of windows.

Abstract: The amplitudes of a signal on the microphone input of a telephone and a signal on the line input of the telephone are compared with each other and with two thresholds. The comparisons are sampled and the samples control an accumulator including an up-down counter and logic to provide adjustable thresholds. The count in the counter is compared with two other thresholds and the results of the comparisons are used to apply either variable data or fixed data to the counter.

Abstract: A telephone having a line input, a line output, a handset microphone, and a handset speaker also includes a first soft mute circuit coupling the handset microphone and the line output and a second soft mute circuit coupling the line input and the handset speaker. The telephone is operated in a first mode and can change modes only after muting one or both soft mute circuits, changing mode, and then operating in the second mode only after unmuting the circuits. The muting may be momentary or prolonged, depending upon the particular mode of operation. An additional soft mute circuit is used in a speakerphone.

Abstract: This invention provides joystick interfaces and methods of providing position information of a joystick.

Abstract: Correlation is improved by comparing the output of a multiplier and low pass filter to a first threshold and incrementing a counter when the output from the filter exceeds the first threshold; comparing the output of the filter to a second threshold and decrementing the counter when the output is below a second threshold. Correlation is indicated by the count in the counter exceeding a predetermined amount.

Abstract: The amplitudes of a signal on the microphone input of a telephone and a signal on the line input of the telephone are compared with each other and with two thresholds. The comparisons are sampled and the samples control an up-down counter. The count in the counter is compared with two thresholds and the results of the comparisons are used to control at least two accumulators. A first accumulator counts consecutive comparisons having the same result and a second accumulator counts up or down in accordance with the comparisons. The counts in the first and second accumulators are logically analyzed to determine whether to receive or transmit. A plurality of samples defines a window, at the end of which the up-down counter is reset. The accumulators store data from a plurality of windows.

Abstract: An audio signal is divided into a plurality of bands prior to generating a shadow. The shadow is created by delaying the portion of the audio signal in at least one band by less than fifty milliseconds and combining the shadow signal with the portion of the audio signal. The portions, with any shadows, are combined to produce a reconstructed audio signal. The presence or absence of a shadow signal represents data or the data is represented by two or more shadow signals, in one or more bands. The period of delay of a portion in a band should not equal the period of the center frequency of that band. Preferably, the period of delay of a portion in a band does not equal the period of any frequency within the pass band.

Abstract: This invention provides joystick interfaces and methods of providing position information of a joystick.

Abstract: A virtual contiguous system for combining multiple and arbitrarily-sized and aligned digital data packets from a PCI bus to a DSP circuit is disclosed. Information from the PCI bus is supplied directly to a plurality of FIFO RAM memory units. Each packet of digital data includes data packet descriptors identifying at least the start address for each data packet and the size of each data packet. The system utilizes this information to operate a read pointer and a write pointer to remove data from the FIFO RAM memory units on a sequential bit-by-bit basis and to supply said data packets to said RAM memory units by means of a write pointer operated by said control circuit. The information transfer is managed on the read side of the FIFO RAM memory units with minimal processing on the write side.

Abstract: The present invention relates to a system and a method for reducing access times for retrieving audio samples. The system uses a wave table cache. The wave table cache allows devices such as a Digital Signal Processor (DSP) to retrieve audio samples in a linear fashion from the wave table cache at a rate much faster than individually fetching the required portions of the audio sample from the main memory of the system. The DSP may then use the audio samples to generate signals to create sounds based on the audio samples.

Abstract: A method for storing and transferring wave table audio samples from system memory to a cache unit. The method creates a linked-list of pages in system memory for storing the audio sample. The linked-list is actually a pointer list indicating the locations in system memory where the audio samples are stored. A Digital Signal Processor (DSP) is able to translate the starting address of the pointer list to retrieve a requested audio sample from the system memory. The requested audio sample is then transferred to the cache unit where the DSP is able to retrieve audio samples in a linear fashion at a rate much faster than individually fetching the required portions of the audio sample from the main memory of the system.

Abstract: A universal asynchronous receiver/transmitter (UART) computer programming interface emulates three-wire interface control. A register select circuit is supplied with address signals from a host CPU and has a plurality of register outputs organized into first and second groups. One of these groups of outputs are those which are required for three-wire operation in communications devices; and these outputs are mapped to the appropriate communications devices or registers. The other group of outputs required for three-wire operation, but with no corresponding function in a communications device, are implemented by means of an UART emulator circuit producing a data output which is coupled to an internal data bus, along with the output of the registers for the communications devices.

Abstract: A method for storing and transferring wave table audio samples from system memory to a cache unit. The method creates a linked-list of pages in system memory for storing the audio sample. The linked-list is actually a pointer list indicating the locations in system memory where the audio samples are stored. A Digital Signal Processor (DSP) is able to translate the starting address of the pointer list to retrieve a requested audio sample from the system memory. The requested audio sample is then transferred to the cache unit where the DSP is able to retrieve audio samples in a linear fashion at a rate much faster than individually fetching the required portions of the audio sample from the main memory of the system.

Abstract: A digital power management system for an analog-to-digital converter operates to cause the sample rate of the analog-to-digital converter to function at an original desired frequency so long as changing input signals are present. Whenever activity at the input of the analog-to-digital converter ceases to change, the system automatically decreases the clock signal sampling rate to a slower clock frequency, or shuts down the application of clock signals. This conserves power until a change in the analog input is detected, whereupon the system automatically increases the sample clock frequency back to the original frequency.

Abstract: An interrupt based positioning system for a joystick. A potentiometer is coupled to the joystick for supplying a voltage signal representative of a current position of the joystick. An analog-to-digital converter changes the voltage signal to a digital voltage signal which is then stored in a register. Interrupt generation logic monitors the output of the register and generates a position interrupt signal when the digital voltage signal stored in the register indicates a change in the axial position of the joystick.