Abstract: A tone fault detection system is coupled to a telephonic system, such as an automatic call distributor (ACD) via an ISDN communication link. The ACD includes a multiport switch with a plurality of ports on which tones and messages are provided, and a basic rate line interface device coupled to the multiport switch for communicating with the tone fault detection apparatus. The tone fault detection system includes a telephonic adapter configured to communicate with the ACD and a central processor coupled to the telephonic adapter where the central processor is configured to send and receive data signals and control signals. Also included is an audio detection circuit coupled to the telephonic adapter to receive signals representative of the tones and messages provided by a selected port of the ACD, where the audio detection circuit is configured to measure a power level of the received signal and to provide an indication to the central processor whether the measured power level is within a predetermined range.

Abstract: A pulse code modulation (PCM) modem system employs a relatively white training signal to optimize the adaptive filter coefficients in the receiver equalizers. During the training mode, any line coding or equivalent spectral shaping is disabled to provide a training signal sequence having a substantially even spectral content. The presence of DC within the training signal reduces the likelihood that the error function of the equalizers will settle at a local minimum. Following the training interval, the encoder enables the line coder to condition the digital input sequences, introduce DC nulls, and reduce the detrimental effects of baseline wander.

Abstract: A method and apparatus are provided for identifying a call record by a source automatic call distributor to a host computer of a telephone call received from a PSTN and overflowed from the source automatic call distributor to a destination automatic call distributor in a call distribution system using telescripted call control. The call record is stored under a call identifier of the source automatic call distributor in a memory of a host computer serving both the source automatic call distributor and the destination automatic call distributor. The method comprises the steps of executing a telescript sequence by the source automatic call distributor which sends a call identifer assigned by the source automatic call distributor and an identifier of the source automatic call distributor to a call overflow identification table of the host and transferring the call to the destination automatic call distributor along with the call identifier of the source automatic call distributor.

Abstract: An apparatus and method are provided for identifying a call record of a telephone call to be overflowed from a source automatic call distributor to a destination automatic call distributor. The call record is of a type having been previously stored under a call identifier of the source automatic call distributor in a memory of the host computer serving both the source automatic call distributor and destination automatic call distributor in an area of the memory reserved for the source automatic call distributor. The method includes the step of storing a call action provided message in a call overflow table of the host computer including the call identifier of the telephone call and an identifier of the source automatic call distributor.

Abstract: A low cost, high performance near direct conversion FM receiver having a single local oscillator is configured to equalize in-phase and quadrature-phase IF signals. The receiver includes a downconverter and a processor. The downconverter receives an RF signal and downconverts the RF signal to an in-phase IF signal (IF.sub.I) and a quadrature-phase IF signal (IF.sub.Q). The processor digitizes IF.sub.I and IF.sub.Q, corrects these signals so that they are substantially equal in magnitude and substantially 90.degree. out of phase, and then downconverts the IF signals to baseband signals (I, Q).

Abstract: A DRAM controller refreshers a DRAM having a maximum refresh interval. The DRAM controller measures a time interval after a refresh cycle, monitors a memory request input of the DRAM for an idle period after a measured time interval of substantially less than the maximum refresh interval, and refreshes the DRAM with a refresh cycle upon detecting one of an idle period and a measured time interval of the maximum refresh interval.

Abstract: A synthesizer system includes a CPU and host memory operating a software routine. The software routine stores a first part of each waveform signal in a sample pool of host memory and provides remaining portions of selected musical sounds from the hard drive to a stream cell array without an audio perceivable delay. The synthesizer system utilizes a caching system which allows low cost, high storage devices to be utilized in an audio synthesizer system. MIDI control signals are provided to an audio processor for selecting appropriate digital waveform signals.

Abstract: A multi-purpose current source which provides both a PTAT and a constant current source and which requires only one precision external or laser trimmed resistance. The PTAT constant current circuit includes a differential amplifier having one input coupled to a V.sub.PTAT reference voltage and the other input coupled to a V.sub.bg scaling circuit. The tail current for the differential amplifier is held constant at the current level of an associated constant current source based upon V.sub.bg. Therefore, the amount of current output from the PTAT current source will be dependent upon the current of the constant current source, rather than upon a resistance value. By setting the scaling circuit appropriately, the current that flows through the output leg of the differential amplifier in the PTAT current source when the ambient temperature is equal to 25.degree. C. will be equal to one half the tail current through the differential amplifier, and thus one half the current output from the constant current source.

Abstract: The present invention relates to circuitry for a receiver having a low cost filter using automatic alignment of the center frequency of signals input to the filter to suppress noise and out-of-band signals from the filter output over a narrow bandwidth. An RF input signal to the receiver is downconverted to an IF frequency using a VCO, and the IF signal is provided to the low cost filter. The output of the filter is input to a frequency correction circuit and a distortion detection circuit. The distortion detection circuit provides an error signal including positive frequency shift errors determined from digital ones identified from the filter output signal, and negative frequency shift error signals determined from digital zeros in the filter output signal.

Abstract: An improved frame structure for use in mobile communications systems utilizing slotted protocols is provided. According to the present invention, consecutive slots in a frame are assigned to each mobile unit so that the mobile unit transmits to a base station during the first slot and receives a transmission from the base station during the second slot. This frame structure, permits the mobile unit to monitor various frequencies for a longer and more continuous period of time. It is important for the mobile unit to have enough time to monitor frequencies while it is not transmitting or receiving so that base station handoff and interference avoidance handoff techniques can be performed by the mobile communications system. Furthermore, according to the frame structure provided by the present invention, the mobile units can be designed with a standard frequency synthesizer.

Abstract: The present invention provides methods for combining antenna diversity and gain control in a communications system using a single chain of receiver electronics. A number of input parameters related to various characteristics of a received signal are used to determine the quality of the received signal. The antenna diversity and gain control procedures are enabled or disabled based on the signal quality. The antenna diversity procedure estimates the signal level of the non-operational antenna using an infinite impulse response digital filter. The gain control procedure selects one of three gain paths based on the received signal strength.

Abstract: The present invention provides methods for combining antenna diversity and gain control in a communications system using a single chain of receiver electronics. A number of input parameters related to various characteristics of a received signal are used to determine the quality of the received signal. The antenna diversity and gain control procedures are enabled or disabled based on the signal quality. The antenna diversity procedure estimates the signal level of the non-operational antenna using an infinite impulse response digital filter. The gain control procedure selects one of three gain paths based on the received signal strength.

Abstract: The present invention provides methods for combining antenna diversity and gain control in a communications system using a single chain of receiver electronics. A number of input parameters related to various characteristics of a received signal are used to determine the quality of the received signal. The antenna diversity and gain control procedures are enabled or disabled based on the signal quality. The antenna diversity procedure estimates the signal level of the non-operational antenna using an infinite impulse response digital filter. The gain control procedure selects one of three gain paths based on the received signal strength.

Abstract: An integrated circuit chip set is provided for use in a radio communication system in which a modulated digital input signal is processed for transmission and a modulated signal received from an antenna is processed to provide an output signal, wherein the modulation of the signals is either QPSK or FSK and the signal transmission and reception is by either TDD or FDD.