Abstract: A system and method for controlling the time occupation of signalling frequencies is disclosed, in a frequency hopping system including a plurality of remote stations communicating under control of transceivers with a transceiver of a base station, such communication being performed over a shared medium through a sequence of frequency hopping periods in a plurality of operating frequencies. The method consists in selecting a set of signalling frequencies among the operating frequencies, and interleaving signalling messages transmitted on each signalling frequency within each frequency hopping period to allow a remote station to enter the network for the first time or by re-acquiring synchronization, by scanning each signalling frequency for receiving a signalling message.

Abstract: A method and apparatus is provided which allows overlapping of DMA line read and line write cycles. In an exemplary embodiment, the PLB Line Read Word Address bus is used with a DMA controller sideband signal to detect the conditions required to allow the DMA controller to start the line write one cycle prior to the completion of the line read cycle. A reference bit is set when the first word of a multi-word line transfer has been read. A sideband timing signal is generated one cycle prior to the completion of the read cycle indicating that there is only one read data phase remaining of the line read. If the first word to be written out to memory has been read or is available when the timing signal is generated, the write operation is begun prior to the final phase of the memory read transfer, and the read and write operations are overlapped thereby accomplishing an overlapped read/write transfer in fewer cycles than the sum of read and write transfer cycles if done sequentially.

Abstract: A system and method for tracing program code within a processor having an embedded cache memory. The non-invasive tracing technique minimizes the need for trace information to be broadcast externally. The tracing technique monitors changes in instruction flow from the normal execution stream of the code. The tracing technique monitors the updating of processor branch target register contents in order to monitor branch target flow of the code. Tracing of the program flow includes tracing instructions both before and after a trace triggering event. The implementation of periodic synchronizing events enables the tracing of instructions occurring before and after a triggering event.

Abstract: A computer telephone relay service for interfacing between a textphone and a telephone. A textphone call is made to the computer which makes a further call to a telephone or vice versa. The computer then translates the messages between the text-phone and telephone using voice recognition and text-to-speech hardware.

Abstract: The invention features a system and method to enable real-time establishment and maintenance of a standard of operation for a data communications network. The standard is a data set which includes network activity which is historically categorized by traffic type and by activity. The process begins with monitoring the network media or some network component over some period of time. The monitoring information is used to build benchmark data sets. The benchmark data sets contain a standard of operation for the network, which are historically categorized by either traffic type or activity. This standard of operation is constantly built by the intelligent monitoring facilities. After some period of time which is referred to as the benchmark data set refresh interval, the benchmark that was created is employed in a fashion to allow a determination as to whether the data that is taken from the current monitoring activity indicates normal network behavior.

Abstract: Multi-channel recording system for audio signals comprising a general purpose computer (13) having a sound card (18) with two analog-to-digital converters (20, 22) for receiving two analog audio signals and recording these signals into digital form into a memory, and comprising an analog multiplexer (10, 12) arranged to combine a plurality n of input audio signals in analog form and to supply two resulting multiplexed signals (14, 16) to the analog-to-digital converters (20, 22), the computer (13) being arranged to function as a digital de-multiplexer (28, 30) for recovering the input audio signals in digital form and recording them into memory.

Abstract: According to the present invention, an adaptive and efficient MAC protocol for wireless access to an ATM network is capable of supporting any type of ATM service class with associated Quality of Services parameters. An ATM cell-switched architecture is utilized in which several ATM Mobile Terminals within a given geographic cell (small cells covering a range of several tens of meters) communicate with an ATM Access Point using radio frequency channels, which is connected to an infrastructure ATM network by the means of conventional ATM links. Mobile Terminals can operate both indoor and outdoor with limited range and have wireless access to the Access Points on the ATM network.

Abstract: A data transceiver employing optical radiation comprises transmitter assembly with an optical emitter operable in a first band and an optical emitter in a second band and a receiver assembly with a wide band optical detector which can receive signals transmitted via both the first and second band. In a second embodiment, the receiver includes both a wide band optical detector and a second optical detector which is operable in only one of the first and second bands, the receiver subtracting signals received at the second optical detector from those received at the wide band detector to separate signals received via the first and second bands. In a preferred aspect, the optical radiation employed is infrared radiation and the first and second bands are near and medium infrared bands.

Abstract: After the medium has been processed by the medium processing apparatus 100 (receipt journal printer), it lands on the top cover 120 of the medium processing apparatus 100 as a curled medium 160. The ejected medium drop prevention mechanism 110 is disposed at the point where the edge of the ejected medium lands. The ejected medium drop prevention mechanism 110 has a ladder like structure and holds the edge of the ejected medium by introducing the edge into the opening of the ladder like structure, thereby preventing the ejected medium from dropping down.

Abstract: An apparatus and system for reducing noise detected by a magnetic read head. In particular it relates to reducing magnetic interference at a magnetic read head by dynamically positioning a piece of highly permeable nickel-copper alloy near the magnetic read head thereby shunting the interfering magnetic radiation away from the read head.

Abstract: The wireless communication system, comprising a transmitter and a receiver, operates according to the present PPM-FSK modulation format with two subcarrier frequencies f.sub.1 and f.sub.2. The PPM encoded data on the main data channel 43 are fed to two pulse shaping circuits (30, 31) for additional frequency modulation with said frequencies. The resulting hybrid PPM-FSK signal is used to drive a light source (32). The receiver comprises a photodiode (34) coupled to an amplifier (35). The electrical signal obtained at the output of the amplifier (35) is fed to bandpass filters (36, 37) and envelope detectors (38, 39). The outputs of the envelope detectors are fed to a device (40) designed for pulse restoration and frequency decision. In a first operation, device (40) uses the output signals of the two envelope detectors (38, 39) to derive from them the estimated PPM encoded data signal. It then uses this signal to produce estimated restored pulses and outputs them.

Abstract: A wireless modem is provided with a passive power source using a first PCMCIA slot that is normally provided in mobile computer systems. Most mobile computing systems today provide for two or more PCMCIA slots. In the preferred embodiment of the present invention one slot is used by a first PCMCIA adapter that provides for baseband signal processing and power signals to a transceiver device. A second PCMCIA adapter card supplements the power signals provided by the first PCMCIA adapter card to the transceiver. The second PCMCIA adapter card occupies a second PCMCIA slot. The second PCMCIA adapter card supplements the power signals provided by the first PCMCIA card, permitting the transceiver to draw more current than that available from the first PCMCIA card. The transceiver and PCMCIA cards are interconnected by a Y cable in the preferred embodiment and a three connector housing in an alternative embodiment.

Abstract: A method, apparatus and article of manufacture is disclosed for eliminating periodic noise detected by a magnetic read head. In particular a time varying signal electrical signal is provided by a magnetic read head. The signal is sampled and stored in memory. Samples known not to contain a desired signal are used to extract a waveform representative of a single period of periodic noise. The representative waveform is synchronized with samples containing the desired signal and used to compensate the samples containing the desired signal in order to minimize, reduce, cancel or remove the effects of the periodic noise on samples containing the periodic noise. The compensated samples are then processed to obtain information from the desired signals.

Abstract: A phase shift modulator at the transmitter has a control input connected to a binary signal source. A high frequency carrier signal is applied to a carrier signal input of the modulator. The modulated carrier signal is transmitted to a receiver where it is mixed with a local oscillator frequency. At the receiver, a modulated signal is amplified by a limit amplifier to form the received signal into square wave pulses of a uniform height. The demodulator detects when the spacing between the edges of the square wave signal change in response to the phase shift modulation at the transmitter. When the spacing between the edges of the square wave IF signal is detected to be shorter than the normal spacing for a steady IF signal with no modulation, this signifies a first binary value. A longer than normal spacing between the edges of the square wave IF signal signifies a second binary value. Frequency drift compensation circuits are disclosed to overcome frequency variations in the carrier and the local oscillator.

Abstract: A method and apparatus for content coding of Audio-Visual materials is presented. The content coding can then be decoded by a home station where the content coding is collected and processed. The content codes are utilized by the subscribers home station to collect information on the subscribers selection of AVM streams and record information on which AVMs have been presented to the subscriber. An audio-video material distribution system is described for supplying AVM streams to home station via a local distribution network. The home stations decode the content coding from the AVM streams and collect the encoded content codes. The collected content codes are then sent to collection centers for processing. The encoded information may also utilized to provide management of an upstream channel between the home stations and the video distribution node.

Abstract: A low voltage CMOS multiplier uses a transconductance stage to generate a dynamic bias current which is used to compensate for non-linear terms in a Gilbert Cell multiplier circuit. Common mode dependence is minimized by using balanced differential input stages for both the transconductance and multiplier stages.

Abstract: Disclosed is an antenna mounted on a dielectric card with three pairs of dipoles. The dielectric card may be made of epoxy or epoxy glass or Teflon with glass fibers or any plastic with low dielectric loss and/or glass. Each dipole pair is designed to resonate at a different frequency band. Thus, for instance, a first pair provide signals in 800 MHZ range, a second dipole pair provide signals in the 1900 MHZ range and a third dipole pair provide signals in the 2400 MHZ range. With multiple dipoles the antenna can be used to provide wireless communications for several different frequency bands. The antenna card may hingeable or slideably mounted to a mobile computer. Thus, using a single antenna card a mobile computer can operate in several different frequency bands.

Abstract: A method and apparatus for causing a data line to be fetched in an order consistent with the data structure of a processor's modified little endian mode or big endian mode of operation is accomplished when the processor requests a particular word that is not currently stored in cache memory. The request includes an address of the particular word and an indication is provided as to whether the processor is operating in the modified little endian mode or the big endian mode. A memory manager, upon receiving the request, retrieves a line of data from memory (storage device) based on the address and the mode of operation. For example, when the big endian mode is used, the line of data is retrieved using a target word first ordering and when the modified little endian mode is used, the line of data is retrieved using a reverse target word first ordering.

Abstract: The wireless optical (in particular infrared) communication system with at least one transmitter (75) and one receiver (76) comprises control means (77, 78), which dynamically adapt the data rate and/or the optical power of the transmitter in dependence of signal-to-noise ratio of the receiver. Due to this adjustment, optimized system performance is maintained even under the influence of ambient light which statistically changes the signal-to-noise ratio of the receiver. The best compromise between data rate, bit error rate and transmission range is dynamically determined. The control function is distributed between transmitting and receiving system unit. The control information is communicated via wireless optical communication.

Abstract: An infrared transceiver for use with a computer in a wireless Local Area Network. The transceiver comprises a light emitting diode array and photodiodes. The transceiver is operable in a diffused beam arrangement and a directed beam arrangement. The transceiver is converted to directed beam operation by attaching a user installable collimator. The collimator redirects the beams into parallel beams, and the direction of the parallel beams is controlled through an adjustable tilt stand. The collimator is detachable for converting back to diffused beam operation.