Abstract: Apparatus for driving an optical system modulator to modulate data signals onto a light wave of the optical system. The modulator driver apparatus has a limited amplifier for receiving multiplexed low speed binary data signals and for generating amplified and limited frequency output signals representative of the received multiplexed binary data signals. A differential amplifier connected to an output of the limited amplifier precisely controls the amplitude and generates a low level of over and undershoot of output signals over a wide range of the limited amplifier output signals and has an output connected to central processor unit controlled linear amplifier means for generating gain controlled high fidelity output signals characterized with low over and undershoot and a high extinction ratio for driving the modulator.

Abstract: A network link tester couples to a LAN port with the LAN port having both a network transmit pair and a node transmit pair line. The link detector scans the network transmit pair and node transmit pair lines for the presence of link signals. Upon finding a link signal, the link tester indicates if the link signals were on the network transmit pair or on the node transmit pair line. Further, the link tester determines the network standard used and identifies the available operational nodes. The process of using a LAN tester includes coupling the tester to the LAN port, scanning network lines for the presence of link signals and determining and displaying operational capabilities. Optionally, the link tester may generate a tone signal on the network lines to assist in identifying line faults. Further, the link tester may generate link signals responsive to receive link signals.

Abstract: A method to detect a collision on a carrier medium, such as UTP or POTS wiring, commences with a transmission of a first identifier for a network device over the carrier medium. The first identifier comprises a first series of pulses transmitted over a first time interval. Each pulse of the first series has a respective temporal location within the first time interval. A second identifier comprising a second series of pulses is received at the network device over a second time interval. A determination is made as to whether the first identifier corresponds to the second identifier and, if not, a collision is detected on the carrier medium. The determination of whether the first and second identifiers correspond may comprise determining whether the respective temporal locations, within the first time interval, of each pulse of the first series of pulses corresponds to a respective temporal location, within the second time interval, of a pulse in the second series of pulses.

Abstract: A digital data modulator includes a source of a plurality of digital data signals having a common data bit period. A plurality of encoders each encode a corresponding one of the plurality of digital data signals using a variable pulse width code having edges occurring in respective non-overlapping intervals within the data bit period. A plurality of pulse signal generators each generate respective pulses representing the edges of the corresponding one of the encoded plurality of digital data signals. A carrier signal generator generates a carrier signal having carrier pulses corresponding to the respective pulses.

Abstract: A system and associated methods that use separate paths to send amplified data. The method expands, or amplifies, the amount of data that can be transmitted over a dedicated bandwidth-limited communications medium by using a first channel for transmitting clock synchronization pulses and transmitting the data as pulse position modulated (PPM) data over a second separate bandwidth-limited communication channel. Data for transmission is encoded by determining if the period of a pulse encroaches into the frame of the subsequent pulse. In response to a determination of encroachment, one or both of the pulses are inverted and time shifted to eliminate the encroachment. In the event that inversion of one or both of the pulses does not eliminate the encroachment, a blank is inserted between the two pulses.

Abstract: A first spread spectrum pulse position modulated signal with a pseudonoise code is generated. A second spread spectrum pulse position modulated signal with an inverted pseudonoise code is generated. A third spread spectrum pulse position modulated signal with a pseudonoise code is generated. A fourth spread spectrum pulse position modulated signal with an inverted pseudonoise code is generated. The first and second spread spectrum pulse position modulated signals are added together and thus a fifth spread spectrum pulse position modulated signal is formed. The third and fourth spread spectrum pulse position modulated signals are added together and thus a sixth spread spectrum pulse position modulated signal is formed. Quadrature modulation is performed on the fifth and sixth spread spectrum pulse position modulated signals.

Abstract: An output signal pulse width error correction circuit and method wherein errors in a data signal conforming to a communications protocol having a prescribed duty cycle are corrected by monitoring a duty cycle of the data signal, comparing the duty cycle to a duty cycle reference voltage corresponding to the prescribed duty cycle, and adjusting a pulse width of the data signal to conform to the prescribed duty cycle of the protocol. An embodiment is shown that low pass filters the input data signal to introduce greater slope to the input data signal which is then compared to a pulse width control voltage in order to generate an output data signal. The pulse width control voltage is produced by integrating the output data signal to obtain an average value corresponding to the duty cycle of the output data signal and comparing the average value to a duty cycle reference voltage corresponding to the prescribed duty cycle for the communications protocol.

Abstract: A tone generating circuit comprises a counter circuit having a clock input for receiving a clock signal and a plurality of outputs which generate sequential binary values in response to transitioning of the clock signal; a multiplexer having several inputs, a number of select lines connected to the counter circuit outputs, and at least one output; and a resistor divider network connected to the multiplexer inputs. The multiplexer select lines select one of the multiplexer inputs in accordance with the binary value received from the counter circuit. The multiplexer inputs are connected to different taps on the resistor divider network. The counter selects multiplexer inputs on the falling edge of the clock signal, while the output signal level transitions before the rising edge of the clock signal.

Abstract: A method and apparatus for encoding data into a pulse pattern begins by encoding header data based on a first pulse encoding convention to produce a header pulse pattern. The resulting header pulse pattern occupies multiple time chips and indicates that subsequent pulse pattern signals are valid. After generating the header pulse pattern, a set of bits of a stream of data is encoded based on a second pulse encoding convention to produce a data pulse pattern. The data pulse pattern occupies at least one time chip. The first and second encoding conventions are used to ensure that the header data and data are encoded in distinguishing manners such that both can be accurately decoded. Such conventions include using a predetermined pulse pattern to represent the header data, which is only used for the header data.

Abstract: A system for, and method of, generating a spread spectrum code position modulated waveform and a wireless local area network (LAN) containing the system or the method. The system includes: (1) a spread-spectrum encoder that receives and encodes portions of an information signal with a multi-chip code having a predetermined length to create therefrom a stream of sequences, each of the sequences having the predetermined length and (2) a transmitter that periodically transmits the each of the sequences at a time interval that differs from the predetermined length, a data rate of transmission of the information signal thereby allowed to increase.

Abstract: A system for receiving information encoded in a train of pulse position modulated signals and then decoding the pulse train to produce amplitude modulated signals representing the original information includes a circuit for detecting the beginnings of successive PPM signals, a one-shot multivibrator responsive to the beginnings of the PPM signals for producing pulse width signals whose duration varies in accordance with the received intelligence, and an R-C low pass output circuit coupled to the output of the multivibrator to produce amplitude modulated output voltage waves. The R-C circuit has a time constant substantially greater than the unmodulated period between PPM pulses, and produces a rising voltage that spans the time duration of an associated high voltage level square pulse and whose decaying voltage level varies in amplitude in accordance with the maximum voltage attained at the output of the R-C integrator by the trailing edge of the associated high voltage level pulse.

Abstract: A first spread spectrum pulse position modulated signal with a pseudonoise code is generated. A second spread spectrum pulse position modulated signal with an inverted pseudonoise code is generated. A third spread spectrum pulse position modulated signal with a pseudonoise code is generated. A fourth spread spectrum pulse position modulated signal with an inverted pseudonoise code is generated. The first and second spread spectrum pulse position modulated signals are added together and thus a fifth spread spectrum pulse position modulated signal is formed. The third and fourth spread spectrum pulse position modulated signals are added together and thus a sixth spread spectrum pulse position modulated signal is formed. Quadrature modulation is performed on the fifth and sixth spread spectrum pulse position modulated signals.

Abstract: A spread spectrum pulse position modulation/demodulation system which receives an input signal including frames and which includes first and second pulse position modulators. The first pulse position modulator modulates each frame by inserting a first pseudo noise code into a selected slot of each frame according to the input signal to generate a first spread spectrum pulse position modulating signal. The second pulse position modulator modulates each frame by inserting a second pseudo noise code into a selected slot of each frame according to the input signal to generate a second spread spectrum pulse position modulating signal. An adder adds together the first and second spread spectrum pulse position modulating signals to generate a third spread spectrum pulse position modulating signal. This third spread spectrum pulse position modulating signal may be transmitted by a radio transmitter, and then received by a radio receiver.

Abstract: An impulse radio communications system using one or more subcarriers to communicate information from an impulse radio transmitter to an impulse radio receiver. The impulse radio communication system is an ultrawide-band time domain system. The use of subcarriers provides impulse radio transmissions added channelization, smoothing and fidelity. Subcarriers of different frequencies or waveforms can be used to add channelization of impulse radio signals. Thus, an impulse radio link can communicate many independent channels simultaneously by employing different subcarriers for each channel. The impulse radio uses modulated subcarrier(s) for time positioning a periodic timing signal or a coded timing signal. Alternatively, the coded timing signal can be summed or mixed with the modulated subcarrier(s) and the resultant signal is used to time modulate the periodic timing signal. Direct digital modulation of data is another form of subcarrier modulation for impulse radio signals.

Abstract: An asynchronous time-hopping multiple access "(ATHMA") protocol and a simplex mode communication system utilizing the same requires no synchronization between transmitting stations, no handshaking between transmitters and receivers and no system manager to coordinate data message transmission. The ATHMA protocol ensures that for an n-channel asynchronous simplex mode communication system, each transmitter repeatedly sends each unique data message n successive times according to its own time-hopping schedule. In the preferred embodiment the time-hopping schedules are coordinated such that at least one duplication of each unique message will not collide with any other messages over a given period. Thus, at most n-1 transmissions out of the total n transmissions of each unique data message will be collided and lost. The ATHMA protocol and communication system of the present invention is ideally suited for applications requiring a low throughput rate and channel capacity.

Abstract: A method and apparatus for detecting a collision between signal transmissions on a carrier medium, such as UTP wiring, are described. The method commences with the transmission of an access identifier from a transmitter of a network device. The transmitted access identifier has a predetermined duration and includes a pulse at a temporal location within the transmitted access identifier specific thereto. An access identifier is also received at a receiver of the network device. The received access identifier also has a predetermined duration, and includes a pulse at a temporal location therein. A determination is then made as to whether the temporal location of the pulse within the received access identifier corresponds to the temporal location of the pulse within the transmitted access identifier. If not, a collision is detected on the network.

Abstract: A data format is formed by a start code, an identification code and its inverted code, a first data code and a second data code, each of these codes being a single byte code, which is then followed by an interrupt arbitration period. Thus, when compared with a prior art data format, an inverted data code and an stop code of the prior art one are replaced respectively by the second data code and the interrupt arbitration period TI to realize upper compatibility. A remote controller transmitting a signal transmits an acknowledge code or a non-acknowledge code within the interrupt arbitration period depending on the interrupt code it receives after its current signal transmitting operation is temporarily switched to a signal receiving operation within the interrupt arbitration period.

Abstract: A spread spectrum pulse position modulation/demodulation system which receives an input signal including frames and which includes first and second pulse position modulators. The first pulse position modulator modulates each frame by inserting a first pseudo noise code into a selected slot of each frame according to the input signal to generate a first spread spectrum pulse position modulating signal. The second pulse position modulator modulates each frame by inserting a second pseudo noise code into a selected slot of each frame according to the input signal to generate a second spread spectrum pulse position modulating signal. An adder adds together the first and second spread spectrum pulse position modulating signals to generate a third spread spectrum pulse position modulating signal. This third spread spectrum pulse position modulating signal may be transmitted by a radio transmitter, and then received by a radio receiver.

Abstract: The disclosure relates to a method of reception of signals from at least two transmitters (RCi), wherein for each transmitter the data ("0", "1") are represented by the time interval (T0i, T1i) between two consecutive pulses transmitted by this transmitter, said time intervals and the pulse widths (Tpi) being characteristic of each transmitter, and wherein said method includes the following steps: reception of a resultant signal that is the sum of the signals from by said transmitters; determination of the parameters of said resultant signal, these parameters including the width and spacing of the pulses; analysis of said parameters and assignment of a data item to one of said transmitters. The invention also concerns a receiver device, a remote controller, and a system of reception. The invention is applicable notably in the field of television and video.

Abstract: N signals are transmitted from each of N transmitting units to a receiving unit every signal transmission cycle (N.gtoreq.2). In this case, N signal transmitting periods of N I-th signals and (N-1) I-th transmission short pausing periods for each of the I-th transmitting units are alternately placed in each of I-th signal grouping periods (1.ltoreq.I.ltoreq.N), and an I-th transmission long pausing period follows each of the I-th signal grouping periods to set one signal transmission cycle composed of one I-th signal grouping period and one I-th transmission long pausing period for each of the I-th transmitting unit. A time length of each first transmission short pausing period is equal to that of the signal transmitting period, a time length of each I-th transmission short pausing period is (2N+2I-5) times as long as that of the signal transmitting period, and a time length of the signal transmission cycle is 4N(N-1) times as long as the signal transmitting period.

Abstract: A method for modulating a radio signal has the steps of: predetermining a first time interval so as to define a data word; generating a synchronization pulse, the synchronization pulse initiating a single data word having a length of the predetermined first time interval; and generating a single data pulse within the data word after a second time interval with respect to the synchronization pulse, the length of the second time interval defining at least one character. Defining at least one character by a single data pulse after a second time interval with respect to the synchronization pulse enhances an energy efficiency of the transmitted radio signal while mitigating a duty cycle thereof.

Abstract: An optical data communication and location apparatus for at least one location in a facility having at least one receiver at said at least one location. A plurality of portable transmitters provides optical wireless data links with the receiver. Each of the transmitters has a power supply with circuitry for transmitting data packets over said optical wireless data links to the receiver. The circuitry for transmitting data packets generates a data code having at least two time frames, each of the at least two times frames being divided into at least two data time slots. Each frame has exactly one pulse in one data time slot whereby in each data packet, there is encoded n-bits of binary data where 2.sup.n is equal to the number of time slots in each frame.

Abstract: A radio control device includes a transmitter, in which a crystal type high frequency module equipped with a high frequency circuit corresponding to a frequency band of a carrier and a PLL high frequency module equipped with the high frequency circuit and a PLL circuit for controlling a frequency of the carrier depending on a phase difference between the carrier and a reference signal of oscillator are detachably mounted. Such construction permits the crystal type high frequency module and PLL high frequency module to be selectively used as desired and transmission data to be output by means of the carrier of a desired frequency set depending on the high frequency module.

Abstract: A method and apparatus for detecting and indicating a collision on a wireless channel are provided. According to the method, data is transmitted over the wireless channel using pulse position modulation. The channel is monitored during each pulse position modulation frame to determine whether a pulse occurs during more than one pulse window of the pulse position modulation frame. If a pulse occurs during more than one pulse window of a pulse position modulation frame, then the devices on the wireless channel determine that a collision has occurred. A transceiver is disclosed for connecting a device to a wire-based network via a wireless connection. The device and transceiver communicate over the wireless connection using pulse position modulation. If a collision occurs on the wire-based network, then the transceiver transmits to the device a signal in which pulses are asserted during more than one pulse window of a pulse position modulation frame.

Abstract: A method and apparatus for transmitting information over a wireless connection are provided. A correlation is established between a set of symbols and a set of pulse position/signal characteristic combinations. Thus, each symbol has a corresponding pulse position and a corresponding signal characteristic. The signal characteristic may be, for example, a particular frequency, amplitude or phase. To communicate a symbol, a device generates a signal in which a tone burst is sent during the pulse position that corresponds to the symbol. In addition, at least some portion of the signal reflects the signal characteristic that corresponds to the symbol. A receiving device determines the pulse position in which the tone burst was sent and determines the signal characteristic reflected in the signal. The receiving device then determines the symbol based on the pulse position and the signal characteristic. Synchronization is improved by generating synchronization tone bursts before each pulse position modulation frame.

Abstract: A covert communication system utilizes a series of low level duty cycle coded pulse train transmissions which at the necessary end have signal to noise ratios much smaller than unity. Such transmissions are buried in noise and hence are undetectable by ordinary means. The coded pulse trains do not carry data and their sole purpose is only to be compressed by a code matched correlator into a single large pulse per pulse train. Data are encoded in the timing between adjacent compressed pulses of adjacent pulse trains. The low duty cycle of the pulse trains is used to force an unfriendly receiver, which does not know the code of the pulse train transmissions, to integrate its own receiver noise into its detection circuits, thus making the transmissions even less detectable.

Abstract: An optical data communication and location apparatus for at least one location in a facility having at least one receiver at said at least one location. A plurality of portable transmitters provides optical wireless data links with the receiver. Each of the transmitters has a power supply with circuitry for transmitting data packets over said optical wireless data links to the receiver. The circuitry for transmitting data packets generates a data code having at least two time frames, each of the at least two times frames being divided into at least two data time slots. Each frame has exactly one pulse in one data time slot whereby in each data packet, there is encoded n-bits of binary data where 2.sup.n is equal to the number of time slots in each frame.

Abstract: A spread spectrum code pulse position modulated communication system is disclosed. The communication system includes a spread spectrum code pulse position modulated receiver that compensates for the delay spread of a transmission medium, such as a wireless radio channel of a local area network. Delay spread may cause signal components of one transmitted spread spectrum codeword to spill over into chip positions of adjacent symbols, causing intersymbol interference, or into chip positions on quadrature channels of a given symbol interval, such as in a QPSK implementation, causing interchip interference. The disclosed receiver decodes a transmitted spread spectrum code pulse position modulated signal in the presence of such delay spread, utilizing a tentative symbol estimator to sample the matched filter data.

Abstract: A system provides for detection of enhanced capabilities of stations on a communications network. A specified pattern of link test pulses are detected and transmitted to provide for the indication of enhanced capabilities. This is particularly useful for determining whether a particular station is in full duplex or half duplex mode without affecting overall network performance.

Abstract: A spread spectrum code pulse position modulated communication system is disclosed. The frequency spectrum of a transmitted signal is spread by encoding bits with a predefined spectrum-spreading codeword which is in accordance with regulatory requirements or other standardization decisions. When the predefined spread spectrum codeword is passed through a filter matched to the characteristics of the codeword, a peak is detected in the main lobe. A positive main lobe can indicate a binary value of "0" and a negative main lobe, associated with the inverse of the predefined codeword, can represent a binary value of "1". Additional information is conveyed by modulating the position of the center of the codeword within the symbol duration. In one embodiment, the position of the center of the codeword is varied among eight positions. Thus, eight signal states are available, and three additional bits may thereby be conveyed.

Abstract: A method and apparatus are shown for generating and transmitting very short and widely separated high frequency sine-wave pulses of electromagnetic energy into space. A transistor, a charging capacitor, and an inductor are coupled into a first series loop path to form a discharge circuit. A bias voltage source, the same charging capacitor, and a charging resistor are coupled into a second series loop path to form a recharging circuit. The bias voltage source is selected to be capable of biasing the forward conduction path of the transistor near its breakdown condition. An original information signal is sampled upon each occurrence of a periodic reference signal, and the transistor is then triggered into its breakdown or avalanche mode. The starting times of successive transmitted pulses are modified in accordance with a pulse position modulation protocol.