Abstract: The invention relates to a digital method of detecting pulses of short duration and an arrangement for implementing the method. A threshold value is generated by means of a statistical procedure which is common in radar engineering, by means of which short pulses to be detected can be differentiated as opposed to long pulses. The method includes sorting a predeterminable number of temporally consecutive signal samples by amplitude and creating a ranking of the signal samples. An associated amplitude value for a predeterminable rank within the ranking is determined and multiplied by a predeterminable weighting factor (k) so that an amplitude threshold value (SW) is generated. All signal samples whose amplitude is greater than the amplitude threshold value (SW) are then marked with a marking signal.

Abstract: A clock reproduction unit provides a reproduced clock signal from a received PPM signal. The results of sampling the PPM signal with a reproduced clock signal is held by a sample result holding unit. Symbol synchronization is achieved from a received PPM signal by a symbol synchronizing signal generation unit. According to the sample result, the reproduced clock signal, and symbol synchronization, a reception data reproduction unit analyzes the result of a plurality of previous samples to decode reception data according to a specific procedure.

Abstract: An infrared remote-control receiver employs at its front end a gyrator-configured transistor operating as a current-to-voltage converter, but derives its data information from a negative-going gyrator output pulse in preference to the more conventionally used positive-going pulse. This negative-going pulse may be wider than the positive-going pulse and reduces the bandwidth demand on subsequent processing circuitry. This enables low-bandwidth, low-current hardware to be used which makes the receiver ideal for use in battery-operated systems. Also, the negative-going pulse is easier to detect, as it directly follows a disturbance known to be in the opposite direction. The result is an increased receiver sensitivity.

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 data transmission system includes a source of a data signal and a modulator, responsive to the data signal, producing a first modulated signal representing the data signal and a second modulated signal representing a signal 180 out-of-phase with the data signal. The first and second modulated signals are transported via a transmission channel. A first demodulator demodulates the transported first modulated signal and a second demodulator demodulates the transported second modulated signal. A subtractor, responsive to the first and second demodulators, produces a signal representative of the data signal.

Abstract: In a demodulation circuit for demodulating a pulse position modulation (PPM) signal, and a camera having the demodulation circuit, a change in PPM signal is counted by an up/down counter which is switched between count-up and count-down modes every time the PPM signal changes. When a carry signal is output from the counter, the carry signal is latched, and the PPM signal is demodulated into binary data on the basis of the presence/absence of the carry signal in the count-up mode and the carry signal in the count-down mode.

Abstract: In a communications-receiving system for demodulating phase-coded signals and displaying the resultant information on a cathode-ray tube (CRT), an information code is modulated on a carrier by shifting the phase of the carrier by an integral multiple of predetermined phase step. At the receiver a locally generated reference signal is compared with received pulses to ascertain their phase offsets. The resulting demodulated information is presented in a CRT display that indicates not only the received information but also, by the slope of bright dots, the frequency difference between the local reference and the signal, so that frequency drift can be corrected. The CRT's horizontal sweep represents time and the vertical sweep represents phase angle. The start of each vertical sweep is synchronized with zero-crossings of the locally generated reference signal. The intensity of the CRT beam is controlled by the message.

Abstract: There is provided a system for decoding a digital code and in particular a biphase-coded data, by detecting edges of the biphase-coded data and the time intervals between edge conditions. A system for decoding the biphase-code data includes a microcomputer 1 to control the system, a remote receiver module (RRM) 2 for logicizing code data received in infrared rays, filtering the waveform, and applying the output to the microcomputer 1; a first remote transmitter (RTTP) 5 for generating Pulse Position Modulation (PPM) code; a second remote transmitter (RTTB) 7 for generating biphase-code according to the pressing of a key; a tuner 9, display unit 11, and servo 13 operated under the control of the microcomputer 1; and a key matrix 15 for entering key data to the microcomputer 1.

Abstract: A biphase-mark coded digital audio signal comprising short and long pulses (IEC 958) is decoded despite substantial variation of sample rate but without a separate synchronization or timing signal and without a phase locked loop. The pulse lengths are measured and then compared with two thresholds. One is a variable threshold which is 1.5 times the average length of the short pulses, this average being stored in a register. This will normally be adequate to discriminate the short and long pulses. The second comparison is with a fixed value which is lower than 1.5 times the pulse length at the highest input frequency. When the comparators disagree irreconcilably in their determination, the resultant of the second comparison is used instead of the first. This allows the system to respond quickly to start-up or sudden change in input data rate.

Abstract: A circuit for filtering pulse sequences of a given frequency out of a composite signal includes a series combination of a monostable multivibrator (MF) and a random-access memory (RAM), an address register and a clock. The monostable multivibrator (MF) serves as a pulse shaper of incoming signals. The input (D.sub.E) and output (D.sub.A) of the random-access memory (RAM) are connected to the inputs of an AND gate (UG). An address counter register (AR) associated with the random-access memory (RAM) has a count cycle whose duration is equal to the pulse spacing of the sequence to be recognized. During each clock period (T2), the current signal state of the input (D.sub.E) of the random-access memory (RAM) and the content of the addressed memory cell are checked for equality by the AND gate (UG) and the current signal state is then written into the cell.

Abstract: An infrared detector output of a radiometer is amplified and inverted to provide a first signal which is amplified to a predetermined level and a second signal which is inverted with respect to the first signal and amplified to a fraction of the predetermined level of the first signal. The first and second signals are alternately sampled to sample portions of those signals which occur when the detector of the radiometer is viewing the target and then viewing the reference. The signals are sampled once while the detector of the radiometer is looking at the target and twice occurring on each side of the target sample when the detector is looking at the reference signal. The first and second signals are separately integrated in accordance with a predetermined timing pattern determined by the sampling rate of the first (target) and second (reference) signals. The peak integrated outputs of the first and second signals are held then sampled to produce the demodulated output from the radiometer.

Abstract: The disclosed method consists in sampling the phase of the detected modulated signal, inside each symbol T period, with a comb of sampling pulses obtained from N clock pulses evenly spaced out by a time interval equal to T/N; computing the differential phase angle d.phi. between symbols for each phase sample of the detected current symbol, encoding each differential phase angle d.phi. in assigning it an encoding cost, computing the sums of the encoding costs for the samples of the same order belonging to a determined number L of consecutive symbols; memorizing, among the N sums obtained, that sum which gives the greatest result, taking, as a symbols synchronizing clock, that clock which, in the comb of pulses, has the same order as the order of the sample which have lead to the greatest sum and decoding the differential phase angle having the same order as the memorized sample.

Abstract: In a demodulator for demodulating into a demodulated signal a quadrature phase modulated signal having a large varying amplitude caused by various radio transmission link conditions, a preprocessing circuit (21) logarithmically processes the envelope to produce a first preprocessed signal having a logarithmically compressed and digitized amplitude and limits the amplitude to multiple values to produce a second preprocessed signal. A phase detecting circuit (22) detects a phase difference between a reference signal having a reference frequency and the second preprocessed signal and produces a phase difference signal representative of the phase difference. A processing circuit (23) processes the first preprocessed signal and the phase difference signal to produce first and second processed signals collectively as the demodulated signal.

Abstract: Electrical circuits suitable for decoding binary information, in accordance with either of two novel modulation methods. The novel modulation methods are referenced in the instant case, and it is explained that the methods may be used when an encoding or decoding information transfer rate may be dependent on unpredictable and variable transfer rate velocities and accelerations. The present electrical circuits provide a novel means to realize the utility of either of the modulation methods.

Abstract: For locking a locally generated baud rate clock signal to the baud rate of a received phase-modulated signal, a multiplifer and measuring circuit produces two quadrature phase bi-level channel signals. In each channel signal the two levels over two given periods which are phased apart by 90.degree. are measured to determine the sign (1=+1, 0=-1) of the channel signals in each of the two periods. A circuit for recovering the timing of the incoming baud rate produces a narrow pulse corresponding to each of the four sign signals thus produced. These pulses are combined into a single continuous pulse sequence. Phase detectors determine the occurrence of successive pairs of the narrow pulses relative to the edge of the local baud clock pulses, and the phase of these clock pulses is adjusted in accordance with the average of the early and late detections.

Abstract: A method of deriving the word timing or word boundaries of a PPM signal, without requiring a synchronizing marker to be added to the PPM signal, employs a bipolar evaluation signal which begins at any time slot of the PPM signal. The evaluation signal is multiplied repeatedly with successive portions of the PPM signal within a time frame of the PPM signal which extends over a plurality of word lengths, and the product signals are integrated. Such repeated multiplications with subsequent integration are performed a number of times, with the evaluation signal being offset by one time slot each time. The time position of the evaluation signal which, after repeated multiplication and integration, produces the smallest possible signal, is considered to be in phase synchronism with the word timing of the PPM signal.