Abstract: A spread-spectrum clock circuit is applied to microprocessor or other clocked digital electronic equipment for the purpose of reducing spectral emissions residing at harmonic and subharmonic multiples of the clock frequency. This clock randomly varies the frequency of its output within a frequency constraint bound centered at the average clock frequency. The center frequency of the spread-spectrum clock is stable and is usable for timing and measurement applications. The spread-spectrum clock is a sealed, self-contained circuit module that can be applied to existing digital electronic equipment without modification.

Abstract: A circuitry with a pseudorandom noise generative function has a shift register for converting serial data into parallel data, an exclusive OR gate electrically connected to the shift register for fetching outputs from the shift register, the exclusive OR gate supplying exclusive ORed data to the shift register for use in generating a pseudorandom noise and a switch electrically connected to a data line transmitting serial digital data to be processed therein and an output of the exclusive OR gate for fetching the digital data and the exclusive ORed data respectively to select the serial digital data or the exclusive ORed data in response to a selective signal, the switch being electrically connected to the shift register for supplying the serial digital data or the exclusive ORed data to the shift register, thereby selecting a normal processing mode for the digital data or a pseudorandom noise generative mode for the exclusive ORed data.

Abstract: An oscillator generates a signal that is applied to one input of a phase shifter circuit. The other input of the phase shifter is connected to a source of a phase modulation signal. In response to the phase modulationsignal, the phase shifter provides a clock signal with a spread spectrum.

Abstract: A dynamic range tester which simultaneously generates two signals, each of hich is composed of a clean signal plus an excess quantity of independent and isolated random noise is disclosed for use in producing real world signals which can be used to provide a simulated operating environment within which to evaluate the dynamic range or evaluate the processing gain of an electronic or acousto-optic system. The power level of the signal and power level of the noise in each of the two outputs of the dynamic range tester can be independently varied such that a range of signal-to-noise ratios may be set-up in each output.

Abstract: An audio mixing console incorporates a number of audio modules connected in series, with the first module being serially connected to a digital controller. The digital controller provides digital signals to the audio modules, the digital signals comprising both clock signals and data. Data is sent by the controller to each audio module by way of a data coder which randomizes or scrambles the data stream such that it is not cyclic or repetitive. The coding circuit may be a maximal length pseudo number sequence generator, and this enables decoding to be made by a complementary decoding circuit without links between coder and decoder being required. As the data output appears completely random, it has no fundamental frequency and consequently there is no interference from crosstalk.

Abstract: A method and apparatus for generating the PN code employed for spread spectrum communication are disclosed. Maximal period sequence signals from a maximal period sequence generator 11 and shift vector from a shift vector outputting circuit 10 are transmitted to a vector multiplier 12 for vector multiplication. Outputs of the vector multiplier 12 are transmitted directly to a selector 14 and via a one-chip delay flipflop 13 to the selector 14. The selector 14 is changed over at an externally set control timing. The PN code employed in a CDMA system Cellular may be arbitrarily time-shifted using the vector multiplication so that changeover between transmitting base stations desired to be received may be achieved in a shorter time using a simplified circuit construction.

Abstract: A method and apparatus for improving the security of an electronic codebook encryption scheme comprises a transmitter unit for encoding or encrypting data and a separate authorized receiver for decoding or decrypting the data. During the encryption of the plaintext data, a randomly generated offset is introduced into the PN sequence to vary the starting point of the PN sequence as it is applied to the plaintext data. The offset is encrypted with the secret key and the unencrypted IV, encrypted offset, and ciphertext are exported by the transmitter to the receiver for decrypting.The encoded communication is imported by the receiver and the encrypted offset portion is extracted. The receiver combines the encrypted offset with the secret key to decipher the offset value. The offset and PN sequence are then combined with the ciphertext, using an XOR gate, to recover the original plain text from the ciphertext.

Abstract: Apparatus and a method are disclosed for synthesizing a pseudorandom communications signal having a smooth, flat, power spectrum. The system comprises frequency modulation circuitry for deriving a first analog signal from a digital encoding signal. The first analog signal is derived to have a substantially constant amplitude and a frequency varying in response to the amplitude of the digital encoding signal. Fourier transform circuitry is connected to the modulation circuitry and is operative to derive a second analog signal from the first analog signal. The resulting second analog signal is the fourier transform of the first analog signal, having a substantially constant power spectral density over the bandwidth of said second analog signal, and having an amplitude that varies in response to the amplitude of the digital encoding signal.

Abstract: A method and apparatus for encoding information on a chaotic system by causing tiny perturbations in an accessible system control variable, or trajectory, uses the natural underlying symbolic dynamics of the system to encode the information. The system is allowed to behave chaotically even while tracking a pre-specified information-containing symbol sequence, thus maximizing the efficiency of information encoding and transmission.

Abstract: A cascaded synchronized nonlinear system includes a nonlinear transmitter having stable first and second subparts. The first subpart produces a first transmitter signal for driving the second subpart and the second subpart produces a second transmitter signal for driving the first subpart. The nonlinear transmitter transmits the second transmitter signal to a nonlinear cascaded receiver. The receiver, being for producing an output signal in synchronization with the second transmitter signal, includes a first stage (a duplicate of the first subpart) responsive to the second transmitter signal for producing a first receiver signal. The receiver further includes a second stage (a duplicate of the second subpart) responsive to the first receiver signal for producing the output signal. The cascaded synchronized nonlinear system can be used in an information transfer system. The transmitter, responsive to an information signal produces a drive signal for transmission to the receiver.

Abstract: A method and apparatus for generating a pseudo-random bit sequence is provided. A first input bit is determined as a function of bits stored in a shift register in accordance with a first feedback algorithm. In addition, a second input bit is determined as a function of bits stored in the shift register in accordance with a second feedback algorithm. Subsequently, a particular input bit to be provided to the shift register is deterministically selected from the group consisting of the first input bit and the second input bit such that a non-linear pseudo random sequence may be produced by the shift register. In addition, a communication unit which utilizes the pseudo-random bit sequence in encrypting a signal to be transmitted and decrypting a received signal is described.

Abstract: An authenticator circuit and message authentication apparatus. The circuit includes a plurality of shift register stages, some of which are separated by adders having an input from a succeeding stage. Switching circuits selectively control the second adder inputs to determine the shifting sequence of information passing through the register stages. A message authentication apparatus includes a key generator and authenticator circuit converted at the output of a transmitter. The input of a receiver includes a similar authenticator circuit and key generator, plus a counter.

Abstract: A keystream generation system for producing a cryptographically secure keystream by an "amorphous" process. Three types of keystream generation are preferred. A large seed key is directly amorphously expanded into a cryptographically secure keystream. A small seed key seeds a pseudo random number generator whose output is made cryptographically secure through a contracting amorphous process or, alternately, the security of an extended keystream is strengthened through contraction. Finally, a state machine whose output and transition functions are based on amorphousness recursively operates on a seed key to generate an arbitrarily long, cryptographically secure, keystream. The recursive performance of such amorphous logical operations on seed keys in order to generate keystreams is akin to the encryption of data.

Abstract: A chaotic transmitter (100) operates according to preselected chaotic protocols, such as a set of Lorenz equations. Modulation is accomplished by modifying a predetermined parameter of the set of chaotic Lorenz equations with a message signal, thereby producing a spread spectrum chaotic transmitted signal. A corresponding receiver (200) reconstructs a synchronizing drive signal, which is used by a demodulator (412) of the receiver (200) to detect the message signal.

Abstract: A tone signal synthesizer for simulating musical tones of a brass instrument faithfully. A nonlinear portion and a pipe linear portion are combined to simulate a brass instrument. The nonlinear portion has a resonance circuit having a resonance frequency in the vicinity of the frequency of a musical tone on the basis of an upper model, and a resonance circuit having a low resonance frequency on the basis of an outer model. Not only oscillation in the frequency of the musical tone is made by the former, but the instability of a brass instrument upon starting of tone generation is simulated by the latter. Further, not only a random number generation circuit gives a random number component to a flow rate signal, but a function table and a multiplier make the level of the random number component proportional to the square root of the flow rate signal.

Abstract: The present invention provides a MRP generator comprising m MRP generating circuits connected in parallel which are operated at a 1/m clock speed and have a predetermined time relation to each other, wherein the MRP generating circuits are operated on the multiplex basis. The operating speed is improved.

Abstract: A system for producing two synchronized signals comprises a nonlinear dynamical primary system and a nonlinear dynamical secondary response subsystem. The primary system comprises a nonlinear dynamical drive subsystem for producing at least one drive signal, and a nonlinear dynamical primary response subsystem responsive to said at least one drive signal for producing a primary signal, wherein said primary response subsystem has a complete set of at least one primary sub-Lyapunov exponents, all of said at least one primary sub-Lyapunov exponents being negative. The second response subsystem is responsive to said at least one drive signal for producing a secondary signal in synchronization with said primary signal, said secondary response subsystem being substantially a duplicate of said primary response subsystem, wherein said secondary response subsystem has a complete set of at least one secondary sub-Lyapunov exponents, all of said at least one secondary sub-Lyapunov exponents being negative.

Abstract: A noise generating device comprises a generator (1) including a shift register (1a) which performs shift operations to sequentially shift a bit in an input stage to a next higher significant stage. An exclusive-OR circuit (1b) performs exclusive-OR operations between a pair of bits from selected stages of the shift register and feeds back to the input stage of the shift register. A filter (2) receives the pseudo-random data and outputs an analog signal. The filter comprises an operational amplifier (2a). Respective outputs of the stages of the shift register are alternately applied to non-inverting and inverting inputs of the operational amplifier through respective resistors (R1, . . . ,R23).

Abstract: An improved high speed word generator (30) which includes a white noise generator (12) for providing first and second bits and exclusive or (XOR) means (32) for providing an output signal which is the exclusive or of said first and second bits. In an alternative embodiment, the invention provides an improved N-bit high speed word generator including noise generator means for providing N bits, either through N one bit noise generators or one one bit noise generator and means for storing the output thereof, and exclusive or (XOR) means for providing M stages of N output signals the first stage of which provides N output signals each of which is the exclusive or of two of said bits and the subsequent stages of which provide N output signals each of which is the exclusive or of the output of the previous stage and an output of said noise generator means.

Abstract: An apparatus for synthesizing musical tones is provided with an excitation device and time delay device so as to form a loop circuit, and also, a noise generation device for generating a blowing noise signal when blowing a wind instrument, and noise mixing device for mixing the blowing noise signal with excitation signal corresponding to musical information output from the wind instrument are incorporated in the loop circuit, thereby the excitation signal is circulated in the loop circuit and mixed with the blowing noise signal.

Abstract: A music synthesizer simulates the musical tones of bowed string and wind instruments. The synthesizer includes a noise generator which generates pulsed noise signals, as well as a resonant system or signal generator which generates deterministic or periodic signals. In one embodiment, the pulsed noise signals are combined with the periodic signals to generate an improved synthesized musical sound. In another embodiment, pulsed noise is added to an excitation signal for energizing a resonating system, which may or may not be dynamically coupled to the excitation generator, resulting in the generation of synthesized sound having appropriate noise characteristics for bowed string and wind instruments.

Abstract: The pseudo-random-bit sequence generators are clocked by separate clock signals of different frequency. The two pseudo-random-bit sequence generator outputs are logically combined by an exclusive-or gate to provide a pseudo-random-bit sequence generator which, when converted to analog signal has improved white noise characteristics.

Abstract: An improved security system is disclosed which uses an IC card to enhance the security functions involving component authentication, user verification, user authorization and access control, protection of message secrecy and integrity, management of cryptographic keys, and auditability. Both the security method and the apparatus for embodying these functions across a total system or network using a common cryptographic architecture are disclosed. Authorization to perform these functions in the various security component device nodes in the network can be distributed to the various nodes at which they will be executed in order to personalize the use of the components.

Abstract: A monolithic microwave integrated circuit device provides a microwave transmission line with a resistor coupled thereto and a heating element thermally coupled to the resistor but electrically insulated therefrom by a dielectric layer. Heating the resistor with the heating element causes either a change in resistance of the resistor or the generation of noise by the resistor. Either the resistor or the heating element is constructed using monolithic integrated circuit construction techniques on the same circuit substrate with the transmission line.

Abstract: A tester simulates high energy pulses typically present at the inputs to an avionics device after an aircraft carrying the avionics device has been struck by lightning. The tester is used to assist in determining whether the avionics device is sufficiently protected against the effects of a lightning strike on the aircraft. The tester includes a trigger circuit for generating trigger signals at fixed or random intervals so that the pulses which make up each burst as well as the bursts themselves are generated at fixed or random intervals. A number of individual pulse generating circuits are provided to generate high energy pulses which are output to the avionics device under test. A sequencing circuit feeds the trigger signals to the pulse generating circuits so as the generate the high energy pulses and bursts at the selected fixed or random intervals.

Abstract: A smart card (1) which includes a random access memory RAM (10) and a read-only memory PROM (7) incorporating a production key (PK), a distributor key (MK), a bearer code (CP) and a serial number (NS) generates a unique number (NU) which is stored in the memory RAM (10) in the card after execution of the following steps of a program which is specific of the card:a - modulo-2 addition and storage in the RAM (10) of the result:PK.sym.MK=KMP,b - the encryption of a unique input message ME, generated by the card, by means of a reversible algorithm (ALG, ALB.sup.-1) using the key KMP:NU=ALG.sub.KMP (ME).

Abstract: An improved short cycled sequencer of a P-code generator is disclosed for generating a ranging code in a Global Positioning System receiver. A shift register in the sequencer has a predetermined number of stage outputs exclusive-ored with a decoded outpout of the shift register stages and the exclusive-ored output is fed back to the serial input of the shift register. At the end of sequencing through a plurality of vectors, reinitialization of the shift register occurs without having to load an initialization vector from an external source.

Abstract: An SSC device according to the SSC method using a correlator is disclosed, in which a plurality of stages of shift register is connected in series, the outputs of the stages of the shift register being given selectively to the correlator and the initial value of the shift register in the pseudo noise code generator on the receiving side are set in a mirror image relation with respect to the initial value of the transmitted signals of the pseudo noise code generator at the code synchronization.

Abstract: An inexpensive yet effective circuit for producing an irregular pulse train of variable frequency and duty cycle, particularly for generating simulated sounds, such as engine sounds for toy vehicles, is disclosed. The circuit comprises an integrated circuit including a plurality of Schmitt trigger inverters (U1A, U1B) configured for oscillation at different frequencies, and a resistance element (R3, R7) in series with one, and preferably both, of the power supply connections to the inverters, with the circuit output comprising the output of one of the Schmitt trigger inverters (U1B). In a preferred embodiment, a capacitance element (C4) is connected between the output of a Schmitt trigger inverter and its system voltage input for further modulating the circuit output.

Abstract: Apparatus for digitally synthesizing substantially Gaussian white noise of an adjustable bandwidth but of substantially constant amplitude. The apparatus comprises a pair of pseudorandom sequence generators, plural delay circuits, plural finite impulse response filters, and a summing network. The pseudorandom sequence generators are made up of a pair of shift registers having a large plurality of output stages to provide a first digital electrical signal representing a pseudorandom number sequence of a long repetition rate at the output stages. The delay circuits are coupled to selected output stages of the pseudorandom sequence generators for providing second respective digital electrical signals representing respective uncorrelated pseudorandom number sequences whose spectrum is a predetermined function, e.g., (sine X)/X.

Abstract: An electronic musical instrument having a plurality of operators for generating audio frequency waveforms and performing frequency modulation thereof. The operator comprises a wave generator, a phase generator, and an amplitude-envelope generator. The phase generator produces phase-angle data on the basis of frequency-number data modulated by ratio-of-frequency data. While the frequency-number data is common to all operators, ratio-of-frequency data varies independently of those applied to the other operators. This enables operators to create rich, dynamic, lifelike sound. One or more operators are provided with feedback loops that are capable of varying the amount of the feedback in response to key touch, etc., thus achieving expressive tone. A pitch-envelope generator is provided with a random-number generator which modulates the pitch envelope in a random manner to more closely simulate a performance on a real musical instrument.

Abstract: A tester simulates high energy pulses typically present at the inputs to an avionics device after an aircraft carrying the avionics device has been struck by lightning. The tester is used to assist in determining whether the avionics device is sufficiently protected against the effects of a lightning strike on the aircraft. The tester includes a trigger circuit for generating trigger signals at fixed or random intervals so that the pulses which make up each burst as well as the bursts themselves are generated at fixed or random intervals. A number of individual pulse generating circuits are provided to generate high energy pulses which are output to the avionics device under test. A sequencing circuit feeds the trigger signals to the pulse generating circuits so as to generate the high energy pulses and bursts at the selected fixed or random intervals.

Abstract: Apparatus for generating trigger signals for a serial stream of bits which has continuously repeating patterns and which has been formed by serializing a plurality of parallel streams, for example, a maximal length PRBS. The apparatus operates by identifying with which parallel stream cycle a trigger signal should occur and with which bit of the parallel stream in that cycle the trigger signal should be associated. Embodiments constructed in accordance with the invention can operate mainly at the clock rate of the parallel streams, that is, the lower clock rate.

Abstract: The electronically tuned power oscillator (ETPO) of the present invention provides a method and apparatus that drives a narrow-band (high Q) transducer over a relatively broad band of frequencies. A pseudo-random sequence generator dynamically switches a bank of capacitors varying the resonant frequency of the power oscillator. A node on the power oscillator provides the clock for the pseudo-random sequence generator thereby providing a synchronized frequency change on every time varying cycle.

Abstract: A signal generator produces a spread-spectrum bandwidth signal in the frequency range 40 to 90 KHz for use in a domestic mains signalling system. In the generator, sixteen individual frequencies, equi-spaced in that range, pass to samplers operating at a clock frequency of 204.8 KHz and then to quantisers before storage. The resulting signals are then assembled in appropriate manner by selector switch before being filtered when (temporarily) in the frequency domain.The resultant signals duly reach catalogue store, whose output can be used for programming an EPROM in a mains signalling interface unit.

Abstract: Pseudorandom pulse code generators utilize XOR gates constructed of a pair of back to back parallel connected laser diodes, and fiber optic delay lines connecting the XOR gates to generate PN code sequences with tens of Gbits/s data rates. The single tap generator uses a fiber optic line of a length representing a selected number of delay stages connected to the optical output of the XOR gate and with optical splitters at the end of the delay line and at a selected delay stage feeding back optical signals to the optical inputs of the XOR gate to produce the PN sequence at the end of the delay line. Multi-tap generators utilize additional electro-optical XOR gates connected in serial-parallel, or preferably in a converging cascade arrangement to feed back pulses to the delay line.

Abstract: A circuit for generating jitter includes a mixer which mixes a jittered signal from a jitter generator with the output of a variable frequency oscillator to produce a broadband jittered output. A preferred form of the circuit uses a double frequency translation technique in which the output from a reference oscillator is applied to a jitter generator and to a first frequency translation device to translate a variable input frequency to an intermediate frequency. The jittered signal and the intermediate frequency signal are then applied to a second frequency translation device to produce a jittered output at the variable input frequency.

Abstract: A signal generator produces a spread-spectrum bandwidth signal in the frequency range 40 to 90 KHz for use in a domestic mains signalling system. In the generator, sixteen individual frequencies, equi-spaced in that range, pass to samplers operating at a clock frequency of 204.8 KHz and then to quantizers before storage. The resultant signals are then assembled in appropriate manner by selector switch before being filtered when (temporarily) in the frequency domain.The resultant signals duly reach catalogue store, whose output can be used for programming an EPROM in a mains signalling interface unit.

Abstract: A signal generator includes a pseudo-random bit generator that feeds bits three screening gates and three interconnected counters to simulate the electronic interference noise source attributed to three 400 hertz motors. The electronic interference effect includes fluctuations of frequencies to represent the slight variations in motor-generator speeds attributed to the 400 hertz motors so that a more realistic evaluation can be made on nearby communications and navigation equipments.

Abstract: An apparatus for generating pseudo-random codes is disclosed. The apparatus uniquely stores a set of codes in a memory and uniquely retrieves a particular code sequence. The apparatus has particular application to Global Position Satellite (GPS) earth receivers.

Abstract: A pseudo-noise sequence generator includes a memory which is accessed by a (2n+m)-bit address signal and outputs a parallel n-bit pseudo noise sequence prestored at a corresponding address, and n registers for delaying each bit of the parallel n-bit output signal from the memory by one clock. The (2n+m)-bit address signal consists of a parallel n-bit digital input signal, the outputs from the n registers, and an m-bit control signal.

Abstract: An integrated circuit random number generator which uses a triangular output analog oscillator to vary the frequency of a higher frequency voltage controlled oscillator. The output of the voltage controlled oscillator is sampled at a rate much less than the rate of oscillation of the voltage controlled oscillator to produce random digital values.

Abstract: Pseudorandom noise having a predetermined frequency spectrum is generated by implementing a finite impulse response filter as an integral part of a feedback shift register sequence generator.

Abstract: A zener diode random number generator circuit is described which produces a random binary number output having a statistical distribution exhibiting a controlled degree of randomness determined in response to an input control signal. A microprocessor feedback circuit monitors the random number output and produces the input control signal in response to the difference between the degree of randomness of the output signal and that of a pre-determined statistical distribution. The digital feedback automatically adjusts the zener diode biasing point and the limiter threshold such that part-to-part tolerance, component aging, temperature variations, or voltage fluctuations will not adversely affect the randomness of the bit stream output. In the preferred embodiment, the microprocessor tests the ratio of ONES bits to ZERO bits of the random number such that a desired 1:1 ONES/ZERO ratio is approximated.

Abstract: Linear and nonlinear bits are logically combined to form each of at least three sequences, one of which is selectively used to couple either one of the others to the output of the sequence generator.

Abstract: Audio beat notes produced by sampling a square wave in a digital quadrature FM demodulator are reduced by adding random noise, or dither, to the signal to be demodulated to randomly vary the width of successive pulses in the square wave.

Abstract: This system generates signals which vary randomly in frequency. The system includes a digital pulse generator generating multibit digital numbers varying randomly according to an encoded statistical distribution pattern. A first source of digital signals is connected to the pulse generator which perturbates the signals in frequency and applies them to an adder. Another source of digital signals connected to the adder combines with the perturbated first signal. A digital integrator connected to the pulse generator triggers release of the perturbated first signals and converts the combined perturbated signals to multibit outputs which may be applied to digital-to-analog converters, and in turn to frequency modulators to produce analog signals perturbated in accordance with the statistical distribution pattern.

Abstract: A random number generator designed for use with an electronic key uses a triangular output analog oscillator to vary the frequency of a higher frequency voltage controlled oscillator. The output of the voltage controlled oscillator is sampled at a rate much less than the rate of oscillation of the voltage controlled oscillator to produce random digital values.

Abstract: A random digital signal generator circuit responsive to a clock signal from a block signal source for outputting a sequential series of logic signals. The circuit comprises a clocked flip-flop that provides a signal at its output terminal that has a value corresponding to the state of its input signal until a subsequent clock signal is received. An array of oscillator signal generators is provided with each oscillator signal generator operating at a different frequency. An EXCLUSIVE-OR network means having an array of input terminals has each input terminal of the EXCLUSIVE-OR network coupled to the output terminal of a corresponding oscillator signal generator. The EXCLUSIVE-OR network provides a random output signal at its output terminal. The EXCLUSIVE-OR network means output terminal is coupled to the flip-flop input terminal. The flip-flop responds to each the clock signal to sample the state of the random output signal from the EXCLUSIVE-OR network.

Abstract: Audio beat notes produced by sampling a square wave in a digital quadrature FM demodulator are reduced by adding filtered random noise, or dither, to the signal to be demodulated to randomly vary the width of successive pulses in the square wave. Filtration of the random noise prevents feedthrough of noise which would degrade the demodulated signal.