Abstract:
PURPOSE: To decrease the estimate error of a true line error rate by extimating the line code error stably even if the operating point of a nonlinear element existing on a transmission line is fluctuated by means of a branching circuit, a carrier regenerating circuit, a phase modulation and demodulation circuit and a comparator circuit. CONSTITUTION: An input modulation wave from a terminal 401 is branched into three by a signal branching circuit, and one branched output signal is inputted to the carrier regenerating circuit 403. Then, an output signal of the circuit 403 is branched 404, and one of the other branched signals by the circuit 402 is phase- demodulated by the phase demodulating circuit 405 by using the branched signal. Further, the other signal branched at the circuit 404 is inputted to the phase modulator 407 and subject to phase modulation by an output signal of an oscillator 408. Moreover, the remaining signal branched by the circuit 402 is phase- demodulated 406 by using a phase modulating signal outputted from the circuit 407. Then, the output of the circuit 405 is taken as a reference, the output of the phase demodulating circuit 406 is compared 409 and its output is outputted from an output terminal as a pseudo error signal. COPYRIGHT: (C)1984,JPO&Japio
Abstract:
PURPOSE:To attain accurate measurement of pseudo error rate by using a regenerated clock phase-shifted so as to identify and regenerate a receiving data signal thereby controlling the sampling point of time of a regenerating device always in the vicinity of the maximum point of the eye opening. CONSTITUTION:An up-down counter CT11 is reset by a reset signal l3 and a pseudo error pulse sampled by a lead clock from a phase shifter 6 at an identifying and regenerating device 3 is inputted to an UP terminal of the CT11 via an EXOR9. On the other hand, the pseudo error pulse sampled by a lag clock from the phase shifter 7 at an identifying and regenerating device 4 is inputted to a DOWN terminal of the CT11 via an EXOR10. The CT11 controls the output phase of the phase shifter 8 based on the count value for a prescribed time and a threshold value. Thus, the output phase of the phase shifter 8 is controlled so that the sampling point of the regenerating device 2 may be at the maximum point of the eye opening at all times.
Abstract:
Various aspects describe an on-chip, hardware error-generator component. In some cases, the hardware error-generator component connects to a data path between two components contained within a same chip. Upon receiving an error simulation input, the hardware error-generator component modifies data being transmitted on the data path by inserting a data pattern that simulates an error condition. Alternately or additionally, the hardware error-generator randomly alters one or more of the transmitted data bits.
Abstract:
A method for evaluating the quality of a cable circuit which transmits a digital modulation signal in both directions is provided with a step of extracting a noise signal of an upstream line from either a node that connects a head-end of the cable circuit whose quality is to be evaluated and the cable circuit or a node that connects a tap-off and the cable circuit, a step of generating a pseudo-random signal, a step of outputting a test carrier by modulating a carrier signal of a predetermined frequency with the pseudo-random signal, a step of outputting an output signal of the sun of the noise signal of the upstream line and the test carrier, a step of selectively receiving the signal of the predetermined frequency from the output signal and demodulating the same, and a step of evaluating the bit error rate by comparing the demodulated signal and the pseudo-random signal for every bit.
Abstract:
A dummy error addition circuit for adding a dummy error to an orthogonal modulation symbol data, wherein a value based on a specified bit error rate is loaded to count clock signals at a counter (11), a carrier of the counter (11) stores outputs from a PN data generator (21) in a shift register (22), outputs from a PN comparison circuit (3) when stored data agree with count values of the counter (11) are recognized as error pulses, a bit selector (40) randomly selects, on receiving error pulses and based on outputs from a PN data generator (41), bits to which to add errors in an orthogonal modulation data, e.g. a PSK modulation symbol data, at intervals based on a bit error rate, and bits selected from the orthogonal modulation data are inverted in a bit inversion circuit (5) for outputting to thereby add errors.
Abstract:
Telecommunications networks require a variety of tests to monitor their proper operations. Performance monitoring (and fault detection) of the physical layer of a transmission system is one of them and is usually accomplished by using a bit error rate test (BERT). The BERT of the invention uses modified ATM idle cells to conduct one-way, bidirectional and loopback BERT. ATM idle cells are loaded with BERT data at the transmit end and recovered at the receive end. The BERT data are processed according to the different data rates of the ATM transmission system. Performance parameters are derived from the received BERT data. The disclosure describes a method as well as a system for performing such a test.
Abstract:
The invention relates to a method for transmitting digital signals, especially in AM bands (radio broadcast bands). A high level modulation, preferably 32 ASPK or 64 ASPK is used for data blocks which are to be transmitted. The invention is characterized by periodic measurement of interference at the receiver end and the subtraction of thus determined interference signals from reception signals.