摘要:
In a process for analog transmission or storage of digital data, the digital data are imposed on a total train of oscillations produced by the cumulative superposition of several narrow-band partial trains of oscillations. The digital data are decomposed into partial data each containing several data bits and an amplitude value from a store of values containing a number of amplitude steps is imposed on each partial train of oscillations in function of the data bits of the partial data. The invention also concerns a circuit for carrying out this process.
摘要:
Procédé de codage d'un signal numérique, codeur et décodeur pour la mise en oeuvre de ce procédé, procédé de régénération et régénérateur correspondant. Un détecte, à chaque temps bit, la présence éventuelle d'un motif binaire parmi un nombre quelconque n de motifs binaires comprenant au moins deux bits ; on divise ledit temps bit en n intervalles de temps égaux auxquels on associe n positions temporelles ; on établit une correspondance entre chacun des n motifs binaires et chacune des n positions temporelles ; on engendre, en cas de présence de l'un des n motifs binaires, une impulsion occupant une position temporelle correspondant audit motif binaire et on reporte la prochaine détection de présence éventuelle d'un motif binaire à partir du bit suivant le dernier bit dudit motif binaire dont la présence est détectée. Application à la transmission numérique.
摘要:
A data modulation interface is provided for serial data transmission. A biphase signal is encoded with the binary bits of a parallel data word. The bits of the parallel data word are examined to determine whether there are more one bits or zero bits in the word. A polarity bit is provided in addition to the other bits to indicate which bit-state occurred most often. The biphase signal is modulated to create different time intervals between phase reversals with one time interval corresponding to a bit-state of one and another time interval corresponding to a bit-state of zero. The shortest time interval is assigned to correspond to the bit-state occurring most often in the word so that the total time required to transmit each word is minimized. A time interval can be assigned to a sync signal transmitted after each parallel data word. A time interval can also be assigned to correspond to plural bit combinations so they can be represented by a single phase interval and transmitted quickly.
摘要:
Disclosed is a pulse width decoder which receives a double frequency modulated (DFM) waveform and recovers therefrom the contained NRZ-L data and clock information. Basically, the decoder looks for long and short pulses in the DFM waveform. A long pulse is decoded as a «0», while a pair of short, opposite polarity pulses are decoded as a «1». In addition, in order to allow for pulse shortening in the DFM waveform, a short pulse followed by a long pulse is interpreted as a «1». The clock signal is primarily derived from two delayed versions of the DFM waveform to create one clock edge every bit time.
摘要:
A variable oscillator, suitable for integration as part of a phase lock loop (PLL) clock source in a complementary metal oxide semiconductor (CMOS) integrated circuit, includes an amplifier and terminals for connection to a a tank circuit, for example a crystal resonator. A passive reactance is alternately coupled and decoupled in relation to the amplifier to cause oscillatory operation at lower and higher frequencies. In the CMOS circuit the reactance is conveniently provided by conductive layers of predetermined dimensions being carried by an oxide layer. Each layer provides a capacitive reactance which is arranged in series with a field effect defice being controlled by associated PLL control circuitry.
摘要:
A device an method for detecting digital impairments affecting an upstream pulse code modulation (PCM) channel in a digital communication network (36), involves: receiving, by a digital PCM modem (38) interconnected to the digital communication network (36), a random sequence of digital values selected from a constellation of digital values transmitted over the upstream PCM channel of the digital communication network (36); establishing distributions of the received digital values, each distribution corresponding to one of a plurality of time intervals; and deriving from the distributions the types of robbed bit signaling and digital loss affecting the upstream PCM channel of the digital communication network (36) for each time interval.