The most favorable clock signal among n available signals which present equal successive phase shifts is selected by comparison with a synchronization burst. For this, a logic phase comparison is effected between the signals obtained by division by 2 of each of the n clock phases with the bits of the synchronization burst by averaging the comparison signal obtained over several bits, and the most favorable clock phase is selected, corresponding to a phase shift close to .pi., as being the one represented by a voltage level located within a determined interval F.

A high capacity time-division switching system is disclosed which includes a digital data transmission system for transmitting both digital data words and synchronizing information. The predetermined bit positions of each data word, which bit positions are to convey data only, are encoded and transmitted as a combination of the true and complement representation of those digits. The remaining bit positions, which are used to convey both data and synchronizing information, are encoded and transmitted as true representations only. A digital data receiver responds to the data so encoded by extracting synchronizing information based on the violation of the predominately true and complement coding format.

A device for the decommutation of messages, which device extracts data in a digitalized form by controlling a bits detector, without having available any external clock signals. The device comprises, for this purpose, at least one phase comparator including a pair of chains which are fed in parallel by a message, each of said chains comprising, in series, an integrator and a non-linear element, and the integrators each functioning for a duration which is equal to one clock period with partial overlapping of these durations, and the phase comparator comprises commutation means controlled by locally recreated clock signals and functions at a frequency which is a sub-multiple of that of the clock signals, for the purpose of taking out the signals, which are formed by integrators in an interval of time comprising a whole number of clock periods and are stored for a succeeding and equal interval of time, with a view to producing by differentiation error signals controlling an oscillator, which generates the local clock signals, acting on the phase comparator and the bits detector.

Electrical signals recorded on a magnetic medium as magnetic indicia represent digital data. Digits of data are recorded as encoded pairs of indicia (couples) by corresponding pair of signals. Successive encoded indicia are recorded on the medium serially in sequence; for example, in stripes oriented diagonally across magnetic tape. During reading, defects in the medium, or errors in data transfer, resulting in a loss of synchronization between encoded indicia and the digit represented, are compensated for. Encoded indicia are continuously compared with a resynchronization pattern dispersed throughout recorded data at regular intervals. When an error is detected, the encoded indicia are decoded and stored in two buffers, each storing sets of digits decoded from differently chosen indicia pairs. The contents of one of these buffers is thereafter utilized when a resynchronization pattern identifies the correct set of digits.

A device and method are disclosed for the acquisition of data at high flow rates and with high accuracy. The device, called a "Selective Digital Integrator" (SDI), provides many improved features relative to older techniques, and in certain instances it provides a less-expensive replacement for lock-in amplifiers while affording greater functionality and versatility. The device can be integrated into existing instrumentation and technology for high-resolution measurements using various radiation sources (e.g., lamps, lasers, synchrotrons), various polarizations (e.g., linear, circular, elliptical), and various detectors (e.g., photo multipliers, diodes). Unlike the case with conventional lock-in amplifiers, the signal need not be known (or presumed) in advance to have a particular shape, but instead may have an arbitrary or unknown waveform. Examples of the new capabilities include the ability to measure circular dichroism by separating out the left circular and right circular components of that spectrum; and the ability to make polarization-selective measurements that simultaneously measure both linear and circular dichroism. The device has a substantially better signal-to-noise ratio than that of previous systems. It has the ability to perform over wide (and continuous) ranges of signal strength. It has a wide dynamic range (.about.10 orders of magnitude). It is particularly good at separating and discriminating small signal components. It has high time-, spectral-, polarization-, and average-value-of-detector-current resolution (.about.1 part in 10.sup.10). Applications where the SDI device will be useful include, for example, the following areas: chemistry (e.g., analysis); pharmaceuticals (e.g., molecular structures and configurations); electronics (e.g., as replacements for lock-in amplifiers as part of data acquisition systems); materials science (e.g., crystal structures, optical and magneto-optical properties, films, thin layers, etc.); medicinal chemistry and physics (e.g., structures and properties of molecules in molecular medicine); environmental measurements and studies (e.g., data acquisition for environmental studies); and physics and chemistry (research pertaining to electronic and nuclear structures).