An equalizer, having a variable amplitude characteristic, for equalizing amplitude distortion especially in frequency-division multiplexed systems. The equalizer includes parallel signal paths, one path transmitting received signals essentially unchanged while the second path includes a circuit network having the transfer function t.sub.A = (2.alpha. k/1 + .alpha.k). The parallel paths are coupled to a subtraction circuit, the output of the subtraction circuit appearing as the output of equalize...

Disclosed is an automatic equalizer which, through a simple and inexpensive arrangement, performs precise equalization irrespective of timing phase error at the time of transmission. Specifically, there is provided an automatic equalizer for equalizing received data, which has a data transmission interval T, by a predetermined equalization characteristic, including a plurality of automatic equalizing units for performing equalization at different timings within the data transmission interval T. ...

An automatic equalizer includes a transversal filter having delay elements with N+1 taps and N+1 multipliers for outputting an output signal Y.sub.n which is described by the following formula (A) depending on a modulated input signal X.sub.n which is received via a transmission path and a coefficient C.sub.i.sup.(n) of each of the multipliers which are arranged in a sequence such that an integer i increases from -(N/2) to (N/2) towards latter stages of the delay elements, ##EQU1## a gain contro...

An apparatus and method for pressurizing the inside of tubular members of an offshore structure that are immersed in sea water so that the internal pressure resists the hydrostatic pressure of the sea water. To achieve this internal pressure, gas is generated automatically on the inside of the members as the structure descends to its in-place location. The gas can also be used to deballast a tubular member.

A signal equalizer for equalizing a waveform of a digital data sequence includes a discriminator for discriminating average measuement levels at plural frequencies of the digital data sequence. It also includes an error operating unit for finding the ratio or difference between an equalizing target average level which correspond to the plural frequencies that has been found in advance and an average level obtained by the discriminator. The signal equalizer further includes a controller for contr...

A baseband signal, obtained by quasi-coherent detecting a received signal, is sampled and written as a sequence of baseband signal samples into a buffer memory. For each baseband signal sample read out from the buffer memory, a maximum likelihood sequence estimation part generates a desired symbol sequence and feeds it to a transversal filter having a characteristic based on an estimated impulse response of the transmission path in correspondence with the timing of the baseband signal sample. A ...

An automatic equalizer is used in a radio transmission path for improving convergent characteristics of a control loop in an automatic equalizing mode when the amplitude ratio of reflected and direct waves is greater than 1. The automatic equalizer has an adaptive matched filter, a decision feedback equalizer, and a reset control circuit for outputting first and second reset signals, respectively, to the adaptive matched filter and the decision feedback equalizer when an asynchronous condition i...

An adaptive equalizer which has a decision feedback adaptive equalizer unit 41, a linear adaptive equalizer unit 42, comparing circuit 47 which compares integrated equalizing error value of the decision feedback adaptive equalizer 41 with integrated estimation error value of the linear adaptive equalizer unit 42, and selecting circuit 48. The selecting circuit 48 selects one of the equalizer units 41 and 42, which has the better performance based on the result of the comparison of comparing circ...

An automatic equalizer that can realize high-quality signal equalization without erroneous decision in the environment where a sequence candidate tends to be erroneously selected due to noises because the component corresponding to a demodulation point is close to the precursor component in magnitude. The automatic equalizer outputs the absolute values of impulse response signals, determines as candidate signals response absolute value signals larger than a threshold value, selects as a demodula...

An optical equalizer for a wavelength division multiplexed optical signal in an optical communications system utilises an array of parallel waveguides using planar waveguide technology. Waveguides having a range of different lengths have transmission controlled respectively in amplitude and/or phase in accordance with parameters calculated from a Fourier transform of an input frequency characteristic. Calculation of the parameters may be simplified by a Hilbert transform applied to determine pha...