Method and apparatus for equalizing phase-modulated signals

Claim 3

The method as described in claim 1, further comprising the steps of: generating from said extracted carrier frequency a signal in quadrature with the signal received from the transmission medium; passing said signal in quadrature with the signal received from the transmission medium through a second transversal filter identical with said first transversal filter; and generating said adjustment error signal by comparing the output signal of said first transversal filter with said reference signal, and the output signal of said second transversal filter with a signal in quadrature with said reference signal.

Claim 4

The method of claim 2, wherein: said step of generating said adjustment error signal further includes the generation, using said extracted carrier frequency, of n signals in quadrature with said n possible reference signals; and a step of selecting from said n signals in quadrature the particular one which is to be used at a given characteristic instant.

Claim 5

A method as described in claim 1, wherein: said step of selecting said reference signal to be used at said given characteristic instant includes the steps of: determining from Said extracted carrier frequency n sectors within which said n possible reference signals are present; comparing a signal representative of said first transversal filter output signal and a signal representative of a signal in quadrature with said output signal with said n sectors; and selecting as a reference signal the particular one of said n possible reference signals which is in the sector within which said representative signal is present.

Claim 6

A method as described in claim 3, wherein: said selection of said reference signal and said signal in quadrature therewith includes the steps of: determining from said extracted carrier frequency n sectors within which the possible reference signals are present; comparing a signal representative of the output signals of said first and second transversal filters with said n sectors; selecting as reference signal the particular one of said n possible reference signals which is present in the sector within which said representative signal is present; and selecting the signal in quadrature with the selected reference signal.

Claim 7

A method as described in claim 1, wherein: said generation of said adjustment error signal includes the steps of: multiplying the result of the comparison of the output signal of said first transversal filter and said reference signal by each of the signals present on each of said different delay taps of said first transversal filter; and integrating the result of each multiplication, the integrated signal providing the adjustment error signal for the tap considered.

Claim 8

A method as described in claim 2, wherein: said generation of said adjustment error signal further includes the steps of: multiplying the result of the comparison of the output signal of said first transversal filter and said reference signal by each of the signals present on each of said different delay taps of said filter, the multiplication of said result by the signal present on the nth tap of said filter providing the nth partial result of a first type; multiplying the result of the comparison of the output signal of said second transversal filter and said signal in quadrature with said reference signal by each of the signals present on each of said taps of said second transversal filter, the multiplication by the signal present on the nth tap of said second transversal filter providing the nth partial result of a second type; and integrating the sum of the nth partial result of the first type and the nth partial result of the second type, the result of this integration providing the adjustment error signal for the nth taps of said first and second transversal filters.

Claim 9

Phase equalizing apparatus, for data signal reception, comprising: an input terminal; a first transversal filter with 2p+1 taps each of which has a variable gain coefficient, the input of said filter being connected to said input terminal and its output being connected to the output of said apparatus; carrier frequency extraction means whose input is connected to said input terminal; a phase-locked oscillator whose input is connected to the output of said carrier frequency extraction means to provie an extracted carrier frequency exhibiting n possible phase values, the n signals supplied by said oscillator making up n possible reference signals; a clock that determines the characteristic instants at the rate at which the data are transmitted; selection means to select from said n possible reference signals the particular one to be used at a given characteristic instant; gating means connected to said phase-locked oscillator and to said selection means to provide said selected reference signal to be used at a given characteristic instant; first comparison means to compare the signal at the output of said first transversal fIlter with the selected reference signal provided by said gating means; first correlation means connected to said taps of said first transversal filter and to the output of said first comparison means to provide an adjustment error signal; and means responsive to said adjustment error signal to vary the gain of said taps to minimize said error signal.

Claim 10

Phase equalizing apparatus, for data signal reception, comprising: an input terminal; a first transversal filter with 2p+1 taps each of which has a variable gain coefficient, the input of said filter being connected to said input terminal and its output being connected to the output of said apparatus; carrier frequency extraction means whose input is connected to said input terminal; a phase-locked oscillator whose input is connected to the output of said carrier frequency extraction means to provie an extracted carrier frequency exhibiting n possible phase values, the n signals supplied by said oscillator making up n possible reference signals; a clock that determines the characteristic instants at the rate at which the data are transmitted; selection means to select from said n possible reference signals the particular one to be used at a given characteristic instant; gating means connected to said phase-locked oscillator and to said selection means to provide said selected reference signal to be used at a given characteristic instant; first comparison means to compare the signal at the output of said first transversal fIlter with the selected reference signal provided by said gating means; first correlation means connected to said taps of said first transversal filter and to the output of said first comparison means to provide an adjustment error signal; and means responsive to said adjustment error signal to vary the gain of said taps to minimize said error signal.

Claim 11

Apparatus as described in claim 8, wherein: said selection means includes a sector selection device connected to said carrier frequency extraction means, to said phase-locked oscillator, to the output of said first transversal filter, to said clock and to said gating means, to determine in which of n predefined sectors within which said n possible reference signals are present the signal obtained at the output of said first transversal filter is available at the given characteristic instant, and to select as reference signal for said given characteristic instant the reference signal which is present in that sector.

Claim 12

Apparatus as described in claim 8, further comprising: phase conversion means to generate an output signal in quadrature with the input signal applied thereto, the input of said phase conversion means being connected to said input terminal; a second transversal filter identical with said first transversal filter, the input of said second filter being connected to the output of said phase conversion means; second comparison means to compare the signal obtained at the output of said second transversal filter with a signal in quadrature with the reference signal, said signal in quadrature being provided by said phase-locked oscillator through said gating means; and second correlation means connected to the taps of said second transversal filter and to the output of said second comparison means to provide, in conjunction with said first correlation means, the adjustment error signal.

Claim 13

Apparatus as described in claim 10, wherein: said selection means includes a sector selection device connected to said carrier frequency extraction means, to said phase-locked oscillator, to the outputs of said first and second transversal filters, to said clock and to said gating means, for determining in which of said n predefined sectors a signal representative of the other signals of said first and second transversal filters is present at the given characteristic instant, for selecting as reference signal for said characteristic instant the one which is present in the sector thus determined, and for selecting the signal in quadrature with the reference signal thus selected.

Claim 14

Apparatus as described in claim 9, wherein: said first and second transversal filters consist of a single time-multiplexed transversal filter.