Method and apparatus for performing bandedge equalization
View Patent ↗A method and apparatus for performing bandedge equalization. Specifically, the apparatus contains a pre-equalizer for adjusting the amplitudes of the bandedges of a broadband signal in response to a control signal. A bandedge filter is connected to the pre-equalizer and extracts a bandedge signal from the broadband signal. Lastly, a bandedge signal processor that is connected to the bandedge filter generates the control signal in response to said bandedge signal. In this manner, when the bandedges of the broadband signal are asymmetric, the apparatus adjusts the signal strength of each bandedge with respect to one another to equalize (balance) the bandedges. The balanced signal can then be used by a bandedge timing recovery circuit. As such, the accuracy of a bandedge timing recovery circuit is not impacted by the asymmetric bandedges of the input signal.
1. Apparatus for equalizing the amplitudes of the bandedges of a broadband signal comprising:
a pre-equalizer for adjusting the amplitudes of the bandedges of said broadband signal in response to a control signal;
a bandedge filter, connected to said pre-equalizer, for extracting a bandedge signal from said broadband signal; and
a bandedge signal processor, connected to said bandedge filter, for generating said control signal in response to said bandedge signal, wherein said bandedge signal processor comprises:
a first filter for producing a first bandedge signal from said bandedge signal;
a second filter for producing a second bandedge signal from said bandedge signal;
a first magnitude processor, connected to said first filter, for generating a first magnitude value representing the magnitude of said first bandedge signal; and
a second magnitude processor, connected to said second filter, for generating a second magnitude value representing the magnitude of said second bandedge signal.
2. The apparatus of claim 1 wherein said bandedge signal processor further comprises:
a subtractor, connected to said first and second magnitude processors, for producing a difference value representing the difference between said first and second magnitude values; and
a loop filter, connected to said subtractor, for generating said control signal from said difference value.
3. The apparatus of claim 1 wherein said first filter is a first Hilbert filter.
4. The apparatus of claim 1 wherein said second filter is a second Hilbert filter.
5. The apparatus of claim 4 wherein said first Hilbert filter has a form
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.
6. The apparatus of claim 4 wherein said second Hilbert filter has a form
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.
7. Apparatus for equalizing the amplitudes of the bandedges of a broadband signal comprising:
a pre-equalizer for adjusting the amplitudes of the bandedges of said broadband signal in response to a control signal;
a bandedge filter, connected to said pre-equalizer, for extracting a bandedge signal from said broadband signal;
a first Hilbert filter connected to said bandedge filter for producing a first bandedge signal from said bandedge signal;
a second Hilbert filter connected to said bandedge filter for producing a second bandedge signal from said bandedge signal;
a first magnitude processor, connected to said first Hilbert filter, for generating a first magnitude value representing the magnitude of said first bandedge signal; and
a second magnitude processor, connected to said second Hilbert filter, for generating a second magnitude value representing the magnitude of said second bandedge signal
a subtractor, connected to said first and second magnitude processors, for producing a difference value representing the difference between said first and second magnitude values; and
a loop filter, connected to said subtractor, for generating said control signal from said difference value.
8. A method of equalizing the amplitudes of the bandedges of a broadband signal comprising the steps of:
adjusting the amplitudes of the bandedges of said broadband signal in response to a control signal;
extracting a bandedge signal from said broadband signal; and
generating said control signal in response to said bandedge signal, wherein said generating step further comprises the steps of:
producing a first bandedge signal from said bandedge signal;
producing a second bandedge signal from said bandedge signal;
generating a first magnitude value representing a magnitude of said first bandedge signal; and
generating a second magnitude value representing a magnitude of said second bandedge signal.
9. The method of claim 8 wherein said control signal generating step further comprises the steps of:
producing a difference value representing the difference between said first and second magnitude values; and
generating said control signal from said difference value.