US 5,331,416 AGranted

Methods for operating ghost-cancelation circuitry for TV receiver or video recorder

AssigneeSamsung Electronics Co., Ltd.

InventorsChandrakant B. Patel, Jim Yang

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Abstract

Ghosts accompanying composite video signals are suppressed using separate filters for suppressing macroghosts and microghosts, the filtering parameters of these filters being adjustable responsive to digital programming signals generated by a computer. Computation includes data acquisition and channel characterization steps followed by a decision step for comparing the most recent set of channel characterization results with the next most recent set to determine whether stable ghosting conditions obtain. Data acquisition and channel characterization steps are repeated until stable ghosting conditions obtain, so the subsequent calculations with respect to the filter used for suppressing macroghosts are accurately performed. Where the filter suppressing macroghosts includes IIR and FIR sections for suppressing post-ghosts and preghosts, respectively, these calculations are carried out substantially on a separable basis, simplifying the calculations. Then, a step of calculating the filtering parameters for the FIR filter used for suppressing microghosts is followed by further data acquisition and channel characterization steps and a decision step comparing the most recent set of further channel characterization results with the next most recent set of further channel characterization results to determine similarity. If the sets of further channel characterization results are substantially the same, either method loops back to the further data acquisition step; if not, the adjustable filtering parameters for the filters are reset to initial values and the method restarts automatically.

Claims29

Dependent claims

A method for operating apparatus comprising a receiver for receiving through a reception channel a video signal with accompanying ghost cancelling reference (GCR) signal both subject at times to being ghosted;

a ghost-suppression filter connected for responding to said video signal, said ghost-suppression filter having adjustable filtering parameters;
a computer for calculating the adjustable filtering parameters of said ghost-suppression filter, said computer provided with read-only memory for permanently storing data descriptive of ghost-free GCR signal and with further memory for purposes of temporary storage;
and a GCR-signal separator for separating a separated GCR signal from the response of said ghost-suppression filter;
said method avoiding the erroneous adjustment of the filtering parameters of said ghost-suppression filter during non-stable ghosting conditions such as "aircraft flutter" and comprising the steps of:
a) initializing the adjustable filtering parameters of said ghost-suppression filter;
b) loading said separated GCR signal into said further memory of said computer, for purposes of temporary storage, which loading is done at least after step (a);
c) each time after step (b) is performed, performing calculations within said computer for characterizing the reception channel as described by the separated GCR signal loaded into said computer during that step (b) to generate a set of updated channel characterization results;
d) each time after step (c) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (c);
e) each time after step (c) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a first threshold value, said method looping back to step (b) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said first threshold value;
and
f) each time ghosting conditions are determined not to have changed when step (e) is performed, thereafter performing calculations within said computer for determining the adjustable filtering parameters for said ghost-suppression filter.

8 more elements

a ghost-suppression filter connected for responding to said video signal which ghost-suppression filter comprises in a cascade connection a first filter of a type having adjustable filtering parameters that can be adjusted for suppressing macroghosts in its output response and a second filter of a type having adjustable filtering parameters that can be adjusted for suppressing microghosts in its output response;
a computer for calculating the adjustable filtering parameters of said first and said second filters, said computer provided with read only memory for permanently storing data descriptive of ghost-free GCR signal and with further memory for purposes of temporary storage;
and a GCR-signal separator for separating a separated GCR signal from the response of said ghost-suppression fitter;
said method comprising the steps of:
a) initializing the adjustable filtering parameters of said first and second filters;
b) loading said separated GCR signal into said further memory of said computer, for purposes of temporary storage, which loading is done at least after step (a);
c) each time after step (b) is performed, performing calculations within said computer for characterizing the reception channel as described by the separated GCR signal loaded into said computer during that step (b) to generate a set of updated channel characterization results;
d) each time after step (c) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (c);
e) each time after step (c) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a first threshold value, said method looping back to step (b) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said first threshold value;
f) each time ghosting conditions are determined not to have changed when step (e) is performed, thereafter performing calculations within said computer for determining the adjustable filtering parameters for said first filter;
g) after step (f) has been performed so that the adjustable filtering parameters for said first filter satisfactorily reduce all ghosts in the separated GCR signal, performing calculations within said computer for determining the adjustable filtering parameters for said second filter;
h) after step (g) has been performed, loading an updated separated GCR signal into said further memory of said computer, for purposes of temporary storage;
i) each time after step (h) is performed, performing calculations within said computer for characterizing the reception channel as described by the updated separated GCR signal loaded into said computer during that step (h) to generate a set of updated channel characterization results;
j) each time after step (i) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (i);
k) each time after step (i) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a second threshold value, said method looping back to step (a) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said second threshold value.

12 more elements

an IIR filter of a type having adjustable filtering parameters that can be adjusted for suppressing in its output response trailing macroghosts or post-ghosts accompanying its input signal;
an FIR filter of a type having adjustable filtering parameters that can be adjusted for suppressing in its output response leading macroghosts or pre-ghosts accompanying its input signal;
a ghost-suppression filter connected for responding to said video signal which ghost-suppression filter comprises the cascade connection of said IIR filter and said FIR filter;
a computer for calculating the adjustable filtering parameters of said first and said second digital filters, said computer provided with read-only memory for permanently storing data descriptive of ghost-free GCR signal and with further memory for purposes of temporary storage;
and a GCR-signal separator for separating a separated GCR signal from the response of said ghost-suppression filter;
said method comprising the steps of:
a) initializing the adjustable filtering parameters of said first and second digital filters;
b) loading said separated GCR signal into said further memory of said computer, for purposes of temporary storage, which loading is done at least after step (a);
c) each time after step (b) is performed, performing calculations within said computer for characterizing the reception channel as described by the separated GCR signal loaded into said computer during that step (b) to generate a set of updated channel characterization results;
d) each time after step (c) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (c);
e) each time after step (c) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a first threshold value, said method looping back to step (b) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said first threshold value;
f) each time ghosting conditions are determined not to have changed when step (e) is performed, thereafter performing calculations within said computer for determining the adjustable filtering parameters for said IIR filter and said FIR filter in the cascade connection which said ghost-suppression filter comprises;
g) after step (f) has been performed so that the adjustable filtering parameters for said IIR filter and said FIR filter satisfactorily reduce all ghosts in the separated GCR signal, proceeding from step (f) to step (h);
h) loading an updated separated GCR signal into said further memory of said computer, for purposes of temporary storage;
i) each time after step (h) is performed, performing calculations within said computer for characterizing the reception channel as described by the updated separated GCR signal loaded into said computer during that step (h) to generate a set of updated channel characterization results;
j) each time after step (i) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (i);
k) each time after step (i) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a second threshold value, said method looping back to step (a) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said second threshold value.

14 more elements

an IIR filter of a type having adjustable filtering parameters that can be adjusted for suppressing in its output response trailing macroghosts or post-ghosts accompanying its input signal;
a first FIR filter of a type having adjustable filtering parameters that can be adjusted for suppressing in its output response leading macroghosts or preghosts accompanying its input signal;
a second FIR filter of a type having adjustable filtering parameters that can be adjusted for suppressing in its output response microghosts accompanying its input signal;
a ghost-suppression filter connected for responding to said video signal which ghost-suppression filter comprises the cascade connection of said IIR filter, said first FIR filter, and said second FIR filter;
a computer for calculating the adjustable filtering parameters of said first and said second digital filters, said computer provided with read-only memory for permanently storing data descriptive of ghost-free GCR signal and with further memory for purposes of temporary storage;
and a GCR-signal separator for separating a separated GCR signal from the response of said ghost-suppression filter;
said method comprising the steps of:
a) initializing the adjustable filtering parameters of said first and second digital filters;
b) loading said separated GCR signal into said further memory of said computer, for purposes of temporary storage, which loading is done at least after step (a.);
c) each time after step (b) is performed, performing calculations within said computer for characterizing the reception channel as described by the separated GCR signal loaded into said computer during that step (b) to generate a set of updated channel characterization results;
d) each time after step (c) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (c);
e) each time after step (c) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a first threshold value, said method looping back to step (b) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said first threshold value;
f) each time ghosting conditions are determined not to have changed when step (e) is performed, thereafter performing calculations within said computer for determining the adjustable filtering parameters for said IIR filter, said first FIR filter and said second FIR filter in the cascade connection which said ghost-suppression filter comprises;
g) after step (f) has been performed so that the adjustable filtering parameters for said IIR filter, said first FIR filter and said second FIR filter satisfactorily reduce all ghosts in the updated separated GCR signal, proceeding from step (f) to step (h);
h) loading an updated separated GCR signal into said further memory of said computer, for purposes of temporary storage;
i) each time after step (h) is performed, performing calculations within said computer for characterizing the reception channel as described by the separated GCR signal loaded into said computer during that step (h) to generate a set of updated channel characterization results;
j) each time after step (i) is performed, temporarily storing within the further memory of said computer the set of updated channel characterization results generated by that step (i);
k) each time after step (i) is performed, determining within said computer whether or not ghosting conditions have changed, by comparing each portion of the updated set of channel characterization results with a corresponding portion of the previously temporarily stored set of channel characterization results, ghosting conditions being determined not to have changed only when corresponding portions of the compared sets of channel characterization results in every comparison differ by less than a second threshold value, said method looping back to step (a) when ghosting conditions are determined to have changed when corresponding portions of the compared sets of channel characterization results in any of said comparisons differ by as much as or more than said second threshold value.

15 more elements

Dependencies are inferred from the claim text.