Ghost canceling circuit promptly responsive to channel change
AssigneeNEC Corporation
InventorMitsuhiro Matsunaga
Life of this patent
Estimating the term…
Abstract
Digital ghost eliminating filters incorporated in a ghost canceling circuit are responsive to weighted coefficients for canceling ghost components of a digital video signal assigned to a selected channel for a clear video image, and has an auxiliary receiving circuit sequentially tuned in other channels so as to previously produce sets of weighted coefficients for non-selected channels, thereby immediately supplying one of the sets of weighted coefficients to the digital ghost eliminating filters when a main receiving circuit is tuned in another channel.
Claims5
A ghost canceling circuit associated with a main receiving circuit for eliminating a ghost image from a video image on a screen, said main receiving circuit being tuned in one of channels assigned to one of broadcasting signals supplied from an antenna for producing a main analog video signal, each of said broadcasting signals containing a ghost canceling reference component, said ghost canceling circuit entering through a transition period into a stable period when said main receiving circuit is tuned in another channel, and comprising:
- a) a main analog-to-digital converting circuit for converting said main analog video signal to a main digital video signal;
- b) a ghost component canceling means coupled with said main analog-to-digital converting circuit, and responsive to a weighted coefficient signal indicative of weighted coefficients for canceling ghost components indicative of said ghost image from said main digital video signal;
- c) a digital-to-analog converting circuit coupled with said ghost component canceling means, and converting said main digital video signal without said ghost components into an analog video signal without ghost components;
- d) an auxiliary receiving circuit electrically coupled with said antenna, and sequentially tuned in others of said channels respectively assigned to others of said broadcasting signals for producing an auxiliary analog video signal from one of said others of said broadcasting signals;
- e) an auxiliary analog-to-digital converting circuit coupled with said auxiliary receiving circuit, and converting said auxiliary analog video signal into an auxiliary digital video signal;
- and
- f) a controlling circuit having
- f-1) a channel controller sequentially selecting said others of said channels for said auxiliary receiving circuit, and tuning said auxiliary receiving circuit with a presently selected channel,
- f-2) a coefficient producing means for producing said weighted coefficients from a combination of said main analog video signal, said main digital video signal and a standard ghost canceling reference component without an influence of reflected waves of each broadcasting signal or from a combination of said auxiliary analog video signal, said auxiliary digital video signal and said standard ghost canceling reference component,
- f-3) a memory circuit for storing a plurality sets of weighted coefficients for said others of said broadcasting signals, each of said plurality sets of weighted coefficients being produced from said combination of said auxiliary analog video signal, said auxiliary digital video signal and said standard ghost canceling reference component, and
- f-4) a transfer circuit having a first port for transferring said weighted coefficients produced from said combination of said auxiliary analog video signal, said auxiliary digital video signal and said standard ghost canceling reference component from said coefficient producing means to said memory circuit, and a second port for continuously supplying said weighted coefficient signal indicative of said weighted coefficients produced from said combination of said main analog video signal, said main digital video signal and said standard ghost canceling reference component to said ghost component canceling means, said transfer circuit temporally supplying one of said plurality sets of weighted coefficients read out from said memory circuit from said second port to said ghost component canceling means in said transition period after said main receiving circuit is tuned with another channel.
A ghost canceling circuit associated with a main receiving circuit for eliminating a ghost image from a video image on a screen, said main receiving circuit being tuned in one of channels assigned to one of broadcasting signals supplied from an antenna in response to a channel selecting signal for producing a main analog video signal, each of said broadcasting signals containing a ghost canceling reference component, said ghost canceling circuit entering through a transition period into a stable period when said channel selecting signal tunes said main receiving circuit in another channel, and comprising:
- a) a main analog-to-digital converting circuit for converting said main analog video signal to a main digital video signal;
- b) a ghost component canceling means coupled with said main analog-to-digital converting circuit, and responsive to a weighted coefficient signal indicative of weighted coefficients for canceling ghost components indicative of said ghost image from said main digital video signal;
- c) a digital-to-analog converting circuit coupled with said ghost component canceling means, and converting said main digital video signal without said ghost components into an analog video signal without ghost components;
- d) an auxiliary receiving circuit electrically coupled with said antenna, and responsive to an auxiliary channel selecting signal so as to be sequentially tuned in others of said channels respectively assigned to others of said broadcasting signals for producing an auxiliary analog video signal from one of said others of said broadcasting signals;
- e) an auxiliary analog-to-digital converting circuit coupled with said auxiliary receiving circuit, and converting said auxiliary analog video signal into an auxiliary digital video signal;
- and
- f) a controlling circuit having
- f-1) a channel controller operative to supply said auxiliary channel selecting signal to said auxiliary receiving circuit for tuning said auxiliary receiving circuit with a presently selected channel,
- f-2) a coefficient producing means for producing said weighted coefficients from a combination of said main analog video signal, said main digital video signal and a standard ghost canceling reference component without an influence of reflected waves of each broadcasting signal or from a combination of said auxiliary analog video signal, said auxiliary digital video signal and said standard ghost canceling reference component,
- f-3) a selecting means having a first input port connected with said main receiving circuit and said main analog-to-digital converting circuit, a second input port connected with said auxiliary receiving circuit and said auxiliary analog-to-digital converting circuit and an output port connected with said coefficient producing means, and responsive to a shifting signal for selectively connecting said first input port and said second input port with said output port,
- f-4) a memory circuit for storing a plurality sets of weighted coefficients for said others of said broadcasting signals, each of said plurality sets of weighted coefficients being produced from said combination of said auxiliary analog video signal, said auxiliary digital video signal and said standard ghost canceling reference component,
- f-5) a transfer circuit having a first port for transferring said weighted coefficients produced from said combination of said auxiliary analog video signal, said auxiliary digital video signal and said standard ghost canceling reference component from said coefficient producing means to said memory circuit in said stable period, and a second port for continuously supplying said weighted coefficient signal indicative of said weighted coefficients produced from said combination of said main analog video signal, said main digital video signal and said standard ghost canceling reference component to said ghost component canceling means in said stable period, and
- f-6) a processor means responsive to said channel selecting signal for producing said shifting signal, said processor means being further operative to cause said channel controller to sequentially change said presently selected channel indicated by said auxiliary channel selecting signal in said stable period, said processor means being further operative to cause said transfer circuit to temporally supply one of said plurality sets of weighted coefficients read out from said memory circuit from said second port to said ghost component canceling means in said transition period after said main receiving circuit is tuned with another channel.
Dependencies are inferred from the claim text.