Digital television broadcast signal receiver

A digital television broadcast signal receiver, to which a multi-directional antenna having sixteen signal receiving directions in compliance with a predetermined technical standard, receiving a digital television broadcast signal by making only one signal receiving direction among the sixteen signal receiving directions effective, comprising:

• a control signal output means for outputting a control signal for directing a signal receiving direction to the multi-directional antenna so as to receive a television broadcast signal;
• a television broadcast signal receiving means connected to the multi-directional antenna for receiving a digital television broadcast signal;
• a signal processing means for performing a predetermined signal processing to the television broadcast signal received by the television broadcast signal receiving means;
• a signal output means for outputting a signal processed by the signal processing means to a monitor display apparatus;
• a memory means for temporarily memorizing the signal processed by the signal processing means;
• a signal receiving direction deciding means for deciding an optimum signal receiving direction with respect to each receivable channel with using the signals memorized in the memory means;
• a term measuring means for measuring a term necessary for switching or changing an effective signal receiving direction of the connected multi-directional antenna;
• and
• an entire control means for controlling each component of the digital television broadcast signal receiver, and wherein
• when any multi-directional antenna is connected to the tuner,
• the control signal output means outputs control signals at a first interval longer than a signal receiving direction switching term of a multi-directional antenna which needs the longest term for switching or changing the effective signal receiving direction thereof among connectable multi-directional antennas;
• the television broadcast signal receiving means serially receives television broadcast signals of a channel in each signal receiving direction through the connected multi-directional antenna at the first interval;
• the signal processing means measures sensitivities of received television broadcast signals, and memorizes data of sensitivities with respect to the signal receiving directions into the memory means;
• the signal receiving direction deciding means selects two data of sensitivities among a plurality of data of sensitivities larger than a predetermined threshold value memorized in the memory means;
• the control signal output means outputs a first control signal so as to switch or change the effective signal receiving direction of the multi-directional antenna to a first signal receiving direction corresponding to one of data of sensitivity among selected two data of sensitivities, and outputs a second control signal so as to switch or change the effective signal receiving direction of the multi-directional antenna to a second signal receiving direction corresponding to the other data of sensitivity among selected two data of sensitivities, after outputting the first control signal and passing at least the first interval;
• after outputting the second control signal, the television broadcast signal receiving means receives a television broadcast signal of the channel at a second interval shorter than the first interval;
• the signal processing means measures a sensitivity of received television broadcast signal;
• the term measuring means compares a measured data of sensitivity with the data of sensitivity in the second signal receiving direction memorized in the memory means, and judges that the switching or changing the effective signal receiving direction of the multi-directional antenna from the first signal receiving direction to the second signal receiving direction has been completed when the data of sensitivities coincide with each other;
• when it is judged that the effective signal receiving direction of the multi-directional antenna from the first signal receiving direction to the second signal receiving direction at the second interval, the control signal output means outputs a third control signal so as to switch or change the effective signal receiving direction of the multi-directional antenna from the second signal receiving direction to the first signal receiving direction;
• after outputting the third control signal, the television broadcast signal receiving means receives a television broadcast signal of the channel at the second interval;
• the signal processing means measures a sensitivity of received television broadcast signal;
• the term measuring means compares a measured data of sensitivity with the data of sensitivity in the first signal receiving direction memorized in the memory means, and judges that the switching or changing the effective signal receiving direction of the multi-directional antenna from the second signal receiving direction to the first signal receiving direction has been completed when the data of sensitivities coincide with each other;
• the entire control means repeats switching or changing of the effective signal receiving direction of the multi-directional antenna between the first signal receiving direction and the second signal receiving direction, measurement of television broadcast signals of the channel, comparing of measured data of sensitivities with data of sensitivities memorized in the memory means with shortening the second interval little at each time until any measured data of sensitivity does not coincide with the data of sensitivity memorized in the memory means and it is judged that the switching or changing of the effective signal receiving direction of the multi-directional antenna between the first signal receiving direction and the second signal receiving direction by the term measuring means;
• and
• the term measuring means sets a proximate value of the second interval as a term suitable for switching or changing the effective signal receiving direction of the connected multi-directional antenna, when it is judged that the switching or changing of the effective signal receiving direction of the multi-directional antenna between the first signal receiving direction and the second signal receiving direction.