Diversity reception device

1. A diversity reception device, comprising:

a first antenna serving as a reference antenna;

a second antenna serving as an antenna-to-be-measured;

a power combiner configured to combine electric powers of OFDM signals respectively, each of the OFDM signals being received by the first and second antennas;

a digital terrestrial broadcast tuner connected to an output side of the power combiner;

a switch configured to change connections between branched output-ports of the first and second antennas, in mid-stream of effective symbol periods, the effective symbol periods are assigned respectively in each of symbol periods of the OFDM signals;

a receiver connected to an output side of the switch, configured to demodulate the OFDM signals;

a phase shifter connected to an output side of the second antenna, configured to shift phases of the OFDM signals received by the second antenna, and to transfer the phase-shifted OFDM signals to the power combiner; and

an arithmetic and control processing circuit, after accepting the demodulated OFDM signals, configured to calculate complex correlation coefficient between a guard interval, which is assigned in each of the symbol periods associated with the first antenna, and a copy-source interval, which is assigned in each of the symbol periods associated with the second antenna, and to determine rotation angle on a complex plane on the basis of the complex correlation coefficient, and to transfer phase-shift signal to the phase shifter so that the phase shifter can shift the phase by amount of the rotation angle.

2. The diversity reception device of claim 1 , further comprising:

a first directional coupler inserted into a part of a transmission route from the first antenna to the power combiner, configured to branch a part of the OFDM signals, which are received by the first antenna, toward the switch; and

a second directional coupler inserted into a part of a transmission route from the second antenna to the phase shifter, configured to branch a part of the OFDM signals, which are received by the second antenna, toward the switch.

3. A diversity reception device, comprising:

a reference antenna;

a plurality of antennas-to-be-measured;

a power combiner configured to combine electric powers of OFDM signals respectively, each of the OFDM signals being received by the reference antenna and the plurality of antennas-to-be-measured;

a digital terrestrial broadcast tuner connected to an output side of the power combiner;

a switch configured to change connections between branched output-ports of the reference antenna and any of the plurality of antennas-to-be-measured, in mid-stream of effective symbol periods, the effective symbol periods are assigned respectively in each of symbol periods of the OFDM signals;

a receiver connected to an output side of the switch, configured to demodulate the OFDM signals;

a plurality of phase shifters connected respectively to output sides of the plurality of antennas-to-be-measured, configured to shift respectively phases of the OFDM signals, which are received by the plurality of antennas-to-be-measured, and to transfer the phase-shifted OFDM signals to the power combiner, respectively; and

an arithmetic and control processing circuit configured to perform a sequence of processes against the plurality of antennas-to-be-measured, respectively, after accepting the demodulated OFDM signals, the sequence of processes includes:

calculating complex correlation coefficient between a guard interval, which is assigned in each of the symbol periods associated with the reference antenna, and a copy-source interval, which is assigned in each of the symbol periods associated with any of corresponding antennas-to-be-measured,

determining rotation angle on a complex plane on the basis of the complex correlation coefficient, and

transferring phase-shift signal to a phase shifter connected to corresponding antennas-to-be-measured so that the phase shifter connected to the corresponding antennas-to-be-measured can shift the phase by amount of the rotation angle.

4. The diversity reception device of claim 3 , further comprising:

a first directional coupler inserted into a part of a transmission route from the reference antenna to the power combiner, configured to branch a part of the OFDM signals, which are received by the reference antenna, toward the switch; and

a plurality of second directional couplers inserted respectively into a part of respective transmission routes from the plurality of antennas-to-be-measured to the phase shifter, configured to branch a part of the corresponding OFDM signals, which are respectively received by the plurality of antennas-to-be-measured, toward the switch, respectively.

5. The diversity reception device of claim 4 , wherein, as N is a positive integer equal to or greater than three, the number of the plurality of antennas-to-be-measured is set as (N−1), the arithmetic and control processing circuit sequentially carries out the sequence of processes with continuous (N−1) symbol periods, by calculating sequentially complex correlation coefficients between a guard interval, which is assigned in each of the symbol periods associated with the reference antenna, and a copy-source interval, which is assigned in each of the symbol periods associated with any of corresponding antennas-to-be-measured, and sequentially determining rotation angles on the complex plane on the basis of the complex correlation coefficients.

6. The diversity reception device of claim 4 , wherein, as N is a positive integer equal to or greater than three, the number of the plurality of antennas-to-be-measured is set as (N−1), the arithmetic and control processing circuit sequentially carries out the sequence of processes, after dividing each of the guard interval and the copy-source interval, which are assigned respectively in the symbol periods, into (N−1) segments, by calculating complex correlation coefficients between the reference antenna and any of the plurality of antennas-to-be-measured with each of the divided guard intervals and the divided copy-source intervals, and by sequentially determining rotation angles on the complex plane on the basis of the complex correlation coefficients.

7. The diversity reception device of claim 4 , wherein the arithmetic and control processing circuit does not combine the signals of the antennas-to-be-measured, when the correlation coefficients of the signals are equal to or less than a threshold.

8. The diversity reception device of claim 3 , wherein, as N is a positive integer equal to or greater than three, the number of the plurality of antennas-to-be-measured is set as (N−1), the arithmetic and control processing circuit sequentially carries out the sequence of processes with continuous (N−1) symbol periods, by calculating sequentially complex correlation coefficients between a guard interval, which is assigned in each of the symbol periods associated with the reference antenna, and a copy-source interval, which is assigned in each of the symbol periods associated with any of corresponding antennas-to-be-measured, and sequentially determining rotation angles on the complex plane on the basis of the complex correlation coefficients.

9. The diversity reception device of claim 8 , wherein the arithmetic and control processing circuit does not combine the signals of the antennas-to-be-measured, when the correlation coefficients of the signals are equal to or less than a threshold.

10. The diversity reception device of claim 3 , wherein, as N is a positive integer equal to or greater than three, the number of the plurality of antennas-to-be-measured is set as (N−1), the arithmetic and control processing circuit sequentially carries out the sequence of processes, after dividing each of the guard interval and the copy-source interval, which are assigned respectively in the symbol periods, into (N−1) segments, by calculating complex correlation coefficients between the reference antenna and any of the plurality of antennas-to-be-measured with each of the divided guard intervals and the divided copy-source intervals, and by sequentially determining rotation angles on the complex plane on the basis of the complex correlation coefficients.

11. The diversity reception device of claim 10 , wherein the arithmetic and control processing circuit does not combine the signals of the antennas-to-be-measured, when the correlation coefficients of the signals are equal to or less than a threshold.

12. The diversity reception device of claim 3 , wherein the arithmetic and control processing circuit does not combine the signals of the antennas-to-be-measured, when the correlation coefficients of the signals are equal to or less than a threshold.