JP2003318854A - Diversity receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity receiver for performing stable diversity reception by controlling a state of an output signal from other antenna in which an output signal is combined with an output signal from an antenna being received. <P>SOLUTION: A gain of a variable gain amplifier 10 that amplifies an output signal of an antenna 2 that combines the output signal with the output signal from an antenna 1 is selectively controlled as maximum or minimum in a guard interval section, whether or not a level of correlational output is maximized is discriminated by selectively controlling a phase inversion state of a phase inversion circuit 32 corresponding to the antenna 2 to a state of phase inversion or phase non-inversion in the guard interval section, the gain of the antenna variable gain amplifier 10 is gradually increased by every guard interval at a phase state of the phase inversion circuit 32 when a level of the correlational output is maximized. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiver that receives a broadcast signal modulated (OFDM modulated) by an orthogonal frequency division multiplexing system.

[0002]

2. Description of the Related Art 1OFD of OFDM modulated broadcast signal
The M transmission symbol period is composed of an effective symbol section and a section called a guard interval. The effective symbol period is a signal period required for data transmission. The guard interval is for preventing intersymbol interference such as multipath, and is a cyclic copy of the last predetermined period length portion of the effective symbol section to the beginning of the effective symbol section.

Diversity receivers for receiving OFDM modulated broadcast signals such as digital terrestrial television broadcast signals are known. A conventional diversity receiver of this type is proposed by the applicant (Japanese Patent Application No. 2002-023678).

In this diversity receiver, a received signal from a plurality of antennas is amplified by a variable gain amplifier, the amplified outputs are combined, and the combined output is demodulated into a baseband signal. (Also referred to as a variable gain amplifier) is detected, and the gain of one variable gain amplifier in the variable gain amplifier is stepwise changed based on the level of the correlation output during the period corresponding to the guard interval section.

The diversity receiver B is constructed as shown in FIG. In the diversity receiver B, the RF signals received by the antennas 1, 2, 3, 4 are amplified by the low noise amplifiers 5, 6, 7, 8 respectively, and the amplified outputs are respectively variable gain amplifiers 9, 10, 11, The signal is amplified by 12 and input to a combiner 13 for combination, and the output of the combiner 13 is supplied to a tuner 14.

The tuner 14, which has received the combined output from the combiner 13, amplifies the combined output, frequency-converts it, and limits the band to convert it into an intermediate-frequency signal. The intermediate frequency signal output from the tuner 14 is an AD converter 15
To a digital signal, and the converted digital signal is supplied to the quadrature detector 16 for quadrature detection,
Convert to baseband I and Q signals.

The baseband I and Q signals output from the quadrature detector 16 are supplied to the effective symbol extraction circuit 17, and based on the timing signal (FFT-WINDOW) indicating the effective symbol section output from the timing reproduction circuit 21, In the effective symbol extraction circuit 17, only the signal in the period corresponding to the effective symbol is fetched from the baseband I and Q signals, and the signal in the period corresponding to the effective symbol section is F.
The data is supplied to the FT circuit 18, FFT processing is performed in the FFT circuit 18 to demodulate the OFDM modulated signal to separate into information for each carrier, and the information is supplied to the demapper circuit 19 to be demapped and transmitted as demodulated data.

On the other hand, the baseband I and Q signals output from the quadrature detector 16 are supplied to the guard correlator 20, and the input baseband I and Q signals of the guard correlator 20 and the baseband I and Q signals are validated. The product of the delayed baseband I and Q signals delayed by the time width of the symbol period is integrated over the time width of the guard interval period, and the integration is sequentially performed for each sample period for A / D conversion in the A / D converter 15. By performing the shift, the correlation output is obtained from the integrated value, the correlation output is supplied to the timing reproduction circuit 21, the timing of the OFDM symbol is obtained from the peak position of the correlation output, and the timing signal (FFT-WINDOW) is obtained.
To the effective symbol extraction circuit 17.

The diversity receiver B is provided with a diversity control circuit 22, and the correlation output CORR and timing signal (FFT-WI) output from the guard correlator 20.
NDOW is supplied to the diversity control circuit 22, and the correlation output CORR and the timing signal (FFT-WIN) are supplied.
Gain control signals CONT1, CONT2, CONT3, CON for controlling the gains of the variable gain amplifiers 9, 10, 11, 12 from the diversity control circuit 22 based on DOW).
T4 is sent to the variable gain amplifiers 9, 10, 11, and 12, respectively, so that the output level of the combiner 13, that is, the combined reception signal level becomes high.
Control the gain of 10, 11, and 12.

The operation of the diversity control circuit 22 will be described with reference to the timing charts shown in FIGS. 8 and 9 using the gain control signal CONT1 as an example.

Here, in the diversity receiver B, the timing signal (FFT-WINDOW) indicates a period corresponding to the effective symbol period when the potential is high, and indicates a period corresponding to the guard interval period when the potential is low.
The gain control signal CONT1 is a signal for controlling the gain of the variable gain amplifier 9, and when the level of the gain control signal CONT1 is the minimum, the gain of the variable gain amplifier 9 is controlled to the minimum and the level of the gain control signal CONT1 is the maximum. In this case, the gain of the variable gain amplifier 9 becomes maximum. Gain control signal CO
The case of NT2, 3, 4 is the same as that of the gain control signal CONT1.

In the diversity control circuit 22, the correlation output CORR is used to judge whether or not the reception condition is improved. In the diversity control circuit 22, the gains of the variable gain amplifiers 9, 10, 11, 12 are changed during the period when the timing signal (FFT-WINDOW) is low potential, that is, during the period corresponding to the interval of the guard interval.

In FIG. 8, the variable gain amplifiers 10, 11, 12 are arranged so that the input of the combiner 13 is not lost.
Among them, at least one gain is maximized, and in the initial state, the level of the gain control signal CONT1 is minimum, that is, the gain of the variable gain amplifier 9 is minimum. Here, in order to evaluate the signal received by the antenna 1, the gain control signal CONT is detected in a section where the timing signal (FFT-WINDOW) is at a low potential (see FIG. 8A).
The level of 1 is maximized (see FIG. 8B), and the gain of the variable gain amplifier 9 is maximized.

As a result, the signal received by the antenna 1 is also combined by the combiner 13 and input to the tuner 14. At this time, in FIG. 8, the peak level of the correlation output CORR is higher than that of the previous correlation output CORR. The figure also shows a case where the height also rises (see FIG. 8C).
In this case, if the combiner 13 combines the signals received by the antenna 1, the output level of the combiner 13 increases, and it is determined that the reception condition is improved. In order to avoid the change, the level of the gain control signal CONT1 is temporarily returned to the minimum at the timing when the timing signal (FFT-WINDOW) becomes high potential,
As shown by the arrow in FIG. 8, after that, the steps are performed until the level of the gain control signal CONT1 becomes maximum in the section where the timing signal (FFT-WINDOW) is at a low potential, that is, until the gain of the variable gain amplifier 9 becomes maximum. Gradually increase.

The initial state of the diversity receiver B is shown in FIG.
However, as in the case of FIG. 8B, in the section where the timing signal (FFT-WINDOW) is at a low potential,
By maximizing the level of the gain control signal CONT1 and maximizing the gain of the variable gain amplifier 9, the correlation output COL
When the level of R decreases, the signal received by the antenna 1 is combined by the combiner 13 to lower the output signal level of the combiner 13, and the correlation output CORR
It is considered that the peak level of the signal has decreased, and it is determined that the reception condition has deteriorated. Therefore, the timing signal (F
The level information of the gain control signal CONT1 is returned to the minimum, that is, the gain of the variable gain amplifier 9 is returned to the minimum at the timing when FT-WINDOW) becomes high potential.

When the gain of the variable gain amplifier 9 is maximized in the period corresponding to the guard interval section in the state where the gain of the variable gain amplifier 9 is maximum as in the case shown in FIG. When the peak level of the correlation output CORR in the period corresponding to the guard interval section is higher than the peak level of the correlation output in the period corresponding to the preceding guard interval section, the period corresponding to the next guard interval section The gain of the variable gain amplifier 9 is minimized, that is, restored to its original value, in a period corresponding to the guard interval section following
The gain of the variable gain amplifier 9 is stepwise increased to the maximum in the period corresponding to the subsequent guard interval section. As a result, it is possible to set a gain that allows stable reception.

Further, when the gain of the variable gain amplifier 9 is maximized in the period corresponding to the guard interval section in the state where the gain of the variable gain amplifier 9 is maximized as described above, it is correlated with the next guard interval period. When the peak level of the output CORR is lower than the peak level of the correlation output in the period corresponding to the preceding guard interval section, it corresponds to the subsequent guard interval section when the gain of the variable gain amplifier 9 is maximized. From the period, the gain of the variable gain amplifier 9 is minimized, that is, restored to the original. As a result, it is possible to set a gain that allows stable reception.

Even in the case of FIG. 9, variable gain amplifiers 10 and 1
At least one of the gains 1 and 12 has the maximum gain, and in the initial state, the level of the gain control signal CONT1 is the maximum, that is, the gain of the variable gain amplifier 9 is the maximum. Here, in order to evaluate the signal received by the antenna 1, a timing signal (FFT-WINDOW) is used.
The level of the gain control signal CONT1 is minimized (see FIG. 9B) in the section where W) is at a low potential (see FIG. 9A), and the gain of the variable gain amplifier 9 is minimized.

As a result, the signal received by the antenna 1 is amplified with the minimum gain, combined by the combiner 13 and input to the tuner 14. As a result, FIG. 9 shows a case where the peak level of the correlation output CORR rises (see FIG. 9C). In this case, if the signal received by the antenna 1 is amplified by the variable gain amplifier 9 with the minimum gain, the level of the correlation output CORR rises,
It is determined that the reception condition is improved, and then the level of the gain control signal CONT1 is once returned to the maximum (see FIG. 9B) at the timing when the timing signal (FFT-WINDOW) becomes high potential (see FIG. 9B), and is indicated by an arrow in FIG. As described above, the timing signal (FFT-WINDOW) is sequentially changed stepwise until the level of the gain control signal CONT1 becomes minimum in the low potential section, that is, until the gain of the variable gain amplifier 9 becomes minimum (FIG. 9 (b)).

The initial state of the diversity receiver B is shown in FIG.
However, as in the case of FIG. 9B, in the section where the timing signal (FFT-WINDOW) becomes low potential,
The level of the gain control signal CONT1 is minimized, and the gain of the variable gain amplifier 9 is minimized.
When the level of R decreases, the level of the output signal of the combiner 13 decreases by combining the signals received by the antenna 1 in the combiner 13, and the correlation output COR
It is considered that the peak level of R has decreased, and it is determined that the reception conditions have deteriorated. Therefore, the timing signal (FFT
The level of the gain control signal CONT1 is maximized, that is, the gain of the variable gain amplifier 9 is returned to the maximum when −WINDOW) becomes a high potential.

When the gain of the variable gain amplifier 9 is minimized in the period corresponding to the guard interval section in the state where the gain of the variable gain amplifier 9 is maximum as in the case shown in FIG. When the peak level of the correlation output CORR in the guard interval period is higher than the peak level of the correlation output in the period corresponding to the preceding guard interval section, the guard interval following the period corresponding to the next guard interval section. The gain of the variable gain amplifier 9 is maximized in the period corresponding to the section, that is, restored to its original value, and the gain of the variable gain amplifier 9 is gradually reduced to the minimum in the period corresponding to the subsequent guard interval section. As a result, it is possible to set a gain that allows stable reception.

As described above, when the gain of the variable gain amplifier 9 is minimized in the period corresponding to the guard interval section in the state where the gain of the variable gain amplifier 9 is maximum, the next guard interval section is set. When the peak level of the correlation output CORR in the corresponding period is smaller than the peak level of the correlation output in the period corresponding to the preceding guard interval section, the guard is continued when the gain of the variable gain amplifier 9 is minimized. The gain of the variable gain amplifier 9 is maximized from the period corresponding to the interval section, that is, the gain is restored to the original value. As a result, it is possible to set a gain that allows stable reception.

In this way, the variable gain amplifiers 9 and 1 are maintained with the gain of one or more variable gain amplifiers being maintained at the maximum.
The gains of 0, 11, and 12 are sequentially controlled to control the signal level input to the tuner 14 at the maximum level. As a result, stable diversity reception can be performed.

[0024]

However, as described above, the gain of the variable gain amplifier corresponding to one antenna is maximized, and it corresponds to another antenna for combining the output signal from the one antenna with the output. Even if an attempt is made to control the gain of the variable gain amplifier for each OFDM symbol so as to always keep the reception level high, there is a delay in the output from the variable gain amplifier corresponding to the other antenna.

When this delay is approximately an odd multiple of 1/2 of the received signal wavelength, the phase of the output signal from the variable gain amplifier corresponding to the other antenna is from the variable gain amplifier corresponding to the one antenna. However, the combined signal level is lowered, which is substantially equivalent to the fact that the other antenna is not selected, and stable diversity reception cannot be performed. .

In this case, if the output level from the variable gain amplifier corresponding to the other antenna is higher than the output level from the variable gain amplifier corresponding to the one antenna, antenna selection is performed. It was not performed optimally, and there was a problem that stable diversity reception could not be performed.

The present invention provides a diversity receiver capable of performing stable diversity reception by controlling the state of the output signal from another antenna in which the output signal from the receiving antenna is combined with the output signal. The purpose is to do.

[0028]

In a diversity receiver according to claim 1 of the present invention, one symbol period is an OF having an effective symbol period and a guard interval period.
A diversity receiver including a plurality of antennas for receiving a DM-modulated signal, wherein a variable gain amplifying means for amplifying received signals from the plurality of antennas and a phase of selectively outputting an output from the variable gain amplifying means. Phase inversion means for inverting, demodulation means for demodulating and outputting a combined output obtained by combining the output signals from the phase inversion means, and detection of the correlation of the period corresponding to the guard interval section of the baseband signal obtained by the demodulation means The gain of the variable gain amplifying means corresponding to the antenna for synthesizing the output signal from the correlation detecting means and the output signal from the receiving antenna output through the phase inversion circuit is set to the maximum or the minimum in the guard interval section. A guard interval is set for the phase inversion state of the phase inversion means corresponding to the antenna for selectively controlling and synthesizing the output signals. By selectively controlling the phase inversion or phase non-inversion during the period, it is determined whether or not the correlation output level is maximized, and the output signals are synthesized when the correlation output level is maximized. Diversity control means for gradually increasing the gain of the variable gain amplifying means corresponding to the antenna for combining the output signals in the phase state of the phase inverting means corresponding to the antenna.

According to the diversity receiver according to claim 1 of the present invention, the variable gain amplification corresponding to the antenna for synthesizing the output signal with the output signal from the receiving antenna output through the phase inverting means. The gain of the means is selectively controlled to the maximum or the minimum in the guard interval section, and the phase inversion state of the phase inversion means corresponding to the antenna that synthesizes the output signals becomes the phase inversion or the phase non-inversion state in the guard interval section. The phase of the phase inverting means corresponding to the antenna for synthesizing the output signal when the level of the correlation output is maximized by determining whether the level of the correlation output is maximum by selectively controlling In this state, the gain of the variable gain amplifying means corresponding to the antenna that synthesizes the output signals gradually increases in each guard interval section. Provoking.

Therefore, according to the diversity receiver according to claim 1 of the present invention, since the phase inverting means is present and the phase is selectively inverted, the output signal from the antenna being received and the output signal are Even if there is a phase difference with the output signal from the combining antenna, stable diversity reception can be performed.

A diversity receiver according to claim 2 of the present invention is a diversity receiver including a plurality of antennas for receiving an OFDM-modulated signal in which one symbol period includes an effective symbol section and a guard interval section. And a variable gain amplifying means for respectively amplifying received signals from a plurality of antennas, a phase inverting circuit for selectively inverting the output from the variable gain amplifying means, and a phase inverting circuit which are cascade-connected to selectively 90 degrees. Corresponding to the guard interval section of the baseband signal obtained by the demodulating means, the phase changing means including the phase shift circuit, the demodulating means for demodulating and outputting the combined output obtained by combining the output signals from the phase changing means. From the correlation detection means that detects the correlation for the specified period and the receiving antenna that is output via the phase change circuit The gain of the variable gain amplifying means corresponding to the antenna that synthesizes the output signal with respect to the output signal is selectively controlled to the maximum or the minimum in the guard interval section, and the phase of the phase changing means corresponding to the antenna that synthesizes the output signal is changed. The level of the correlation output is determined by determining whether the level of the correlation output is maximized by selectively controlling the state to the phase inversion, phase non-inversion, phase shift, or phase non-shift state in the guard interval section. Diversity control for gradually increasing the gain of the variable gain amplifying means corresponding to the antenna combining the output signals in the phase state by the phase changing means corresponding to the antenna combining the output signals when Means and are provided.

According to the diversity receiver of claim 2 of the present invention, the variable gain amplification corresponding to the antenna for combining the output signal from the receiving antenna output through the phase changing means. The gain of the means is selectively controlled to the maximum or the minimum in the guard interval section, and the phase change state of the phase changing means corresponding to the antenna for combining the output signals is phase inversion, phase non-inversion, phase shift in the guard interval section. , Or the phase non-shifted state is selectively controlled to determine whether the level of the correlation output is maximized, and the output signals are synthesized when the level of the correlation output is maximized. Of the variable gain amplifying means corresponding to the antenna for combining the output signals in the phase state by the phase changing means corresponding to the antenna Obtained is increased gradually for each guard interval.

Therefore, according to the diversity receiver of the second aspect of the present invention, since the phase changing means is present and the phase is selectively changed, the output signal from the receiving antenna and the output signal are received. Even if there is a phase difference with the output signal from the combining antenna, stable diversity reception can be performed.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION A diversity receiver according to the present invention will be described below with reference to an embodiment.

FIG. 1 is a block diagram showing the configuration of a diversity receiver according to an embodiment of the present invention, and FIG.
In order to avoid redundant description with the diversity receiver B shown in FIG. 2, in the diversity receiver A according to the embodiment of the present invention, the same components as those of the diversity receiver B are designated by the same reference numerals, and The description is omitted.

The diversity receiver A has an antenna 1,
2, 3, 4, low noise amplifiers 5, 6, 7, 8, variable gain amplifiers 9, 10, 11, 12, combiner 13, tuner 1
4, an AD converter 15, a quadrature detector 16, an effective symbol extraction circuit 17, an FFT circuit 18, a demapper 19, a guard correlator 20, and a timing recovery circuit 21, which operate in the same manner as in the diversity receiver B. .

Furthermore, in the diversity receiver A, the phase inverting circuits 31, 32, 32 for selectively inverting the phases of the output signals of the variable gain amplifiers 9, 10, 11, 12 and outputting the outputs to the combiner 13 are provided. 33, 34 and a diversity control circuit 30 in place of the diversity control circuit 22.

The correlation output CORR output from the guard correlator 20 and the timing signal (FFT-WINDOW) output from the timing reproduction circuit 21 are supplied to the diversity control circuit 30, and the correlation output CORR and the timing signal (FFT-WINDOW) are supplied. Under the control of the diversity control circuit 30 based on
The gains of 0, 11, and 12 are changed and controlled, and the phase inversion circuits 31, 32, 33, and 34 selectively perform phase inversion control.

That is, under the control of the diversity control circuit 30, the output signals from the variable gain amplifiers 9, 10, 11, 12 whose gain is controlled based on the level of the correlation output CORR are selectively phase-inverted circuit 31 ,. 32, 33, 3
And substantially selecting an antenna for combining the output signal with the output signal of the antenna corresponding to the variable gain control amplifier in which the gain is controlled to the maximum,
The signal of the variable gain amplifier corresponding to the selected antenna and the output signal of the antenna corresponding to the variable gain control amplifier whose gain is controlled to the maximum are respectively combined by the combiner 13 through the phase inversion circuit, and the combined reception is performed. Antenna diversity operation is performed in which the gain is stepwise changed and controlled so that the signal level becomes higher.

Next, the operation of the diversity control circuit 30 will be described with reference to the timing charts shown in FIGS. 2, 3 and 4 show the case where the receiving antenna is the antenna 1 and the output signal of the antenna 1 is combined with the output signal of the antenna 2 when the output signal of the antenna 1 is received. Is an example of. In this case, the variable gain control amplifier whose gain is controlled to the maximum is the variable gain amplifier 9 corresponding to the antenna 1, and the output signal of the antenna 2 is substantially combined to combine the output signal of the antenna 1 with the output signal. An example of selecting and synthesizing output signals is illustrated.

When the output signal from the antenna 1 is combined with the output signal from the antenna 1 while receiving the output from the antenna 1, the output signal level from the antenna 2 is large, and the output signal from the antenna 1 and the antenna 2 FIG. 2 shows an example of the case where the phase of the output signal is different from that of the output signal. Figure 2
2A shows the state of the gain of the variable gain amplifier 9, and FIG.
Solid line sections (a) to (f) sandwiched by the arrows in (b) show guard interval sections, FIG. 2 (c) shows a state of phase inversion by the phase inversion circuit 31, and FIG. 2 (d). 2 (e) shows the state of gain of the variable amplifier 10, FIG. 2 (e) shows the state of phase inversion by the phase inversion circuit 32, and FIG. 2 (f) shows the level of the correlation output CORR.

In FIG. 2, the gain of the variable gain amplifier 9 is controlled to the maximum (see FIG. 2A), and the phase inversion circuit 31 is controlled to the non-inversion state (see FIG. 2C). . In this state, in the first guard interval section (a), the gain of the variable gain amplifier 10 is controlled to the maximum (see a in FIG. 2D), and the phase inversion circuit 32 is controlled to the non-inversion state (FIG. 2). (See (e)), the level of the correlation output CORR is checked (Fig. 2 (f)).
B)).

The level of the correlation output CORR at this time is
The gain of the variable gain amplifier 9 is maximum and the output signal is in the non-inverted state, and the gain of the variable gain amplifier 10 is maximum and the output signal is the level of the correlation output CORR in the non-inverted state.

In the next guard interval section (b), while maintaining the gain of the variable gain amplifier 9 and the state of the phase inverting circuit 31, the gain of the variable gain amplifier 10 is controlled to the minimum and the phase inverting circuit 32 is set. The non-inversion state is controlled, and the level of the correlation output CORR in that state is checked (see c in FIG. 2 (f)). In this case, only the output signal of the variable gain amplifier 9 is substantially selected, and the correlation output CO in b of FIG. 2 (f) is selected.
Correlation output C in FIG. 2 (f) rather than RR level
Since the ORR level is high, the output of the variable gain amplifier 10 is not selected, that is, the antenna 2 is not selected.

Further, in the next guard interval section (C), the variable gain amplifier 1 is maintained with the gain of the variable gain amplifier 9 and the state of the phase inverting circuit 31 maintained.
The gain of 0 is controlled to the maximum (see a in FIG. 2 (d)) and the phase inversion circuit 32 is controlled to the inverted state (see h in FIG. 2 (e)), and the correlation output CORR in the state at that time is controlled. The level is checked (see d in FIG. 2 (f)). In this case, the output signal of the variable gain amplifier 9 is in the non-inverted state,
The output signal of the variable gain amplifier 10 is in the inverted state, and the antenna 2 is substantially selected.
The level of the correlation output CORR in FIG. 2 (f) is larger than the level of the correlation output CORR in c of (f).

Further, in the next guard interval section (d), the variable gain amplifier 1 is maintained while the gain of the variable gain amplifier 9 and the state of the phase inversion circuit 31 are maintained.
The gain of 0 is controlled to the minimum (see FIG. 2 (d)), and the phase inversion circuit 32 is controlled to the non-inversion state (see FIG. 2 (e)), and the level of the correlation output CORR in the state at that time is set. Check (see e in FIG. 2F). In this case, the output signal of the variable gain amplifier 9 is in the non-inverted state, the output signal of the variable gain amplifier 10 is also in the non-inverted state, and the antenna 2 is substantially not selected.
The level of the correlation output CORR in e of FIG. 2 (f) is smaller than the level of the correlation output CORR in d of (f).

Corresponding to the state where the correlation output CORR becomes maximum (see d in FIG. 2 (f)), the gain of the variable gain amplifier 9 and the state of the phase inversion circuit 31 in the next guard interval section (e). While maintaining the above, the gain of the variable gain amplifier 10 is gradually increased (see i in FIG. 2 (d)), and the phase inversion circuit 32 is controlled to the inversion state (see FIG. 2 (e)). The gain of the amplifier 10 is gradually increased in the guard interval section (f) (Fig. 2 (d)).
I)), the output signal of the phase inverting circuit 31 and the output signal of the phase inverting circuit 32 are combined by the combiner 13. As the gain of the variable gain amplifier 10 is gradually increased, the level of the correlation output CORR increases (see f and g in FIG. 2 (f)). This state corresponds to the state shown in FIG. 8, and the output of the antenna 2 whose phase has been inverted is substantially selected.

When the output signal from the antenna 1 is combined with the output signal from the antenna 1 while receiving the output from the antenna 1, the output signal level from the antenna 2 is large, and the output signal from the antenna 1 and the antenna 2 FIG. 3 shows an example in which the output signal from the output signal is out of phase. Figure 3
3A shows the state of the gain of the variable gain amplifier 9, and FIG.
Solid line sections (a) to (f) sandwiched by arrows in (b) show guard interval sections, FIG. 3 (c) shows a state of phase inversion by the phase inversion circuit 31, and FIG. 3 (d). Shows the state of gain of the variable amplifier 10, FIG. 3 (e) shows the state of phase inversion by the phase inversion circuit 32, and FIG. 3 (f) shows the level of the correlation output CORR.

In FIG. 3, the gain of the variable gain amplifier 9 is controlled to the maximum (see FIG. 3A), and the phase inversion circuit 31 is controlled to the non-inversion state (see FIG. 3C). . In this state, in the first guard interval section (a), the gain of the variable gain amplifier 10 is controlled to be maximum (see a in FIG. 3 (d)), and the phase inversion circuit 32 is controlled to the non-inversion state (FIG. 3). (See (e)), the level of the correlation output CORR is checked (Fig. 3 (f)).
B)).

The level of the correlation output CORR at this time is
The gain of the variable gain amplifier 9 is maximum and the output signal is in the non-inverted state, and the gain of the variable gain amplifier 10 is maximum and the output signal is the level of the correlation output CORR in the non-inverted state.

In the next guard interval section (b), while maintaining the gain of the variable gain amplifier 9 and the state of the phase inverting circuit 31, the gain of the variable gain amplifier 10 is controlled to the minimum and the phase inverting circuit 32 is set. The non-inversion state is controlled, and the level of the correlation output CORR in that state is checked (see c in FIG. 3 (f)). In this case, only the output signal of the variable gain amplifier 9 is substantially selected, and the correlation output CO in b of FIG.
Correlation output C in c of FIG. 3 (f) rather than the level of RR
Since the ORR level is low, the output signal of the antenna 2 is added in a non-inverted state.

Next, corresponding to the state in which the correlation output CORR becomes maximum (see b in FIG. 3 (f)), in the next guard interval section (c), the gain and phase inversion circuit of the variable gain amplifier 9 is obtained. While maintaining the state of 31, the gain of the variable gain amplifier 10 is set to the guard interval section (C).
At the same time (see i in FIG. 3D), and the phase inversion circuit 32 is controlled to the non-inversion state (see FIG. 3E),
The gain of the variable gain amplifier 10 is gradually increased in each successive guard interval section (d) to (f) (see FIG. 3).
(See i in (d)), the combiner 13 combines the output signal of the phase inverting circuit 31 and the output signal of the phase inverting circuit 32.
By gradually increasing the gain of the variable gain amplifier 10, the correlation output CO
The level of RR increases (see d, e, f, and g in FIG. 3 (f)). This state corresponds to the state shown in FIG. 8, and the output of the antenna 2 whose phase has been inverted is substantially selected.

FIG. 4 shows an example in which the output signal level from the antenna 2 is low when the output signal from the antenna 1 is combined with the output signal from the antenna 1 while receiving the output from the antenna 1. . FIG. 4A shows a variable gain amplifier 9
4B shows the state of gain, the solid line sections (a) to (f) sandwiched by the arrows in FIG. 4B indicate the guard interval sections, and FIG. 4C shows the phase inversion by the phase inversion circuit 31. 4 (d) shows the state of gain of the variable amplifier 10, FIG. 4 (e) shows the state of phase inversion by the phase inversion circuit 32, and FIG. 4 (f) shows the level of the correlation output CORR. Shows.

In FIG. 4, the gain of the variable gain amplifier 9 is controlled to the maximum (see FIG. 4A), and the phase inversion circuit 31 is controlled to the non-inversion state (see FIG. 4C). . In this state, in the first guard interval section (a), the gain of the variable gain amplifier 10 is controlled to be maximum (see a in FIG. 4D), and the phase inversion circuit 32 is controlled to the non-inversion state (FIG. 4). (See (e)), the level of the correlation output CORR is checked (Fig. 4 (f)).
B)).

The level of the correlation output CORR at this time is
The gain of the variable gain amplifier 9 is maximum and the output signal is in the non-inverted state, and the gain of the variable gain amplifier 10 is maximum and the output signal is the level of the correlation output CORR in the non-inverted state.

In the next guard interval section (b), the gain of the variable gain amplifier 10 is controlled to the minimum while the gain of the variable gain amplifier 9 and the state of the phase inversion circuit 31 are maintained, and the phase inversion circuit 32 is turned on. The non-inversion state is controlled, and the level of the correlation output CORR in that state is checked (see c in FIG. 4 (f)). In this case, it is the level of the correlation output CORR in the state where only the output signal of the variable gain amplifier 9 is substantially selected.
Since the level of the correlation output CORR in c of FIG. 4F is higher than the level of the correlation output CORR in b of FIG. 4F, the output of the variable gain amplifier 10 is not selected, that is, the antenna 2 is not selected.

Further, in the next guard interval section (C), the variable gain amplifier 1 is maintained while the gain of the variable gain amplifier 9 and the state of the phase inversion circuit 31 are maintained.
The gain of 0 is controlled to the maximum (see a in FIG. 4D), and the phase inversion circuit 32 is controlled to the inverted state (see h in FIG. 4E), and the correlation output CORR in the state at that time is controlled. Check the level (see d in FIG. 4 (f)). In this case, the output signal of the variable gain amplifier 9 is in the non-inverted state,
The output signal of the variable gain amplifier 10 is in the inverted state, and the correlation output C when the antenna 2 is substantially selected.
This is the ORR level, and the level of the correlation output CORR in d of FIG. 4 (f) is lower than the level of the correlation output CORR in c of FIG. 4 (f).

Further, in the next guard interval section (d), the variable gain amplifier 1 is maintained while the gain of the variable gain amplifier 9 and the state of the phase inversion circuit 31 are maintained.
The gain of 0 is controlled to the minimum (see FIG. 4 (d)), and the phase inversion circuit 32 is controlled to the non-inversion state (see FIG. 4 (e)), and the level of the correlation output CORR in that state is adjusted. Check (see e in FIG. 2F). In this case, the output signal of the variable gain amplifier 9 is in the non-inverted state, the output signal of the variable gain amplifier 10 is also in the non-inverted state, and the correlation output C when the antenna 2 is not substantially selected.
This is the ORR level, and the level of the correlation output CORR in e of FIG. 4 (f) is larger than the level of the correlation output CORR in d of FIG. 4 (f). Therefore, the antenna 1
Select only the output from.

In the next guard interval section (e), the gain of the variable gain amplifier 10 is maintained while maintaining the gain of the variable gain amplifier 9 and the state of the phase inverting circuit 31 as in the guard interval section (d). The correlation output CORR is controlled to the minimum (see FIG. 4D) and the phase inversion circuit 32 is controlled to the non-inversion state (see FIG. 4E).
The level is checked (see f in FIG. 4 (f)). In the subsequent guard interval section (F), the same state as in the guard interval section (D) is repeated to check the level of the correlation output CORR (Fig. 4).
(See f of (f)). In this repetition, the correlation output C
When there is no change in the ORR level, if there is another antenna, check with another antenna.

In the above description, the case where the output signal from the antenna 1 is combined with the output signal from the antenna 1 has been described. However, instead of the output signal from the antenna 2, the output signal from another antenna is output from the antenna 1. The same applies to the case of combining with the output signal of. Further, the same applies to the case where the combined output of the output signal from the antenna 1 and the output signal from the antenna 2 is combined with the output signal from another antenna, for example, the output signal from the antenna 3.

An inverting amplifier can be used for the phase inverting circuits 31 to 34. Furthermore, antenna 1
As shown in FIG. 5 of FIGS. 2 and 2, the coupling coil 37 having windings that are wound in opposite directions and grounded at one end as primary windings is used as a combiner, and other primary windings of the coupling coils are used. The output of the variable gain amplifiers 9 and 10 is applied to the ends through the changeover switches 35 and 36, respectively, and the phase inversion circuits 31 and 3 selectively invert the phase by the changeover switches 35 and 36 and the coupling coil 37.
2 may be configured.

Further, as shown in FIG. 6 showing the antennas 1 and 2, the output signals of the variable gain amplifier 9 are directly output by the changeover switches 35 and 39 which are interlocked with each other, or a strip line which constitutes a delay circuit of 180 degrees. The selector switches 36 and 40 are configured so as to be guided to the synthesizer 43 via 41, and are similarly switched in conjunction with each other.
The output signal of the variable gain amplifier 10 directly or by
A phase inversion circuit 31 configured to lead to a combiner 43 via a strip line 42 that constitutes an 80-degree delay circuit and selectively perform phase rotation by the changeover switches 35 and 39 and the strip line 41. The phase inversion circuit 32 that selectively performs the phase rotation by 36 and 40 and the strip line 42 may be used.

A 90-degree phase shift circuit (not shown) is connected in cascade to each of the phase inversion circuits 31 to 35, and in addition to the selective phase inversion and the phase non-inversion by the phase inversion circuits 31 to 35, the phase shift circuit selectively selects the phase inversion. A 90 degree phase shift may be performed to check the correlation output CORR level.

In this case, for example, when the output signal from the antenna 2 is combined with the output signal from the antenna 1, according to the experimentally confirmed example, the phase shift is from (-45) degrees to (+).
When the angle is 45), it is combined without phase rotation and phase shift. When the phase shift is (+45) to 135 degrees, it is combined by 90 degree and the phase shift is (+135) to 18
When it is 0 degree, the phase is rotated and combined, and the phase shift is (-13
When the angle is 5) to (-180) degrees, the phase is rotated and combined. When the phase shift is (-45) to (-135) degrees, the phase is rotated and the phase shift of 90 degrees shifts the phase by 270 degrees. Diversity effect was obtained by synthesizing.

Therefore, according to the diversity receiver A, the signals whose phases are selectively inverted by the phase inversion circuit are combined, so that the output signal from the receiving antenna and the output signal from the antenna which combines the output signals from the antenna are combined. Even if there is a phase difference with the output signal, stable diversity reception can be performed.

[0066]

As described above, according to the diversity receiver of the present invention, the reliability of substantial selection of the antenna is improved, and stable diversity reception can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a diversity receiver according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining a combining process in the case of the diversity receiver according to the embodiment of the present invention.

FIG. 3 is a timing diagram for explaining a combining process in the case of the diversity receiver according to the embodiment of the present invention.

FIG. 4 is a timing chart for explaining a combining process in the case of the diversity receiver according to the exemplary embodiment of the present invention.

FIG. 5 is a configuration explanation of a phase inversion circuit in the diversity receiver according to the embodiment of the present invention.

FIG. 6 is a configuration diagram of a phase inversion circuit in the diversity receiver according to the embodiment of the present invention.

FIG. 7 is a block diagram showing the configuration of a proposed diversity receiver.

FIG. 8 is a timing chart for explaining the operation of the diversity receiver shown in FIG.

9 is a timing diagram for explaining the operation of the diversity receiver shown in FIG.

[Explanation of symbols]

1-4 antenna 9-12 Variable gain amplifier 13 synthesizer 14 Tuner 15 AD converter 16 Quadrature detector 17 Effective symbol extraction circuit 18 FFT circuit 20 Guard correlator 21 Timing recovery circuit 30 Diversity control circuit 31-34 Phase inversion circuit

Claims (2)

[Claims] 1. A diversity receiver having a plurality of antennas for receiving an OFDM-modulated signal in which one symbol period includes an effective symbol section and a guard interval section, each receiving signal from each of the plurality of antennas. Variable gain amplifying means for amplifying, phase inverting means for selectively inverting the phase of the output from the variable gain amplifying means, demodulating means for demodulating and outputting a combined output obtained by combining output signals from the phase inverting means, and demodulating Correlation detection means for detecting the correlation in the period corresponding to the guard interval section of the baseband signal obtained by the means, and the output signal from the receiving antenna output via the phase inversion circuit If the gain of the variable gain amplifying means corresponding to the antenna is selectively controlled to the maximum or the minimum in the guard interval section, Whether or not the level of the correlation output is maximized by selectively controlling the phase inversion state of the phase inversion means corresponding to the antenna that synthesizes the output signal to the phase inversion or phase non-inversion state in the guard interval section. And the gain of the variable gain amplifying means corresponding to the antenna combining the output signals in the phase state of the phase inverting means corresponding to the antenna combining the output signals when the level of the correlation output becomes maximum. A diversity receiver, comprising: diversity control means for gradually increasing each guard interval section. 2. A diversity receiver having a plurality of antennas for receiving an OFDM-modulated signal, one symbol period of which includes an effective symbol section and a guard interval section, each receiving signal from each of the plurality of antennas. Phase changing means including a variable gain amplifying means for amplifying, a phase inverting circuit for selectively inverting the phase of the output from the variable gain amplifying means, and a 90-degree phase shift phase shift circuit connected in cascade to the phase inverting circuit. A demodulating means for demodulating and outputting a combined output obtained by combining the output signals from the phase changing means; and a correlation detecting means for detecting a correlation in a period corresponding to the guard interval section of the baseband signal obtained by the demodulating means. , An antenna that combines the output signal with the output signal from the receiving antenna that is output via the phase change circuit The gain of the corresponding variable gain amplifying means is selectively controlled to the maximum or the minimum in the guard interval section, and the phase change state of the phase changing means corresponding to the antenna that synthesizes the output signal is phase-inverted or non-phased in the guard interval section. It is determined whether or not the level of the correlation output is maximized by selectively controlling the state of inversion, phase shift, or phase non-shift, and the output signal when the level of the correlation output is maximum is determined. Diversity control means for gradually increasing the gain of the variable gain amplifying means corresponding to the antenna that synthesizes the output signal in the phase state by the phase changing means corresponding to the synthesizing antenna, Diversity receiver.