JP4452350B2 - Digital television broadcast receiving apparatus and transmission / reception system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus and receiving method for digital broadcasting between a base station and a receiving terminal, and particularly relates to an improving method having a great effect on a reception failure of digital broadcasting.
[0002]
[Prior art]
As one of the reception obstacles in conventional analog television broadcast reception, there is a multipath obstacle due to reflection / scattering of radio waves. A video that has undergone a multipath failure may be distorted or skipped. For example, in Japanese Patent Laid-Open No. 63-109676, radio wave propagation characteristics are estimated based on a reference signal inserted when a television signal is transmitted, such as during fixed reception of terrestrial analog television broadcasts, and interference A method of constructing a filter that cancels waves and removing ghosts is disclosed.
[0003]
However, when a terrestrial television broadcast is received by a mobile body, it is difficult to predict a reception failure situation because the reception situation of radio waves changes drastically with movement.
[0004]
In recent years, a terrestrial digital television broadcasting system has been proposed to improve the problems of conventional terrestrial analog television broadcasting. In terrestrial digital television broadcasting, a communication method using a large number of orthogonal carriers called OFDM is introduced, and various countermeasures against multipath failures are taken. For example, a guard interval period called a guard interval is provided between transmitted effective symbols for the purpose of preventing intersymbol interference due to delayed waves.
[0005]
[Problems to be solved by the invention]
However, even in the terrestrial digital television broadcasting system, reception obstacles such as frequency selective fading due to interference such as reflected waves from buildings occur. Furthermore, in terrestrial digital television broadcasting, a method for transmitting the same program at the same frequency from a plurality of transmitting stations called SFNs has been proposed in order to effectively use the frequency band. As a result of this SFN broadcasting system, there is always a delay time between signals transmitted from adjacent stations, and as a result, the signal causes interference and reception failure also occurs.
[0006]
SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a digital television broadcast receiving apparatus and a receiving method for improving reception failure in mobile reception of digital data.
[0031]
[Means for Solving the Problems]
The digital television broadcast receiver of the present invention is broadcast Input means for converting a wave into a plurality of electrical signals; receiving means for performing frequency conversion on the plurality of electrical signals obtained from the input means; and frequency converting the plurality of signals obtained from the receiving means Obtained from the frequency analysis means, the adjustment means for operating the plurality of signals obtained from the frequency analysis means, and the adjustment means Belief Decoding means for decoding the signal and the decoding means And the frequency analysis means Information on the demodulation status obtained in step 1 is received and included in the broadcast wave At least one of the intensity of the delay wave, the phase difference between the delay wave and the direct wave, or the delay time between the delay wave and the direct wave Based on the delayed wave estimation means for estimating the delayed wave information, and the delayed wave information, In order for the adjusting means to select the best signal Said adjusting means Transfer function And a demodulating control means for generating a control signal for controlling the above, thereby achieving the above object.
[0034]
The digital television broadcast receiver includes a position detector that detects a reception position of the digital television broadcast receiver, and a position information determination unit that determines a radio wave condition at the reception position according to a signal from the position detector. The demodulation control means generates a control signal based on the delayed wave information obtained from the delayed wave estimation means and the radio wave situation obtained from the position information determination means, and the generated A control signal may be given to the adjusting means.
[0035]
The digital television broadcast receiving apparatus includes speed detecting means for detecting a moving speed of the digital television broadcast receiving apparatus, position detecting means for detecting a receiving position of the digital television broadcast receiving apparatus, and the detected movement. Position information determination means for determining a radio wave condition at the reception position according to speed and the detected reception position, and the demodulation control means includes information on the delayed wave obtained from the delay wave estimation means, A control signal may be generated based on the radio wave situation obtained from the position information determination unit and a signal obtained from the frequency analysis unit, and the generated control signal may be provided to the adjustment unit.
[0036]
The speed detection unit and the position detection unit may be a navigation system.
[0037]
The input unit may include a plurality of antennas having different reception characteristics.
[0045]
The demodulation status is the broadcast It can be represented by a pilot signal included in the wave.
[0046]
The position information determination unit may obtain the position of the transmission station, and estimate the radio wave condition at the reception position based on information obtained from the vehicle information detection unit and the position of the transmission station.
[0047]
The position information determination unit may store radio wave conditions at a plurality of points in advance and estimate the radio wave condition at the reception position based on information obtained from the vehicle information detection unit.
[0048]
The position information determination unit obtains radio wave conditions at a plurality of points as needed, updates the radio wave conditions at the plurality of points, and determines the radio wave conditions at the reception position based on information obtained from the vehicle information detection unit. It may be estimated.
[0049]
In the transmission / reception system of the present invention, the broadcast station transmits reception information data indicating the reception status of a plurality of points, and the digital television broadcast receiver according to claim 42 receives the reception information data. The above-mentioned object is achieved by estimating the radio wave condition.
[0050]
The position information determination unit obtains reception statuses at a plurality of points as needed, and based on information obtained from the vehicle information detection unit or the position information determination unit and reception statuses at the plurality of points, radio waves at the reception points are obtained. The situation may be estimated.
[0051]
The digital television broadcast receiver further comprises an error rate measuring unit that measures an error rate of the signal in the demodulating unit and generates a control signal when the error rate exceeds a predetermined value for a predetermined period or longer, and the input The means may include a selection unit that selects a signal to be output based on a control signal from the error rate measurement unit.
[0053]
The selection timing for selecting the signal to be output by the input means may be an interval equal to or greater than a prescribed value of the received signal.
[0055]
The selection timing at which the input means selects the signal to be output may be every received frame of the received signal, or may be a specified value or an arbitrary frame interval.
[0058]
The input unit may include a plurality of antennas, and at least one of the plurality of antennas may be moved in time.
[0059]
The distance traveled by at least one of the plurality of antennas may be controlled according to the wavelength of the television signal to be received.
[0060]
The at least two installation intervals of the plurality of antennas may be shorter than the wavelength of the television signal to be received.
[0076]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
A digital television broadcast receiver according to Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing a configuration of a digital television broadcast receiving apparatus according to Embodiment 1 of the present invention.
[0077]
The digital television broadcast receiving apparatus according to the first embodiment includes an input unit 1, a delay unit 2, a synthesis unit 3, a reception unit 4, a demodulation unit 5, a synthesis control unit 6, and a delay wave estimation unit 7.
[0078]
Television broadcast radio waves are converted into electrical signals by the input means 1 such as the receiving antenna 11 and transmitted to the delay means 2 and the combining means 3. The television broadcast signal converted into the electric signal is delayed by the delay means 2 in accordance with the delay control signal from the synthesis control means 6 and transmitted to the synthesis means 3. The synthesizing unit 3 synthesizes each of the signal obtained from the input unit 1 and the signal obtained from the delay unit 2 with gain (gain) according to the synthesis control signal from the synthesis control unit 6, and receives the signal. 4 is transmitted. Here, as a synthesis method, a simple operation such as addition or maximum value selection can be used.
[0079]
Here, the control of the delay time in the delay means 2 in the embodiment of FIG. 1 will be described.
[0080]
The frequency band of the signal handled by the delay means 2 of this embodiment is the transmission frequency of the television signal. For this reason, as for control of the delay time in the delay means 2, for example, as shown in FIG. 11, one of the plurality of paths 1 to N may be selected by a switch. The plurality of paths 1 to N may be signal lines having different path lengths. The switch shown in FIG. 11 may select one of the plurality of paths 1 to N based on the delay control signal obtained by the synthesis control means 6.
[0081]
The plurality of paths 1 to N may be signal lines having different signal propagation characteristics. Also in this case, the switch shown in FIG. 11 may select one of the plurality of paths 1 to N based on the delay control signal obtained by the synthesis control unit 6.
[0082]
Further, the delay unit 2 shown in FIG. 1 may be configured to change the phase by controlling the variable reactance element by voltage instead of switching the path length by the switch shown in FIG.
[0083]
The receiving unit 4 extracts only a signal having a necessary frequency band from the signal obtained by the synthesizing unit 3, converts the extracted signal into a signal having a processable frequency, and transmits the signal to the demodulating unit 5. The demodulating means 5 demodulates and outputs the received signal. That is, the demodulation unit 5 transmits the demodulation information to the delay wave estimation unit 7.
[0084]
The delay wave estimation means 7 estimates the delay wave included in the received wave based on the demodulation information obtained from the demodulation means 5. For example, the delay wave estimation means 7 based on the information obtained by the demodulation means 5, the intensity of the delay wave included in the signal obtained by the input means 1, the intensity of the delay wave with respect to the direct wave, and the direct wave Estimate at least one delay information of phase difference and delay time for.
[0085]
Hereinafter, a method of demodulation and delayed wave estimation will be described.
[0086]
In Japanese terrestrial digital broadcasting where standardization activities of broadcasting systems are currently being performed, OFDM (Orthogonal Frequency Division Multiplexing) is used as a modulation system. The demodulating means 5 performs a process of performing OFDM demodulation and decoding the transmitted code. In this decoding process, frequency analysis using FFT (Fast Fourier Transform) or the like is performed. When frequency analysis is performed by FFT, the delay time can be detected by detecting the dip position and the number of dip of the frequency component of the received signal from the result. Alternatively, the demodulator 5 can demodulate data by using various pilot signals included in the signal. The demodulating means 5 can estimate the signal transfer characteristics using these pilot signals.
[0087]
FIG. 7 is a diagram illustrating an example in which a frequency in OFDM is analyzed. When there is no delay wave, the frequency characteristic is flat. When a delay wave exists in the received signal, as shown in FIG. 7, dip exists in some frequency components.
[0088]
When dip exists in some frequency components, that is, when there is a delay wave in the received signal, the delay wave estimation means 7 detects the delay wave by observing the signal change of the pilot signal or the lack of the pilot signal. It is also possible to do.
[0089]
When there is a delayed wave in the received signal, the delayed wave estimating means 7 acquires information on the data position having an error from the error correction process after the FFT process, and estimates the delay time of the interference wave based on the information. Is also possible.
[0090]
In the above description, the digital broadcasting system in Japan has been described, but it goes without saying that the present invention is not limited to this and can be applied to analog broadcasting and digital broadcasting in each country. For example, the present invention may be applied to a single carrier transmission scheme other than OFDM.
[0091]
Hereinafter, generation of the combined gain and the delay time will be described.
[0092]
The synthesis control unit 6 outputs a signal for controlling the delay unit 2 and the synthesis unit 3 based on the delay wave information estimated by the delay wave estimation unit 7. The synthesis control means 6 has, for example, a gain control means 61 and a delay time control means 62 as shown in FIG.
[0093]
The gain control unit 61 sets the combined gain in the combining unit 3 based on the delayed wave information obtained from the delayed wave estimating unit 7. This setting method will be described with reference to FIG. The horizontal axis shown in FIG. 8 represents the magnitude of the delayed wave, and the vertical axis represents the ratio (signal A gain / signal B gain). Here, a case where the delay means is constituted by a first delay unit and a second delay unit will be described with reference to FIG. The signal A gain indicates the gain of the signal from the first delay unit to the synthesizing unit 3, and the signal B gain indicates the gain of the signal from the second delay unit to the synthesizing unit 3.
[0094]
When the level of the delayed wave is large, especially when the level of the delayed wave is about the same as the level of the direct wave, control is performed so that both gains are the same.
[0095]
Further, when the delay wave level is small, or when the delay wave level is greater than the direct wave level, the gain of the signal from the delay means 2 or the signal from the input means 1 is reduced to provide a gain difference to be combined. To control.
[0096]
When gain control is performed based on the delay time of the delay wave obtained from the delay wave estimating means 7, when the delay time is large (a in FIG. 8) and when the delay time is small (b in FIG. 8), FIG. As shown in FIG. 4, the control is performed so that the gain difference increases as the delay time increases.
[0097]
Next, the operation of the delay time control means 62 will be described. The delay time control means 62 sets the delay time to be delayed by the delay means 2 so that the delay means 2 delays substantially the same time as the delay time estimated by the delay wave estimation means 7.
[0098]
FIG. 9 is a diagram illustrating an example of the relationship between the delay wave and the error rate of the demodulated signal. As shown in FIG. 9, when the delay time is small (point B: less than about 2.5 μs), the error rate may deteriorate rapidly. For this reason, when the delay time obtained by the delay wave estimating means 7 is small, a predetermined delay time (default value), for example, the delay time control means 62 is not shown in FIG. By setting a delay time longer than or equal to the point in the combining means 3, it is possible to effectively avoid the deterioration of the error rate.
[0099]
However, the upper limit of the delay time given here needs to be shorter than the guard interval period added to the OFDM signal. In addition, in order to prevent the error rate from deteriorating due to such a delayed wave having a small delay time, the delay means 2 can always set a predetermined delay time. In this case, for example, by setting a value about twice the point B (about 5 μs), the influence of a short delay time can be surely eliminated.
[0100]
In addition, when a signal is obtained from one antenna as shown in FIG. 1, a delay time smaller than the reciprocal of the bandwidth of the received signal is given to the signal and added to reduce the noise level of the received signal. It is possible to improve the rate. This is because the dip position generated by the added signal can be outside the signal bandwidth. For example, if the signal bandwidth is 500 kHz, the given delay time needs to be 2 μs or less. The above-described method of adding signals with a short delay time is an effective means because it has the effect of improving the reception level of the signal band, particularly in narrowband broadcasting used as service broadcasting for mobile reception.
[0101]
When the first embodiment is mounted on a vehicle, the digital television broadcast receiving apparatus according to the first embodiment includes a position information determination unit 8 and a vehicle information detection unit 9. Even if the digital television broadcast receiver in the first embodiment is not mounted on a moving body, the digital television broadcast receiver may include the position information determination unit 8 and the vehicle information detection unit 9.
[0102]
The digital television broadcast receiving apparatus according to the first embodiment is mounted on a vehicle, that is, a digital television broadcast receiving operation on a mobile body will be described.
[0103]
The vehicle information detection means 9 detects information of the vehicle that is moving and receiving. The vehicle information detection means 9 has a speed (vehicle speed) detection means 91 and a position detection means 92, for example.
[0104]
The speed (vehicle speed) detecting means 91 detects the speed of the vehicle performing the movement reception, and the position detecting means 92 detects the position of the vehicle. Needless to say, a navigation device can be used as the vehicle information detection means 9, and the position detection means 92 can be a GPS device or a location detection by a road control system such as PHS, mobile phone, or VICS. is there. The detected vehicle information is transmitted to the position information determination means 8.
[0105]
The position information determination means 8 obtains information such as terrain, checks where broadcast waves are likely to be received at the position where the digital television broadcast is actually received, and determines the distance from those broadcast stations or In consideration of reflections from mountains and buildings, the delay time or radio wave strength at the receiving point is estimated. For this purpose, the position information determining means 8 has information such as the frequency and the position of the transmitting station transmitted from a transmitting station such as a broadcasting station or a relay station, or transmission output in advance, or the information is broadcast or telephoned. The information is downloaded and stored by the communication means, and compared with the position information from the vehicle information detection means 9, the delay time or the strength of the radio wave at the reception point is obtained. Thereby, the delay wave time and the magnitude at the reception point can be obtained.
[0106]
Further, the position information determination means 8 shows information such as the position, size and height of the building around the reception point on the map together with the broadcast station position, and more accurately delay wave time by taking into account reflections and the like by these. And you can know the size. It goes without saying that a system such as navigation can be used as a device for handling such information as a transmitting station, a building, and a mountain. Further, in this embodiment, since the speed of the mobile reception is known by the speed detection unit 91, the next delayed wave can be predicted, and the delayed wave can be followed more quickly than a system that does not consider the speed.
[0107]
In the synthesis control means 6, synthesis gain control and delay time control are performed based on the delayed wave information obtained by the position information determination means 8 as described above. As a control method in this case, it can be performed in the same manner as when the delayed wave information by the delayed wave estimating means 7 is used.
[0108]
Furthermore, in the present embodiment, it is also possible to use a combination of the information of the delay wave estimation means 7 and the position information determination means 8. In this case, gain and delay time control is performed only when the two pieces of delay information are close. In this embodiment, when two pieces of delay information are separated, control is performed based on information that maintains the current state or has a large delay wave level.
[0109]
In the above description, the case where the digital television broadcast receiving apparatus according to the first embodiment having the speed detecting means 91 and the position detecting means 92 as the vehicle information detecting means 9 has been described for mobile movement has been described. Even if the broadcast receiving apparatus has only the position detecting means 92 as the vehicle information detecting means 9, the digital television broadcast receiving apparatus according to the first embodiment can perform mobile reception. Needless to say, even such a digital television broadcast receiving apparatus can perform fixed reception.
[0110]
Even if the digital television broadcast receiving apparatus according to Embodiment 1 has only the position detecting means 92 as the vehicle information detecting means 9, it can be used for mobile reception and fixed reception.
[0111]
Although FIG. 1 shows one antenna 11 and amplifying means 12 as the input means 1 of the digital television broadcast receiving apparatus, the number of antennas and the like is not limited to one in the present invention. In the present embodiment, for example, a plurality of antennas 11 and a plurality of delay units corresponding to the plurality of antennas 11 may be provided.
[0112]
FIG. 2 is a diagram illustrating a digital television broadcast receiving apparatus in which the input unit 1 includes a plurality of antennas 11 and the delay unit 2 includes a delay unit corresponding to the antennas 11.
[0113]
In this case, even when the plurality of antennas 11 shown in FIG. 2 receive the same broadcast radio wave, the state of multipath interference differs among the respective antennas 11. For this reason, a different input signal is obtained from each of the plurality of antennas 11. In these input signals, the dip position (frequency) and depth are generated at different locations as shown in FIG.
[0114]
Therefore, by adding a plurality of different input signals, signals having different dip positions and dip depths can be obtained. As a result, in this embodiment, the error rate indicating that the received signal is erroneously recognized is lowered. It becomes possible.
[0115]
In the delay unit 2, the delay time obtained by the synthesis control unit 6 is relatively set from the first delay unit to the N-th delay unit. The synthesizing unit 3 sets the gain obtained by the synthesizing control unit 6 according to the delayed signal. The receiving operation of other means in the digital television broadcast receiving apparatus shown in FIG. 2 is substantially the same as the receiving operation of the digital television broadcast receiving apparatus shown in FIG.
[0116]
Moreover, the correlation of a some input signal can be made low because the installation position space | interval of the some antenna 11 shall be about 1/4 or more of the transmission signal wavelength of a television signal. Thereby, the quality of a received signal can be improved by adding a plurality of input signals from a plurality of antennas 11.
[0117]
Further, by making the directivity characteristics and polarization characteristics of the plurality of antennas 11 different, it is possible to further reduce the correlation between the plurality of input signals, and to add the input signals having a low correlation. It is possible to improve the received signal quality.
[0118]
Further, the digital television broadcast receiving apparatus shown in FIG. 2 gives gains to a plurality of signals output from the delay means 2 in accordance with the control signal from the gain control means 61, and synthesizes these signals. In the digital television broadcast receiving apparatus shown in FIG. 15, the gains of the signals given by the first to N-th amplification units may be changed according to the control signal obtained from the gain control means 61.
[0119]
As described above, according to the digital television broadcast receiving apparatus in the first embodiment, the signal dip can be reduced by synthesizing the signals output from the delay means 2, and as a result, the error rate of the digital data can be improved.
[0120]
Further, by setting the delay time so as to avoid the influence of a signal having a short delay time, it is possible to prevent the error rate from increasing.
[0121]
Further, by obtaining an accurate delayed wave by the delayed wave estimating means 7, the vehicle information detecting means 9 and the position information determining means 8, it is possible to avoid signal dip more accurately and thereby reduce the error rate.
[0122]
On the other hand, signals obtained from a plurality of antennas can be used while being switched according to the error status. Hereinafter, antenna switching conditions when switching antennas will be described with reference to FIG.
[0123]
FIG. 10 is a diagram showing a flowchart of the antenna switching condition.
[0124]
First, according to the present embodiment, the C / N (the ratio of carrier to noise) of the signal input to the antenna 11 and the error occurrence status in a certain past period such as one frame period are obtained. As a result, when the C / N ratio is larger than the threshold value (Yes in Step S100) and the error rate is lower than the threshold value (Yes in Step S101), antenna switching is not performed (Step S102).
[0125]
Even when the error rate is not lower than the threshold value, antenna switching is not performed when the error occurs in a short burst and is not continuous (Yes in step S103).
[0126]
On the other hand, when the level of the C / N ratio of the input signal is not greater than the threshold value (No in step S100), or the error rate is not lower than the threshold value (No in step S101), the occurrence of an error is a short burst. If not (No in step S103), the antenna is switched (step S104).
[0127]
Here, the antenna switching timing may be a guard interval period added to the OFDM signal. In addition, this embodiment may calculate the timing which performs antenna switching based on vehicle speed information and position information.
[0128]
The antenna switching timing may be a guard interval period added to the OFDM signal. Thereby, in this embodiment, it becomes possible to switch an antenna optimally with respect to the change of the receiving conditions at the time of mobile reception.
[0129]
(Embodiment 2)
A digital television broadcast receiver according to Embodiment 2 of the present invention will be described below with reference to FIG. FIG. 3 is a block diagram showing a configuration of a digital television broadcast receiver according to Embodiment 2 of the present invention.
[0130]
The digital television broadcast receiving apparatus according to the second embodiment includes an input unit 1, a delay unit 2, a synthesis unit 3, a reception unit 4, a demodulation unit 5, a synthesis control unit 6, and a delay wave estimation unit 7. The synthesis control unit 6 includes a gain control unit 61 and a delay time control unit 62. When the digital television broadcast receiving apparatus in the second embodiment is mounted on a moving body such as a vehicle, the digital television broadcast receiving apparatus in the second embodiment further includes position information determination means 8 and vehicle information detection means 9. I have. The vehicle information detection means 9 has a speed detection means 91 and a position detection means 92. In addition, even if the digital television broadcast receiver in the second embodiment is not mounted on a moving body, the digital television broadcast receiver may include the position information determination unit 8 and the vehicle information detection unit 9.
[0131]
When comparing the digital television broadcast receiver in the second embodiment and the digital television broadcast receiver in the first embodiment described above, in the first embodiment,
The receiving unit 4 is connected immediately after the combining unit 3, but in the second embodiment, the receiving unit 4 is connected immediately after the input unit 1.
[0132]
Hereinafter, the reception operation of the digital television broadcast by the mobile body in the second embodiment will be described.
[0133]
Television broadcast radio waves are converted into electrical signals by the input means 1 such as the receiving antenna 11 and transmitted to the receiving means 4. The receiving unit 4 extracts only a signal in a necessary frequency band from the signal obtained from the input unit 1 and transmits it to the delay unit 2 and the combining unit 3. The signal obtained by the receiving means 4 is delayed by the delay means 2 in accordance with the delay control signal from the synthesis control means 6 and transmitted to the synthesis means 3. The synthesizing unit 3 weights and synthesizes the signal obtained from the receiving unit 4 and the signal obtained from the delay unit 2 with gain (gain) according to the synthesis control signal from the synthesis control unit 6. To the demodulation means 5. Here, as in the case of the first embodiment, a simple operation such as addition or maximum value selection can be used as the synthesis method. The demodulator 5 demodulates and outputs the signal.
[0134]
The delay wave estimation means 7 estimates the delay wave in the delay wave estimation means 7 based on the demodulation information from the demodulation means 5 and transmits it to the synthesis control means 6 as in the first embodiment. Further, the position information determination unit 8 estimates a delay wave from the mobile reception information obtained from the vehicle information detection unit 9 and transmits it to the synthesis control unit 6 as in the first embodiment.
[0135]
The synthesis control unit 6 obtains control signals (delay time and synthesis rate) for the delay unit 2 and the synthesis unit 3 based on the signals from the delay wave estimation unit 7 and the position information determination unit 8.
[0136]
In the reception operation, the operation of the synthesis control unit 6 and the operation of the vehicle information detection unit 9 are the same as those in the first embodiment. According to the receiving apparatus according to the second embodiment, the processing of the delay unit 2 or the synthesizing unit 3 can be simplified compared to the first embodiment because the frequency and the band are limited by the receiving unit 1 in the previous stage. Although possible, the same effect as in the first embodiment can be obtained.
[0137]
Further, in the present embodiment, the signal band handled by the delay unit 2 is lower than that in the first embodiment. Therefore, for example, when the delay means 2 gives a delay time, the delay time can be controlled by digital signal processing after the input signal is converted into a digital signal.
[0138]
In the digital television broadcast receiving apparatus in the second embodiment, as shown in FIG. 4, the input means 1 has a plurality of antennas 11, the receiving means 4 has first to Nth receiving sections, and delay means. 2 may include a first delay unit to an Nth delay unit.
[0139]
Since the operation of the digital television broadcast receiving apparatus shown in FIG. 4 is the same as that of the above-described embodiment, detailed description thereof is omitted.
[0140]
Since the digital television broadcast receiving apparatus has a plurality of antennas 11, a first receiving unit to an Nth receiving unit, and a first delay unit to an Nth delay unit, each of the plurality of antennas 11 receives the same broadcast radio wave. In this case, the interference state is different, and the levels of the signals output from the plurality of antennas 11 are also different.
[0141]
Therefore, the dip position (frequency) and depth as shown in FIG. Therefore, by adding a plurality of different inputs, the dip position and dip depth can be changed, and as a result, the signal error rate can be lowered.
[0142]
(Embodiment 3)
A digital television broadcast receiver according to Embodiment 3 of the present invention will be described below with reference to FIG. FIG. 5 is a block diagram showing a configuration of a digital television broadcast receiver according to Embodiment 3 of the present invention.
[0143]
The digital television broadcast receiving apparatus according to the third embodiment includes an input unit 1, a receiving unit 4, a demodulating unit 5, a delayed wave estimating unit 7, and a demodulation control unit 55. When the digital television broadcast receiving apparatus in the third embodiment is mounted on a moving body such as a vehicle, the digital television broadcast receiving apparatus in the third embodiment further includes position information determination means 8 and vehicle information detection means 9. I have. In addition, even if the digital television broadcast receiver in the third embodiment is not mounted on the mobile body, the digital television broadcast receiver may include the position information determination unit 8 and the vehicle information detection unit 9.
[0144]
Hereinafter, a digital television broadcast reception operation in a mobile body or a digital television broadcast reception operation in a fixed place will be described with reference to FIG. The operations of the position information determination unit 8 and the vehicle information detection unit 9 are the same as those in the first embodiment and the second embodiment described above, and are therefore omitted.
[0145]
Television broadcast radio waves are converted into electrical signals by the input means 1 such as the receiving antenna 11 and transmitted to the receiving means 4. The receiving unit 4 extracts only a signal in a necessary frequency band from the signal obtained from the input unit 1 and transmits it to the demodulating unit 5. The demodulator 5 demodulates the signal from the receiver 4 and outputs a digital signal, and transmits the demodulation status to the delay wave estimator 7.
[0146]
Here, the operation of the demodulation means 5 will be described in detail.
[0147]
The demodulating unit 5 includes a frequency analyzing unit 51, an adjusting unit 52, and a decoding unit 53.
[0148]
The signal obtained from the receiving means 4 is subjected to frequency analysis by a frequency analysis means 51 such as FFT, real FFT, DFT, or FHT, and the frequency-analyzed signal is transmitted to the adjusting means 52. For example, a frequency-analyzed signal is represented by a frequency and its magnitude.
[0149]
The adjustment unit 52 operates the signal on the frequency axis obtained by the frequency analysis unit 51 based on the control signal from the demodulation control unit 55. As an operation method, based on the signal from the demodulation control means 55, a method of applying a transfer function to the signal obtained by the frequency analysis means 51, a method of calculating a filter, emphasizing a specific frequency component, or A method such as interpolation of frequency components considered to be missing can be considered. The decoding unit 53 decodes the signal obtained by the adjustment unit 52 into a digital code.
[0150]
The delay wave estimation means 7 estimates information on the delay wave based on the signal obtained from the demodulation means 5. As a signal to be referred to at this time, there are a frequency spectrum obtained from the frequency analysis means 51, a pilot signal obtained in the decoding process of the decoding means 53, and the like.
[0151]
FIG. 7 is a diagram illustrating an example of a frequency spectrum of a received signal. In general, in the OFDM modulation method used in digital television broadcasting, the frequency spectrum is flat. If a delay wave exists, a dip or the like occurs as shown in FIG. Thus, it is possible to estimate the magnitude of the delay wave and the delay time.
[0152]
In addition, the magnitude of the delay wave and the delay time can be estimated from the phase change or omission of the pilot signal.
[0153]
The demodulation control means 55 controls the adjustment means 52 based on the delay wave information obtained from the delay wave estimation means 7 or the position information determination means 8. The demodulation control means 55 determines a control parameter corresponding to the adjustment means 52 and transmits it to the adjustment means 52. For example, when the adjusting unit 52 requires a transfer function related to the delayed wave, the demodulation control unit 55 obtains a transfer function corresponding to the delayed wave and transmits it to the adjusting unit 52. Alternatively, when the adjustment unit 52 is a filter, the demodulation control unit 55 transmits the filter coefficient to the adjustment unit 52. When the adjustment unit 52 is configured to perform interpolation, the demodulation control unit 55 transmits the interpolation value to the adjustment unit 52. Here, the configuration of the position information determination unit 8 and the vehicle information detection unit 9 is the same as that of the first and second embodiments.
[0154]
As described above, according to the present embodiment, since the adjusting unit 52 operates so that the influence of the delayed wave is reduced, accurate decoding is possible, and the error rate of the received digital signal is improved. .
[0155]
FIG. 6 is a diagram illustrating another digital television broadcast receiving apparatus according to the third embodiment. In the digital television broadcast receiving apparatus shown in FIG. 6, the input means 1 has a plurality of antennas 11, and the receiving means 4 has first to Nth receiving sections. 6 shows one frequency analysis unit 51, one adjustment unit 52, and one decoding unit 53, but at least of the frequency analysis unit 51, the adjustment unit 52, and the decoding unit 53. The number according to the antenna 11 may be sufficient as one number. The number of the means differs depending on the configuration of the means. For example, even if the digital television broadcast receiving apparatus shown in FIG. 6 has only one frequency analyzing means, a selector (not shown) has a plurality of outputs from the first receiving unit to the Nth receiving unit. By selecting one signal to be processed by the frequency analysis means 51 from the signal, the digital television broadcast receiver shown in FIG. 6 operates normally. The same applies to the numbers of adjusting means 52 and decoding means 53.
[0156]
In the digital television broadcast receiving apparatus shown in FIG. 6, since the frequency analysis is performed for each signal output from the input means 1, the magnitude of the delay wave corresponding to the signals output from the input means 1 and Delay time can be estimated. Therefore, it is possible to select the signal with the best reception state by the adjusting means 52.
[0157]
Further, the transfer function, the filter operation, or the adjustment such as the above-described adjustment may be performed for each signal, and the plurality of signals may be decoded by the decoding unit 53.
[0158]
In the decoding means 53 or the adjusting means 52, it is possible to demodulate a good digital code by selecting and processing only the signal of the frequency spectrum with good reception state from the frequency analysis result of the signal from each antenna 11.
[0159]
As described above, reception errors can be improved by providing a plurality of antennas 11 in the configuration of FIG.
[0160]
(Embodiment 4)
A digital television broadcast receiver according to Embodiment 4 of the present invention will be described below with reference to FIG. FIG. 12 is a block diagram showing a configuration of a digital television broadcast receiver in Embodiment 4 of the present invention.
[0161]
The digital television broadcast receiver in the fourth embodiment includes an input unit 1, a synthesis unit 3, a reception unit 10, a demodulation unit 5, a synthesis control unit 6, and a delay wave estimation unit 7. When the digital television broadcast receiving apparatus in the fourth embodiment is mounted on a moving body such as a vehicle, the digital television broadcast receiving apparatus in the fourth embodiment further includes position information determination means 8 and vehicle information detection means 9. I have. Even if the digital television broadcast receiver in the fourth embodiment is not mounted on a moving body, the digital television broadcast receiver may include position information determination means 8 and vehicle information detection means 9.
[0162]
In the digital television broadcast receiving apparatus shown in FIG. 4, the delay means 2 is arranged between the receiving means 4 and the synthesizing means 3. However, the digital television broadcast receiving apparatus shown in FIG. Not done.
[0163]
In the digital television broadcast receiver shown in FIG. 12, the description of the same configuration as that of the digital television broadcast receiver shown in FIG. 4 is omitted.
[0164]
The receiving means 10 converts the signal obtained from the input means 1 into a frequency band signal that can be processed by the demodulating means 5. A signal transmitted in a frequency band such as VHF or UHF is detected and converted into a frequency band signal before transmission that can be processed by the demodulating means 5.
[0165]
Hereinafter, the receiving means 10 will be described in detail.
[0166]
The receiving means 10 performs detection processing. FIG. 13 is a diagram illustrating a configuration example of a detector. The reception unit 10 includes a band pass filter 101, a reference signal generation unit 102, a low pass filter 103, and a sine wave generation unit 104. The bandpass filter 101 includes a first bandpass filter to an Nth bandpass filter. The reference signal generation means 102 includes a first reference signal generator to an Nth reference signal generator. The low-pass filter 103 includes a first sine wave signal generator to an Nth sine wave signal generator.
[0167]
A plurality of received signals obtained by the input means 1 are each passed through a band pass filter. Next, the reference signal generation unit 102 generates a sine wave signal having the same frequency as the transmission signal. When the transmission frequency of the reception signal is 500 MHz, for example, the reference signal generator of the reference signal generation unit 102 generates a 500 MHz sine wave signal. Note that the first reference signal generator to the Nth reference signal generator of the reference signal generation unit 102 can generate the reference signals, respectively.
[0168]
Next, the signal that has passed through the bandpass filter 101 is multiplied by the sine wave signal obtained by the reference signal generation means 102, and then the multiplied signal is passed through the low-pass filter 103 to convert the frequency band. The signal is output from the low pass filter 103.
[0169]
The sine wave generation unit 104 generates a sine wave signal according to the phase information obtained by the reference signal control unit 64. The sine wave generating means 104 generates a low frequency signal of about 0 to several tens Hz. For example, the first sine wave signal generator generates a signal (DC signal) having a frequency of 0 Hz, the second sine wave signal generator generates a sine wave signal having a frequency of 10 Hz, and the Nth sine wave signal generator has a frequency of 15 Hz. Is generated. The plurality of signals generated by the sine wave signal generator 104 are multiplied with the plurality of signals that can pass through the low-pass filter 103.
[0170]
As described above, the receiving unit 10 can temporally change the phases of a plurality of signals obtained from the input unit 1. For this reason, in the digital television broadcast receiving apparatus according to the fourth embodiment, when signals are synthesized by the synthesizing unit 3 located at the subsequent stage of the receiving unit 10, it is assumed that signals having opposite phases are added together. Even if it exists, it can prevent that such time continues over a long period of time.
[0171]
FIG. 14 is a diagram showing another receiving means 10 ′. In the receiving means 10 shown in FIG. 13, the sine wave signal generator 104 is required to change the phase. However, in the receiving means 10 ′ shown in FIG. 14, the phase is changed by the reference signal generating means 102 ′. Can do.
[0172]
The receiving unit 10 ′ illustrated in FIG. 14 includes a band pass filter 101, a reference signal generating unit 102 ′, and a low pass filter 103. Note that the receiving unit 10 ′ does not include the sine wave generating unit 104 of the receiving unit 10. Further, the reference signal generating means 102 ′ of the receiving means 10 ′ includes a first reference signal generator to an Nth reference signal generator.
[0173]
The reference signal generation unit 102 ′ shown in FIG. 14 adjusts the frequency of the generated sine wave signal according to the phase information output from the reference signal control unit 64. For example, when the transmission frequency of the television signal is 500 MHz, the first reference signal generator of the reference signal generation unit 102 ′ generates a 500 MHz sine wave signal, and when the transmission frequency of the television signal is 500 MHz. The second reference signal generator of the reference signal generating means 102 ′ generates 500,000,010 Hz. That is, the reference signal generation unit 102 ′ is configured to give a slight difference to the frequency of the transmission frequency of the television signal. Thereby, the receiving means 10 ′ shown in FIG. 14 has the same effect as the receiving means 10 shown in FIG.
[0174]
In the reference signal generating means shown in FIGS. 13 and 14, the frequencies of a plurality of reference signals (first reference signal to Nth reference signal) generated by the first reference signal generator to the Nth reference signal generator are the same. The frequency of the signal received by each reference signal generator must be the same value or the difference between the frequencies of these signals must be within a predetermined range. It may be difficult to meet.
[0175]
In such a case, receiving means 10 '' as shown in FIG. 26 is useful.
[0176]
FIG. 26 shows still another receiving means 10 ''.
[0177]
The receiving unit 10 ″ includes a band pass filter 101, a reference signal generating unit 102 ″, a low pass filter 103, and a phase shift unit 105. The configurations of the bandpass filter 101 and the lowpass filter 103 are the same as those of the receiving means 10. The phase shift means 105 has a first phase shift unit to an Nth phase shift unit. Each of the first to N-th phase shift units controls the phase of the reference signal in accordance with the control signal from the reference signal control means 64. The phase shift means 105 can be realized by a variable reactance element, for example. The first phase shifter to the Nth phase shifter can each independently change the phase of the reference signal in accordance with a control signal (control voltage or the like) from the reference signal control means.
[0178]
In the receiving means 10 ″, the reference signal generating means 102 ″ generates one reference signal. Compared to the receiving means 10 ', it is possible to shift the phase of the reference signal by a minute amount with respect to the frequency of the signal to receive.
[0179]
A method for controlling the phase in the phase shift circuit 105 will be described in detail in a sixth embodiment to be described later.
[0180]
(Embodiment 5)
Hereinafter, a digital television broadcast receiving apparatus according to Embodiment 5 of the present invention will be described with reference to FIGS. 16 and 17.
[0181]
FIG. 16 is a diagram illustrating an installation state of an antenna used as input means. FIG. 17 is a detailed view of an antenna used as input means. In the digital television broadcast receiving apparatus according to the fifth embodiment, the configuration other than the input unit may be the configuration in one of the above-described first to fourth embodiments and later-described sixth and seventh embodiments. .
[0182]
The operation of the antenna 110 will be described in detail with reference to FIGS. As shown in FIG. 16, the antenna 110 is installed on the rear glass portion of the vehicle, the trunk upper surface, or the vehicle body upper surface. In the present embodiment, the antenna 110 is configured so that the installation position can be changed even when the antenna 110 is receiving radio waves.
[0183]
As shown in FIG. 17, the antenna 110 includes antenna elements 111 and 112 and an antenna support 113. For changing the installation position, for example, the antenna elements 111 and 112 and the antenna support 113 are configured so that their connection portions are movable, and the antenna elements 111 and 112 are remotely controlled by the power of a motor or the like. Can be moved in the direction indicated by the arrow in FIG.
[0184]
By controlling the antenna 110 so that the installation position always moves during mobile reception, the transmission path characteristics between the transmission antenna and the reception antenna are temporally different. For this reason, when a signal is received in a multipath environment, it is possible to change the state of failure (such as a dip in the frequency direction). For this reason, when adding a plurality of antenna reception signals, the signals are in an opposite phase relationship, and when these signals are added, the signals cancel each other. It is possible to change reception signal characteristics and improve the occurrence of reception data errors. In particular, this embodiment is an effective means when the state in which the received signals cancel each other during a low-speed movement or stop continues for a certain time or more. It is conceivable that the moving range of the antenna is, for example, about one quarter of the transmission signal wavelength of the television signal desired to be received.
[0185]
It is also conceivable to change and fix the installation positions of the antenna elements 111 and 112 according to the signal wavelength desired to be received when determining the reception channel. For example, the positional relationship between the two antenna elements 111 and 112 is moved within a range of about a quarter of the transmission signal wavelength of the television signal to be received, and the signals output from the two antenna elements 111 and 112 are added. When the reception characteristics are improved, the positions of the two antenna elements 111 and 112 are fixed. In such a case, there is a high possibility that the signals output from the two antenna elements 111 and 112 do not have an antiphase relationship with each other. In addition, the dip positions and the like due to multipath failures are likely to be different from each other.
[0186]
For this reason, it is possible to improve the reception characteristics by changing the antenna position according to the frequency of the received signal. Further, although the configuration in which the antenna installation position is variable has been described so far, it goes without saying that the same effect can be obtained even if the installation positions of the two antenna elements are fixed close to each other.
[0187]
(Embodiment 6)
A digital television broadcast receiver according to Embodiment 6 of the present invention will be described below with reference to FIGS. 18A, 18B, 18C, and 18D. 18A, FIG. 18B, FIG. 18C, and FIG. 18D are block diagrams each showing a configuration of a digital television broadcast receiving apparatus according to Embodiment 6 of the present invention.
[0188]
The digital television broadcast receiving apparatus according to the sixth embodiment includes an input unit 1, a synthesis unit 3, a reception unit 4, a demodulation unit 5, a delay wave estimation unit 7, an amplification unit 12, a phase shift unit 13, and a synthesis control unit 600. Yes. The synthesis control unit 600 includes a gain control unit 61 and a phase control unit 63. The amplifying unit 12 includes a first amplifying unit to an Nth amplifying unit. The phase shift means 13 has a first phase shift part to an Nth phase shift part.
[0189]
When the digital television broadcast receiving apparatus in the sixth embodiment is mounted on a moving body such as a vehicle, the digital television broadcast receiving apparatus in the sixth embodiment further includes position information determination means 8 and vehicle information detection means 9. I have. In that case, the vehicle information detection means 9 has a speed detection means 91 and a position detection means 92. In addition, even if the digital television broadcast receiving apparatus in the sixth embodiment is not mounted on the moving body, the digital television broadcast receiving apparatus may include the vehicle information detecting means 9.
[0190]
18A, 18B, 18C, and 18D, the amplifying means 12 and the phase shift means 13 are used instead of the delay means 2 shown in FIG. In place of the composition control means 6 shown in FIG.
[0191]
Hereinafter, the reception operation of the digital television broadcast by the mobile body in the sixth embodiment will be described with reference to FIG. 18A.
[0192]
Television broadcast radio waves are converted into electrical signals by the input means 1 such as the receiving antenna 11 and transmitted to the amplifying means 12. The amplification means 12 amplifies the gain of the signal obtained from the input means 1 for each input signal in accordance with the control information obtained from the gain control means 61. The phase shift means 13 changes the phase of the signal obtained by the amplification means 12 for each input signal in accordance with the phase control signal obtained from the phase control means 63. The synthesizing unit 3 synthesizes the signals obtained by the phase shifting unit 13. The receiving means 4 extracts only necessary frequency band components from the signal obtained from the synthesizing means 3 and transmits them to the demodulating means. The demodulator 5 demodulates the signal input from the receiver 4 and outputs digital data. Further, the demodulating unit 5 outputs information about the delayed wave included in the received signal to the delayed wave estimating unit 7. The delay wave estimation means 7 outputs information on the delay wave included in the received signal using the information obtained from the demodulation means 5.
[0193]
The synthesis control unit 600 uses the information obtained from at least one of the delay wave estimation unit 7 and the position information determination unit 8 to obtain a control signal to the amplification unit 12 and the phase shift unit 13. Here, the operations of the input unit 1, the synthesis unit 3, the reception unit 4, the demodulation unit 5, the delay wave estimation unit 7, the position information determination unit 8, the vehicle information detection unit 9, and the amplification unit 12 are the same as those in the second embodiment. The description is omitted because it is the same as described above.
[0194]
Hereinafter, the operation of the composition control unit 600 will be described in detail. The synthesis control unit 600 includes a gain control unit 61 and a phase control unit 63.
[0195]
The gain control means 61 receives information related to the received signal from at least one of the delayed wave estimation means 7 and the position information determination means 8. For example, the gain control means 61 determines the presence / absence of a delayed wave component (interference signal) in the received signal, and when there is a delayed wave, the intensity of the delayed wave, the delay time and phase information of the delayed wave, and the mobile object Get information such as the movement status and past reception failure status. The main purpose of the gain control means 61 is to provide gain control information to the amplifying means 12 when the received signal is disturbed by a delayed wave or the like, thereby improving the characteristics of the received signal. It is to be. For example, when the reception failure is large, the gain control unit 61 gives a gain to each of the plurality of input signals, and when the reception failure is small, the gain control unit 61 gains only one input signal. And only that one input signal may be selected. As a result, as described in the first embodiment, it is possible to improve the frequency characteristics of a signal that has undergone frequency selective fading due to an interference wave. Further, even when the level of the input signal is insufficient, the amplifying unit 12 can also amplify the signal level.
[0196]
Next, the operation of the phase control means 63 will be described. Similarly to the gain control means 61, the phase control means 63 uses a plurality of information obtained from at least one of the delayed wave estimation means 7 and the position information determination means 8, and the plurality of phase shift means 13 receive from the amplification means 12. The amount of phase change given to each of the input signals is determined. The phase shift means 13 changes the phase of the plurality of input signals according to the control signal obtained from the phase control means 63. Since a plurality of signals whose phases have been changed by the phase shifting means 13 are added by the synthesizing means 3, the signals cancel each other out of phase with each other as compared with adding the signals output from the amplifying means 12 as they are. Probability decreases.
[0197]
Below, the detailed structure and operation | movement of the phase shift means 13 are demonstrated. FIG. 19 is a diagram illustrating a configuration example of the phase shift means 13.
[0198]
19 includes an input unit 131, a phase shift circuit 132, negation circuits 133 and 134, multiplication circuits 135, 136, 137, and 138, and an adder circuit 139. The negation circuits 133 and 134 invert the received signal. Multiplier circuits 135, 136, 137 and 138 amplify the received signal to an appropriate value.
[0199]
The signal received by the input unit 131 is sent to the phase shift circuit 132, the negation circuit 133, and the multiplication circuit 136. The signal sent to the phase shift circuit 132 is given a phase delay of 90 degrees, for example, by the phase shift circuit 132. One of the signals output from the phase shift circuit 132 is sent to the addition circuit 139 via the negation circuit 134 and the multiplication circuit 137. The other signal output from the phase shift circuit 132 is sent to the adder circuit 139 via the multiplier circuit 138.
[0200]
The signal sent to the negation circuit 133 is inverted by the negation circuit 133 and sent to the addition circuit 139 via the multiplication circuit 135. The signal sent to the multiplier circuit 136 is amplified and sent to the adder circuit 139. The adder circuit 139 receives these signals and synthesizes these signals.
[0201]
As a result, the output signal of the adder circuit 139 can have an arbitrary phase difference from 0 degrees to 360 degrees with respect to the input signal. Further, in order to change the phase of the signal with time, the gain value applied to the multiplication circuits 135, 136, 137, and 138 may be changed with time.
[0202]
The phase shift circuit 132 can be realized by controlling the voltage of the variable reactance element. FIG. 24 is a diagram illustrating a relationship in which a voltage applied to a certain variable reactance element and a phase change amount thereby change. For example, as shown in FIG. 24, a variable reactance element capable of linearly changing the phase of an input signal from 0 ° to 360 ° with respect to an input voltage of 0V to 1V is used in the phase shift means 13 shown in FIG. The phase may be controlled by using it as a phase shifter (first phase shifter, second phase shifter,... Nth phase shifter).
[0203]
Hereinafter, an example of a method for temporally changing the phase will be described with reference to (a), (b), and (c) of FIG. (A), (b), and (c) of FIG. 25 are diagrams showing the relationship between the voltage applied to the phase shift unit and time. For example, in the case where the phase shift circuit 132 is configured by three phase shift units, that is, a first phase shift unit, a second phase shift unit, and a third phase shift unit, the first phase shift unit includes (a ), The signal shown in FIG. 25B is input to the second phase shifter, and the signal shown in FIG. 25C is input to the third phase shifter. At this time, the phase of the signal input to each phase shift unit can be changed independently. In the above description, the phase is changed from 0 ° to 360 °. However, it is not always necessary to change the phase by 360 °.
[0204]
In addition, as described in the first embodiment, the phase shift circuit 132 can be realized by changing the path length of the signal path or using a SAW element.
[0205]
With the above configuration, the phase of a plurality of signals obtained can be controlled according to the control signal from the phase control means 63. As a result, the same effect as that of the delay means used in the first embodiment can be realized. Therefore, when adding a plurality of signals, the signals can be prevented from canceling out of phase with each other. Compared with the case of adding and using, the occurrence of reception failure is greatly reduced.
[0206]
In FIG. 18A, after the signal obtained by the input means 1 is controlled by the amplification means 12 and the phase shift means 13, the signal is synthesized by the synthesis means 3, and further the frequency conversion is performed by the reception means 4. Is called.
[0207]
However, as shown in FIG. 18B, in the present embodiment, the receiving means 4 ′ is arranged immediately after the amplifying means 12, and the first to Nth receiving parts are arranged, and the phase shift means 13 is placed after the receiving means 4 ′. It may be arranged. In the embodiment shown in FIG. 18B, the phase shift process in the phase shift means 13 and the synthesis process in the synthesis means 3 are performed in the baseband band.
[0208]
Further, as shown in FIG. 18C, the present embodiment may use a receiving means 4 ″ instead of the receiving means 4 in FIG. 18A. In the embodiment shown in FIG. 18C, the signal received by the input means 1 is amplified by the amplifying means 12 and then converted into a frequency band signal (intermediate frequency signal) intermediate between the signal transmission frequency and the band frequency of the baseband signal. Converted. Later, the intermediate frequency signal is converted into a frequency (for example, baseband) that can be handled by the demodulating means 5 by the receiving means 4 ′ ″.
[0209]
In the embodiment shown in FIG. 18C, since the phase shifting means 13 is arranged immediately after the receiving means 4 ″, the frequency band of the signal processed by the phase shifting means 13 is made lower than that in the embodiment of FIG. 18A. It is possible. Further, when the signal is converted into the intermediate frequency signal by the receiving means 4 '', it is always converted into a constant frequency band signal. For example, even if the channel of the signal to be received is different, the frequency of the reception channel Accordingly, the phase control method in the phase shift means need not be changed. Even if a configuration that changes the characteristics of the received signal in the intermediate frequency band is used instead of the delay means of the first to fourth embodiments, such an embodiment has the same effect as the present embodiment.
[0210]
In the embodiment shown in FIGS. 18A, 18B, and 18C, the amplifying unit 12 is arranged immediately after the input unit 1, and the gain of each input signal is controlled according to the control signal from the gain control unit 61. As shown in FIG. 18D, the gain of the output signal of the phase shift means 12 may be controlled.
[0211]
In the embodiment shown in FIGS. 18A, 18B, and 18C, the gain control means 61 may be omitted, and the signal may be simplified so as to always amplify the signal by a certain level.
[0212]
(Embodiment 7)
A digital television broadcast receiver according to Embodiment 7 of the present invention will be described below with reference to FIG. FIG. 20 is a block diagram showing a configuration of a digital television broadcast receiving apparatus according to Embodiment 7 of the present invention.
[0213]
The digital television broadcast receiving apparatus according to the seventh embodiment includes an input unit 1, a delay unit 2, a combining unit 3, a receiving unit 4, a demodulating unit 5, a combining control unit 6, and a reception status estimating unit 14. The synthesis control unit 6 includes a gain control unit 61 and a delay time control unit 62. The delay means 2 has a first delay unit to an Nth delay unit. The synthesizing unit 3 includes a first synthesis unit to an Nth synthesis unit.
[0214]
When the digital television broadcast receiving apparatus according to the seventh embodiment is mounted on a moving body such as a vehicle, the digital television broadcast receiving apparatus according to the seventh embodiment further includes vehicle information detection means 9. In that case, the vehicle information detection means 9 has a speed detection means 91. Even if the digital television broadcast receiver in the seventh embodiment is not mounted on a moving body, the digital television broadcast receiver may include vehicle information detection means 9.
[0215]
In the digital television broadcast receiving apparatus shown in FIG. 20, reception status estimating means 14 is used instead of the delay wave estimating means 7 of the digital television broadcast receiving apparatus shown in FIG. 2, and the digital television broadcast receiving apparatus shown in FIG. The vehicle information detecting means 9 is different in configuration. FIG. 20 shows the detailed configuration of the synthesizing means 3.
[0216]
Hereinafter, the reception operation of the digital television in the mobile body in the seventh embodiment will be described.
[0217]
Television broadcast radio waves are converted into electric signals by the input means 1 such as the receiving antenna 11 and transmitted to the delay means 2. The delay means 2 gives a delay to the received signal in accordance with the control signal obtained from the delay time control means 62. The delayed signal is transmitted to the synthesis unit 3. The synthesizing unit 3 adjusts the synthesis ratio of the plurality of signals obtained from the delay unit 2 in accordance with the control signal obtained from the gain control unit 61. The synthesizing unit 3 adds the obtained signals. The receiving unit 4 extracts only a necessary frequency band component from the signal added by the synthesizing unit 3 and transmits it to the demodulating unit 5. The demodulating means 5 demodulates the signal obtained from the receiving means 4 and outputs a digital signal.
[0218]
In order for the reception status estimation means 14 to estimate the reception status (radio wave status), the demodulation means 5 outputs information on the demodulation status to the reception status estimation means 14. The reception status estimation unit 14 determines the reception status based on the input status such as the level change of the signal output from the input unit 1 and / or the demodulation status information obtained from the demodulation unit.
[0219]
As described above, the synthesis control unit 6 includes the gain control unit 61 and the delay time control unit 62. The gain control unit 61 gives gain control information to the gain adjustment unit 31 using information obtained from at least one of the reception state estimation unit 14 and the vehicle information detection unit 9. The delay time control means 62 gives delay time control information to the delay means 2 using information obtained from at least one of the reception status estimation means 14 and the vehicle information detection means 9. Here, the operations of the input unit 1, the delay unit 2, the reception unit 4, the demodulation unit 5, the synthesis control unit 6, and the speed detection unit 91 have been described so far in the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment. The description is omitted because it is the same as described above.
[0220]
Hereinafter, the operation of the reception status estimation means 14 will be described in detail. The reception status estimation means 14 obtains information such as the transfer characteristic of the received signal obtained by the demodulation means 5 and determines the presence or absence of an interference signal such as a delayed wave included in the received signal. When a delay wave is present in the input signal, the reception state estimation unit 14 estimates a multipath failure state that is at least one of the delay wave signal level, the delay time, and the phase information of the delay wave. The reception status estimation means 14 also obtains information regarding the error amount in the demodulated data. Since the method for estimating the received signal characteristics has been described in the first embodiment, the description thereof is omitted. Further, the reception status estimation unit 14 obtains level information of the signal received by the input unit 1 and obtains data such as the reception status of each input antenna 11 over a certain period in the past. Then, the reception status estimation means 14 estimates the current reception status using the information on the reception status obtained from the input means 1 and the demodulation means 5 and transmits the estimated reception status to the synthesis control means 6. In addition, the reception status estimation means 14 obtains the received signal modulation method, transmission mode information, and the like, if necessary.
[0221]
Hereinafter, the operation of the gain control means 61 which is one component of the composition control means 6 will be described. The gain control unit 61 obtains control information of the gain adjustment unit 31 that is a component of the combining unit 3 based on the reception state information obtained by the reception state estimation unit 14. At this time, as described in the first embodiment or the like, when the reception condition is good, sufficient characteristics can be obtained even when only one input signal is used. The gain control means 61 outputs a control signal for attenuating the signal to the synthesizing means 3. As a result, only one antenna input is selected, and it is possible to create the same reception situation as when one antenna is received. On the other hand, when the signal level decreases or when the multipath interference becomes strong, the gain control unit 61 outputs a control signal that gives a gain to a plurality of input signals to the combining unit 3.
[0222]
At this time, in order to reduce the correlation between the input signals, it is effective for the gain control means 61 to output a control signal that gives different gain amounts to all the signals to the synthesizing means 3. However, when controlling the gain, the gain control means 61 needs to instruct the synthesizing means 3 not to change the gain suddenly. This is because the OFDM modulation signal contains a control signal used for demodulation, and if the antenna is switched suddenly, the data accumulated in the past fixed period may become invalid. is there. Further, as a configuration example of the present embodiment, a method of simplifying the gain control means 61 and giving a fixed amount of gain can be considered. Furthermore, in the present embodiment, the configuration for controlling the delay time of the signal has been described. However, as described in the sixth embodiment, the same effect can be expected with a configuration in which the phase of the signal is directly controlled.
[0223]
Hereinafter, the operation of the delay time control means 62 will be described. The delay time control means 62 determines the delay amount to be given to each input signal by the delay means 2 based on the information such as the reception status obtained by the reception status estimation means 14. As a configuration example in the present embodiment, as described in the fourth embodiment, a delay amount control method in the case where the phases of a plurality of input signals are added while being temporally varied will be described. However, the delay amount given by the delay means 2 can be controlled by the method described in the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment.
[0224]
Below, the relationship between the movement state of a digital television broadcast receiver and the reception of a terrestrial digital television signal by adding input signals from a plurality of antennas 11 will be described.
[0225]
Digital television broadcasting has various countermeasures against multipath interference. Regardless of the state of movement of the digital television broadcasting receiver, digital television broadcasting has a higher reception impairment than conventional analog television broadcasting. Has characteristics that are difficult to receive.
[0226]
For example, (1) the OFDM modulation system is adopted in digital television broadcasting, (2) a guard interval period is provided between effective symbols transmitted for the purpose of preventing intersymbol interference due to delayed waves, (3 This is because, for the purpose of avoiding reception errors that occur in bursts, the transmission data sequence is rearranged in the time and frequency directions to disperse reception data errors and apply a technique for improving error correction capability by error correction code processing.
[0227]
Hereinafter, the effective symbol, the effective symbol period, and the guard interval period will be described with reference to FIGS.
[0228]
FIG. 28 is a diagram illustrating a configuration example of an OFDM transmission signal, and FIG. 29 is a diagram illustrating a configuration example of an analog TV transmission signal.
[0229]
Since the OFDM transmission signal has a plurality of carriers, for example, when information “A, B, C, D...” Is transmitted, information A to G is simultaneously transmitted as shown in FIG. Next, information of H to N is transmitted simultaneously. A period in which A to G are simultaneously transmitted is referred to as one effective symbol period. One effective symbol period depends on the carrier interval of the OFDM transmission signal. For example, when the carrier interval is 4 kHz, one effective symbol period is 1/4000 = 250 × 10. ^-6 Second. Also, the A block, the B block, and the like are referred to as one effective symbol.
[0230]
In addition, in order to transmit the block A, the OFDM transmission signal may be provided with a guard interval period in addition to one effective symbol period. FIG. 30 is a diagram illustrating one effective symbol period and a guard interval period. For example, A information may be transmitted during one effective symbol period. However, there is an interference wave in A, and the interference wave in A may affect the direct wave in H. For this reason, the information of the rear part of the block is written at the head part of each block. This head period is called a guard interval period. Note that the information to be written may be written at the head of each block at the rear of each block.
[0231]
Even if the above (1) to (3) are applied, when a reception failure such as frequency selective fading occurs due to a decrease in the input signal level or a strong interference wave, an amount of received data exceeding the error correction capability An error is expected to occur. For this reason, it is an effective means for reducing errors to increase the input signal level by adding the input signals from the plurality of antennas 11 and at the same time reduce the failure due to frequency selective fading.
[0232]
Since the received signal characteristics of multiple antennas constantly change during mobile reception when the digital television broadcast receiver is moving, even if the signals output from multiple antennas are added, those signals will continue for a long time. Are in opposite phase to each other and do not cancel each other.
[0233]
However, when the digital television broadcast receiver is not moving or when moving at a low speed, the received signal characteristics of the plurality of antennas do not change greatly, and the situation where these signals cancel each other may continue for a predetermined period or longer. is there. Therefore, the digital television broadcast receiver changes the delay time with respect to at least one of the plurality of input signals obtained. As a result, the phases of a plurality of input signals obtained can be temporally changed from each other. This corresponds to the case where the electromagnetic wave received by the antenna is subjected to the Doppler effect at the time of mobile reception. With such a configuration, the signal characteristics can always be changed.
[0234]
As described above, when the moving body is moving at a high speed, the characteristics of the received signal constantly fluctuate, and therefore the necessity for controlling the phase of the signal is small.
[0235]
Hereinafter, an example of the operation of the delay time control means 62 in consideration of the moving state of the digital television broadcast receiving apparatus will be described with reference to FIG.
[0236]
FIG. 21 is a flowchart related to the operation of the delay time control means 62.
[0237]
In step S <b> 1, the delay time control unit 62 obtains reception status information from the reception status estimation unit 14. In step S2, the delay time control means 62 determines the amount of reception failure due to multipath based on the reception status information. If the delay time control means 62 determines that the multipath failure is large, the moving speed information is obtained from the speed detecting means 91 in step S3. In step S4, the delay time control means 62 determines the moving speed of the moving body based on the moving speed information. In step S4, if the delay time control means 62 determines that the moving body is moving at a low speed or is stopped, the delay time control means 62 obtains the broadcast mode information from the reception status estimation means 14 in step S5. The low speed movement means a speed at which the Doppler frequency generated with the movement of the vehicle on which the present embodiment is mounted is, for example, about 0 Hz to about 10 Hz. In step S6, the delay time control means 62 refers to the table relating to the delay time control amount for the broadcast mode stored in advance and obtains the optimum value of the delay time control amount, and then in step S7, the delay time control means. 62 outputs delay time control information.
[0238]
On the other hand, if the determination conditions of step S2 and step S4 are not met, the delay time control means 62 outputs the delay time control information so that the delay time is not controlled in step S8. In step S7 and step S8, the delay time control means 62 outputs delay time control information, and the process ends.
[0239]
Hereinafter, the delay time control amount table referred to in step S6 will be briefly described. When controlling the delay time and changing the phase of the signal with time, the phase change causes inter-carrier interference of the OFDM modulated signal, so the delay time control means 62 sets the upper limit of the phase change amount. There is a need. It is conceivable that the upper limit value of the phase change amount is, for example, about 1% or less of the carrier interval. In addition, since the influence of inter-carrier interference differs depending on the transmission mode such as the modulation method and time interleaving, it is effective to set the phase change amount or the upper limit value of the phase change amount depending on the carrier modulation method and the transmission mode. For example, when the carrier interval of the OFDM modulation signal is 2 kHz and the carrier modulation method is the DQPSK modulation method, the upper limit value of the phase change amount is 20 Hz which is 1% of the carrier interval, and the data is modulated by the 16QAM modulation method. In such a case, a configuration is conceivable in which the delay time is controlled so that the amount of phase change is 10 Hz, which is 0.5% of the carrier interval.
[0240]
In the present embodiment, the method for controlling the delay time has been described so far. However, as in the sixth embodiment, a configuration in which the phase of the signal is directly controlled is also conceivable. A configuration example of the digital television broadcast receiving apparatus in this case is shown in FIG. In the digital television broadcast receiving apparatus shown in FIG. 22, the phase shift means 13 is used instead of the delay means 2 of the digital television broadcast receiving apparatus shown in FIG. 20, and the delay time of the digital television broadcast receiving apparatus shown in FIG. Instead of the control means 62, a phase control means 63 is used. Since the operations of the phase shift means 13 and the phase control means 63 shown in FIG. 22 are the same as those of the sixth embodiment, their descriptions are omitted.
[0241]
With reference to FIG. 23, description will be given of a situation in which a reception error occurs when the phases of a plurality of input signals are added while being temporally changed by the above method. (A) of FIG. 23 is a diagram illustrating an error occurrence situation when a signal is received using one antenna in an environment where reception impairment is large, and (b) of FIG. 23 is (a) of FIG. It is a figure which shows the error generation condition at the time of receiving a signal using a plurality of antennas in the same environment. The horizontal axes in FIGS. 23A and 23B indicate time, and the vertical axes in FIGS. 23A and 23B indicate the number of errors.
[0242]
FIG. 23 (a) and FIG. 23 (b) show that the number of data errors is reduced and the timing of occurrence of errors is dispersed in time when a plurality of antenna signals are received from a plurality of antennas. ing. In this way, by adding while controlling the phases of a plurality of antenna input signals, occurrence of burst errors can be suppressed.
[0243]
Furthermore, by applying the receiving method according to the present embodiment, it is possible to prevent the continuation of burst errors and reduce the number of error data, so that the length of time interleaving processed at the time of transmission can be shortened. . This is because data errors can be dispersed in time even if the time interleave length is short because reception errors do not occur continuously. By reducing the length of time interleaving applied at the time of transmission, the amount of memory for storing received data can be reduced when the data series is recovered in the digital television broadcast receiving apparatus, so that a great effect can be expected.
[0244]
As described above, according to the digital television broadcast receiver in the seventh embodiment, information on the reception status and moving speed is obtained and added while adjusting the phase and gain of a plurality of input signals according to the obtained information. Thus, it is possible to reduce the frequency of occurrence of reception failures. In addition, by changing the phase of the addition signal with time, there is an effect of suppressing the occurrence of a burst error, which was a problem when adding a plurality of antenna input signals. Furthermore, compared to the conventional method, the proposed method does not cause continuous reception errors, so that it is possible to disperse errors even when the time interleaving length is short. It is possible to reduce the length of interleaving. Needless to say, this embodiment and the processes described in the first to sixth embodiments can be combined to form a new configuration.
[0245]
The input unit 1 of the first to seventh embodiments described above may include a plurality of antennas 11, and a signal output from the input unit 1 may be selected from signals output from the plurality of antennas 11. That is, even if it is a signal output from the antenna 11, reception efficiency can be raised by thinning out an undesirable signal.
[0246]
A part of the digital television broadcast receiving apparatus having such a configuration will be described with reference to FIG. FIG. 27 is a diagram illustrating an input unit 1 having a plurality of antennas 11 and a selection unit, and an error rate measurement unit. The configuration of the digital television broadcast receiving apparatus excluding the input unit 1 and the error rate measuring unit is the same as that of the above-described first to seventh embodiments.
[0247]
The input unit 1 includes a plurality of antennas 11 and a selection unit that selects a signal to be output based on a control signal from the error rate measurement unit. The error rate measuring unit measures the error rate of the signal in the demodulating unit, and when the error rate exceeds a predetermined value for a predetermined period or longer, the signal level of the signals output from the plurality of antennas 11 is equal to or higher than the predetermined level. A control signal for the selection unit to select the signal is output to the selection unit of the input means 1. With the configuration shown in FIG. 27, digital television broadcasting can be stably received.
[0248]
Note that the selection unit of the input unit 1 selects a signal having a signal level equal to or higher than a predetermined level from signals output from the plurality of antennas 11. The selection timing may be an interval equal to or greater than a specified value of the received signal. The specified value of the received signal means, for example, the time required for transmitting data for one frame of the OFDM transmission signal. The selection timing may be every received frame of the received signal. The selection timing may be an arbitrary frame interval.
[0249]
Further, the configuration for thinning out undesired signals from the signal output from the antenna 11 is not limited to the configuration shown in FIG.
[0250]
For example, the synthesis control unit 6 may generate a control signal for changing the synthesis rate of the synthesis unit 3 based on the signal output from the delayed wave estimation unit 7. In other words, the synthesis rate is changed, and the corresponding signal is attenuated so that the level of the signal corresponding to the signal whose error rate at the demodulation unit 7 exceeds a predetermined value among the signals received by the synthesis unit 3 becomes almost zero. Let
[0251]
In addition, the change timing which changes a synthetic | combination rate may be the space | interval more than the regulation value of a received signal. The change timing may be every received frame of the received signal. The change timing may be an arbitrary frame interval.
[0252]
In the first to seventh embodiments described above, the period during which the set value such as the combining rate of the combining unit 3, the delay time of the delay unit, the amplification factor of the amplifying unit, or the phase value of the phase shifting unit is updated It may be immediately after the end of the guard interval period or the effective symbol, or just before the start of the effective symbol.
[0253]
In the first to seventh embodiments described above, the position information determination unit 8 obtains the position of the transmission station, and estimates the radio wave condition at the reception position based on the information obtained from the vehicle information detection unit and the position of the transmission station. May be. The position information determination unit 8 may store the radio wave conditions at a plurality of points in advance, and estimate the radio wave conditions at the reception position based on information obtained from the vehicle information detection unit 9. Further, the position information determination means 8 obtains the radio wave conditions at a plurality of points as needed, updates the radio wave conditions at the plurality of points, and determines the radio wave conditions at the reception position based on the information obtained from the vehicle information detection means 9. It may be estimated. Note that “anytime” may be a predetermined interval or an arbitrary interval. In addition, the broadcast station transmits reception information data indicating the reception status of a plurality of points, and the digital television broadcast receiver in the above-described first to seventh embodiments receives the reception information data. The radio wave condition may be estimated.
[0254]
The present invention can not only improve the reception obstacle at the time of mobile reception, but also can improve the reception obstacle that occurs due to a change in transmission path characteristics due to, for example, an airplane flying. That is, the present invention may be applied not only to a mobile receiver but also to a fixed receiver.
[0255]
【The invention's effect】
As is apparent from the above description, the present invention can provide a reception control for delaying a reception signal, such as a multipath failure or a decrease in the electric field strength of a television signal, when receiving a digital television signal. By using a plurality of antennas used as signal input means, signal processing such as signal combining, reception failure estimation, etc., or by controlling the installation position of the antenna, it is possible to greatly improve the conventional technique. In addition, by transmitting data on the reception status at the reception point of digital television broadcasting, and receiving and using the data, it is possible to estimate the reception failure status at the reception point and use it for improving the reception failure.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital television broadcast receiver in an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 3 is a block diagram showing the configuration of another digital television broadcast receiver of the present invention.
FIG. 4 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 5 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 6 is a block diagram showing the configuration of another digital television broadcast receiver of the present invention.
FIG. 7 is a conceptual diagram showing a frequency analysis result after reception when receiving a delay wave interference during reception.
FIG. 8 is a conceptual diagram showing gain control of a combining unit.
FIG. 9 is a conceptual diagram showing delay times and error rates of delayed waves.
FIG. 10 is a diagram for explaining antenna switching conditions when switching antennas;
FIG. 11 is a diagram for explaining a method of controlling a delay time in the delay means.
FIG. 12 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 13 is a block diagram illustrating a configuration example of a receiving unit.
FIG. 14 is a block diagram illustrating another configuration example of the receiving unit.
FIG. 15 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 16 is a diagram illustrating another configuration example of the input unit.
FIG. 17 is an enlarged view of FIG. 16;
FIG. 18A is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 18B is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 18C is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 18D is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 19 is a block diagram illustrating a configuration example of a signal phase control circuit;
FIG. 20 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIG. 21 is a diagram showing a flowchart of the operation of the delay time control means.
FIG. 22 is a block diagram showing a configuration of another digital television broadcast receiver of the present invention.
FIGS. 23A and 23B are conceptual diagrams showing a reception error occurrence state of digital television broadcasting in an environment where reception failure is large.
FIG. 24 is a diagram illustrating a voltage applied to a certain variable reactance element and a relationship in which a phase change amount changes accordingly.
25 (a), (b) and (c) are diagrams showing the relationship between the voltage applied to the phase shift section and time. FIG.
FIG. 26 is a block diagram illustrating still another configuration example of the receiving unit.
FIG. 27 is a diagram illustrating an input unit having a plurality of antennas and a selection unit, and an error rate measurement unit.
FIG. 28 is a diagram illustrating a configuration example of an OFDM transmission signal.
FIG. 29 is a diagram illustrating a configuration example of a transmission signal of an analog TV.
FIG. 30 is a diagram illustrating one effective symbol period and a guard interval period.
[Explanation of symbols]
1 Input means
2 Delay means
3 Synthesis means
4 Receiving means
5 Demodulation means
6 Synthesis control means
7 Delayed wave estimation means
8 Location information judging means
9 Vehicle information detection means
11 Antenna
12 Amplification means
13 Phase shift means
14 Reception status estimation means
61 Gain control means
62 Delay time control means
63 Phase control means
91 Speed detection means
92 Position detection means
101 Bandpass filter
102 Reference signal generating means
103 Low-pass filter
104 Sine wave generating means
110 Antenna
111 Antenna element
112 Antenna element
113 Antenna support
131 Input section
132 Phase shift circuit
133, 134 Negative circuit
135, 136, 137, 138 multiplication circuit
139 Adder circuit

Claims (17)

Input means for converting broadcast waves into a plurality of electrical signals;
Receiving means for performing frequency conversion on the plurality of electrical signals obtained from the input means;
Frequency analysis means for frequency-converting the plurality of signals obtained from the reception means;
Adjusting means for operating the plurality of signals obtained from the frequency analyzing means;
And decoding means for decoding the signal that is obtained from the adjusting means,
The information on the demodulation status obtained by the decoding means and the frequency analysis means is received, the intensity of the delay wave included in the broadcast wave, the phase difference between the delay wave and the direct wave, or the delay wave and the direct wave Delay wave estimation means for estimating information of at least one delay wave of the delay time of
A digital television broadcast receiver comprising: a demodulation control unit that generates a control signal for controlling a transfer function of the adjustment unit so that the adjustment unit selects a best signal based on the information on the delayed wave. The digital television broadcast receiver is
Position detecting means for detecting a receiving position of the digital television broadcast receiver;
Position information determination means for determining a radio wave condition at the reception position in accordance with a signal from the position detection means;
The demodulation control means generates a control signal based on the delayed wave information obtained from the delayed wave estimation means and the radio wave situation obtained from the position information determination means, and the generated control signal is 2. The digital television broadcast receiver according to claim 1, which is given to the adjusting means. The digital television broadcast receiver is
Speed detecting means for detecting a moving speed of the digital television broadcast receiver;
Position detecting means for detecting a receiving position of the digital television broadcast receiver;
Position information determination means for determining a radio wave condition at the reception position according to the detected moving speed and the detected reception position;
The demodulation control means generates a control signal based on the delayed wave information obtained from the delayed wave estimation means, the radio wave situation obtained from the position information determination means, and the signal obtained from the frequency analysis means. The digital television broadcast receiver according to claim 1, wherein the generated control signal is supplied to the adjusting unit. 4. The digital television broadcast receiver according to claim 3 , wherein the speed detection unit and the position detection unit are a navigation system. The digital television broadcast receiver according to any one of claims 1 to 4 , wherein the input unit includes a plurality of antennas having different reception characteristics.   The digital television broadcast receiver according to claim 1, wherein the demodulation state can be represented by a pilot signal included in the broadcast wave. 3. The digital signal according to claim 2 , wherein the position information determination unit obtains a position of a transmission station and estimates the radio wave condition of the reception position based on information obtained from a vehicle information detection unit and a position of the transmission station. Television broadcast receiver. 3. The digital television broadcast according to claim 2 , wherein the position information determination unit preliminarily stores radio wave conditions at a plurality of points, and estimates the radio wave conditions at the reception position based on information obtained from the vehicle information detection unit. Receiver device. The position information determination means obtains radio wave conditions at a plurality of points as needed, updates the radio wave conditions at the plurality of points,
The digital television broadcast receiver according to claim 2 , wherein the radio wave condition at the reception position is estimated based on information obtained from vehicle information detection means. The broadcast station transmits reception information data indicating reception statuses at a plurality of points, and the digital television broadcast receiver according to claim 9 receives and transmits the reception information data to estimate the radio wave status. system. The position information determination means obtains the reception status of a plurality of points as needed,
The digital television broadcast receiver according to claim 2 , wherein the radio wave condition at the reception point is estimated based on information obtained from vehicle information detection means or the position information determination means and reception conditions at the plurality of points. The digital television broadcast receiving apparatus further includes an error rate measuring unit that measures an error rate of the signal in the demodulating unit and generates a control signal when the error rate exceeds a predetermined value for a predetermined period or longer,
The digital television broadcast receiver according to claim 1, wherein the input unit includes a selection unit that selects a signal to be output based on a control signal from the error rate measurement unit. The digital television broadcast receiver according to claim 12 , wherein a selection timing at which the input unit selects the signal to be output is an interval equal to or greater than a specified value of a received signal. The digital television broadcast receiver according to claim 12 , wherein the selection timing at which the input means selects the signal to be output is for each received frame of the received signal, or a predetermined value or an arbitrary frame interval. The input means is composed of a plurality of antennas,
Said plurality of at least one temporally installation position of the antenna is moved, the digital television broadcast receiver according to any one of claims 1-14. The digital television broadcast receiver according to claim 15 , wherein a distance traveled by at least one of the plurality of antennas is controlled according to a wavelength of a television signal to be received. The digital television broadcast receiver according to claim 15 or 16 , wherein an interval between at least two of the plurality of antennas is shorter than a wavelength of a television signal to be received.

Images