JP2009081721A - Digital demodulator and control method thereof - Google Patents

Abstract

Power consumption of a digital demodulator is reduced by optimally controlling power according to reception conditions around the digital demodulator.
A digital demodulator 2 according to the present invention includes a tuner 4 having a plurality of processing units, a demodulator 5 that performs a demodulation process on a received signal received by the tuner 4, and supplies power to the plurality of processing units. A power supply unit 12, a reception status acquisition unit 19 that acquires the reception status of the received signal, a current location acquisition unit 22 that acquires the current location, a control parameter acquisition unit 21 that acquires control parameters corresponding to the current location, and a reception status Based on the reception status acquired by the acquisition unit 19 and the control parameter acquired by the control parameter acquisition unit 21, the control unit 6 controls the power supplied from the power supply unit 12 to the plurality of processing units.
[Selection] Figure 4

Description

  The present invention relates to a digital demodulator and a control method therefor.

  In an apparatus that receives and demodulates a modulated digital signal, in order to obtain an accurate demodulated signal, power supplied to a plurality of processing units that process the received signal in a form that can be demodulated is obtained. It must be secured to a certain size. The magnitude of the required supply power differs depending on the signal reception status. For example, in a certain processing unit, the supply power must be increased when the reception condition is not good, but it is not necessary to increase the supply power so much when the reception condition is good. Therefore, in order to reduce power consumption, it is conceivable to control the power supplied to the processing unit according to the signal reception status.

  A digital broadcast receiving apparatus disclosed in Patent Document 1 is disclosed as controlling power supplied to a processing unit in accordance with a signal reception state. The digital broadcast receiving apparatus disclosed in Patent Literature 1 performs control to limit the power supply of the digital broadcast receiving apparatus within a period in which error correction related to the received signal determined based on the reception status obtained in the demodulation unit is possible. In addition, the digital broadcast receiving apparatus disclosed in Patent Literature 1 performs control to limit the power supply of the digital broadcast receiving apparatus within a period in which error correction regarding a signal determined based on the reception state estimated from the acquired position information is possible. Do.

Moreover, the broadcast viewing terminal apparatus of patent document 2 is disclosed as what controls the power supply to a process part according to the reception condition of a signal similarly to the digital broadcast receiver apparatus of patent document 1. FIG. The broadcast viewing terminal device of Patent Document 2 includes a receiving unit that receives a broadcast signal, an extracting unit that extracts a video signal from the broadcast signal received by the receiving unit, and a decoding unit that decodes the video signal extracted by the extracting unit. An output means for outputting the video signal decoded by the decoding means to a display screen; and a control means for controlling the extraction means, the decoding means and the output means, and the control means includes the extraction means, A plurality of control modes including a low power broadcast viewing mode in which at least one of the decoding means and the output means is operated intermittently;
JP 2006-66959 A (published March 9, 2006) JP 2006-32996 A (published February 2, 2006)

  In the digital broadcast receiving apparatus of Patent Document 1, only the distance between the transmitting station and the digital broadcast receiving apparatus is used as a control parameter for power control, and power is taken into consideration only by attenuation of received signal power according to the distance from the transmitting station. I have control. However, the actual signal reception status is not only the attenuation of the received signal power depending on the distance from the transmitting station, but also the influence of interference waves transmitted from other digital broadcasting or analog broadcasting transmitting stations, buildings, elevated buildings, etc. There is also the possibility of being affected by other structures. Therefore, not only the attenuation of the received signal power depending on the distance from the transmitting station, but also the influence of jamming waves transmitted from other digital broadcasting or analog broadcasting transmitting stations, the influence of other structures such as buildings and overheads, etc. It is necessary to perform power control in consideration of

  In the present invention, the control parameter corresponding to the position information is not only the attenuation of the received signal power depending on the distance from the transmission station, but also the influence of interference waves transmitted from other digital broadcast or analog broadcast transmission stations, buildings, The purpose is to perform power control with optimal control parameters that match the current location, taking into account the effects of other structures such as elevated structures.

  In order to solve the above problems, a digital demodulator according to the present invention includes a processing unit having a plurality of processing units for processing a received signal into a form capable of performing a demodulation process, and a received signal processed by the processing unit. Demodulation means for performing demodulation processing, power supply means for supplying power to the plurality of processing units, reception status acquisition means for acquiring the reception status of the received signal, and current location indicating the current position of the digital demodulation device Based on the current location acquisition means, the control parameter acquisition means for acquiring the control parameter corresponding to the current location, the reception status acquired by the reception status acquisition means and the control parameter acquired by the control parameter acquisition means, the power supply means Control means for controlling the power supplied to the plurality of processing units, the control parameter is a positional relationship between the current location and the transmitting station, The positional relationship between the current location and other transmitting stations that may transmit an interference wave to the received signal, and the positional relationship between the current location, the transmitting station, and other structures that may interfere with the received signal. It is determined based on what added at least one.

  According to the above invention, not only the attenuation of the received signal power according to the distance from the transmission station, but also the influence of interference waves transmitted from other digital broadcast or analog broadcast transmission stations, buildings, or other overheads, etc. It is possible to set control parameters corresponding to the current location taking into account the influence of the structure, etc., and power control is performed with the optimal control parameters for the reception status of the current location, so more effective power reduction is possible In addition, it is possible to prevent reception interference due to power reduction using inappropriate parameters.

  In the digital demodulator, when it is determined that the reception status acquired by the reception status acquisition unit is better than the reference indicated by the control parameter, the control unit is configured so that the power supply unit performs the plurality of processes. You may reduce the electric power supplied to a part.

  Further, in the digital demodulator, when it is determined that the reception status acquired by the reception status acquisition unit is worse than a reference indicated by the control parameter, the control unit is configured so that the power supply unit You may increase the electric power supplied to a some process part.

  Furthermore, in the digital demodulator, when the control parameter indicates that the reception status of the current location is so bad that the control means cannot control the power supplied to the plurality of processing units, the control The means may stop control of power supplied to the plurality of processing units and maintain power necessary for reception.

  By configuring the control means as described above, the control means can control the power supplied to the plurality of processing units according to the reception status of the current location acquired by the reception status acquisition means.

  In the digital demodulator, the control parameter includes any one of a control reference, a default value, a control amount, a control range, a control period, and control availability corresponding to a certain point or area. May be determined for each of the plurality of processing units, and the control reference, the control amount, the control cycle, and the control availability may be determined in common by the plurality of processing units.

  Accordingly, the control unit can control the power supplied from the power supply unit to the plurality of processing units based on the reception status acquired by the reception status acquisition unit and the control parameter.

  The control method of the digital demodulator according to the present invention includes a processing unit having a plurality of processing units for processing a received signal in a form capable of performing a demodulating process, and a demodulator for performing a demodulating process on the received signal processed by the processing unit. And a power supply means for supplying power to the plurality of processing units, a method for controlling the digital demodulator, a reception status acquisition step for acquiring the reception status of the received signal, and a current position of the digital demodulator A current location acquisition step for acquiring a current location, a control parameter acquisition step for acquiring a control parameter corresponding to the current location, a reception status acquired by the reception status acquisition step, and a control parameter acquired by the control parameter acquisition step. And a control step for controlling the power supplied to the plurality of processing units based on the control parameter, The positional relationship between the current location and the transmitting station, the positional relationship between the current location and another transmitting station that may transmit an interference wave for the received signal, and the current location, the transmitting station, and the received signal are disturbed. It is defined based on what added at least 1 of the positional relationship with the other structure which can do.

  According to the above invention, not only the attenuation of the received signal power according to the distance from the transmission station, but also the influence of interference waves transmitted from other digital broadcast or analog broadcast transmission stations, buildings, or other overheads, etc. It is possible to set control parameters corresponding to the current location taking into account the influence of the structure, etc., and power control is performed with the optimal control parameters for the reception status of the current location, so more effective power reduction is possible In addition, it is possible to prevent reception interference due to power reduction using inappropriate parameters.

  As described above, the digital demodulating device and the control method thereof according to the present invention obtain the reception status of the received signal, obtain the current location indicating the current position of the digital demodulating device, obtain the control parameter corresponding to the current location, Based on the reception status and the control parameter, power supplied to a plurality of processing units included in the processing means is controlled.

  Therefore, the control parameters corresponding to the position information are not only attenuated received signal power depending on the distance from the transmitting station, but also the influence of interference waves transmitted from other digital broadcasting or analog broadcasting transmitting stations, buildings, Thus, there is an effect that power control can be performed with an optimum control parameter suitable for the current location.

  An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1A is an outline view of the mobile communication device 1 according to the present embodiment, and FIG. 1B is a block diagram of a digital demodulation device 2 provided in the mobile communication device 1.

  The mobile communication device 1 of this embodiment includes a digital demodulator 2. The received signal Sr received from the antenna 3 by the mobile communication device 1 is demodulated by the digital demodulator 2 and output as a demodulated signal Sd. Then, by a processing device (not shown) provided at the subsequent stage of the digital demodulator 2, information relating to data such as characters, images, sounds, and programs is extracted from the demodulated signal Sd, and these characters, images, sounds, programs, and the like are extracted. The data is reproduced. These characters, images, or sounds are provided to the user of the mobile call device 1 through a display or a speaker (not shown) provided in the mobile call device 1. The digital demodulator 2 may be employed in a digital TV (Television), a wireless LAN (Local Area Network) device, a PC (Personal Computer) equipped with a wireless LAN, and the like, in addition to the portable telephone device.

  The digital demodulator 2 includes a tuner 4, a demodulator 5, and a control unit 6. Further, the tuner 4 receives the reception signal Sr received by the antenna 3 and performs channel selection processing on the reception signal Sr. That is, a signal related to one channel is selected from signals related to a plurality of channels included in the received signal Sr from the antenna 3. Then, the tuner 4 converts the signal related to the selected one channel into an IF (Intermediate Frequency) signal Si and outputs it to the demodulator 5. The demodulator 5 receives the IF signal Si output from the tuner 4, generates a demodulated signal Sd, for example, a so-called TS (Transport Stream) signal from the IF signal, and outputs the demodulated signal Sd to the outside.

  The digital demodulator 2 includes a plurality of processing units. Unless otherwise specified in the following, each processing unit may be specialized to have a plurality of circuit elements and perform independent functions, or a general-purpose processor circuit and the following functions. It may be composed of a program that causes hardware such as a processor circuit to function. In the latter case, the processing unit is constructed by combining hardware and a program.

[Signal train]
The following is a description of the signal sequence received by the mobile communication device 1. The signal sequence received by the mobile communication device 1 is carried by a plurality of carrier waves. In the following, an example in which an OFDM (Orthogonal Frequency Division Multiplexing) system is adopted as a transmission system of a signal sequence received by the mobile communication device 1 is shown as an example of the present embodiment.

  A signal sequence transmitted by the OFDM method is a signal sequence in which a large number of symbols having a prescribed length are connected, and one symbol includes a plurality of unit signals overlapping each other. The plurality of unit signals are obtained by modulating carrier waves having different frequencies according to data having a predetermined data length. Further, each symbol includes a guard interval in addition to an effective portion including data. The guard interval has exactly the same signal component as a part of the rear end of the effective portion, and is inserted at the front end of the symbol. The guard interval is used to remove the influence of a plurality of multipath waves generated in the transmission path from the transmitting station that transmits the signal train to the mobile communication device 1 from the received signal. Note that the length of an effective portion included in one symbol is called an effective symbol length.

  Furthermore, the signal sequence transmitted by the OFDM method includes a plurality of scattered pilot signals. Scattered pilot signals included in a signal sequence transmitted by the OFDM method are the same for each of the frequency direction and the time direction when the unit signals included in the signal sequence are arranged on a plane composed of the time direction and the frequency direction. Arranged at intervals. A scattered pilot signal is a signal sequence in which a number sequence represented by a prescribed coding method or the like is inserted into a signal sequence in a predetermined arrangement order. In other words, the scattered pilot signal is included in the signal sequence so that the numerical sequence represented by the specified coding method is reproduced when the numerical values indicated by the scattered pilot signal are taken in the predetermined arrangement order in the signal sequence. Has been placed.

  In addition, the signal sequence assumed in the present embodiment is subjected to interleaving and various encodings for performing error correction processing for correcting errors occurring in the signal sequence. For example, Reed-Solomon code (hereinafter referred to as “RS code”) or Viterbi code is used for encoding. Interleaving includes bit interleaving, byte interleaving, time interleaving, and frequency interleaving. These rearrange data corresponding to signals included in the transmission signal in time or frequency. If a signal sequence that has been subjected to various types of encoding and interleaving is subjected to later-described decoding processing and deinterleaving processing in the mobile communication device 1, errors contained in the signal sequence can be corrected.

  Note that the signal sequence assumed in this embodiment can be applied to, for example, Japanese terrestrial digital broadcasting. An ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) system is adopted as a signal transmission system related to terrestrial digital broadcasting in Japan.

[Tuner]
FIG. 2 is a block diagram showing the configuration of the tuner 4. The tuner 4 includes an RF amplifier unit 7, a mixer unit 8, a VCO / PLL unit 9, a filter unit 10, and an IF amplifier unit 11. The reception signal Sr input to the tuner 4 is amplified by the RF amplifier unit 7, and the amplified reception signal Sr is output to the mixer unit 8. On the other hand, the VCO / PLL unit 9 generates a mixing signal (channel selection process). The frequency of the mixing signal is a frequency corresponding to a specific channel. The mixing signal generated by the VCO / PLL unit 9 is output to the mixer unit 8. The mixer unit 8 generates an IF signal Si from the amplified signal output from the RF amplifier unit 7 and the mixing signal output from the VCO / PLL unit 9. The frequency of the IF signal Si is referred to as the IF frequency.

  The IF signal Si generated by the mixer unit 8 is output to the filter unit 10. The filter unit 10 removes unnecessary signal components from the IF signal Si output from the mixer unit 8. The IF signal Si from which unnecessary signal components are removed is output to the IF amplifier unit 11. The IF amplifier unit 11 amplifies the IF signal Si output from the filter unit 10 and outputs the amplified IF signal Si to the demodulator 5.

  The tuner 4 further includes a power supply unit 12. The power supply unit 12 supplies power to each of the RF amplifier unit 7, the mixer unit 8, the filter unit 10, and the IF amplifier unit 11 (supply unit). The RF amplifier unit 7, the mixer unit 8, the filter unit 10, and the IF amplifier unit 11 operate with power supplied from the power supply unit 12, and this power supply is input to the power supply unit 12 from the control unit 6 described later. It is controlled based on the power setting value.

  The power supply unit 12 also supplies power to the VCO / PLL unit 9. However, if the power supplied to the VCO / PLL unit 9 is controlled and reduced based on the power setting value, the operation of the VCO / PLL unit 9 may stop, and the operation of the digital demodulator 2 may stop. . Therefore, the power supplied to the VCO / PLL unit 9 is not controlled based on the power setting value.

  Table 1 shows current values of the RF amplifier unit 7, the mixer unit 8, the filter unit 10, and the IF amplifier unit 11 corresponding to the power setting values. Here, each current value included in Table 1 is set to satisfy, for example, Ir1 ≧ Ir2 ≧ Ir3... ≧ Irn (<Ir1). That is, the current value when the power setting value is large is set to be smaller.

  The power supply unit 12 stores any one of 1 to n indicating the current power setting value. Then, referring to Table 1, a current having a current value corresponding to the current power setting value is supplied to the RF amplifier unit 7, the mixer unit 8, the filter unit 10, and the IF amplifier unit 11. For example, when the current power setting value is 2, the RF amplifier unit 7 is supplied with the current Ir2, the mixer unit 8 is supplied with the current Im2, the filter unit 10 is supplied with the current If1, and the IF amplifier unit 11 is supplied with the current Ii1. . In addition, when a new power setting value is output from the control unit 6, the power supply unit 12 supplies the RF amplifier unit 7, the mixer unit 8, the filter unit 10, and the IF amplifier unit 11 based on the new power setting value. Change the supplied current. Thus, the power supplied to the RF amplifier unit 7, the mixer unit 8, the filter unit 10, and the IF amplifier unit 11 is controlled.

[Demodulator]
The following is a description of the demodulator 5. FIG. 3 is a block diagram showing the configuration of the demodulator 5. The demodulator 5 includes an ADC unit 13, an AFC / symbol synchronization unit 14, an FFT unit 15, a frame synchronization unit 16, a waveform equalization unit 17, and an error correction unit 18. The IF signal Si output from the tuner 4 is input to the ADC unit 13. The ADC unit 13 converts the IF signal Si, which is an analog signal, into a digital signal, and outputs the converted digital signal to the AFC / symbol synchronization unit 14.

  The AFC / symbol synchronization unit 14 performs frequency correction processing by AFC on the digital signal from the ADC unit 13 to correct a frequency shift of the IF signal Si. The AFC / symbol synchronization unit 14 determines a Fourier transform start point by the FFT unit 15 described later, that is, a symbol synchronization point, performs symbol synchronization, and outputs a digital signal to the FFT unit 15.

  In the ISDB-T system, the mode indicating the effective symbol length includes mode 1 indicating the effective symbol length 252 μs, mode 2 indicating the effective symbol length 504 μs, and mode 3 indicating the effective symbol length 1008 μs. In the determination of the symbol synchronization point, the point at which optimum reception with the least influence of the multipath wave is possible is set as the synchronization point. As a method for determining such a synchronization point, a method of referring to signal correlation, a method of correcting a phase shift using a pilot signal such as a scattered pilot signal, and the like are used.

  An FFT (Fast Fourier Transform) unit 15 performs a Fourier (time-frequency) transform on the digital signal from the AFC / symbol synchronization unit 14. A so-called fast Fourier transform (FFT) is generally used for the Fourier transform. The FFT unit 15 sequentially outputs the digital signal subjected to the Fourier transform to the frame synchronization unit 16.

  The frame synchronization unit 16 performs synchronization in units of frames in the digital signal sent from the FFT unit 15. One frame is composed of, for example, 204 symbols, and one set of TMCC information is acquired from one frame signal. The digital signal synchronized by the frame synchronization unit 16 is output to the waveform equalization unit 17.

  The waveform equalization unit 17 performs waveform equalization processing on the digital signal synchronized by the frame synchronization unit 16 based on the scattered pilot signal included in the digital signal (waveform equalization means). The waveform equalization processing is a kind of signal correction processing that corrects a deviation from the reference value of the constellation generated in the unit signal. Such a deviation from the reference value of the constellation mainly occurs due to noise generated on the signal transmission path.

  The waveform equalization process is performed in the following procedure. First, the waveform equalization unit 17 extracts a scattered pilot signal from the signal sequence from the frame synchronization unit 16. On the other hand, the waveform equalization unit 17 sequentially generates a signal indicating a sequence based on a specified coding method used for the scattered pilot signal as a reference signal. Then, the scattered pilot signal extracted by the generated reference signal is divided.

  Next, the waveform equalization unit 17 interpolates the division result in both the time direction and the frequency direction. For such interpolation, linear interpolation, maximum likelihood method, or the like is used. Then, the waveform equalization unit 17 divides each unit signal included in the signal sequence from the frame synchronization unit 16 by the interpolated numerical value. Thereby, waveform equalization processing is performed on the signal sequence. The unit signal subjected to the waveform equalization process is demapped to each data having a predetermined data length. The demapped result is output to the error correction unit 18.

  On the other hand, the waveform equalization unit 17, when demapping the signal sequence, calculates the difference between the constellation of the signal sequence subjected to the waveform equalization processing and the constellation reference value, that is, the MER (Modulation Error Ratio). Measure for each unit signal. MER indicates an error related to the constellation of the received signal, and this error substantially corresponds to the amount of noise included in the received signal. In the present embodiment, the MER is calculated so as to indicate that the larger the value, the smaller the amount of noise with respect to the intensity of the received signal. The MER measurement value for each unit signal measured by the waveform equalization unit 17 is output to the control unit 6 in the order in which the waveform equalization processing is performed.

  The error correction unit 18 performs error correction processing on the signal from the waveform equalization unit 17. The error correction process includes a deinterleave process and a decoding process corresponding to the interleave process and the encoding process performed on the signal at the transmission source. The digital signal that has been subjected to various interleaving processes is returned to the digital signal before the interleaving process is performed by the deinterleaving process, and the digital signal that has been subjected to the encoding process is a digital signal that has not been encoded by the decoding process. Returned to As a result, various errors included in the signal in the transmission path are corrected. Further, the error correction unit 18 may measure an error correction amount when the error correction processing is performed on the digital signal, and may calculate a BER (Bit Error Rate). Then, the calculated BER may be output to the control unit 6.

  The digital signal demodulated by the demodulator 5 as described above is output from the demodulator 5 as a TS signal.

(Control part)
FIG. 4 is a block diagram illustrating a configuration of the control unit 6. The control unit 6 includes a reception status acquisition unit 19, a supply power control unit 20, a control parameter acquisition unit 21, and a current location acquisition unit 22.

  The reception status acquisition unit 19 acquires the MER measurement value output from the waveform equalization unit 17 of the demodulator 5 as the reception status. The supply power control unit 20 determines a power setting value based on the reception status acquired by the reception status acquisition unit 19 and the control parameter acquired by the control parameter acquisition unit 21, and outputs the power setting value to the power supply unit 12 To do. The control parameter acquisition unit 21 acquires a control parameter corresponding to the current location acquired by the current location acquisition unit 22 from the control parameter database 23. The control parameter acquisition unit 21 may be configured to directly acquire the control parameter from the outside through communication.

  In the present embodiment, as shown in FIG. 6, the control parameter database 23 stores points having similar reception conditions as areas and stores the control parameters for each area. This storage format is an example, and the control parameters may be stored in a different format.

  The control parameter database 23 may be configured outside the control unit 6, and the control parameter acquisition unit 21 may acquire the control parameters from the control parameter database 23 via a communication line or the like. Alternatively, the control parameter database 23 may be configured inside the control unit 6. Further, instead of the control parameter database 23, the control parameters may be stored in a storage device such as a memory of the mobile communication device 1 or an HDD.

[Control parameters]
FIG. 5 shows an example of storing control parameters in the control parameter database 23. The control parameter includes a control amount, a control reference, a default value, a control range, a control cycle, and control availability of each processing unit. Further, the areas A to C described in FIG. 5 correspond to the areas A to C in FIG.

  The unit of the control reference is dB when MER is used as the reference of the reception status. In FIG. 5, it is assumed that the modulation method is 2/3 of QPSK, that is, the modulation method is a one-seg broadcasting modulation method.

  Also, the power value varies depending on the processing unit such as mW or μW. In FIG. 5, the numerical values shown in the default value and the control range are the setting values of the supply power setting register included in the control parameter database 23, and may be set so as to correspond to the power values on a one-to-one basis. For example, in FIG. 5, the numerical value of 1 in the filter unit corresponds to 1 mW, 2 corresponds to 2 mW, 3 corresponds to 3 mW, the numerical value of 1 in the mixer unit corresponds to 4 mW, 2 corresponds to 6 mW, and 3 corresponds to 8 mW. May be set. When the control amount is 1, the set value of the supply power setting register is changed from 1 to 2 or 2 to 1 by a single control. When the control amount is 2, the control value is 1 The set value of the power supply setting register is changed from 1 to 3, or from 3 to 1.

  In the present embodiment, the control cycle is 1 [frame]. As the frame described here, for example, an OFDM frame (204 symbols × effective symbol length 1.008 ms = 206 ms) is used. In addition to the frame, a time unit such as a symbol length or milliseconds may be used as a unit of the control cycle.

  In the present embodiment, the control reference is defined by an increase threshold for determining whether to perform power increase control and a decrease threshold for determining whether to perform power decrease control. The control range is defined by determining the maximum value and the minimum value of the power supplied to each processing unit.

  In this embodiment, in order to simplify the expression, some control parameters are shared by a plurality of processing units, but each control parameter may be subdivided for each processing unit.

  Note that the control parameters shown here are merely examples, and control parameters of a different format may be used.

  The control parameter is determined based on three criteria. The first criterion is the positional relationship between the current location and the transmitting station. The second criterion is the positional relationship between the current location and another transmitting station that may transmit an interference wave for the received signal. The third criterion is the location of the current location, transmitting station, and other structures that can interfere with the received signal, i.e., the shielding. FIG. 6A to FIG. 6C are schematic diagrams showing how to determine an area using the same control parameter. Hereinafter, how to determine the control parameters in each criterion will be described.

  FIG. 6A is a schematic diagram showing the transmitting station and each area when the area division is determined based on the distance from the transmitting station. In FIG. 6A, the areas A, B, and C are divided according to the distance from the transmission station 24. That is, area A is the area closest to the transmitting station 24, area B is the area closest to the transmitting station 24 next to area A, and area C is the area from the transmitting station 24 among areas A, B, and C. It is the farthest area.

  First, in area A, since it is closest to the transmitting station 24, the power of the received signal is large and the reception condition is good. Therefore, it is possible to greatly reduce the power supplied to each processing unit of the tuner provided in the digital demodulator. Therefore, it is possible to set the control parameter so that the power can be easily lowered. As setting examples of control parameters in area A, the following setting examples 1 to 4 can be considered.

  Setting example 1 is to increase the control amount. Setting example 2 is to reduce the reduction threshold of the control reference so that the power can be easily lowered. The increase threshold of the control reference is always smaller than the decrease threshold. In the setting example 2, when the decrease threshold is made smaller than the increase threshold by decreasing the decrease threshold, the decrease threshold is made smaller than the increase threshold by decreasing the increase threshold. Setting example 3 is to lower the default value. Setting example 4 is to lower the upper limit and lower limit of the control range.

  Next, in area B, since the distance is larger than in area A, the power of the received signal is smaller, and the reception situation is slightly deteriorated, so that the signal can be reliably received without being affected by noise. It is necessary to reduce the amount of power supplied to each processing unit of the tuner included in the digital demodulator. Therefore, as setting examples of the control parameter in the area B, the following setting examples 5 to 8 can be considered.

  Setting example 5 is to reduce the control amount. Setting example 6 is to increase the reduction threshold of the control reference and make it difficult for the power to decrease. Setting example 7 is to increase the default value. Setting example 8 is to increase the upper limit and the lower limit of the control range.

  Finally, in area C, since the distance is further away than in area B, the power of the received signal is further reduced, and the reception situation is extremely deteriorated. For this reason, it is necessary to stop the control of the power supplied to each processing unit and maintain the power necessary for reliably receiving a signal without being affected by noise. Therefore, it is conceivable that the control parameter is set so as to indicate that control of supplied power is not permitted.

  FIG. 6B is a schematic diagram illustrating the jamming wave transmitting station and each area when the area division is determined based on the distance from another transmitting station that may transmit the jamming wave with respect to the received signal. In FIG. 6B, the areas D, E, and F are divided according to the distance from the jamming wave transmission station 25. That is, the area D is the area closest to the jamming wave transmission station 25, the area E is the area next to the jamming wave transmission station 25 after the area D, and the area F is among the areas D, E, and F. This is the area farthest from the jamming wave transmitting station 25.

  First, in area D, since it is closest to the jamming wave transmitting station 25, the power of the jamming wave is large, and the reception situation is very deteriorated. Therefore, it is necessary to stop the power control and maintain the power necessary to maintain the performance of each circuit component. Therefore, it is conceivable that the control parameter is set so as to indicate that control of supplied power is not permitted.

  Next, in area E, since the distance from the jamming wave transmitting station is farther than in area D, the power of the jamming wave becomes smaller, and the degree of deterioration of the reception status is slightly reduced, but the influence of the jamming wave is affected. . Therefore, it is necessary to set control parameters so that each processing unit maintains linearity that can withstand the influence of the interference wave. For this reason, the following setting examples 9 to 12 may be set for the control parameters of the processing units that are particularly susceptible to linearity, such as the RF amplifier unit and the mixer unit.

  Setting example 9 is to reduce the control amount. Setting example 10 is to increase the decrease threshold of the control reference and make it difficult for the power to decrease. Setting example 11 is to increase the default value. Setting example 12 is to increase the upper limit and the lower limit of the control range.

  Finally, in area F, since the distance from the jamming wave transmission station is further away than in area E, the power of the jamming wave is further reduced, and the reception condition is improved. Therefore, the settings shown in the following setting examples 13 to 16 can be made even for the control parameters of processing units that are particularly susceptible to linearity, such as the RF amplifier unit and the mixer unit.

  Setting example 13 is to increase the control amount. Setting example 14 is to reduce the control reference decrease threshold value and to easily reduce the power. Similar to setting example 2, when the decrease threshold is equal to or less than the increase threshold, the decrease threshold is made smaller by increasing the decrease threshold. Setting example 15 is to lower the default value. Setting example 16 is to lower the upper limit and lower limit of the control range.

  FIG. 6C shows the transmission station, the shielding object, and each area when the area division is determined based on the positional relationship between the transmission station and another structure that may interfere with the received signal, that is, the shielding object. It is a schematic diagram which shows.

  First, an area G indicates an area where a reception signal transmitted from the transmission station 24 is obstructed by the shield 26. In area G, the reception power is reduced, and the reception situation is very deteriorated. Therefore, as in setting examples 5 to 8 in the case of area B, the control parameter is set so that the power does not easily decrease, or the control parameter is not allowed to control the supply power as in the case of area C. Therefore, it is necessary to maintain the power necessary for reliably receiving a signal without being affected by noise.

  Next, area H indicates an area where the reception signal transmitted from the transmission station 24 is not obstructed by the shield 26. In area H, since the received power is large and the reception status is good, it is possible to set the control parameters so that the power is likely to decrease as in setting examples 1 to 4 in the case of area A. is there.

  In this way, by setting the control parameter for each area determined according to the reception status, attenuation of the received signal due to the distance from the transmitting station, interference waves that may be transmitted from other transmitting stations Considering the influence and the influence on the received signal by other structures, it is possible to perform power control with the optimum control parameter suitable for the current location. These criteria may be combined when determining the control parameters. Further, the control parameter setting method shown here is an example, and a different method may be used.

[Processing of control unit]
FIG. 7 is a flowchart illustrating processing executed by each functional unit of the control unit 6. The process shown in the flowchart of FIG. 7 is executed when a condition for causing the control unit 6 to control the supplied power is satisfied. For example, the control of the supplied power by the control unit 6 is executed at a timing when reception of a specific broadcast is started by the mobile communication device 1.

  First, the control unit 6 transmits a default power setting value to the power supply unit 12 (step S1). As this default power value, a value that gives the best characteristics of the tuner 4 is generally selected. And the control part 6 waits for a fixed time (step S2).

  Next, the current location acquisition unit 22 acquires the current location of the digital demodulator 2 (step S3). The current location acquisition unit 22 may use GPS to acquire the current location. Further, the current location acquisition unit 22 may acquire the current location via a communication line.

  Next, the control parameter acquisition unit 21 acquires a control parameter corresponding to the current location from the control parameter database 23 (step S4), and the supply power control unit 20 checks a control availability item in the control parameter (step S5). . When the control permission / prohibition item is “× (No)” and the control of the supplied power is not permitted (in the case of N in Step S5), the power value is set to the default value and the process is ended (Step S10). When the control availability item is “◯ (possible)” and the control of the supplied power is permitted (Y in step S5), the reception status acquisition unit 19 acquires the MER measurement value from the demodulator 5 ( Step S6). The supplied power control unit 20 compares the MER measurement value with the increase threshold value in the control parameter (step S7).

  When the MER measurement value is equal to or less than the increase threshold value (in the case of Y in step S7), the supply power control unit 20 increases the supply power to the processing unit according to the control amount set in the control parameter (step S11). The process proceeds to step S9. When the MER measurement value is larger than the increase threshold value (when N in Step S7), the supply power control unit 20 compares the MER measurement value with the decrease threshold value in the control parameter (Step S8).

  When the MER measurement value is equal to or greater than the decrease threshold (in the case of Y in step S8), the supply power control unit 20 decreases the supply power to the processing unit according to the control amount set in the control parameter (step S12). The process proceeds to step S9.

  When the MER measurement value is larger than the increase threshold value and smaller than the decrease threshold value (in the case of Y in step S7), it is confirmed whether or not it is necessary to end the power control by some interruption operation or the like (step S9) and supply When the control of power is continued (N in Step S9), the process returns to Step S2, and when the control of supplied power is ended (Y in Step S9), the power value is set to a default value. The process ends (step S10). As an interrupt operation in step S9, a case where the reception of the broadcast signal itself is terminated, a case where a channel is selected, or the like can be considered.

[Other variations]
The above is a description of a preferred embodiment of the present invention. However, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the means for solving the problem. Is possible.

  For example, in the above-described embodiment, the current supplied to each processing unit of the tuner 4 is controlled, but the voltage may be controlled.

Further, in the above-described embodiment, it is determined whether or not the reception state is good based on the MER measured by the waveform equalization unit 17. However, the error correction process is one of the correction processes performed to accurately demodulate the received signal, similarly to the waveform equalization process. Accordingly, the BER may be calculated when the error correction unit 18 executes the error correction process, and it may be determined whether the reception status is good based on the BER. In the case of terrestrial digital broadcasting, the number of bits whose error is corrected during the decoding process of the RS code is calculated, and the BER is obtained by calculating the ratio of the number of corrected bits to the number of bits of the entire decoded data. I can do it.
In the case of BER, if the BER is large with respect to a certain reference value, there are many errors and the reception situation is bad. If the BER is small, the reception situation is good because there are few errors and conversion is performed so as to correspond to the C / N ratio. The vertical relationship is reversed from MER.

  Note that the present embodiment can be employed in various digital reception devices such as a digital television that performs at least one reproduction process of data such as characters, images, and programs, and audio. Such a digital reception apparatus acquires information on characters, images, data such as programs, voice, and the like from a signal sequence subjected to demodulation processing, and performs reproduction processing on these characters. According to this configuration, since the reproduction process of characters and the like is performed from the signal sequence that has been appropriately demodulated, the accuracy of the reproduction process is improved.

[Summary of Embodiment]
A digital demodulator according to an embodiment of the present invention includes a tuner 4 having a plurality of processing units for processing a received signal into a form capable of performing demodulation processing, and demodulation for performing demodulation processing on the received signal processed by the tuner 4 5, a power supply unit 12 that supplies power to the plurality of processing units, a reception status acquisition unit 19 that acquires the reception status of the received signal, and a current location acquisition that acquires a current location indicating the current position of the digital demodulation device Unit 22, a control parameter acquisition unit 21 that acquires a control parameter corresponding to the current location, a reception status acquired by the reception status acquisition unit 19, and a control parameter acquired by the control parameter acquisition unit 21. And a control unit 6 that controls the power supplied to the plurality of processing units, and the control parameter is based on a positional relationship between the current location and the transmitting station. At least one of a positional relationship with another transmitting station that may transmit an interference wave with respect to the received signal, and a positional relationship with the current location, the transmitting station, and other structures that may interfere with the received signal It is determined based on what added.

  According to the above configuration, not only the attenuation of the received signal power depending on the distance from the transmitting station, but also the influence of interference waves transmitted from other digital broadcasting or analog broadcasting transmitting stations, other buildings, such as elevated buildings, etc. It is possible to set control parameters corresponding to the current location taking into account the influence of the structure, etc., and power control is performed with the optimal control parameters for the reception status of the current location, so more effective power reduction is possible In addition, it is possible to prevent reception interference due to power reduction using inappropriate parameters.

  In the digital demodulator, when it is determined that the reception status acquired by the reception status acquisition unit 19 is better than the reference indicated by the control parameter, the control unit 6 causes the power supply unit 12 to perform the plurality of processes. You may reduce the electric power supplied to a part.

  In the digital demodulator, when it is determined that the reception status acquired by the reception status acquisition unit 19 is worse than the reference indicated by the control parameter, the control unit 6 causes the power supply unit 12 to You may increase the electric power supplied to a some process part.

  Further, in the digital demodulator, when the control parameter indicates that the reception status of the current location is so bad that the control unit 6 cannot allow the power supplied to the plurality of processing units to be controlled, the control unit 6 may stop the control of the power supplied to the plurality of processing units and maintain the power required for reception.

  By configuring the control unit 6 as described above, the control unit 6 can control the power supplied to the plurality of processing units according to the reception status of the current location acquired by the reception status acquisition unit 19.

  In the digital demodulator, the control parameter includes any one of a control reference, a default value, a control amount, a control range, a control period, and control availability corresponding to a certain point or area. May be determined for each of the plurality of processing units, and the control reference, the control amount, the control cycle, and the control availability may be determined in common by the plurality of processing units.

  Accordingly, the control unit can control the power supplied from the power supply unit to the plurality of processing units based on the reception status acquired by the reception status acquisition unit and the control parameter.

  A control method of a digital demodulator according to an embodiment of the present invention includes a tuner 4 having a plurality of processing units that process a received signal into a form capable of performing demodulation processing, and a demodulation process on the received signal processed by the tuner 4. And a power supply unit 12 for supplying power to the plurality of processing units, a reception status acquisition step for acquiring the reception status of the received signal, and a current location Based on the current location acquisition step for acquiring the control parameter, the control parameter acquisition step for acquiring the control parameter corresponding to the current location, the reception status acquired by the reception status acquisition step, and the control parameter acquired by the control parameter acquisition step. A control step for controlling the power supplied to the processing unit, wherein the control parameter is a level between the current location and the transmitting station. The relationship between the current location and other transmitting stations that may transmit a disturbing wave for the received signal, and the current location, the transmitting station, and other structures that may interfere with the received signal. It is determined based on the sum of at least one of the positional relationships.

  According to the above invention, not only the attenuation of the received signal power according to the distance from the transmission station, but also the influence of interference waves transmitted from other digital broadcast or analog broadcast transmission stations, buildings, or other overheads, etc. It is possible to set control parameters corresponding to the current location taking into account the influence of the structure, etc., and power control is performed with the optimal control parameters for the reception status of the current location, so more effective power reduction is possible In addition, it is possible to prevent reception interference due to power reduction using inappropriate parameters.

  The digital demodulating apparatus and the control method thereof according to the present invention acquire the reception status of the received signal, acquire the current location, acquire the control parameter corresponding to the current location, and receive means based on the reception status and the control parameter Since the power supplied to the plurality of processing units included in can be controlled, it can be suitably used for communication devices such as mobile phones.

FIG. 1A is an outline view of a mobile communication device according to an embodiment of the present invention, and FIG. 1B is a block diagram of a digital demodulation device provided in the mobile communication device. It is a block diagram which shows the structure of the tuner which concerns on embodiment of this invention. It is a block diagram which shows the structure of the demodulator which concerns on embodiment of this invention. It is a block diagram which shows the structure of the control part which concerns on embodiment of this invention. It is a figure which shows the example of control parameter storage to a control parameter database. FIG. 6A is a schematic diagram showing the transmitting station and each area when the area division is determined based on the distance from the transmitting station, and FIG. 6B transmits an interference wave for the received signal. FIG. 6C is a schematic diagram showing the jamming wave transmitting station and each area when the area division is determined based on the distance from other possible transmitting stations, and FIG. 6C is the position of the transmitting station and the shielding object. It is a schematic diagram which shows a transmitting station, a shield, and each area at the time of defining an area division based on a relationship. It is a flowchart which shows the process which the control part which concerns on embodiment of this invention performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile telephone apparatus 2 Digital demodulator 3 Antenna 4 Tuner (processing means)
5 Demodulator (demodulation means)
6 Control unit (control means)
7 RF amplifier section 8 Mixer section 9 VCO / PLL section 10 Filter section 11 IF amplifier section 12 Power supply section (power supply means)
13 ADC unit 14 AFC / symbol synchronization unit 15 FFT unit 16 Frame synchronization unit 17 Waveform equalization unit 18 Error correction unit 19 Reception status acquisition unit (reception status acquisition unit)
20 Supply power control unit 21 Control parameter acquisition unit (control parameter acquisition means)
22 Current location acquisition unit (current location acquisition means)
23 Control Parameter Database 24 Transmitting Station 25 Interference Wave Transmitting Station 26 Shielding Object S1 to S12 Steps

Claims (6)

Processing means having a plurality of processing units for processing the received signal into a form capable of performing demodulation processing;
Demodulation means for performing demodulation processing on the received signal processed by the processing means;
Power supply means for supplying power to the plurality of processing units;
Reception status acquisition means for acquiring the reception status of the received signal;
Current location acquisition means for acquiring the current location indicating the current location of the digital demodulator;
Control parameter acquisition means for acquiring a control parameter corresponding to the current location;
Control means for controlling the power supplied by the power supply means to the plurality of processing units based on the reception status acquired by the reception status acquisition means and the control parameter acquired by the control parameter acquisition means;
The control parameter includes a positional relationship between the current location and the transmitting station, a positional relationship between the current location and another transmitting station that may transmit an interference wave to the received signal, and the current location, the transmitting station, and A digital demodulator characterized in that it is determined based on a combination of at least one of positional relationships with other structures that can interfere with the received signal.   When it is determined that the reception status acquired by the reception status acquisition unit is better than the reference indicated by the control parameter, the control unit supplies the power supplied by the power supply unit to the plurality of processing units. The digital demodulator according to claim 1, wherein the digital demodulator is reduced.   When it is determined that the reception status acquired by the reception status acquisition means is worse than the reference indicated by the control parameter, the control means supplies power supplied to the plurality of processing units by the power supply means. The digital demodulator according to claim 1, wherein the digital demodulator increases.   When the control parameter indicates that the reception status of the current location is so bad that the control means cannot control the power supplied to the plurality of processing units, the control unit 2. The digital demodulator according to claim 1, wherein control of power supplied to the power supply is stopped and power required for reception is maintained. The control parameter includes any one of a control standard, a default value, a control amount, a control range, a control cycle, and control availability corresponding to a certain point or area,
The default value and the control range are determined for each of the plurality of processing units,
The digital demodulator according to claim 1, wherein the control reference, the control amount, the control cycle, and the control availability are determined in common by the plurality of processing units. Processing means having a plurality of processing units for processing the received signal into a form capable of performing demodulation processing;
Demodulation means for performing demodulation processing on the received signal processed by the processing means;
A control method of a digital demodulator having power supply means for supplying power to the plurality of processing units,
A reception status acquisition step of acquiring the reception status of the received signal;
A current location acquisition step for acquiring a current location indicating a current position of the digital demodulator;
A control parameter acquisition step of acquiring a control parameter corresponding to the current location;
A control step of controlling power supplied to the plurality of processing units based on the reception status acquired by the reception status acquisition step and the control parameter acquired by the control parameter acquisition step;
The control parameter includes a positional relationship between the current location and the transmitting station, a positional relationship between the current location and another transmitting station that may transmit an interference wave to the received signal, and the current location, the transmitting station, and A method of controlling a digital demodulator, characterized in that it is determined based on a combination of at least one of positional relationships with other structures that can interfere with the received signal.

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