JP2009100255A - Signal receiving device and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal receiving device and a receiving method capable of optimizing the degree of amplification of input signals, as well as, attaining stabilized reception processing. <P>SOLUTION: The receiving device 1 is provided with an RF amplifying AGC portion 3 for amplifying input signals; a resonance portion 4 for selecting a signal of a requested frequency among signals amplified by the RF amplifying AGC portion 3 and receiving the signal; a digital demodulating portion 10 for demodulating the signal selected by the resonance portion 4, based on digital modulation method; an error-correcting portion 11 for correcting the errors of the signal demodulated by the digital demodulating portion 10; and a resonance control portion 22 for controlling the frequency of the signal selected by the resonance portion 4. The resonance control portion 22 determines the propriety of the receiving condition, according to the error condition of the error-correcting portion 11 and determines the resonance frequency so as to improve the error condition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a receiving apparatus that receives radio waves, for example, a receiving apparatus that receives broadcast radio waves typified by terrestrial digital television broadcasting and terrestrial digital audio broadcasting, and a receiving method thereof.

  In recent years, with the development of digital compression coding technology and high-speed communication technology, digitization in satellite and terrestrial broadcast communication and digitization in mobile communication such as mobile phones has been realized. In particular, since digitalization of broadcast communication has been realized, reception devices for receiving digitized broadcast signals are provided in various places.

  Such a receiving apparatus includes an automatic gain control (AGC) unit that controls the amplification degree of a signal to be received and processed according to the state of received radio waves. In particular, when the received radio wave is weak, the signal is amplified by controlling the AGC unit to increase the amplification degree, thereby enabling normal reception processing.

In addition, as a receiving device including such an AGC unit, for example, when a radio wave having a large electric field strength is input, the radio wave is regarded as a jamming radio wave, and the electric field strength of the input signal is reduced before the AGC unit. As described above, a receiving apparatus that changes the frequency of a received radio wave has been proposed (see Patent Document 1).
JP 2004-64258 A

  However, in a receiving apparatus that amplifies the signal input to the antenna at the AGC unit and selects and receives a signal having a desired frequency from the amplified signal, the AGC unit amplifies the signal when the target signal is weak. The degree is set to a large value, and there is a problem that a high-intensity jamming radio wave existing in the vicinity of the target signal is amplified within a range where the amplification characteristic is saturated. In this case, the target signal is not accurately amplified, and it is difficult to normally receive and process the amplified signal.

  In view of such a problem, an object of the present invention is to provide a receiving apparatus and a receiving method capable of optimizing the amplification degree of an input signal and performing stable receiving processing.

  To achieve the above object, a receiving apparatus according to the present invention receives a first amplifying unit that amplifies an input signal and a signal having a desired frequency from the signal amplified by the first amplifying unit. And a resonance control unit that controls a frequency of a signal selected by the resonance unit, a demodulation unit that demodulates the signal, and an error correction that corrects an error in the signal demodulated by the demodulation unit. And a demodulation determination unit that determines the quality of the reception status based on the error status of the signal processed by the error correction unit, and when the reception status is determined to be bad by the demodulation determination unit, The resonance control unit sets a frequency of a signal selected by the resonance unit to a value that improves an error situation.

  In the receiving apparatus having the above configuration, the demodulation determination unit may determine that the reception state is bad when the state where the error state exceeds a predetermined value continues for a predetermined time or longer.

  With this configuration, when the error status is continuously bad, it is determined that the reception status is bad. Therefore, it is possible to prevent the resonance unit from being controlled until the error state instantaneously becomes defective. Therefore, it is possible to perform the reception process more stably. In addition, power consumption can be reduced.

  Further, in the receiving apparatus having the above-described configuration, a frequency conversion unit that converts the frequency of the signal selected by the resonance unit, a control signal determination unit that determines the quality of the reception status based on the voltage value of the first control signal, And the amplification degree in the first amplification unit is determined by the voltage value of the first control signal, and the voltage value of the first control signal is determined based on the intensity of the signal output from the frequency conversion unit. When the demodulation determination unit and the control signal determination unit determine that the reception status is bad, the resonance control unit sets the frequency of the signal selected by the resonance unit to a value that improves the error status. It does not matter if set to

  With this configuration, it is possible to determine the quality of the reception status not only from the error status but also from the amplification level of the amplification unit. Therefore, it becomes possible to determine the reception status more strictly. In addition, since the quality of the received signal can be determined in the front stage of the receiving apparatus and the strength of the received signal can be adjusted to a favorable level, the receiving process in the subsequent stage can be stabilized.

  Moreover, in the receiving apparatus having the above configuration, the control signal determination unit determines that the reception state is bad when a state where the voltage value of the first control signal exceeds a predetermined value continues for a predetermined time or more. It doesn't matter.

  By configuring in this way, it is determined that the reception state is bad even when an abnormality occurs in the signal intensity instantaneously, and control of the frequency of the signal selected by the resonance unit is prevented. it can. Therefore, it is possible to perform the reception process more stably. In addition, power consumption can be reduced.

  In the receiving device having the above-described configuration, the voltage value of the first control signal becomes smaller as the intensity of the signal output from the frequency conversion unit increases, and the control signal determination unit includes the first control signal. When the state where the voltage value of the signal is larger than the predetermined value continues, it may be determined that the reception state is bad.

  With this configuration, the resonance unit is controlled when the electric field strength of the signal is continuously small. For this reason, since the intensity of the target signal is small, the amplification level of the first amplification unit is set to be large, and the target signal is amplified while the high-intensity interference wave is input and the amplification characteristic of the first amplification unit is saturated. Can be suppressed. Therefore, the target signal is amplified with an appropriate amplification degree. For this reason, it is possible to prevent the reception process at the subsequent stage of the first amplification unit from being hindered.

  Further, in the receiving device having the above-described configuration, the frequency converter that converts the frequency of the signal selected by the resonance unit and the signal that is output from the frequency converter are amplified by the voltage value of the second control signal. A second amplifying unit that amplifies the received signal based on the voltage value of the second control signal, and a control signal determining unit that determines whether the reception status is good or not, and the second control signal is demodulated by the demodulating unit. The resonance control unit determines the signal selected by the resonance unit when the reception state is determined to be bad by the demodulation determination unit and the control signal determination unit. The frequency may be set to a value that improves the error situation.

  With this configuration, it is possible to determine the quality of the reception status not only from the error status but also from the amplification level of the amplification unit. Therefore, it becomes possible to determine the reception status more strictly. Further, since the quality of the reception state can be determined based on the strength of the signal to be demodulated and the strength of the signal can be adjusted well, demodulation can be performed more reliably, and errors during demodulation can be reduced.

  Further, in the receiving device having the above configuration, the control signal determination unit determines that the reception state is bad when the voltage value of the second control signal exceeds a predetermined value for a predetermined time or longer. It doesn't matter.

  By configuring in this way, it is determined that the reception state is bad even when an abnormality occurs in the signal intensity instantaneously, and control of the frequency of the signal selected by the resonance unit is prevented. it can. Therefore, it is possible to perform the reception process more stably. In addition, power consumption can be reduced.

  In the receiving device having the above-described configuration, the voltage value of the second control signal becomes smaller as the intensity of the signal demodulated by the demodulator increases, and the control signal determination unit includes the second control signal. When the state in which the voltage value is larger than the predetermined value continues, it may be determined that the reception state is bad.

  With this configuration, the resonance unit is controlled when the electric field strength of the signal is continuously small. For this reason, since the intensity of the target signal is small, the amplification level of the first amplification unit is set to be large, and the target signal is amplified while the high-intensity interference wave is input and the amplification characteristic of the first amplification unit is saturated. Can be suppressed. Therefore, the target signal is amplified with an appropriate amplification degree. For this reason, it is possible to prevent the reception process at the subsequent stage of the first amplification unit from being hindered.

  Further, in the receiving device having the above-described configuration, the frequency converter that converts the frequency of the signal selected by the resonance unit and the signal that is output from the frequency converter are amplified by the voltage value of the second control signal. A second amplifying unit that amplifies at a degree, and a control signal determining unit that determines the quality of the reception status based on the voltage values of the first control signal and the second control signal, and the amplification degree in the first amplifying unit Is determined based on the voltage value of the first control signal, the voltage value of the first control signal is determined based on the intensity of the signal output from the frequency converter, and the second control signal is demodulated by the demodulator. The resonance control unit is selected by the resonance unit when the demodulation determination unit and the control signal determination unit determine that the reception status is poor. The frequency of issue, may be be set to a value that the error conditions improve.

  With this configuration, it is possible to determine whether the reception status is good or not based on the voltage values of the two control signals of the first control signal and the second control signal. Therefore, it is possible to determine the reception status more strictly.

  Further, in the receiving device having the above configuration, the control signal determination unit continues a state where the voltage value of the first control signal exceeds a predetermined value for a predetermined time and the voltage value of the second control signal is When the state exceeding the predetermined value continues for a predetermined time or more, it may be determined that the reception state is bad.

  By configuring in this way, it is determined that the reception state is bad even when an abnormality occurs in the signal intensity instantaneously, and control of the frequency of the signal selected by the resonance unit is prevented. it can. Therefore, it is possible to perform the reception process more stably. In addition, power consumption can be reduced.

  In the receiving device having the above-described configuration, the voltage value of the first control signal becomes smaller as the strength of the signal output from the frequency converter increases, and the voltage value of the second control signal becomes lower than the demodulation value. The intensity of the signal demodulated by the unit becomes smaller, and the control signal determination unit has a state in which the voltage value of the first control signal is greater than a predetermined value for a predetermined time or more, and When the state where the voltage value of the second control signal is larger than the predetermined value continues for a predetermined time or more, it may be determined that the reception state is bad.

  With this configuration, the resonance unit is controlled when the electric field strength of the signal is continuously small. For this reason, since the intensity of the target signal is small, the amplification level of the first amplification unit is set to be large, and the target signal is amplified while the high-intensity interference wave is input and the amplification characteristic of the first amplification unit is saturated. Can be suppressed. Therefore, the target signal is amplified with an appropriate amplification degree. For this reason, it is possible to prevent the reception process at the subsequent stage of the first amplification unit from being hindered.

In the receiving apparatus having the above-described configuration, the error status may be a bit error rate that is a ratio in a bit unit of an error signal included in a transmitted signal. Further, when the bit error rate is greater than 2 × 10 ⁻⁴ , the demodulation determination unit may determine that the reception status is bad.

  The receiving method of the present invention includes a first step for amplifying an input signal, a second step for selecting and receiving a signal having a desired frequency from the signal amplified in the first step, and the second step. A third step of demodulating the signal selected in the step, a fourth step of correcting an error of the signal demodulated in the third step and acquiring an error status, and an error status acquired in the fourth step. 5th step for determining whether the reception status is good or not based on this, and when the reception status is determined to be bad in the fifth step, the frequency of the signal selected in the second step is acquired in the fourth step And a sixth step of setting the error status to a value that improves.

  According to the present invention, the error status of the error correction unit that performs error correction of the demodulated signal is used to determine the quality of the reception status. Since it is determined that the reception status is bad when the error status is bad, it is possible to confirm whether the reception status is correct or not. Therefore, stable reception processing can be performed by controlling the resonance unit only when control of the resonance unit is surely required. In addition, since the resonance unit is not unnecessarily controlled, power consumption can be reduced.

  In addition, since the frequency of the signal selected by the resonance unit is set so that the error situation is improved, the amplification level of the AGC unit is automatically set to an optimum value so that the target signal is appropriately amplified. Become. Therefore, it is possible to perform good reception processing.

<Configuration of receiving device>
First, the configuration of a receiving apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an internal configuration of a receiving apparatus according to this embodiment. In the following, a receiver for terrestrial digital television broadcasting of ISDB-T (Integrated Services Digital Broadcasting for Terrestrial) system in which a signal digitally modulated by an Orthogonal Frequency Division Multiplex (OFDM) system is transmitted. Although the case where the present invention is applied to will be described as an example, other communication methods may be used.

  A receiving apparatus 1 shown in FIG. 1 includes an antenna 2 to which a radio frequency (RF) digital broadcast signal is input, an RF amplification AGC unit 3 that amplifies a signal input from the antenna 2, and an RF amplification AGC unit 3. A resonance unit 4 that selects and receives a signal having a desired frequency from the signals amplified by the local oscillation unit 5; a local oscillation unit 5 that generates a local oscillation signal having a frequency based on the frequency of the signal selected by the resonance unit 4; A frequency mixing unit 6 that mixes a local oscillation signal generated by the oscillation unit 5 and a signal selected by the resonance unit 4 and outputs a signal including an intermediate frequency (IF) signal, and an output from the frequency mixing unit 6 Low-pass filter 7 that cuts off the high-frequency component of the signal to be transmitted, IF amplification AGC unit 8 that amplifies the signal whose high-frequency component is cut off by low-pass filter 7, and IF amplification AG An A / D conversion unit 9 that converts the analog signal amplified by the C unit 8 into a digital signal, and a signal that has been converted into a digital signal by the A / D conversion unit 9 is demodulated based on a digital modulation method and IF amplification AGC A digital demodulator 10 that outputs an IFAGC signal that determines the amplification degree of the unit 8, an error corrector 11 that corrects an error in the signal demodulated by the digital demodulator 10, and a signal whose error has been corrected by the error corrector 11 And an MPEG decoder 12 for decoding the data based on the MPEG compression method.

  In addition, the receiving apparatus 1 shown in FIG. 1 detects an RF level detection that detects the intensity of the IF signal input from the frequency mixing unit 6 to the low-pass filter 7 and outputs an RFAGC signal that determines the amplification degree of the RF amplification AGC unit 3. Unit 13, RF level comparison unit 14 that compares the RFAGC signal output from RF level detection unit 13 with a predetermined signal strength and outputs a comparison signal, and the intensity of IFAGC signal output from digital demodulation unit 10 The IF level comparison unit 15 that compares the signal strengths of the signals and outputs a comparison signal, the comparison signal output from the RF level comparison unit 14 and the comparison signal output from the IF level comparison unit 15 are input and these A level duration measurement unit 16 that monitors the state of the signal of the signal, and a level duration determination unit 17 to which a signal output from the level duration measurement unit 16 is input. , Comprising a.

  Further, the receiving apparatus 1 shown in FIG. 1 receives a signal indicating an error condition in the error correction unit 11 and compares the demodulation deterioration comparison unit 18 for comparing whether or not the error condition is worse than a predetermined condition. The demodulated comparison signal output from the unit 18 is input and the demodulation deterioration time measuring unit 19 that monitors the state of this signal, and the error status change is detected from the signal indicating the error status input from the error correcting unit 11. Demodulation state comparison unit 20, demodulation state determination unit 21 to which a signal output from demodulation degradation time measurement unit 19 and a signal output from demodulation state comparison unit 20 are input, and determination result of level duration determination unit 17 And a determination result of the demodulation state determination unit 21 and a resonance control unit 22 that outputs a control signal for controlling the resonance unit 4.

<Receive operation>
First, the receiving operation, which is the basic operation of the receiving apparatus 1 for receiving a digital broadcast signal, will be described with reference to FIG. In the receiving apparatus 1, first, digital broadcasting based on the OFDM transmission method is input from the antenna 2. The OFDM scheme is a scheme in which a large number of subcarriers orthogonal to each other are multiplexed and transmitted within one channel band.

  First, the RF signal input to the antenna 2 is amplified by the RF amplification AGC unit 3. The amplification degree at this time is determined based on the RFAGC signal output from the RF level detection unit 13, and the RFAGC signal is determined based on the intensity of the IF signal output from the frequency mixing unit 6. Then, the resonance unit 4 selects and receives a signal having a desired frequency from the signals amplified by the RF amplification AGC unit 3. At this time, the resonance control unit 22 controls the resonance frequency of the resonance unit 4 according to a user instruction or the like. The details of the configuration and operation of the RF amplification AGC unit 3 and the resonance unit 4 will be described later.

  The RF signal selected by the co-transmission unit 4 is mixed with the local oscillation signal by the frequency mixing unit 6. The local oscillation signal is generated by the local oscillation unit 5, and the frequency of the local oscillation signal is based on the frequency of the signal selected by the resonance unit 4. Then, the RF signal and the local oscillation signal are integrated in the frequency mixing unit 6 to obtain a signal including a high-frequency signal having a sum frequency of the two signals and an IF signal having a difference frequency.

  The signal output from the frequency mixing unit 6 is blocked from high-frequency components by the low-pass filter 7. Thereby, an IF signal having a predetermined frequency is obtained. Then, the IF signal output from the low-pass filter 7 is amplified by the IF amplification AGC unit 8. The amplification degree at this time is determined based on the IFAGC signal output from the digital demodulator 10, and the IFAGC signal is determined based on the intensity of the signal input to the digital demodulator 10. The details of the IFAGC signal will be described later together with the RFAGC signal described above.

  The IF signal amplified by the IF amplification AGC unit 8 is input to the A / D conversion unit 9 and converted from an analog signal to a digital signal. Then, the digital demodulator 10 demodulates. This demodulation processing is in accordance with the modulation method of the input signal. Examples of the modulation method include QAM (Quadrature Amplitude Modulation), QPSK (Quadrature Phase Shift Keying), and DQPSK (Differential Quadrature Phase Shift Keying). is there. Prior to demodulation, fast Fourier transform may be performed to convert the signal into a frequency axis signal, and equalization may be performed to correct signal distortion due to transmission.

  The MPEG encoded signal obtained by being demodulated by the digital demodulator 10 may contain an error due to noise or the like, and the error is corrected by the error corrector 11. Then, the MPEG encoded signal obtained by correcting the error is supplied to the MPEG decoder 12 and decoded based on the MPEG compression method, and the reproduction signal is output from the receiving device 1. Then, the output reproduction signal is further applied to a display device (not shown) such as a display, whereby an image is reproduced. Note that the reproduction signal may include not only the video signal but also an audio signal and a data signal.

<AGC operation>
Next, the AGC operation of the receiving apparatus in this embodiment will be described. First, the RFAGC signal and the IFAGC signal will be described using FIG. FIG. 2 is a graph showing an example of the electric field strength of the signal input to the receiving device and the voltage values of the RFAGC signal and the IFAGC signal. In FIG. 2, the characteristics of the RFAGC signal are indicated by a one-dot chain line, and the characteristics of the IFAGC signal are indicated by a two-dot chain line.

  As shown in FIG. 2, the voltage value of the RFAGC signal takes a constant value if the electric field strength of the input signal is less than or equal to a predetermined value, and decreases as the electric field strength of the input signal increases if it is greater than or equal to the predetermined value. To do. On the other hand, the voltage value of the IFAGC signal takes a constant value if the electric field strength of the input signal is equal to or higher than a predetermined value, and decreases as the electric field strength of the input signal increases if it is equal to or lower than the predetermined value.

  That is, if the electric field strength of the input signal is equal to or greater than a predetermined value, the voltage value of the RFAGC signal is changed to change the amplification degree of the RF amplification AGC unit 3 to cope with it. On the other hand, when the electric field strength of the input signal is less than or equal to a predetermined value, amplification in the RF amplification AGC unit 3 becomes difficult, and this is dealt with by varying the amplification degree of the IF amplification AGC unit 8. Therefore, when the electric field strength of the input signal is less than or equal to a predetermined value, the voltage value of the RFAGC signal is constant and the voltage value of the IFAGC signal is variable.

  A case where the electric field strength of the input signal is A (dBm) will be described. In this case, the voltage value of the RFAGC signal is Vr. Further, the voltage value of the IFAGC signal is Vi. Therefore, the voltage values of the RFAGC signal and the IFAGC signal are uniquely determined from the electric field strength of the input signal.

  As described above, when the voltage values Vr and Vi of the RFAGC signal and the IFAGC signal are determined, the RF amplification AGC unit 3 and the IF amplification AGC unit 8 determine the amplification degree based on the voltage value of each signal. Amplified.

  Note that the characteristics of the RFAGC signal and the IFAGC signal are not limited to the example shown in FIG. For example, it does not change linearly and may change curvedly. Moreover, it does not matter even if the characteristic does not change at or above a predetermined electric field strength. However, it shall be uniquely determined from the electric field strength of the input signal. In this example, the voltage value of the RFAGC signal and IFAGC signal decreases as the electric field strength of the input signal increases. However, the voltage value of the RFAGC signal and IFAGC signal increases as the electric field strength of the input signal increases. It may be a so-called forward type that increases.

<Resonant part>
Next, the resonance unit 4 will be described. FIG. 3 is a circuit diagram illustrating an example of a configuration of a resonance unit of the receiving device according to the present embodiment. As shown in FIG. 3, the resonance unit 4 in this example includes an input terminal T <b> 1 to which a signal is input via the antenna 2, and an output terminal T <b> 2 that outputs a signal selected by the resonance unit 4 to the RF amplification AGC unit 3. And a control terminal T3 to which a control signal is input from the resonance control unit 22 that controls the resonance unit 4. The signal line S1 connecting the input terminal T1 and the output terminal T2, the coil L1 having one end connected to the signal line S1 and the other end grounded, and one end connected to the signal line S1 and the other end Is connected to the signal line S1, one end of the capacitor C2 is connected to the signal line S1, the other end of the capacitor C2 is connected to the cathode side and the anode is grounded, and the capacitor C2 and the varicap diode are connected. A resistor R1 having one end connected to a connection node with Cvc and the other end connected to a control terminal T3.

When the resonance unit 4 has a circuit configuration including such an LC resonance circuit, the resonance frequency fr of the resonance circuit is expressed by the following formula I. In the following formula I, L ₁ is the inductance of the coil L ₁ , and C _x is a combined capacity obtained by combining the capacitors C ₁ and C ₂ of the capacitors C ₁ and C ₂ and the variable capacitor C _vc of the varicap diode Cvc.
fr = 1 / ((2π) × (L ₁ × C _x ) ^1/2 ) ... I

Further, the composite capacity C _x can be expressed as in the following formula II.
_{C x = C 2 × C vc} / (C 2 + C vc) + C1 ... II

At this time, the variable capacitor C _vc of the varicap diode Cvc is determined by the voltage value of the signal input to the control terminal T3. More specifically, it is determined by the voltage value V _R applied to a connection node between the capacitor C2 and the varicap diode Cvc via the resistor R1.

Here, the characteristics of the varicap diode will be described with reference to FIG. FIG. 4 is a graph showing a characteristic curve of the varicap diode. In FIG. 4, the horizontal axis represents the reverse bias voltage V _R applied to the varicap diode Cvc, and the vertical axis represents the capacitance C _vc of the varicap diode Cvc. As shown in FIG. 4, as the reverse bias voltage V _R increases, the capacitance C _vc of the varicap diode Cvc decreases. For example, when a reverse bias of the voltage value of V _R1 is given, the capacity is uniquely determined by the applied voltage value so that the capacity becomes C _vc1 .

  The resistance value of the resistor R1 is set higher than the impedance of the varicap diode Cvc, and an effect of separating the resonance unit 4 to which the RF signal is input from the resonance control unit 22 can be obtained. .

  As described above, an arbitrary resonance frequency fr is set by the voltage value of the control signal applied from the resonance control unit 22, and a signal having a desired frequency is selected in the resonance unit 4. Note that this example is merely an example, and any configuration of the resonance unit 4 may be used as long as a signal having a desired frequency can be selected and received.

<Resonant part control>
In the following, the resonance unit control of the receiving apparatus according to the present embodiment will be described with reference to the drawings. In the receiving apparatus 1 according to the present embodiment, when the reception state is not good because the received radio wave is included in the received radio wave, the resonance control unit 22 controls the resonance frequency of the resonance unit 4 so that the jammed radio wave etc. And control so that the reception process can be performed satisfactorily. This control method will be described with reference to FIGS. FIG. 5 is a flowchart illustrating the resonance unit control operation of the receiving apparatus according to the present embodiment.

  As shown in FIG. 5, when the operation of the receiving apparatus 1 is started, first, the resonance control unit 22 controls the resonance unit 4 so as to select a signal having a frequency instructed by a user or the like (STEP 1). Hereinafter, the frequency selected and instructed at this time will be described as f0. The resonance unit 4 selects and receives a frequency band having a predetermined width in the frequency direction with the frequency f0 as a center frequency.

  Next, it is confirmed whether or not an instruction to end the control operation is issued (STEP 2). If an instruction to end the control operation has been issued (STEP 2, YES), the control operation is ended. On the other hand, when the end instruction is not issued (STEP 2, NO), the process proceeds to the next step and the control operation is continued.

  When the receiving apparatus 1 is operating, the AGC operation as described above is performed. At this time, an RFAGC signal and an IFAGC signal are output from the RF level detector 13 and the digital demodulator 10. The RF level comparison unit 14 confirms whether or not the voltage value Vr of the RFAGC signal is higher than a predetermined threshold voltage Vr-ref, and outputs a comparison signal. Further, the IF level comparison unit 15 confirms whether or not the voltage value Vi of the IFAGC signal is higher than a predetermined threshold voltage Vi-ref, and outputs a comparison signal (STEP 3). Here, it is assumed that the RFAGC signal and the IFAGC signal adopt a reverse type in which the voltage value increases as the electric field strength of the input radio wave decreases.

  When at least one of the voltage value Vr of the RFAGC signal and the voltage value Vi of the IFAGC signal is equal to or lower than the predetermined threshold voltages Vr-ref and Vi-ref, respectively (STEP 3, NO), a target signal having a low intensity is not input. It is estimated to be. In this case, there is a low possibility that a high-intensity interference radio wave input from the antenna 2 is abnormally amplified in the RF amplification AGC unit 3, and an amplifier provided in the RF amplification AGC unit 3 is saturated, or in the frequency mixing unit 6 Since the possibility of saturation is low, it is determined that the reception condition is good. For this reason, the process returns to STEP 2 to confirm whether or not there is an end instruction.

  On the other hand, when both the voltage value Vr of the RFAGC signal and the voltage value Vi of the IFAGC signal are higher than the predetermined threshold voltages Vr-ref and Vi-ref, respectively (STEP 3, YES), a target signal having a low intensity is input. That is confirmed. In this case, there is a possibility that the amplifier provided in the RF amplification AGC unit 3 is saturated or the frequency mixing unit 6 is saturated by inputting high-intensity interference radio waves. Therefore, it is determined that the reception status is bad, and further confirmation operation is performed.

  If it is confirmed in STEP 3 that a low-intensity target signal is input, then the time during which the low-intensity target signal is input is measured. That is, the time Ta in which both the voltage value Vr of the RFAGC signal and the voltage value Vi of the IFAGC signal continue to be higher than the predetermined threshold voltages Vr-ref and Vi-ref, respectively, is longer than the predetermined time Ta-ref. It is confirmed whether or not (STEP 4).

  The determination in STEP 3 and STEP 4 is based on the comparison signal output from the RF level comparison unit 14 and the comparison signal output from the IF level comparison unit 15, and the level duration measurement unit 16 determines the voltage value of the RFAGC signal. The time duration Ta when the voltage value Vi of both the Vr and the IFAGC signal is higher than the predetermined threshold voltages Vr-ref and Vi-ref is measured, and the level duration determination unit 17 includes a level duration measurement unit 16. Is determined on the basis of a signal indicating the measurement result of the duration Ta output from the.

  In STEP4, when it is determined that the duration Ta is equal to or shorter than the predetermined time Ta-ref (STEP4, NO), the reception status temporarily becomes poor due to an instantaneously input target signal having a small intensity. It is estimated that For this reason, it is determined that the long-term reception state is good and the reception process can be continued, and the process returns to STEP 2 to confirm the presence or absence of an end instruction.

  On the other hand, if the duration time Ta is longer than the predetermined time Ta-ref (STEP 4, YES), the reception status is poor because the target signal with low strength is continuously input, and the reception processing is continued in some cases. Can be difficult to do. Therefore, further confirmation operation is performed.

  At this time, the parameter n is set to 0 (STEP 5). The parameter n indicates the number of times of control in the resonance unit 4. Details of the parameter n and the control method of the resonance unit 4 will be described later.

  When it is confirmed in STEP 4 that the reception status is bad, the demodulation deterioration comparison unit 18 checks the value of the bit error rate (number of error bits / number of transmitted bits) output from the error correction unit 11. To confirm the demodulated state. At this time, the demodulation degradation comparison unit 18 compares the predetermined bit error rate Er-ref with the bit error rate Er (n) input from the error correction unit 11 and inputs from the error correction unit 11. It is confirmed whether or not the bit error rate Er (n) is larger than a predetermined value Er-ref, and a comparison signal is output (STEP 6). At this time, n = 0.

  When the input bit error rate Er (n) is equal to or lower than the predetermined bit error rate Er-ref (STEP 6, NO), the target signal having a small intensity is input, but the reception status is good enough to allow viewing. It is confirmed that In this case, it is determined that the reception process can be continued, and the process returns to STEP 2 to confirm whether there is an end instruction.

  On the other hand, when the input bit error rate Er (n) is larger than the predetermined bit error rate Er-ref (STEP 6, YES), it is confirmed that a target signal with a low intensity is input and viewing is difficult. Is done. In such a case, a strong interfering radio wave may be input and the interfering radio wave may be abnormally amplified. Then, the amplifier provided in the RF amplification AGC unit 3 may continue to be saturated, or the frequency mixing unit 6 may continue to be saturated, making it difficult to perform reception processing continuously. Therefore, further confirmation operation is performed.

  If it is confirmed in STEP 6 that it is difficult to perform the reception process, it is next confirmed whether or not the situation in which the reception process is difficult continues. That is, it is confirmed whether or not the time Tc that continues when the measured bit error rate Er (n) is greater than the predetermined bit error rate Er-ref is longer than the predetermined time Tc-ref ( (Step 7).

  The determination in STEP 6 and STEP 7 is based on the comparison signal output from the demodulation deterioration comparison unit 18, and the bit error rate Er (n) measured by the demodulation deterioration time measurement unit 19 is determined from the predetermined bit error rate Er-ref. While measuring the time Tc during which the large state continues, the demodulation state determination unit 20 performs determination based on the signal indicating the measurement result of the duration output from the demodulation degradation time measurement unit 19.

  In STEP7, when it is determined that the duration Tc is equal to or shorter than the predetermined time Tc-ref (STEP7, NO), the reception status becomes slightly poor due to the input of a low-intensity target signal. Is estimated to be difficult. Therefore, it is determined that the reception process can be continued, and the process returns to STEP 2 to confirm whether or not there is an end instruction.

  On the other hand, when the duration Tc is longer than the predetermined time Tc-ref (STEP 7, YES), a target signal with a small intensity is continuously input, and the reception status is poor and good reception processing can be performed. Judged to be difficult. Then, control of the resonance unit 4 is started in order to perform good reception processing. Specifically, control for increasing the resonance frequency fr of the resonance unit 4 is performed.

In STEP 7, when it is determined that it is difficult to perform good reception processing and control of the resonance unit 4 is started, first, it is confirmed whether or not n exceeds the maximum increase number m ₁ ( (Step 8). The maximum increase number m ₁ is the maximum number of times that the resonance frequency fr of the resonance unit 4 can be increased and controlled to the high frequency side.

The maximum increase number m ₁ will be described with reference to FIG. FIG. 6 is a graph showing the frequency characteristics of the resonance unit of the receiving apparatus according to this embodiment. In FIG. 6, the horizontal axis represents frequency, the vertical axis represents gain, and m ₁ = 2 is shown. As shown in FIG. 6, it can be increased from the initially set resonance frequency f0 to the high frequency side by m ₁ = 2 times. If the frequency increased by one control is fd, the resonance frequency f1 after the first increase is f0 + fd, and the resonance frequency f2 after the second increase is f0 + 2fd.

In step 8, when n is equal to or greater than the maximum increase number m ₁ (STEP 8, NO), the resonance frequency fr cannot be increased further to the higher frequency side, so the increase control is terminated. Then, the process returns to STEP 2 to confirm whether or not there is an end instruction.

On the other hand, when n does not exceed the maximum increase number m ₁ (STEP 8, YES), the resonance frequency fr of the resonance unit 4 is increased by fd (STEP 9). At this time, if the resonance circuit shown in FIG. 3 is used, the resonance controller 22 increases the voltage applied to the connection node between the capacitor C2 and the varicap diode Cvc, and the capacitance C _{vc of the} varicap diode Cvc. Is reduced, the combined capacitance _Cx is reduced, and the resonance frequency fr is increased.

  Further, after performing control to increase the resonance frequency fr by fd in STEP 9, n as the number of times of control is increased by 1 (STEP 10). Then, the bit error rate Er (n) after increasing the frequency fd is compared with the bit error rate Er (n−1) before increasing, and the bit error rate Er (n) after increasing is before increasing. It is confirmed whether or not the bit error rate is smaller than Er (n-1) (STEP 11).

  In STEP 11, the demodulation state comparison unit 20 compares based on the bit error rate input from the error correction unit 11, the demodulation state comparison unit 20 outputs a comparison signal to the demodulation state determination unit 21, and the demodulation state determination unit 21 is performed by determining. Further, the demodulation state comparison unit 20 can hold the input bit error rate, and compares the bit error rate input later and the bit error rate input and held earlier. It is assumed that the configuration can be made.

  In STEP 11, when the bit error rate Er (n) after increasing the frequency fd with respect to the resonance frequency fr is smaller than the bit error rate Er (n-1) before increasing (STEP 11, YES), the resonance frequency It is confirmed that the bit error rate is improved by increasing fr.

  An example of the signal state at this time will be described with reference to FIG. FIG. 7 is a graph showing the jamming radio wave and the target signal superimposed on the frequency characteristics of the resonance unit of the receiving apparatus according to the present embodiment. FIG. 7 shows a case where the frequency of the jamming radio wave N is higher than the frequency of the target signal S. Further, frequency characteristics n and n-1 are indicated by broken lines, a characteristic curve before the resonance frequency fr is increased is indicated by n-1, and a characteristic curve after the increase is indicated by n.

  As shown in FIG. 7, in the state before the increase of the resonance frequency fr, the jamming radio wave N exists outside the characteristic curve n-1. That is, the frequency of the jamming radio wave N having a high intensity is not selected by the resonance unit 4. Therefore, the RF amplification AGC unit 3 sets an amplification factor for amplifying the target signal S having a low intensity, and abnormally amplifies the jamming radio wave N having a high intensity. However, the target signal S and the jamming radio wave N are included inside the characteristic curve n obtained by increasing the resonance frequency fr by fd. Then, in the RF amplification AGC unit 3, an amplification factor is set in consideration of the magnitude of the jamming radio wave N having a high intensity, and the jamming radio wave N is prevented from being amplified to an abnormal level. Therefore, saturation of the amplifier of the RF amplification AGC unit 3 and saturation of the frequency mixing unit 6 are suppressed. Accordingly, the target signal S is accurately amplified and processed for reception, and the bit error rate is improved.

  Further, when the bottom part of the frequency characteristic of the resonance unit 4 extends over a plurality of channels, the jamming radio wave N is present on the higher frequency side by 2 channels (for example, 12 MHz) or more than the target signal S. Can improve the bit error rate more.

If it is confirmed in STEP 11 that the bit error rate has been improved, the process returns to STEP 8 to determine whether or not the resonance frequency fr can be increased again. Then, n becomes the maximum increase number m ₁ or more (STEP 8, NO), or the bit error rate Er (n) after increasing the resonance frequency fr is equal to or more than the error rate Er (n−1) before increasing. The resonance frequency fr is increased until it becomes (STEP11, NO) (STEP8 to STEP11).

  In STEP 11, when the bit error rate Er (n) after increasing the resonance frequency fr is equal to or higher than the bit error rate Er (n−1) before increasing (STEP 11, NO), it is roughly divided into the following two cases: There is. One is a case where the resonance frequency fr is increased to the high frequency side for the first time, but the bit error rate can be improved by actually decreasing the resonance frequency fr to the low frequency side. The other is the case where the increase control is performed at least twice, and the bit error rate is deteriorated by the n-th increase control because the optimal state is achieved by the (n-1) th increase control.

  A distinction between the former and the latter can be made based on whether n = 1 (STEP 12). Specifically, when n = 1 (STEP 12, YES), the bit error rate when n = 0 where the resonance frequency fr is not increased is higher than the bit error rate when the resonance frequency fr is increased. Results in smaller than. Therefore, if n = 1, there is a possibility that the bit error rate can be improved by reducing the resonance frequency fr to the low frequency side.

  If n is not 1 (STEP 12, NO), it is presumed that the optimal state has been obtained by the increase control performed at the (n-1) th time, so the state before the nth increase control, that is, the frequency is set. The resonance frequency fr in the state increased n-1 times is the optimum value. Therefore, the resonance frequency fr is decreased by fd, and the resonance frequency fr is increased n-1 times (STEP 13). Then, the process returns to STEP 2 to confirm whether or not there is an end instruction.

  When n = 1 in STEP 12, control is performed to reduce the resonance frequency fr to the low frequency side. In this case, first, a state where the resonance frequency fr is not reduced, that is, a state where the resonance frequency fr is f0 is reset (STEP 14). Further, since no control is performed, n = 0 is set (STEP 15). Further, the bit error rate Er (n) before control is acquired again (STEP 16).

Then, it is confirmed whether or not n exceeds the maximum frequency of decrease m ₂ to the low frequency side (STEP 17). Maximal decrease the number m ₂ indicates the maximum number of times can be reduced controlling the resonance frequency fr of the resonance unit 4 to the low frequency side.

The maximum decrease number m ₂ will be described with reference to FIG. FIG. 8 is a graph showing the frequency characteristics of the resonance unit of the receiving apparatus according to the present embodiment, and corresponds to FIG. 6 showing the case of increasing to the high frequency side. In FIG. 8, as in FIG. 6, the horizontal axis represents frequency, the vertical axis represents gain, and m ₂ = 2 is shown. As shown in FIG. 8, it is possible to perform a decrease control from the initial resonance frequency f0 to the low frequency side by m ₂ = 2 times. Further, if the frequency to be decreased by one decrease control is fd, the resonance frequency f3 after the decrease is f0-fd, and the resonance frequency f4 after the decrease is f0-2fd. In addition, although it is set as fd similar to the case where the magnitude | size of the frequency reduced at once is increased to the high frequency side, you may make it different.

In STEP 17, when n is equal to or greater than the maximum decrease count m ₂ (STEP 17, NO), the resonance frequency fr cannot be decreased further to the lower frequency side, so the process returns to STEP 2 to confirm whether or not there is an end instruction. . On the other hand, when n does not exceed the maximum decrease number m ₂ (STEP 17, YES), the resonance frequency fr of the resonance unit 4 is decreased by fd (STEP 18). Also, if using the resonant circuit shown in FIG. 3, the resonance control unit 22 to increase the capacitance C _vc of the varicap diode Cvc by reducing the voltage applied to the connection node of the capacitor C2 and the varicap diode Cvc in by increasing the combined capacitance C _x, to reduce the resonant frequency fr.

  Further, after the resonance frequency fr is decreased by fd in STEP 18, n which is the number of times of control is increased by 1 (STEP 19). Then, the bit error rate Er (n) after reducing the resonance frequency fr is compared with the bit error rate Er (n−1) before the reduction, and the bit error rate after the reduction is the bit error rate before the reduction. It is confirmed whether it becomes smaller (STEP 20).

  STEP 20 is the same as STEP 11. Based on the bit error rate input from the error correction unit 11, the demodulation state comparison unit 20 compares and the demodulation state comparison unit 20 outputs a comparison signal to the demodulation state determination unit 21. The demodulation state determination unit 21 performs the determination.

  In STEP20, when the bit error rate Er (n) after decreasing the frequency fd with respect to the resonance frequency fr is smaller than the error rate Er (n-1) before decreasing (STEP20, YES), the resonance frequency fr is set. It is confirmed that the bit error rate is improved by reducing the bit error rate.

  An example of the signal state at this time will be described with reference to FIG. FIG. 9 is a graph in which the jamming radio wave and the target signal are superimposed on the frequency characteristics of the resonance unit of the receiving apparatus according to the present embodiment, and corresponds to FIG. . FIG. 9 shows a case where the frequency of the jamming radio wave N is lower than the frequency of the target signal S. Further, the frequency characteristic is indicated by a broken line, the characteristic curve before the frequency fd is decreased by n−1, and the characteristic curve after the decrease by n.

  As shown in FIG. 9, in the state before the frequency is decreased, the jamming radio wave N exists outside the characteristic curve n-1. That is, the frequency of the jamming radio wave N having a high intensity is not selected by the resonance unit 4. Therefore, the RF amplification AGC unit 3 sets an amplification factor for amplifying the target signal S having a low intensity, and abnormally amplifies the jamming radio wave N having a high intensity. However, the target signal S and the jamming radio wave N are included inside the characteristic curve n obtained by reducing the resonance frequency fr by fd. Then, in the RF amplification AGC unit 3, an amplification factor is set in consideration of the magnitude of the jamming radio wave N having a high intensity, and the jamming radio wave N is prevented from being amplified to an abnormal level. Therefore, saturation of the amplifier of the RF amplification AGC unit 3 and saturation of the frequency mixing unit 6 are suppressed. Accordingly, the target signal S is accurately amplified and processed for reception, and the bit error rate is improved.

  Further, when the bottom part of the frequency characteristic of the resonance unit 4 extends to a plurality of channels, the jamming radio wave N is present on the lower frequency side by 2 channels (for example, 12 MHz) or more than the target signal S. Can improve the bit error rate more.

If it is confirmed in STEP 20 that the bit error rate has been improved, the process returns to STEP 17 to determine again whether or not the resonance frequency fr can be reduced. The bit error rate Er (n) after the control number n becomes equal to or greater than the maximum decrease number m ₂ (STEP 17, NO) or the resonance frequency fr is decreased is the bit error rate Er (n−) before the decrease. 1) The above-described operation for reducing the resonance frequency fr is repeated (STEPs 17 to 20) until the above is reached (STEP 20, NO).

  In STEP 20, when the bit error rate Er (n) after the decrease of the resonance frequency fr is equal to or higher than the bit error rate Er (n-1) before the decrease (STEP 20, NO), before the n-th decrease control is performed. That is, the resonance frequency fr in which the resonance frequency fr is decreased n-1 times is the optimum value. Therefore, the resonance frequency fr is increased by fd and the resonance frequency fr is decreased n-1 times (STEP 21). Then, the process returns to STEP 2 to confirm whether or not there is an end instruction.

  As described above, by increasing the resonance frequency fr to the high frequency side or decreasing the resonance frequency fr to the low frequency side, the amplification degree in the RF amplification AGC unit 3 increases when a weak target signal is input, and strong interference radio waves are generated. By abnormally amplifying, it becomes possible to prevent the amplifier of the RF amplification AGC unit 3 and the frequency mixing unit 6 from being saturated. Therefore, the target signal can be accurately amplified, and stable reception processing can be performed.

  Also, since the reception status is determined based on the bit error rate, it is determined that the reception status is bad only when there are many errors and it is difficult to perform reception processing. Therefore, it is possible to determine the reception status strictly. Furthermore, since the control of the resonance unit 4 is performed only when the reception state is determined to be poor as described above, it is possible to suppress unnecessary control of the resonance unit 4. Therefore, power consumption can be reduced.

  Further, since the resonance frequency fr is controlled based on the bit error rate of the signal in the error correction unit 11, the resonance frequency fr can be reliably controlled in a direction in which the signal state is improved. Therefore, good reception processing can be performed.

  In the above-described example, after the voltage values of the RFAGC signal and the IFAGC signal are determined in STEP 3 and STEP 4, the bit error rate is determined in STEP 6 and STEP 7, but the order of determination is limited to this order. Absent. That is, after the bit error rate is determined, the voltage values of the RFAGC signal and the IFAGC signal may be determined. When the determination is made at the same time and the reception status is poor in the two determination results, STEP 8 is performed. Then, the resonance frequency may be controlled thereafter.

  In STEP3 and STEP4, both the voltage value Vr of the RFAGC signal and the voltage value Vi of the IFAGC signal are higher than the predetermined threshold voltages Vr-ref and Vi-ref, and the duration time Ta of the state is a predetermined time. When it is longer than Ta-ref, it is determined that the reception status is bad. However, the determination may be made based on only one of the voltage values.

Further, the error correction unit 11 performs decoding of the outer code (Reed-Solomon decoding) after decoding of the inner code (Viterbi decoding), and may output the bit error rate after decoding of the inner code. . Further, when the error correction 11 operates as described above, the value of Er-ref may be set to 2 × 10 ^−4, for example. If the bit error rate is less than this value, it can be considered that there is no pseudo error in the signal after Reed-Solomon decoding performed after Viterbi decoding. Therefore, if it is determined that the reception status is good when the bit error rate is 2 × 10 ⁻⁴ or less, it can be more reliably determined whether or not the reception status is good.

  In the above-described example, whether the reception status is good or bad is determined using the bit error rate. However, the demodulation error rate, the number of packet errors, and the like may be used as determination criteria. Furthermore, a combination of these may be used to detect signal error conditions and determine whether the reception conditions are good or bad.

  The above-described control of the resonance unit 4 may be performed whenever the receiving device 1 performs a reception operation, or may be performed by satisfying a user instruction or a predetermined condition. If the channel for reception processing is changed by an instruction from the user or the like, the process returns to STEP 1 and the frequency of the changed channel may be selected for reception processing.

  In addition, although an example using the reverse type in which the voltage value of the RFAGC signal and the IFAGC signal decreases as the electric field strength of the input signal increases, the voltage value of the RFAGC signal and the IFAGC signal increases as the electric field strength of the input signal increases. A forward type may be used. An example of the RFAGC signal and IFAGC signal in the case of the forward type is shown in FIG. FIG. 10 is a graph showing an example of the electric field strength of the signal input to the receiving apparatus and the voltage values of the RFAGC signal and the IFAGC signal in this embodiment, and corresponds to FIG. 2 showing the reverse type. . In FIG. 10, the characteristics of the RFAGC signal are indicated by a one-dot chain line, and the characteristics of the IFAGC signal are indicated by a two-dot chain line.

  As shown in FIG. 10, the voltage value of the RFAGC signal takes a constant value if the electric field strength of the input signal is less than or equal to a predetermined value, and increases as the electric field strength of the input signal increases if it is greater than or equal to the predetermined value. To do. On the other hand, the voltage value of the IFAGC signal takes a constant value if the electric field strength of the input signal is greater than or equal to a predetermined value, and increases as the electric field strength of the input signal increases if the electric field strength of the input signal is greater than or equal to the predetermined value.

  That is, if the electric field strength of the input signal is equal to or greater than a predetermined value, the voltage value of the RFAGC signal is changed to change the amplification degree of the RF amplification AGC unit 3 to cope with it. On the other hand, when the electric field strength of the input signal is less than or equal to a predetermined value, amplification in the RF amplification AGC unit 3 becomes difficult, and this is dealt with by varying the amplification degree of the IF amplification AGC unit 8. Therefore, when the electric field strength of the input signal is less than or equal to a predetermined value, the voltage value of the RFAGC signal is constant and the voltage value of the IFAGC signal is variable. The amplification control is performed in the same manner as the reverse type shown in FIG. When the electric field strength of the input signal is A (dBm), the voltage value of the RFAGC signal is Vrf. The IFAGC signal is Vif. Therefore, the voltage values of the RFAGC signal and the IFAGC signal are uniquely determined from the electric field strength of the input signal.

  When the forward type is used, it is determined in STEP 3 whether or not the voltage values Vrf and Vif of the RFAGC signal and the IFAGC signal are lower than predetermined threshold voltages Vrf-ref and Vif-ref. At this time, when the voltage values Vrf and Vif of the RFAGC signal and the IFAGC signal are lower than the predetermined threshold voltages Vrf-ref and Vif-ref, it is determined that the intensity of the target signal is small, and the state continues in STEP 4 Measure the time to do. Further, other than STEP 3 (STEP 1, STEP 2, STEP 4 to STEP 21), the same as the above-described STEPs.

  Further, in the receiving apparatus 1 according to the present embodiment described above, the RF level detection unit 13, the RF level comparison unit 14, the IF level comparison unit 15, the level duration measurement unit 16, the level duration determination unit 17, and the demodulation degradation comparison unit 18. The operation of the demodulation deterioration time measuring unit 19, the demodulation state comparison unit 20, the demodulation state determination unit 21, and the resonance control units 22 and 22a may be performed by a control device such as a microcomputer. Further, all or part of the functions realized by such a control device is described as a program, and the program is executed on a program execution device (for example, a computer) to realize all or part of the functions. You may make it.

  In addition to the above-described case, the receiving apparatus 1 in FIG. 1 can be realized by hardware or a combination of hardware and software. When the receiving device 1 is configured using software, a block diagram of a part realized by software represents a functional block diagram of the part.

  The embodiment of the receiving apparatus according to the present invention has been described above. However, the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention relates to a receiver for receiving radio waves, for example, a receiver for receiving broadcast radio waves typified by terrestrial digital television broadcast and terrestrial digital audio broadcast, and a method for receiving the same. As described above, the present invention is preferably applied to a receiving apparatus that needs to acquire a target signal from a large number of jamming radio waves.

These are block diagrams which show the internal structure of the receiver in 1st Embodiment. These are the graphs which showed an example of the electric field strength of the signal input into the receiver in 1st Embodiment, and the voltage value of a RFAGC signal and an IFAGC signal. These are the circuit diagrams shown about an example of the structure of the resonance part of the receiver in 1st Embodiment. These are graphs showing characteristic curves of varicap diodes. These are the flowcharts shown about the resonance part control operation | movement of the receiver in 1st Embodiment. These are the graphs which show the frequency characteristic of the resonance part of the receiver in 1st Embodiment. These are the graphs which showed the jamming radio wave and the target signal superimposed on the frequency characteristics of the resonance part of the receiving device in the first embodiment. These are the graphs which show the frequency characteristic of the resonance part of the receiver in 1st Embodiment. These are the graphs which showed the jamming radio wave and the target signal superimposed on the frequency characteristics of the resonance part of the receiving device in the first embodiment. These are the graphs which showed an example of the electric field strength of the signal input into the receiver in 1st Embodiment, and the voltage value of a RFAGC signal and an IFAGC signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Receiver 2 Antenna 3 RF amplification AGC part 4 Resonance part 5 Local oscillation part 6 Frequency mixing part 7 Low pass filter 8 IF amplification AGC part 9 A / D conversion part 10 Digital demodulation part 11 Error correction part 12 MPEG decoder 13 RF level detection Unit 14 RF level comparison unit 15 IF level comparison unit 16 level duration measurement unit 17 level duration determination unit 18 demodulation degradation comparison unit 19 demodulation degradation time measurement unit 20 demodulation state comparison unit 21 demodulation state determination unit 22 resonance control unit

Claims (8)

In a receiving apparatus comprising: a first amplification unit that amplifies an input signal; and a resonance unit that selects and receives a signal having a desired frequency from the signal amplified by the first amplification unit.
A resonance control unit for controlling a frequency of a signal selected by the resonance unit;
A demodulator that demodulates the signal;
An error correction unit for correcting an error of a signal demodulated by the demodulation unit;
A demodulation determination unit that determines the quality of the reception status based on the error status of the signal processed by the error correction unit,
When the demodulation determination unit determines that the reception status is bad, the resonance control unit sets the frequency of the signal selected by the resonance unit to a value that improves the error status. Receiving device.   The receiving apparatus according to claim 1, wherein when the state where the error status exceeds a predetermined value continues for a predetermined time or more, the demodulation determination unit determines that the reception status is bad. A frequency conversion unit that converts the frequency of the signal selected by the resonance unit;
A control signal determination unit that determines the quality of the reception status based on the voltage value of the first control signal,
The degree of amplification in the first amplifying unit is determined by the voltage value of the first control signal, the voltage value of the first control signal is determined based on the strength of the signal output from the frequency converter, and the demodulation determination When the reception status is determined to be bad by the control unit and the control signal determination unit, the resonance control unit sets the frequency of the signal selected by the resonance unit to a value that improves the error status. The receiving apparatus according to claim 1 or 2, characterized in that: A frequency conversion unit that converts the frequency of the signal selected by the resonance unit;
A second amplification unit that amplifies the signal output from the frequency conversion unit with an amplification degree determined by the voltage value of the second control signal;
A control signal determination unit that determines the quality of the reception status based on the voltage value of the second control signal,
When the second control signal is determined based on the intensity of the signal demodulated by the demodulator and the reception status is determined to be bad by the demodulation determination unit and the control signal determination unit, the resonance The receiving device according to claim 1, wherein the control unit sets the frequency of the signal selected by the resonance unit to a value that improves an error situation. A frequency conversion unit that converts the frequency of the signal selected by the resonance unit;
A second amplification unit that amplifies the signal output from the frequency conversion unit with an amplification degree determined by the voltage value of the second control signal;
A control signal determination unit that determines the quality of the reception status based on the voltage values of the first control signal and the second control signal,
The amplification degree in the first amplification unit is determined by the voltage value of the first control signal, the voltage value of the first control signal is determined based on the intensity of the signal output from the frequency conversion unit, and the second control A signal is determined based on the strength of the signal demodulated by the demodulator,
When the reception state is determined to be bad by the demodulation determination unit and the control signal determination unit, the resonance control unit sets the frequency of the signal selected by the resonance unit to a value that improves the error state. The receiving apparatus according to claim 1, wherein the receiving apparatus is set.   The control signal determination unit is configured such that the state where the voltage value of the first control signal exceeds a predetermined value continues for a predetermined time and the state where the voltage value of the second control signal exceeds a predetermined value is predetermined. The receiving apparatus according to claim 5, wherein the receiving state is determined to be bad when the time continues for more than a time. The voltage value of the first control signal becomes smaller as the intensity of the signal output from the frequency converter increases, and the voltage value of the second control signal becomes the intensity of the signal demodulated by the demodulator. The larger the value, the smaller the value.
The control signal determination unit is configured such that a state where the voltage value of the first control signal is greater than a predetermined value continues for a predetermined time and a state where the voltage value of the second control signal is greater than a predetermined value is predetermined. The receiving apparatus according to claim 6, wherein the reception state is determined to be bad when the time continues for a time or more. A first step of amplifying an input signal;
A second step of selecting and receiving a signal of a desired frequency from the signals amplified in the first step;
A third step of demodulating the signal selected in the second step;
A fourth step of correcting an error of the signal demodulated in the third step and obtaining an error status;
A fifth step for determining the quality of the reception status based on the error status acquired in the fourth step;
When it is determined in the fifth step that the reception status is poor, the frequency of the signal selected in the second step is set to a value that improves the error status acquired in the fourth step. Steps,
A receiving method comprising:

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