JP4735064B2 - Tuner receiver and digital signal receiver using the same - Google Patents

Description

  The present invention relates to a tuner receiving unit using a diversity antenna and a digital signal receiving apparatus using the tuner receiving unit.

  A conventional digital signal receiving apparatus will be described below with reference to FIG. In FIG. 6, the digital signal receiving apparatus 1 includes a tuner receiving unit 2 and a reception quality control unit 3. The reception quality control unit 3 includes digital demodulation units 8 and 9, a diversity unit 10, an error correction unit 11, and a diversity control unit 13.

  The tuner receiving unit 2 includes tuner units 6 and 7 to which antennas 4 and 5 are input, respectively. These tuner units 6 and 7 include intermediate frequency amplifiers 6a and 7a that perform gain control when the input signal level is low.

  The outputs of the tuner units 6 and 7 are connected to the digital demodulation units 8 and 9, respectively. The outputs of these digital demodulation units 8 and 9 are separately input to the diversity unit 10. The output of the diversity unit 10 is input to the error correction unit 11. A signal output from the error correction unit 11 is connected to the output terminal 12. A diversity controller 13 that controls power supply to the tuner units 6 and 7 is connected between the diversity unit 10 and the error correction unit 11.

  The operation of the digital signal receiving apparatus 1 configured as described above will be described below. The OFDM digital broadcast signals input from the antennas 4 and 5 are supplied to the respective tuner units 6 and 7, controlled to a constant signal level and converted into a predetermined frequency, and then each digital demodulation unit. 8 and 9 are demodulated. The demodulated signals output from the digital demodulating units 8 and 9 are separately input to the diversity unit 10.

  In the diversity unit 10, a subcarrier signal constituting a digital signal is detected, and this subcarrier detection signal is supplied to the diversity control unit 13. When the subcarrier detection signal is good, the diver control unit 13 selects single reception using one tuner unit and the digital demodulation unit. When the subcarrier detection signal is bad, diversity reception is selected using all the tuners and the digital demodulation unit.

  Therefore, for example, when an OFDM digital broadcast signal is received in an area with good reception quality, power consumption can be reduced by using it as single reception.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2001-156738 A

  In such a conventional digital signal receiving apparatus, when receiving in an area where the input signal level is, for example, −90 dBm or less, the reception quality is poor, the signal from the diversity controller 13 is switched from single reception to diversity reception. Will be used. That is, power is supplied to both the other tuner unit and the digital demodulation unit that have been deactivated in single reception, and after channel selection is performed based on channel selection data, gain control is also performed in the other tuner unit. It will be.

  However, when an input signal of −90 dBm or less is received, the gain control operation is performed in the intermediate frequency amplifier 6a or 7a provided in the tuner unit. The gain control operation in the intermediate frequency amplifier 6a or 7a requires a long time, for example, about 50 msec from the start to the completion. Therefore, it takes a long time to output a stable signal from the output terminal of the tuner unit in the operating state, and switching from single reception to diversity reception cannot be performed smoothly in a short time.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to smoothly switch from single reception to diversity reception in a short time.

  In order to achieve this object, the tuner receiving unit of the present invention receives an AGC control signal via a reception quality control unit to which the first and second tuner output terminals are connected, respectively, and outputs the first, An AGC control unit connected to each of the second AGC inputs is provided, and the AGC control unit is in operation during single reception based on the AGC control signal output from the reception quality control unit. The AGC voltage of the other tuner is supplied to the AGC input of the other tuner that has been inactive during single reception for a certain period of time. Thereby, the intended purpose can be achieved.

  As described above, the tuner receiving unit of the present invention receives the AGC control signal through the reception quality control unit to which the first and second tuner output terminals are connected, and outputs the first and second outputs. An AGC control unit connected to each of the AGC inputs is provided, and the AGC control unit is connected to the one of the tuners that is operating at the time of single reception based on the AGC control signal output from the reception quality control unit. The AGC voltage is supplied to the AGC input of the other tuner that has been inactive during single reception for a certain period of time.

  As a result, even when the OFDM digital broadcast signal is being received, even when moving from a place where reception is stable to a place where reception is unstable, it is operating during single reception based on the AGC control signal output from the reception quality control unit. The AGC voltage of one of the tuners is supplied to the AGC input of the other tuner that has been inactive during single reception for a certain period of time, so the time for generating the AGC voltage from the beginning is shortened. Switching from single reception to diversity reception can be performed smoothly in a short time.

(Embodiment 1)
FIG. 1 is a block diagram of a digital signal receiving apparatus according to Embodiment 1 of the present invention. The digital signal receiving apparatus 20 includes a tuner receiving unit 21 and a reception quality control unit 22.

  In FIG. 1, the tuner receiving unit 21 is provided with tuner units 31 and 32 and an AGC control unit 33 connected between the tuner units 31 and 32. The tuner unit 31 is provided with a high frequency amplifier 51, a mixer 52, an intermediate frequency filter 53, and an intermediate frequency amplifier 54 in order from the antenna input terminal 35 to which the antenna 37 is connected to the tuner output terminal 39. The output of the oscillator 55 is connected to the other input of the mixer 52.

  A gain controller 56 for gain control is connected between the output of the mixer 52 and the AGC input 51 a provided in the high frequency amplifier 51. A smoothing capacitor 56a is connected between the AGC input 51a and the ground.

  Further, a gain controller 57 for gain control is also connected between the output of the intermediate frequency amplifier 54 and the AGC input 54 a provided in the intermediate frequency amplifier 54. Similarly, a smoothing capacitor 58 is connected between the AGC input 54a and the ground.

  Similarly to the tuner unit 31, the tuner unit 32 includes a high frequency amplifier 61, a mixer 62, an intermediate frequency filter 63, an intermediate frequency in order from the antenna input terminal 36 connected to the antenna 38 to the tuner output terminal 40. An amplifier 64 is provided. The output of the oscillator 65 is connected to the other input of the mixer 62.

  A gain controller 66 is connected between the output of the mixer 62 and the AGC input 61 a provided in the high frequency amplifier 61. A smoothing capacitor 66a is also connected between the AGC input 61a and the ground.

  Further, a gain controller 67 for gain control is also connected between the output of the intermediate frequency amplifier 64 and the AGC input 64 a provided in the intermediate frequency amplifier 64. Similarly, a smoothing capacitor 68 is connected between the AGC input 64a and the ground.

  The AGC inputs 54a and 64a are connected to AGC terminals 31a and 32a provided in the tuner sections 31 and 32, respectively. These AGC terminals 31 a and 32 a are connected to terminals 33 a and 33 b of the AGC control unit 33, respectively. Furthermore, the AGC control unit 33 is provided with an AGC control terminal 33c to which an AGC control signal is input.

  Next, the reception quality control unit 22 includes digital demodulation units 42 and 43, a diversity unit 44, an error correction unit 45, and a diversity control unit 46.

  Tuner output terminals 39 and 40 are connected to the input terminals 42a and 43a of the digital demodulation units 42 and 43, respectively. The output terminals 42b and 43b of the digital demodulation units 42 and 43 are connected to the input terminals 44a and 44b of the diversity unit 44, respectively.

  The diversity unit 44 includes a subcarrier detector 81 connected between the input terminals 44a and 44b, and a subcarrier selector / combiner 82 connected to the input terminals 44a and 44b. The output 81 a of the subcarrier detector 81 is connected to the input 82 a of the subcarrier selector / synthesizer 82. The output of the subcarrier selector / combiner 82 is connected to the input terminal 45 a of the error correction unit 45 via the output terminal 44 c of the diversity unit 44.

  The error correction unit 45 is provided with an OFDM frame configuration 83, a deinterleave 84, and an error correction 85 in order from the input terminal 45a toward an output terminal 45b from which an error-corrected signal is output.

  The BER signal output from the error correction 85 is input to one input 86a of the BER determiner 86, and the reference signal is input from the outside to the other input 86b from the BER reference input terminal 86c.

  Next, the diver control unit 46 that controls these components will be described. A subcarrier detection signal from the output 81 b of the subcarrier detector 81 is input to the input 46 a provided in the diver control unit 46. Further, terminals 33a and 33b of the AGC control unit 33 are connected to the inputs 46b and 46c, respectively.

  Further, the AGC control signal output from the output 46 d is input to the AGC control terminal 33 c of the AGC control unit 33. Furthermore, the output 46e to which the power supply voltage is supplied is connected to the power input 31b of the tuner unit 31 and the power input 42c of the digital demodulator 42. From 46f, the power input 32b and the digital demodulator 43 of the tuner unit 32 are connected. Is connected to the power input 43c.

  The operation of the AGC control unit 33 by the diversity control unit 46 when performing single reception or diversity reception using the digital signal receiving apparatus 20 configured as described above will be described below.

  Note that the single reception is reception using the tuner unit 31, the digital demodulation unit 42, or the tuner unit 32 or the digital demodulation unit 43. In the diversity reception, both of the tuner units 31 and 32 and the digital demodulation units 42 and 43 are used, and the demodulated signals from these digital demodulation units 42 and 43 are synthesized by the diversity unit 44 and received. For convenience of explanation, one of the tuner unit and the digital demodulation unit used for single reception will be described as a tuner unit 31 and a digital demodulation unit 42 below.

  First, the reception start time will be described as the first state. Since reception quality is unknown at the start of reception, diversity reception with good reception quality is selected. The power supply voltage from the output 46 e of the diver control unit 46 is supplied to the tuner unit 31 and the digital demodulation unit 42. The power supply voltage from the output 46 f of the diver control unit 46 is also supplied to the tuner unit 32 and the digital demodulation unit 43. As a result, voltage is supplied to both the tuner units 31 and 32 and the digital demodulation units 42 and 43. Then, the same channel selection data is sent to the tuner units 31 and 32, and the reception operation is started.

  Further, the terminals 33a and 33b of the AGC control unit 33 are in an open state by the AGC control signal from the output 46d of the diver control unit 46. Accordingly, the AGC voltages of the AGC inputs 54a and 64a of the intermediate frequency amplifiers 54 and 64 do not affect each other.

  The OFDM digital broadcast signal input from the antenna 37 is input to the high frequency amplifier 51 through the antenna input terminal 35 of the tuner unit 31. In the high frequency amplifier 51, gain control is performed by the gain controller 56 so that the output level from the mixer 52 becomes a constant level.

  Both the output signal from the high frequency amplifier 51 and the output of the oscillator 55 are input to the mixer 52. The intermediate frequency signal output from the mixer 52 is suppressed by the intermediate frequency filter 53. The output signal from the intermediate frequency filter 53 is input to the intermediate frequency amplifier 54. In the intermediate frequency amplifier 54, gain control is performed by the gain controller 57 so that the output level of the intermediate frequency amplifier 54 becomes constant, and then output from the tuner output terminal 39.

  Similarly, the OFDM digital broadcast signal input from the antenna 38 is input to the high frequency amplifier 61 via the antenna input terminal 36 of the tuner unit 32. In the high frequency amplifier 61, gain control is performed by the gain controller 66 so that the output level from the mixer 62 becomes a constant level.

  The output signal from the high frequency amplifier 61 is input to the mixer 62 together with the output of the oscillator 65. The intermediate frequency signal output from the mixer 62 is suppressed by the intermediate frequency filter 63. The output signal from the intermediate frequency filter 63 is input to the intermediate frequency amplifier 64. In the intermediate frequency amplifier 64, gain control is performed by the gain controller 67 so that the output level of the intermediate frequency amplifier 64 becomes constant, and then output from the tuner output terminal 40.

  The intermediate frequency signals output from the tuner output terminals 39 and 40 are input to the digital demodulation units 42 and 43 via the input terminals 42a and 43a, respectively. Digitized demodulated signals are output from the output terminals 42b and 43b of the digital demodulating units 42 and 43, respectively.

  Further, these digital demodulated signals are input via the input terminals 44a and 44b of the diversity unit 44, respectively. In diversity section 44, subcarrier detector 81 detects the signal quality of the subcarriers included in the two demodulated signals. Based on the detected signal quality information, a weighting coefficient for each subcarrier is calculated. This weighting coefficient is input from the output 81 a of the subcarrier detector 81 to the input 82 a of the subcarrier selector / synthesizer 82.

  Further, each of the subcarriers is output from the output terminal 44c by a subcarrier selector / combiner 82, which is synthesized by multiplying the weighting coefficients. The signal synthesized in this way is improved C / N by a maximum of 2 times by the weighting coefficient.

  This subcarrier composite signal is input to the OFDM frame configuration 83 via the input terminal 45 a of the error correction unit 45. In this OFDM frame configuration 83, a frame signal is created from a signal divided and multiplexed on subcarriers. This frame signal is input to the deinterleave 84 and rearranged to the original data. The signal that has been rearranged to the original data is corrected for errors by the error correction 85, and the error corrected signal is output from the output terminal 45b.

  As described above, since reception quality is unknown at the start of reception, the digital signal receiving apparatus 20 is set to diversity reception by the diversity control unit 46. As a result, an error-corrected signal whose C / N is improved by a maximum of 2 times is output, and the reception quality is improved.

  Next, as a second state, an operation of switching to single reception for the purpose of power saving when the reception quality in diversity reception is good will be described below. Note that, when switching to single reception, the tuner unit 31 and the digital demodulation unit 42 are used as operating states, and the tuner unit 32 and the digital demodulation unit 43 are described as non-operating states.

  This is a case where the OFDM digital broadcast signal level input to the antenna input terminals 35 and 36 is good, for example, −90 dBm or higher. In this case, the diver control unit 46 detects subcarriers output from the inputs 46b and 46c to which the AGC voltage that changes according to the magnitude of the OFDM digital broadcast signal level is input, and the output 81b of the subcarrier detector 81. The quality information of the received signal is determined by using at least one of the input 46a to which the signal is input or the input 46g to which the determination signal is input according to the magnitude of the BER output from the BER determiner 86. It becomes possible.

  As described above, when the reception quality in the diversity reception is good, the operation state of the tuner unit 31 and the digital demodulation unit 42 is continued by the power supply voltage output from the output 46e of the diversity control unit 46. Further, the tuner unit 32 and the digital demodulation unit 43 are changed from the operating state to the non-operating state by the power supply voltage output from the output 46 f of the diver control unit 46.

  At this time, the terminals 33a and 33b of the AGC controller 33 are both opened by the AGC control signal from the output 46d of the diver controller 46. As a result, the AGC voltages of the intermediate frequency amplifiers 54 and 64 are not affected by each other.

  Further, since the power supply voltage is supplied only to one tuner unit 31 and the digital demodulation unit 42, only the demodulated signal from the input terminal 44a is input to the subcarrier detector 81, and the demodulated signal is input from the input terminal 44b. Is not entered. Therefore, the subcarrier selector / combiner 82 selects the demodulated signal input from the input terminal 44a based on the signal quality information from the subcarrier detector 81, and then outputs it to the output terminal 44c. The output signal from the subcarrier selector / synthesizer 82 is input to the input terminal 45a of the error correction unit 45, and an error-corrected signal is output from the output terminal 45b.

  As described above, when the diversity control unit 46 determines that the reception quality is good during reception by diversity reception, the diversity control unit 46 switches from diversity reception to single reception. Thereby, any one of the tuner unit 31, the digital demodulation unit 42 or the tuner unit 32, and the digital demodulation unit 43 can be set in an operating state, and the other can be set in a non-operating state, so that power consumption can be reduced.

  Note that a digital demodulator that is in an inoperative state during single reception may be in an operating state. In this case, since both the digital demodulation units 42 and 43 are in the operating state, the reduction in power consumption is reduced, but the operation time from the power supply startup in the digital demodulation unit is shortened.

  Next, as a third state, an operation of switching to diversity reception when reception quality deteriorates during single reception will be described below. In the case of single reception, for example, the case where the tuner unit 31 and the digital demodulation unit 42 are operated and the tuner unit 32 and the digital demodulation unit 43 are in an inoperative state will be described.

  Note that the case where the reception quality deteriorates means that the OFDM digital broadcast signal level input to the antenna input terminals 35 and 36 is, for example, −90 dBm or less. In this case, the C / N of the input OFDM digital broadcast signal is deteriorated, and further, the C / N is deteriorated due to the noise figure of the digital signal receiving device 20, and further, the C / N is affected by the influence of multipath during mobile reception. Degradation occurs. In order to improve the deterioration of C / N, the reception quality is improved by switching from single reception to diversity reception.

  The operation of switching from single reception to diversity reception in this way differs from the diversity reception operation used at the start of reception in the following points. That is, in diversity reception at the start of reception, the tuner units 31 and 32 and the digital demodulation units 42 and 43 are all in the operating state from the non-operating state.

  On the other hand, in the operation of switching from single reception to diversity reception, for example, one tuner unit 31 and the digital demodulation unit 42 are kept in the operating state, and the other tuner unit 32 and the digital demodulation unit 43 are operated from the non-operating state. It is a state. A change in the AGC voltage of the intermediate frequency amplifier 64 in the non-operating state in this case will be described below with reference to FIGS. 2 (a), (b), and (c).

  FIG. 2A is a characteristic diagram of gain control amounts of the high frequency amplifier and the intermediate frequency amplifier with respect to the input signal level to the antenna input terminal. In FIG. 2A, 101 is an input signal level. Reference numeral 102 denotes a gain control amount (gain reduction amount). The AGC voltage 103 is a gain control amount in the high frequency amplifier 51 or 61 with respect to an input signal level to the antenna input terminal 35 or 36. The AGC voltage 104 is a gain control amount in the intermediate frequency amplifier 54 or 64 with respect to the input signal level to the antenna input terminal 35 or 36.

  For example, when an input signal level 107 (−30 dBm) between an input signal level 105 (0 dBm) and 106 (−60 dBm) is input to the antenna input terminals 35 and 36, the AGC voltage is applied to the high frequency amplifiers 51 and 61. The gain control amount 108 is determined by 103. At this time, in the intermediate frequency amplifiers 54 and 64, the gain control amount 109 which is the maximum gain control amount is determined by the AGC voltage 104.

  For example, when a signal with an input signal level 110 (−90 dBm) between the input signal level 106 (−60 dBm) and 109 (−110 dBm) is input to the antenna input terminals 35 and 36, the high-frequency amplifiers 51 and 61. The minimum gain control amount 111 is determined by the AGC voltage 103, and the gain control amount 112 is determined by the AGC voltage 104 in the intermediate frequency amplifiers 54 and 64.

  In this way, gain control is performed by the AGC voltages 103 and 104, and signals at a constant level are output from the tuner output terminals 39 and 40.

  FIG. 2B is a characteristic diagram of the rise of the AGC voltage of the intermediate frequency amplifier 64 when switching from single reception to diversity reception in the conventional example. Here, when switching from single reception to diversity reception, the input signal level at which reception quality begins to deteriorate suddenly is set to −90 dBm or less, for example. Further, this conventional example is the same as the state in which both the terminal 33a and the terminal 33b of the AGC control unit 33 in the present embodiment are opened.

  In FIG. 2B, 120 represents time, and 121 represents the AGC voltage of the intermediate frequency amplifier 64. Further, the AGC voltage 122 is used when the AGC voltage is switched from single reception of the AGC voltage of the intermediate frequency amplifier 64 to diversity reception in a state where both the terminal 33a and the terminal 33b of the AGC control unit 33 are opened (the same state as the conventional example). It represents the rise characteristic.

  That is, before the time 123, since single reception is selected, the AGC voltage is 0V. At time 123 when diversity reception is selected, the power supply voltage is supplied from the output 46f of the diversity control unit to the power input 32b of the tuner unit 32, and the channel selection operation is started almost simultaneously with the channel selection data. At time 123 when the power supply voltage is supplied, there is no output signal from the mixer 62 because the channel selection is not completed. For this reason, the AGC voltage 122 of the intermediate frequency amplifier 64 becomes the AGC voltage value 126 which is the maximum gain.

  The AGC voltage value 126 starts gain control at the time 124 when the channel selection is finished, and becomes an AGC voltage value 127 which is a predetermined value at the time 125, thereby completing the AGC operation.

  A time 128 between the times 123 and 124 is a time required for completing the channel selection operation, and is about 3 msec. However, a time 129 between the times 124 and 125 is a required time from the start of the AGC operation of the intermediate frequency amplifier 64 to the completion thereof, which is about 30 msec. Thereby, the completion time from the non-operating state to the operating state of the tuner unit 32 becomes a total of 33 msec. As described above, the time required for switching from single reception to diversity reception is substantially determined by the time 129 (30 msec) of the AGC operation of the intermediate frequency amplifier 64.

  The AGC operation time 129 of the intermediate frequency amplifier 64 is determined by the capacitor 68 connected between the AGC input 64a and the ground. The capacitance of the capacitor 68 is set to 1 μF in order to stabilize the AGC operation of the intermediate frequency amplifier 64. That is, when the non-operating state is changed to the operating state, a charging time for the capacitor 68 is generated, and therefore a time 129 until the AGC operation of the intermediate frequency amplifier 64 is stabilized is required.

  The capacitor 68 preferably has a large capacitance value in order to absorb fluctuations in the power supply voltage and fluctuations in the reception signal during high-speed movement, such as noise in the digital signal receiving apparatus 20. However, if the capacitance value is extremely large, a long charge / discharge time is required, and the time until stabilization becomes long. Therefore, it is necessary to set the capacity value to an optimum value.

  FIG. 2C is a characteristic diagram of the rising edge of the AGC voltage of the intermediate frequency amplifier 64 in the first embodiment. The AGC voltage 140 indicates the rising characteristic of the AGC voltage of the intermediate frequency amplifier 64 when switching from single reception to diversity reception.

  In FIG. 2C, before time 143, single reception is selected, so the AGC voltage 140 is 0V. After time 143 when diversity reception is selected, the power supply voltage is supplied to the power input 32b of the tuner unit 32 from the output 46f of the diversity control unit, and the channel selection operation is started almost simultaneously with the channel selection data. Then, at time 144, the channel selection is completed. A time 150 between the times 143 and 144 is a time required until the channel selection operation is completed, and is about 3 msec as in the conventional example.

  However, the AGC control signal output from the output 46d of the diver control unit is input to the terminal 33c of the AGC control unit 33, whereby the voltage value almost the same as the AGC voltage of the intermediate frequency amplifier 54 operating at time 143 is obtained. This is supplied to the AGC input 64 a of the intermediate frequency amplifier 64.

  Furthermore, when the channel selection operation is completed (at time 144), the terminals 33a and 33b of the AGC control unit 33 are opened by the AGC control signal output from the output 46d of the diver control unit 46. As a result, the AGC voltages of the intermediate frequency amplifiers 54 and 64 are not affected by each other. Accordingly, the AGC voltage 140 of the intermediate frequency amplifier 64 is completed at time 145 and is instantaneously controlled to the predetermined AGC voltage value 127.

  A time 151 between the times 144 and 145 is a time required until the AGC voltage value 142 slightly changes to 127. This time 151 is about 3 msec, and the AGC operation can be completed in a time shorter than about 1/10 of the conventional example.

  That is, in the conventional example, the total time of 3 msec for the tuning time and the stabilization time of 30 msec for the AGC voltage is 33 msec. In this embodiment, the total time for the tuning time of 3 msec and the stabilization time of the AGC voltage is 3 msec, which is 6 msec. it can.

  As described above, even when the tuner receiving unit 21 is switching from single reception to diversity reception when moving from a place where reception quality is stable to a place where reception quality is unstable during reception of an OFDM digital broadcast signal. The AGC voltage having the same magnitude as the AGC voltage of the intermediate frequency amplifier 54 of one tuner unit 31 that has been single-received by the newly provided AGC control unit 33 is input to the AGC of the intermediate frequency amplifier 64 of the other tuner unit 32. 64a is supplied through the AGC control unit 33 for a predetermined time.

  As a result, it is possible to shorten the time for the AGC voltage of the intermediate frequency amplifier 64 of the tuner unit 32 that has been in the non-operating state at the time of single reception to reach a predetermined voltage, thereby significantly reducing the rise time of the AGC voltage. Can do.

  Therefore, switching from single reception to diversity reception can be performed smoothly in a short time.

  Note that the gain control voltages obtained by detecting the signal levels in the digital demodulation units 42 and 43 may be used as the inputs to the gain controllers 57 and 67. In this case, gain control can be performed at a desired signal level in which interference signals are further suppressed by the filters in the digital demodulation units 42 and 43, so that the intermediate frequency amplifiers 54 and 64 can be optimally gain controlled.

  Further, during single reception, the AGC voltage in the operating state may be supplied to the AGC input of the non-operating intermediate frequency amplifier. Thereby, the time 144 which is the start of rising of the AGC voltage 140 of the intermediate frequency amplifier 64 can be brought close to the time 143. Therefore, at the time of switching from single reception to diversity reception, the effect of time reduction by switching using the AGC control unit 33 can be further increased.

  Further, the BER signal output from the error correction 85 can be input to one input 86a of the BER determiner 86, and the reference signal can be input from the BER reference input terminal 86c to the other input 86b. . Therefore, since the reference signal to the BER determiner 86 can be set to an arbitrary value, the reception quality determination criterion can be optimized.

  Furthermore, when the digital signal receiving apparatus 20 according to the present embodiment is mounted on a mobile portable device, the antennas 37 and 38 cannot be sufficiently separated from each other. For this reason, a large difference is unlikely to occur in the level of the OFDM digital broadcast signal by the antennas 37 and 38 arranged close to each other in the mobile portable device, so that the AGC voltages of the intermediate frequency amplifiers 54 and 64 are substantially the same voltage. Become. Therefore, at the time of switching from single reception to diversity reception, the effect of time reduction by switching using the AGC control unit 33 is further increased.

  In the tuner units 31 and 32, the mixers 52 and 62 are used as a single super, but may be used as a direct conversion. That is, the mixer 52 is composed of two mixers for I and Q signals, and oscillation signals from oscillators having a phase difference of 90 degrees are input to these mixers for I and Q signals.

  Thus, in the case of direct conversion, the frequency after direct conversion is a low frequency signal of I and Q signals. That is, since signal processing is performed at a low frequency, integration is facilitated. Also, interference with other signals is unlikely to occur.

(Embodiment 2)
FIG. 3 is a first specific example of the AGC control unit 33 according to the first embodiment and is represented as an AGC control unit 201. The terminals 33a, 33b, and 33c in FIG. 3 are connected to the same symbols as in FIG.

  Further, an electronic switch 202 and a resistor 203 are connected in series between the terminals 33a and 33b of the AGC control unit 201.

  Before the time 143 in which single reception in FIG. 2C is performed, the electronic switch 202 is opened by inputting the output 46d of the diver control unit 46 to the AGC control terminal 33c. Thereby, the terminal 33a and the terminal 33b are opened and are not influenced by each other.

  Further, after time 143 from the single reception to the diversity reception, power is supplied to the tuner unit 32 and the digital demodulation unit 43, and channel selection data is input to the tuner unit 32. At time 143, the output 46d of the diver control unit 46 is input to the AGC control terminal 33c, so that the electronic switch 202 is short-circuited. As a result, the AGC voltage of the intermediate frequency amplifier 54 is supplied to the AGC input 64 a of the intermediate frequency amplifier 64 via the resistor 203.

  Immediately after that, since it is disconnected from the AGC voltage at time 144, the predetermined AGC voltage value 127 is reached at time 145 after a short time (about 3 msec).

  As described above, the AGC voltage of one tuner unit in operation can be transmitted to the AGC input of the other tuner unit using a simple circuit configuration including the electronic switch 202 and the resistor 203. As a result, the time required for switching from single reception using one tuner unit and digital demodulation unit to diversity reception using two tuner units and digital demodulation unit can be greatly reduced.

  The resistance value of the resistor 203 is, for example, 1 kΩ. By appropriately selecting the resistance value of the resistor 203, when the electronic switch 202 is short-circuited, voltage fluctuations caused by charging / discharging between the AGC inputs 54a and 64a can be reduced.

  Furthermore, during single reception, the AGC voltage in the operating state may be supplied to the AGC input of the non-operating intermediate frequency amplifier. Thereby, the time 144 which is the start of rising of the AGC voltage 140 of the intermediate frequency amplifier 64 can be brought close to the time 143. Therefore, at the time of switching from single reception to diversity reception, the effect of time reduction by switching using the AGC control unit 33 can be further increased.

(Embodiment 3)
FIG. 4 is a second specific example of the AGC control unit 33 according to the first embodiment, and is represented as an AGC control unit 204. Terminals 33a, 33b, and 33c in FIG. 4 are connected to the same reference numerals as in FIG.

  In FIG. 4, the AGC control unit 204 includes electronic switches 205 and 206 and voltage transmission circuits 207 and 208. The terminal 33 a of the AGC control unit 204 is connected to the common terminal 205 a of the electronic switch 205. The electronic switch 205 is provided with terminals 205b, 205c, and 205d for switching.

  The electronic switch 206 is provided with terminals 206b, 206c, and 206d for switching. Further, the terminal 33 b of the AGC control unit 204 is connected to the common terminal 206 a of the electronic switch 206. Nothing is connected to the terminals 205c and 206c, and the terminals 205c and 206c are open.

  Further, the same voltage transmission circuit 207 that outputs the same voltage as the input voltage is connected between the terminal 205 b of the electronic switch 205 and the terminal 206 b of the electronic switch 206. Since this voltage transmission circuit 207 is constituted by a high-impedance circuit with a collector ground, it is possible to transmit the AGC voltage to the non-operating tuner section without affecting the circuit on the operating tuner section. it can.

  The voltage transmission circuit 207 includes a transistor 212 connected to the base of the terminal 205b via a resistor 211, and a resistor 213 connected between the emitter of the transistor 212 and the ground. The connector is connected to the power source, and the emitter is connected to the terminal 206b.

  Similarly, the same voltage transmission circuit 208 that outputs the same voltage as the input voltage is connected between the terminal 206 d of the electronic switch 206 and the terminal 205 d of the electronic switch 205. Since this voltage transmission circuit 208 is also constituted by a collector-grounded high impedance circuit, the AGC voltage is transmitted to the non-operating tuner unit side without affecting the circuit on the tuner unit side in the operating state. can do.

  The voltage transmission circuit 208 is also composed of a transistor 216 connected to the base of the terminal 206d via a resistor 215, and a resistor 217 connected between the emitter of the transistor 216 and the ground. The collector is connected to the power supply, and the emitter is connected to the terminal 205d.

  In the AGC control unit 204 configured as described above, the electronic switches 205 and 206 are controlled by the AGC control signal from the AGC control terminal 33c, so that the conduction state and the open state of the voltage transmission circuit 207, or the voltage transmission circuit. Any one of 208 conductive states and open states can be selected.

  For example, when receiving is started and when diversity is received, the open state is selected so that the AGC voltages of the intermediate frequency amplifiers 54 and 64 of the tuner units 31 and 32 are not affected. Furthermore, when switching from single reception to diversity reception, the same voltage transmission circuit 207 is made conductive when the tuner unit 31 is in an operation state during single reception, and the same when the tuner unit 32 is in an operation state during single reception. The voltage transmission circuit 208 is turned on.

  As a result, the same voltage as the AGC voltage of the intermediate frequency amplifier of the tuner unit in the operating state is supplied to the AGC input of the intermediate frequency amplifier of the tuner unit in the non-operating state.

  As described above, by using the AGC control unit 204 of the present embodiment, when switching from single reception to diversity reception, the same voltage as the AGC voltage of the intermediate frequency amplifier 54 of the tuner unit 31 in the operating state is not operated. The voltage is supplied to the AGC input of the tuner unit 32 in the state, and can be instantaneously set to a predetermined voltage. Therefore, the time until the AGC operation of the tuner unit in the non-operating state is completed can be further shortened compared to the second embodiment.

  Further, the input of the AGC control unit 204 is in a high impedance state, and the AGC voltage of the tuner unit in the operating state is not affected by the AGC voltage of the tuner unit in the non-operating state. Stable switching to reception is possible.

  During single reception, power may be supplied to the AGC control unit 33 to supply the AGC voltage in the operating state to the AGC input of the intermediate frequency amplifier in the non-operating state. Thereby, the time 144 which is the start of rising of the AGC voltage 140 of the intermediate frequency amplifier 64 can be brought close to the time 143. Therefore, at the time of switching from single reception to diversity reception, the effect of time reduction by switching using the AGC control unit 33 can be further increased.

(Embodiment 4)
FIG. 5 is a block diagram of a digital signal receiving apparatus according to Embodiment 4 of the present invention. Since the parts other than the tuner units 331 and 332 are the same as those in the first embodiment, the description is simplified by using the same symbols.

  The tuner units 331 and 332 constituting the tuner receiving unit 321 of the fourth embodiment are different from the first embodiment in the following points. That is, in the first embodiment, the intermediate frequency amplifier 333 capable of gain control is inserted between the intermediate frequency filter 53 and the intermediate frequency amplifier 54. An intermediate frequency amplifier 334 is also inserted between the intermediate frequency filter 63 and the intermediate frequency amplifier 64 of the first embodiment.

  The outputs of the intermediate frequency amplifiers 333 and 334 are connected to the respective AGC inputs 333a and 334a provided in the intermediate frequency amplifiers 333 and 334 via the gain controllers 335 and 336, respectively. Smoothing capacitors 337 and 338 are connected between the AGC inputs 333a and 334a and the ground, respectively. Thereby, the intermediate frequency amplifiers 333 and 334 perform gain control so that the respective output signal levels become constant levels.

  The tuner units 331 and 332 configured as described above have high-frequency amplifiers 51 and 61 and intermediate-frequency amplifiers even if the input signal level input from the antenna input terminals 35 and 36 is input from a large level to a small level. 333 and 334 and the intermediate frequency amplifiers 54 and 64 can sufficiently control the gain over a wide range of input levels.

  Therefore, since the optimum input signal level can be input to each amplifier including the digital demodulator 42, it is possible to realize the digital signal receiving device 320 that has good reception sensitivity and is strong against interference signals.

  In the tuner units 331 and 332 thus configured, the same voltage as the AGC voltage of the intermediate frequency amplifier 54 of one tuner unit 331 used as a single reception by the newly provided AGC control unit 33 is applied to the other tuner unit 332. The signal is supplied to the AGC input 64a of the intermediate frequency amplifier 64 for a predetermined time.

  Thereby, for example, the time for the AGC voltage of the intermediate frequency amplifier 64 of the tuner unit 332 that has been in the non-operating state at the time of single reception to reach a predetermined voltage can be shortened, so that the rise time of the AGC voltage can be greatly shortened.

  Therefore, switching from single reception to diversity reception can be performed smoothly in a short time.

  The AGC control unit 33 can obtain the same effects as those of the first embodiment by using the AGC control units 201 and 204 of the second or third embodiment.

  Note that the AGC voltages of the intermediate frequency amplifiers 333 and 334 of the tuner units 331 and 332 may be used. In this case, AGC inputs 333a and 334a are connected to one of the AGC control unit 33 and the other terminals 33a and 33b, respectively.

  Since the tuner receiver of the present invention can smoothly switch from single reception to diversity reception in a short time, it can be applied to a mobile portable device or the like.

1 is a block diagram of a digital signal receiving apparatus according to Embodiment 1 of the present invention. (A) is the gain control characteristic diagram with respect to the input signal level of the tuner unit, (b) is the AGC voltage characteristic diagram with respect to the time of the tuner unit of the conventional example, and (c) is the first embodiment of the present invention. AGC voltage characteristics with respect to tuner time Circuit diagram of AGC control unit in Embodiment 2 of the present invention Circuit diagram of AGC control unit in Embodiment 3 of the present invention The block diagram of the digital signal receiver in Embodiment 4 of this invention Block diagram of a digital signal receiving apparatus in a conventional example

Explanation of symbols

21 tuner receiving unit 31 tuner unit 32 tuner unit 33 AGC control unit 35 antenna input terminal 36 antenna input terminal 39 tuner output terminal 40 tuner output terminal 52 mixer 53 filter 54 intermediate frequency amplifier 55 oscillator 57 gain controller 62 mixer 63 filter 64 Intermediate Frequency Amplifier 65 Oscillator 67 Gain Controller

Claims (8)

A single reception unit in which a first tuner unit and a second tuner unit are provided in parallel and diversity control is performed , and a signal is received only by the first tuner unit; the first tuner unit and the second tuner unit; A tuner receiving unit having a function of switching to diversity reception for receiving a signal in the unit, wherein the first and second tuner units include first and second antenna input terminals to which a digital signal is supplied; and The first and second mixers to which signals from the first and second antenna input terminals are respectively supplied to one input, and the first and second mixers to be supplied to the other inputs of the first and second mixers, respectively. First and second oscillators, first and second filters to which outputs from the first and second mixers are respectively supplied, and outputs from these first and second filters are respectively supplied. And gain control input ( First and second intermediate frequency amplifiers having a lower AGC input), and provided between the outputs of the first and second intermediate frequency amplifiers and the AGC input, and a gain control voltage (hereinafter referred to as AGC). And first and second tuner output terminals to which outputs from the first and second intermediate frequency amplifiers are supplied, respectively. 1. An AGC control signal is input via a reception quality control unit to which the first and second tuner output terminals are connected, and an AGC control unit whose output is connected to the first and second AGC inputs, respectively. The AGC control unit outputs the first AGC input and the second AGC input in an open state and outputs from the reception quality control unit when switching from single reception to diversity reception. A Based on the C control signal, by the second input AGC and the first AGC input short circuited, the AGC voltage of the one tuner, which has been a running during single reception, A tuner receiver for supplying a fixed time to the AGC input of the other tuner that has been inactive during single reception. 2. The AGC control unit connects the first and second AGC terminals with a series connection body of an electronic switch and a resistor, and performs on / off control of the electronic switch with a signal from a reception quality control unit. The tuner receiver described in 1. The AGC control unit connects the first and second AGC terminals with a series connection of an electronic switch and a high-impedance voltage transmission circuit, and turns on the electronic switch with a signal from the reception quality control unit. The tuner receiver according to claim 1, wherein the tuner receiver is turned off. The tuner receiver according to claim 1, wherein the first and second mixers are direct conversion. The tuner receiver according to claim 1, wherein third and fourth intermediate frequency amplifiers capable of gain control are provided between the first and second filters and the first and second intermediate frequency amplifiers, respectively. A digital signal receiving apparatus comprising the tuner receiving unit according to claim 1 and a reception quality control unit connected to an output of the tuner receiving unit, wherein the reception quality control unit is a first receiver of the tuner receiving unit. The outputs from the second tuner unit are supplied, and the first and second digital demodulation units that demodulate the digital signal and the demodulated signals from the first and second digital demodulation units are supplied, respectively. A subcarrier detector for detecting the signal quality of the subcarrier, an output terminal to which the output of the subcarrier detector is supplied, and the subcarrier signal quality output from the subcarrier detector and the AGC A diver control unit for outputting a control signal, and when the quality of the subcarrier signal output from the subcarrier detector deteriorates, the diver control Digital signal receiving apparatus which outputs the AGC control signal indicating the diversity reception from the single reception. An error correction unit is provided between the output of the subcarrier detector and the output terminal, and an error correction rate (hereinafter referred to as BER) determination unit is provided between the output of the error correction unit and the diver control unit, and the BER determination is performed. The digital signal receiving apparatus according to claim 6, wherein the AGC control unit is controlled based on a determination signal output from the detector. 8. The digital signal receiving apparatus according to claim 7, further comprising a reference value input terminal capable of inputting a reference value of the BER determination device from the outside.

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