WO2011055495A1 - Receiver apparatus and reception method - Google Patents

Abstract

A silence detection circuit (9) detects a silence time interval of a transmitted broadcast content to output a silence detection signal. A calibration signal generation circuit (4) uses, as a trigger, the silence detection signal to output a calibration signal that is to be used for detecting deviation amounts between the I-path and Q-path of a quadrature demodulation circuit (5). An I/Q deviation detection circuit (11) performs comparisons with reference values of a case of no deviations between the I- and Q-paths, thereby outputting an amplitude deviation amount and a phase deviation amount between the I- and Q-paths. A correction calculation circuit (10) generates amplitude correction data and phase correction data that are to be used for the quadrature demodulation circuit (5) to perform amplitude and phase adjustments.

Description

Receiving apparatus and receiving method

The present invention relates to a receiving apparatus and a receiving method in a wireless system, and more particularly to a technique for correcting a mismatch in amplitude and phase between an in-phase (I) component and a quadrature (Q) component in quadrature demodulation.

In the conventional receiving apparatus, it is possible to correct the amplitude and phase mismatch between the I component and the Q component in quadrature demodulation. For this reason, the mode is changed from a reception mode in which an RF signal is received and converted into a baseband signal to a calibration mode in which a calibration signal is input by switching a switch (see Patent Document 1).

JP 2007-104522 A

In the above conventional receiving apparatus, it is necessary to switch the switch to enter the calibration mode in order to input the calibration signal, and during this period, it is impossible to receive the actual broadcast wave. For this reason, actual calibration is limited to the stage of process adjustment, immediately after power-on, or when the user changes the receiving station. When adjustment is necessary, switching to the calibration mode has a problem that the sound period broadcasted in analog radio broadcasting disappears.

The present invention solves the above-mentioned conventional problems, and calibration at the stage of process adjustment is unnecessary, the same broadcasting station is selected after turning on the power, and a change in ambient temperature occurs However, it is an object of the present invention to provide a receiving apparatus and a receiving method that enable broadcast reception without losing the sound period of the broadcast content in a state that is always adjusted to optimum reception characteristics.

In order to solve the above problems, a receiving apparatus according to the present invention has a signal from a receiving antenna as an input, a high-frequency amplifier that outputs the high-frequency signal, an output of the high-frequency amplifier as one input, and the other A selection unit that selects and outputs one of the inputs, and the amplitude of the I signal and the Q signal when the output of the selection unit is input and converted into an I component and a Q component by a mixer A quadrature demodulator that performs quadrature conversion by reflecting phase correction data, an analog-digital converter that converts a demodulated I signal and a demodulated Q signal output from the quadrature demodulator from an analog signal to a digital signal, and Each digital output of the analog-to-digital converter is input, a baseband demodulator that demodulates the reproduction signal, and a silence period of the output signal of the baseband demodulator is detected, and the selection unit And a calibration signal generator for outputting a calibration signal and a calibration period signal indicating the calibration period as the other input to the selection unit according to the output of the silence detection unit, and the base An output signal of a band demodulator is input, a mute unit that performs mute processing on the input signal according to the calibration period signal and outputs it as an audio signal, and each digital output of the analog-digital converter is input, A deviation amount from a reference value is detected for the amplitude and phase of the digital I signal and the digital Q signal when the calibration signal is input, and output as amplitude and phase deviation amount signals for the I signal and the Q signal. An IQ deviation detection unit, and an output of the IQ deviation detection unit as inputs, and performs an operation for returning the amplitude and phase deviations generated in the I signal path and the Q signal path, Characterized in that a correcting operation unit for outputting to the quadrature demodulator as correction data of the amplitude and phase of the signal and the Q signal.

A receiving method according to the present invention is a receiving method for demodulating an audio signal after performing an orthogonal demodulation step of converting a high-frequency signal input from a receiving antenna into an I component and a Q component. A silence period is detected, a calibration signal is used during the silence period, and amplitude and phase deviation correction amounts are calculated and output to the orthogonal demodulation step.

According to the present invention, by adopting silence detection, the correction between the I signal path and the Q signal path is corrected using the calibration signal during the silence period, so that calibration at the stage of the process adjustment becomes unnecessary. Even when the same broadcasting station is still selected after being turned on, there is an effect that reception is always possible in a state adjusted to optimum reception characteristics.

It is a block block diagram of the receiver in Embodiment 1 of this invention. It is a vector top view for demonstrating the deviation amount which is an output of the IQ deviation detection circuit in FIG. It is a vector top view for demonstrating the correction data which is an output of the correction | amendment calculating circuit in FIG. 2 is a timing chart showing the timing of silence detection and calibration in the receiving apparatus of FIG. 1. It is a block block diagram of the receiver in Embodiment 2 of this invention. 6 is a timing chart showing a reception situation in the receiving apparatus of FIG. 5. It is a block block diagram of the receiver in Embodiment 3 of this invention. It is a timing chart which shows the control process of the calibration period in the receiver of FIG. It is a timing chart which shows the example of the adjustment sequence in Embodiment 4 of this invention. It is a block block diagram of the receiver in Embodiment 5 of this invention. 11 is a timing chart showing a control relationship of a time lapse determination circuit in the receiving apparatus of FIG. 10. It is a block block diagram of the receiver in Embodiment 6 of this invention. 13 is a timing chart showing a control relationship of a temperature change determination circuit in the receiving apparatus of FIG. It is a flowchart which shows the reception method in Embodiment 7 of this invention. It is a flowchart which shows the reception method in Embodiment 8 of this invention. It is a flowchart which shows the reception method in Embodiment 9 of this invention. It is a flowchart which shows the receiving method in Embodiment 10 of this invention. It is a flowchart which shows the receiving method in Embodiment 11 of this invention. It is a flowchart which shows the receiving method in Embodiment 12 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

Embodiment 1
FIG. 1 is a block configuration diagram of a receiving apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a receiving antenna, 2 is a high frequency amplifier circuit, 3 is a selection circuit, 4 is a calibration signal generating circuit, 5 is an orthogonal demodulation circuit, 6 and 7 are A / D conversion circuits (ADC), and 8 is a baseband. A demodulation circuit, 9 is a silence detection circuit, 10 is a correction arithmetic circuit, 11 is an IQ deviation detection circuit, and 15 is a mute circuit.

The receiving antenna 1 receives the broadcast wave 1a. The high frequency amplifier circuit 2 amplifies the signal from the receiving antenna 1 and outputs a high frequency amplified signal 2a. The calibration signal generation circuit 4 uses a silence detection signal 9a as a trigger to generate a calibration signal 4a for adjusting variations in amplitude and phase of the IQ signal path of the orthogonal demodulation circuit 5, and a calibration period signal 4b indicating the calibration period. appear. The selection circuit 3 selects either the high-frequency amplified signal 2a or the calibration signal 4a according to the silence detection signal 9a and outputs a selection output signal 3a.

The quadrature demodulation circuit 5 receives the selection output signal 3a, and uses the I amplitude correction data 10a, the Q amplitude correction data 10b, the I phase correction data 10c, and the Q phase correction data 10d to calculate the amplitude and phase of the I signal and the Q signal. Quadrature demodulation is performed while correction is performed, and an in-phase component I signal 5a and a quadrature component Q signal 5b are output. The A / D conversion circuits 6 and 7 perform analog-digital conversion on the in-phase component I signal 5a and the quadrature component Q signal 5b, and output digital I data 6a and digital Q data 7a. The baseband demodulation circuit 8 receives the digital I data 6a and the digital Q data 7a, performs sound demodulation according to the reception mode of the system, and outputs a reproduction L signal 8a and a reproduction R signal 8b. The silence detection circuit 9 receives the reproduction L signal 8a and the reproduction R signal 8b, detects a silence period, and outputs a silence detection signal 9a. The mute circuit 15 mutes the input reproduction L signal 8a and reproduction R signal 8b according to the calibration period signal 4b, and outputs the result as an L audio signal 15a and an R audio signal 15b.

The IQ deviation detection circuit 11 receives the digital I data 6a and the digital Q data 7a which are the outputs of the A / D conversion circuits 6 and 7, and the orthogonality is maintained with no deviation in the path of the I and Q signals. The respective deviation amounts from the amplitude and phase are detected, and an I amplitude deviation amount 11a, a Q amplitude deviation amount 11b, an I phase deviation amount 11c, and a Q phase deviation amount 11d are output. The correction calculation circuit 10 receives the deviation amounts 11a to 11d output from the IQ deviation detection circuit 11 and inputs the deviation of the input in order to correct the amplitude and phase of the I and Q signals in the quadrature demodulation circuit 5. Data calculation from the quantities 11a to 11d to the correction data is performed and output as I amplitude correction data 10a, Q amplitude correction data 10b, I phase correction data 10c, and Q phase correction data 10d.

2 and 3 are vector plan views showing the relationship between the deviation amounts 11a to 11d and the correction data 10a to 10d in the IQ deviation detection circuit 11 and the correction calculation circuit 10. FIG.

There are analog elements (mixers, amplifiers, filters, etc.) in the path until the in-phase component I signal 5a and the quadrature component Q signal 5b are input to the A / D conversion circuits 6 and 7, and due to their variations, It is difficult to input to the A / D conversion circuits 6 and 7 while maintaining the orthogonality.

FIG. 2 shows an I amplitude deviation amount 11a, a Q amplitude deviation amount 11b, an I phase deviation amount 11c, and an in-phase component I signal 5a ′ and a quadrature component Q signal 5b ′ that should be properly maintained in quadrature. The vector relationship on the IQ plane when the Q phase deviation amount 11d is generated by an analog element is shown.

The IQ deviation detection circuit 11 detects these deviation amounts 11 a to 11 d and outputs them to the correction arithmetic circuit 10. In the correction arithmetic circuit 10, the quadrature demodulation circuit 5 generates the I amplitude correction data 10a and the Q amplitude correction data 10b in order to generate the correct in-phase component I signal 5a and quadrature component Q signal 5b from the deviation amounts 11a to 11d. The I phase correction data 10c and the Q phase correction data 10d are obtained by calculation, and the quadrature demodulation circuit 5 performs correction to maintain the orthogonality. Note that the calculation contents of the correction calculation circuit 10 are determined by the contents of the components of the orthogonal demodulation circuit 5 configured for each system.

In FIG. 3, the in-phase component I signal 5a ′ is returned to the in-phase component I signal 5a by the I amplitude correction data 10a and the I phase correction data 10c, and the quadrature component Q signal 5b ′ is converted by the Q amplitude correction data 10b and the Q phase correction data 10d. It shows a state where the quadrature component Q signal 5b is returned to, and as a result, the in-phase component I signal 5a and the quadrature component Q signal 5b having the original correct quadrature relationship are obtained. However, in this embodiment, both the I signal and the Q signal are corrected. However, the orthogonality may be maintained by correcting only the other amplitude component and phase component on the basis of one of them.

FIG. 4 is a timing chart showing the timing of silence detection and calibration. According to the present embodiment, in the normal reception mode, the high frequency amplified signal 2 a obtained by amplifying the broadcast wave 1 a by the high frequency amplifier circuit 2 is input to the quadrature demodulation circuit 5 via the selection circuit 3. In the quadrature demodulation circuit 5, the high frequency amplified signal 2 a is converted into an in-phase component I signal 5 a and a quadrature component Q signal 5 b, converted into digital data by the A / D conversion circuits 6 and 7, and received in the reception mode by the baseband demodulation circuit 8. The reproduction signals 8a and 8b corresponding to the above are output.

The silence detection circuit 9 detects the silence period of the broadcast content to be transmitted. If the silence period continues for a system set value or more, it is determined that the silence period has started, and the silence detection signal 9a is output. Here, “silence” means a state in which only a carrier wave of a broadcast is detected, not a state in which only an audio signal below a certain threshold level is detected. However, the determination condition as silence in this case and the time from the determination to the generation of the silence detection signal 9a can be set by the operated system.

The calibration signal generation circuit 4 outputs a calibration signal 4a for detecting a deviation between the I path and the Q path of the quadrature demodulation circuit 5 using the silence detection signal 9a as a trigger.

As the calibration signal 4a, a one-point calibration method using a constant frequency signal with a predetermined constant amplitude is conceivable. However, depending on the system, there is a frequency dependency in the variation of analog elements (for example, mixers) on the path. In some cases, the system characteristics may be greatly affected, so that the calibration signal may be generated at frequencies at three or plural points of both ends and the center of the reception band in consideration of the reception frequency band. However, it can be set according to the system to be operated and the magnitude of the variation of the analog elements.

When the selection circuit 3 receives the silence detection signal 9a, the selection output is switched from the high frequency amplification signal 2a to the calibration signal 4a and input to the orthogonal demodulation circuit 5. In the quadrature demodulation circuit 5, analog signals that have passed through the I path and Q path are converted into digital I data 6a and digital Q data 7a by A / D conversion circuits 6 and 7, respectively.

The IQ deviation detection circuit 11 compares with a reference value when there is no deviation in the IQ path and the orthogonality is maintained, detects the deviation amount caused by the variation of analog elements when passing through the IQ path, and Output as amplitude deviation amount 11a, Q amplitude deviation amount 11b, I phase deviation amount 11c, and Q phase deviation amount 11d.

In the correction arithmetic circuit 10, the amplitude and phase of the I signal and the Q signal are corrected in order to correct the orthogonality in the orthogonal demodulation circuit 5 from the IQ deviation amounts 11 a to 11 d which are the outputs of the IQ deviation detection circuit 11. The I amplitude correction data 10a, Q amplitude correction data 10b, I phase correction data 10c, and Q phase correction data 10d are calculated and output, respectively.

The quadrature demodulation circuit 5 uses the I amplitude correction data 10a, the Q amplitude correction data 10b, the I phase correction data 10c, and the Q phase correction data 10d, which are outputs of the correction arithmetic circuit 10, to restore the original orthogonal relationship. Processing is performed on the IQ path, and an in-phase component I signal 5a and a quadrature component Q signal 5b are output.

Since the calibration signal 4a is also demodulated by the baseband demodulation circuit 8, the reproduction signals 8a and 8b are muted so that the calibration signal 4a is not output by the calibration period signal 4b by the mute circuit 15, and the L audio signals 15a and R It is assumed that the above-described calibration is performed while outputting as the audio signal 15b.

As described above, according to the present embodiment, since the silence period is detected and the amplitude adjustment and the phase adjustment of the IQ path are performed, calibration at the stage of the process adjustment becomes unnecessary, and the same broadcasting station is turned on after the power is turned on. Even in a state in which is selected, reception is always possible in a state adjusted to optimum reception characteristics.

<< Embodiment 2 >>
FIG. 5 is a block diagram of a receiving apparatus according to the second embodiment of the present invention. The configuration of the receiving apparatus in FIG. 5 is obtained by adding a reception status signal 8c indicating the strength of the received electric field and the presence / absence of multipath as an output of the baseband demodulation circuit 8 to the first embodiment. The function of is the same.

The reception status signal 8c is, for example, an identification signal that can determine whether a multipath has occurred in the current reception status by detecting the AC component of the carrier wave amplitude (reception S meter).

FIG. 6 is an example of a timing chart showing the reception status. When the amplitude of the reproduction signals 8a and 8b is extremely lowered to the silence level due to the multipath effect after changing from silence to sound, only the amplitude is shown. Even if it is determined that there is a silence period when it is detected at, the reception status signal 8c invalidates the silence detection signal 9a in the silence detection circuit 9, so that it is possible to determine that there is no sound and there is a noise. This can be prevented, and even in a multipath situation, reception is always possible with the optimum reception characteristics adjusted.

<< Embodiment 3 >>
FIG. 7 is a block diagram of a receiving apparatus according to the third embodiment of the present invention. The configuration of the receiving apparatus in FIG. 7 is the same as that of the second embodiment in that a voiced disappearance detection circuit 12 is newly provided, and when the silent period ends and the voiced period disappears during the calibration period, the calibration period The control signal 12a is output to the calibration signal generation circuit 4 to perform control so as to shorten the next calibration period, and other configurations and functions of the respective blocks are the same.

FIG. 8 is a timing chart showing the control process during the calibration period. In FIG. 8, the calibration signal 4a for correcting the deviation of the IQ path by the first silence detection signal 9a is input to the quadrature demodulation circuit 5, the deviation is detected by the IQ deviation detection circuit 11, and the quadrature is corrected by the correction arithmetic circuit 10. The deviation in the demodulation circuit 5 is corrected.

The voiced disappearance detection circuit 12 detects the amplitude of the reproduced signals 8a and 8b which are the outputs of the baseband demodulation circuit 8 immediately after the calibration is completed and the calibration period signal 4b changes from the H level to the L level. Or no sound.

In the case of FIG. 8, the result of amplitude detection immediately after is determined to be sound, and the calibration period control signal 12a transitions from L to H and is output.

In the second silent period, since the calibration period control signal 12a is H in the calibration signal generation circuit 4, the H output period of the calibration period signal 4b is the H output of the calibration period signal 4b in the first silent period. The calibration signal 4a is output so that it is set shorter than the period, and the generation period of the calibration signal 4a is also controlled to be shorter than the first silent period. When the amplitude of the reproduction signals 8a and 8b immediately after the signal 4b changes from the H level to the L level is detected, it is determined that there is no sound, and the disappearance of the second sound period is prevented. At this time, the calibration period control signal 12a is returned from H to L to prepare for detection of the subsequent loss of sound.

こ の By shortening the calibration time in this way, it is possible to reduce the disappearance frequency of the sound period actually broadcast.

<< Embodiment 4 >>
FIG. 9 is a timing chart showing an example of an adjustment sequence according to the fourth embodiment of the present invention. The block diagram of the receiving apparatus is the same as that of the third embodiment, but the period of the calibration signal 4a generated by the calibration signal generation circuit 4 is set short, and the I signal path and the Q signal are set over a plurality of silent periods. The calibration signal generation circuit 4, the IQ deviation detection circuit 11, and the correction calculation circuit 10 are controlled so that an adjustment sequence that completes the deviation adjustment of the amplitude and phase between the paths is completed.

FIG. 9 shows an example of a sequence in which the amplitude is adjusted in two silent periods and the phase is adjusted in the subsequent two silent periods. Since it is assumed that calibration is performed over a plurality of silence periods, the period of the calibration signal 4a in FIG. 9 is sufficiently shorter than the normal silence period. The amplitudes of the reproduction signals 8a and 8b, which are the outputs of the baseband demodulation circuit 8 immediately after changing from the H level to the L level, remain silent.

It should be noted that the number of times of silence over a plurality of times and the adjustment contents are examples, and the number of silences and the order of adjustment according to each system may be used.

By making such an adjustment sequence, the calibration period is shortened and the calibration is completed over a plurality of silent periods. Therefore, the silent period continues even when the calibration signal 4a is input in each period. There is almost no loss of the broadcast sound period.

<< Embodiment 5 >>
FIG. 10 is a block diagram of a receiving apparatus according to the fifth embodiment of the present invention. The configuration of the receiving device in FIG. 10 is a configuration in which a time passage determination circuit 13 for controlling the silence detection signal 9a is newly provided in the third embodiment, and the other configurations and the configurations of the respective blocks are the same.

FIG. 11 is a timing chart showing the relationship of control of the time passage determination circuit 13 with respect to the silence detection signal 9a. Immediately after the power is turned on, every time a silence period is detected (t0, t1, t2, t3), the silence detection signal 9a is directly input to the selection circuit 3 and the calibration signal generation circuit 4 as the time lapse determination signal 13a, and the calibration signal The amplitude and phase deviation adjustment between the I signal path and the Q signal path of the quadrature demodulation circuit 5 is performed by 4a.

Furthermore, when a sufficient amount of time has elapsed since the power was turned on and the system set time (t3 in FIG. 11) has been exceeded, sufficient deviation adjustment has been performed, so even if the silence detection signal 9a is output, It is not necessary to adjust the deviation every time. As shown in FIG. 11, the deviation adjustment is not performed at the timings t4, t5, and t10, and the deviation adjustment is performed at the timings t6 and t17. It becomes possible to further reduce the disappearance frequency.

It should be noted that the system settings and the frequency of adjustment over time can be set for each applicable system.

Embodiment 6
FIG. 12 is a block diagram of a receiving apparatus according to the sixth embodiment of the present invention. The configuration of the receiving device in FIG. 12 is a configuration in which a temperature change determination circuit 14 for controlling the silence detection signal 9a is newly provided in the third embodiment, and the other configurations and the configurations of the respective blocks are the same.

FIG. 13 is a timing chart showing the relationship of control of the temperature change determination circuit 14 with respect to the silence detection signal 9a. When the ambient temperature is constant (t0 to t5 and t14 to t20 in FIG. 13), the silence detection signal 9a is used as the temperature change determination signal 14a, and the selection circuit 3 and the calibration signal generation circuit are set at a certain frequency set as a system. 4, and the deviation of the amplitude and phase between the I signal path and the Q signal path of the orthogonal demodulation circuit 5 is adjusted by the calibration signal 4 a.

On the other hand, when a change in ambient temperature occurs (t8 to t13 in FIG. 13), since the variation in the circuit has a temperature characteristic, the reception characteristic becomes insufficient with the adjustment frequency so far. By reflecting the silence detection signal 9a to the selection circuit 3 and the calibration signal generation circuit 4 so that the adjustment is performed at a frequency higher than the fixed frequency set in step 1, the deviation can be sufficiently adjusted. . Therefore, even if the ambient temperature changes after a sufficient amount of time has elapsed since the system power was turned on, deviation adjustment can be performed whenever a temperature change occurs. It becomes possible to receive in the state that has been done.

In addition, a certain frequency set as a system, a temperature change amount, etc. can be set for each applied system.

<< Embodiment 7 >>
FIG. 14 is a flowchart illustrating a control operation example in the reception method according to the seventh embodiment of the present invention. In FIG. 14, when the system is turned on and the system starts receiving, the received signal is quadrature demodulated and converted into an in-phase (I) component and a quadrature (Q) component. Performed (S121).

Silence detection is performed to check whether or not the reproduction signal demodulated in the baseband is silent (S122). If there is sound, the state of the reception mode is continuously maintained. If it is determined that there is no sound, a calibration signal is generated from S123 to S127, and the amplitude and phase between the I component and Q component in the quadrature demodulation circuit are generated. Correct the deviation. Here, a calibration signal period T is set in S123, a calibration signal is generated in S124, a deviation correction amount is calculated in S125, the amplitude and phase of the quadrature demodulation circuit are adjusted in S126, and a calibration end check is performed in S127. Execute.

By repeating S124 to S127, it becomes possible to make the I component and the Q component have no deviation, and even when the same broadcasting station is still selected, it is always adjusted to the optimum reception characteristics. It becomes possible to receive.

Embodiment 8
FIG. 15 is a flowchart illustrating an example of a control operation in the reception method according to the eighth embodiment of the present invention. In FIG. 15, the same control operation as in the seventh embodiment is performed except for S132.

Silence detection is performed to check whether or not the reproduction signal demodulated in the baseband is silent (S122). Furthermore, it is possible to prevent erroneous silence judgment by taking into account information regarding reception status such as the presence / absence of multipath and the strength of the received electric field (S132). Even in a path situation, reception is always possible with the optimum reception characteristics adjusted.

Embodiment 9
FIG. 16 is a flowchart illustrating an example of a control operation in the reception method according to the ninth embodiment of the present invention. In FIG. 16, control operations similar to those in the eighth embodiment are performed except for S141 and S142.

After detecting the silence period (S122, S132), generating a calibration signal from S123 to S127, and correcting the amplitude and phase deviation between the I and Q components in the quadrature demodulation circuit, the signal is demodulated. The magnitude of the signal amplitude of the I component and the Q component is compared with the set value, and the demodulated signal is judged to be sound or silent (S141).

If it is silent at this time, it is considered that calibration is completed normally. On the other hand, if there is sound, it is determined that the silent period has ended during the calibration period, and the length of the calibration signal period T is updated in S142 to shorten the period T of the next calibration signal (T = T-α).

短 く By shortening the calibration time in this way, it is possible to reduce the frequency of disappearance of the sound period actually broadcast.

<< Embodiment 10 >>
FIG. 17 is a flowchart illustrating a control operation example in the reception method according to the tenth embodiment of the present invention. In FIG. 17, control operations similar to those in the seventh embodiment are performed except for S151, S152, S153, S154, and S155.

First, when the silent period of the demodulated audio signal is detected (S122), the number N of calibrations is counted (S151), and the calibration signal period T set by the system is set. Then, calibration signals are generated from S124 to S126 and S153, and the amplitude and phase deviations between the I component and the Q component in the quadrature demodulation circuit are corrected.

It is determined whether the calibration in one silence period has been completed (S153). If it has been completed, it is determined whether the number of calibrations N matches the number set in the system (S154). Continue calibration. If they match, it is considered that the calibration has been completed, the number N of calibrations is reset (S155), and the flow returns to the normal reception operation (S121) flow.

By performing such operation control, the calibration period is shortened and the calibration is completed over a plurality of silent periods, so the silent period continues even when the calibration signal is input in each period, It is possible to significantly reduce the frequency of disappearance of the broadcast sound period.

<< Embodiment 11 >>
FIG. 18 is a flowchart illustrating an example of a control operation in the reception method according to the eleventh embodiment of the present invention. In FIG. 18, control operations similar to those in the seventh embodiment are performed except for S161, S162, S163, and S164.

When the silent period of the demodulated audio signal is detected (S122), the number of silent detections M is counted (S161). In S162, the time elapsed immediately after the power is turned on is measured and compared with the set time set in the system. If the time is shorter than the set time (when the time has not passed since the power was turned on), the process starts from S123. In S127, a calibration signal is generated, and the amplitude and phase deviation between the I component and the Q component in the quadrature demodulation circuit is corrected. When the calibration is completed, the silence detection count M is reset (S164), and the flow returns to the normal reception operation (S121) flow.

If the elapsed time immediately after the power is turned on in S162 is longer than the set time (when the time has passed sufficiently since the power is turned on), the silence detection count M matches the number set by the system. If the silent detection detection count M is equal to or greater than the set number, calibration is executed. If the number is less than the set number, the normal reception operation (S121) flow is performed without performing calibration even during the silent period. Return.

By performing such operation control, it is assumed that the ambient temperature of the system operating environment is sufficiently constant when sufficient time has elapsed since the system power was turned on. It is not necessary to correspond to each result, and the execution frequency of calibration can be lowered, and the frequency of disappearance of the broadcast sound period can be further reduced.

<< Embodiment 12 >>
FIG. 19 is a flowchart illustrating an example of a control operation in the reception method according to the twelfth embodiment of the present invention. In FIG. 19, the same control operation as in the seventh embodiment is performed except for S171, S172, S173, and S174.

When the silent period of the demodulated audio signal is detected (S122), the number of silent detections M is counted (S171). In S172, the ambient temperature change immediately after the power is turned on is measured, and the detected temperature change amount is compared with the temperature change amount set in the system. When the temperature change amount is larger than the set value, A calibration signal is generated from S123 to S127, and the deviation of the amplitude and phase between the I component and Q component in the quadrature demodulation circuit is corrected. When the calibration is completed, the silence detection count M is reset (S174), and the flow returns to the normal reception operation (S121) flow.

When the temperature change amount is smaller than the set value in S172, it is determined whether the silence detection count M matches the system set count (S173), and the silence detection detection count M exceeds the set count. Performs calibration, but if the number is less than the set number of times, the flow returns to the normal reception operation (S121) flow without performing calibration even in the silent period.

By performing this kind of operation control, calibration can be performed every time a temperature change occurs even if the ambient temperature changes after sufficient time has elapsed since the system power was turned on. Therefore, reception is always possible with the optimum reception characteristics adjusted.

As described above, the receiving apparatus and the receiving method of the present invention are useful as techniques for adjusting demodulation characteristics caused by element variations of the receiving apparatus in a wireless system.

DESCRIPTION OF SYMBOLS 1 Reception antenna 2 High frequency amplifier circuit 3 Selection circuit 4 Calibration signal generation circuit 5 Orthogonal demodulation circuit 6,7 Analog-digital (A / D) conversion circuit 8 Baseband demodulation circuit 9 Silence detection circuit 10 Correction calculation circuit 11 IQ deviation detection circuit 12 Voice disappearance detection circuit 13 Time lapse determination circuit 14 Temperature change determination circuit 15 Mute circuit

Claims (12)

1. A high-frequency amplifier that receives the signal from the receiving antenna and outputs the high-frequency signal;
   The output of the high-frequency amplification unit is one input, a selection unit that selects and outputs one of the other inputs, and
   An orthogonal demodulator that inputs the output of the selection unit and performs orthogonal transformation by reflecting correction data of the amplitude and phase of the I signal and the Q signal when converted into an I component and a Q component by a mixer;
   An analog-digital converter that converts the demodulated I signal and demodulated Q signal output from the orthogonal demodulator from an analog signal to a digital signal, respectively;
   A baseband demodulator that receives each digital output of the analog-digital converter as an input and demodulates a reproduction signal;
   Detecting a silence period of an output signal of the baseband demodulator, and outputting to the selector a silence detector;
   In response to the output of the silence detector, a calibration signal generator that outputs a calibration signal and a calibration period signal indicating the calibration period as the other input to the selector;
   The mute unit that receives the output signal of the baseband demodulator, performs a mute process on the input signal in accordance with the calibration period signal, and outputs it as an audio signal;
   Each digital output of the analog-digital conversion unit is input, and the deviation amount from the reference value is detected for the amplitude and phase of the digital I signal and digital Q signal when the calibration signal is input, and the I signal and An IQ deviation detector for outputting amplitude and phase deviation signals for the Q signal;
   Using the output of the IQ deviation detection unit as an input, performing an operation to restore the amplitude and phase deviations generated in the I signal path and the Q signal path, and correcting the amplitude and phase of the I signal and Q signal A receiving apparatus comprising: a correction calculation unit that outputs data to the orthogonal demodulation unit.
2. The receiving device according to claim 1,
   A receiving apparatus, wherein the silence detecting unit performs silence detection together with information related to reception status of strength of received electric field and presence / absence of multipath.
3. The receiving device according to claim 1,
   Input calibration end timing signal at the calibration signal generator and output a calibration period control signal to shorten the calibration time at the calibration signal generator if the demodulated signal is already sounded immediately after calibration A receiving apparatus further comprising a voiced disappearance detecting unit.
4. The receiving device according to claim 1,
   The silence detection unit and the calibration signal generation unit are arranged so that an adjustment sequence is completed so that deviation adjustment of amplitude and phase between the I signal path and the Q signal path is completed over a plurality of silence periods. A receiving device that controls the receiving device.
5. The receiving device according to claim 1,
   The time elapses immediately after the system power is turned on, and immediately after the power is turned on, every time silence is detected by the silence detector, the I signal path and the Q signal path are determined by the calibration signal from the calibration signal generator. The amplitude and phase between the I signal path and the Q signal path when the elapsed time after turning on the power reaches a reference time set by the system or more is adjusted. A receiving apparatus, further comprising a time lapse determination unit that performs execution control of deviation adjustment.
6. The receiving device according to claim 1,
   A change in ambient temperature is detected immediately after the system power is turned on, and when a change in ambient temperature is detected and the silence detection unit detects silence, the calibration signal from the calibration signal generation unit causes the I signal path and the A receiving apparatus, further comprising: a temperature change determining unit that adjusts a deviation in amplitude and phase between the Q signal path and the Q signal path.
7. A reception method for demodulating an audio signal after performing an orthogonal demodulation step of converting a high-frequency signal input from a receiving antenna into an I component and a Q component,
   A receiving method comprising: detecting a silent period in the audio signal; calculating a correction amount of each amplitude and phase deviation using a calibration signal during the silent period; and outputting the calculated deviation correction amount to the orthogonal demodulation step.
8. The receiving method according to claim 7, wherein
   A detection method for detecting silence by performing silence detection together with information on reception status of reception electric field strength / absence of multipath occurrence.
9. The receiving method according to claim 7, wherein
   If the demodulated audio signal is already voiced at the time immediately after the calibration is completed using the calibration signal, the period of the calibration signal is shortened.
10. The receiving method according to claim 7, wherein
    The number of silence periods and the period of the calibration signal are controlled so that the adjustment sequence is completed so that the amplitude and phase deviation adjustment between the I component and the Q component is completed over a plurality of silence periods. And a receiving method.
11. The receiving method according to claim 7, wherein
    Measure the elapsed time, adjust the amplitude and phase deviation between the I component and the Q component by the calibration signal every silence period immediately after power-on, and set the elapsed time after power-on in the system When the time reaches the reference time or longer, execution control of amplitude and phase deviation adjustment between the I component and the Q component is performed.
12. The receiving method according to claim 7, wherein
    A receiving method, wherein an ambient temperature is detected, a change in temperature is detected, and a deviation of amplitude and phase between the I component and the Q component is adjusted by the calibration signal during a silent period. .

Images