JP2005192066A - Dab receiver with self-diagnostic function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DAB receiver with a self-diagnostic function which can be accurately inspected in a short period of time on the stage of factory shipment and the operating state of which can be diagnosed even without using an expensive measuring instrument in a service institution. <P>SOLUTION: An inspector selects either a factory self-diagnostic mode or a service self-diagnostic mode using an operating mode selector 12. If a self-diagnostic mode is started, a control section 11 checks key operations by the inspector, operations of respective sections and the like while advancing to a diagnostic phase for an operating key 9, a diagnostic phase for a stabilizing power supply 8, a diagnostic phase for a PLL circuit 13, a diagnostic phase for a digital signal processing section 3 and a diagnostic phase for reception sensitivity and if there is a defective part, the part is displayed on a display 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a receiver for terrestrial digital audio broadcasting, and more specifically, DAB reception for self-diagnosing whether the operation of each unit constituting the device is normal or abnormal and notifying the examiner of the result of the diagnosis. Related to the machine.

  In recent years, projects providing digital terrestrial audio broadcasting (hereinafter referred to as DAB) are becoming popular mainly in Europe and the United States. One of such projects, European DAB (Eureka 147), covers almost the entire Western European countries. The system is also gradually spreading to Canada and some Asian countries.

  Here, an outline of a well-known technique of audio digital broadcasting will be described.

(1) Generation of transmission frame Tf First, digital audio data is generated for n services. Each audio data is digitally compressed by MPEG1 Audio Layer 2 (hereinafter abbreviated as MP2). As shown in FIG. 2, each MP2 compressed audio data is encoded so as to be a transmission frame (Tf) repeated every certain time T1. As a result, Tf for n services is generated. Each Tf includes a synchronization CH, a fast information channel (FIC), and a main service channel (MSC). The synchronization CH is added at the beginning of Tf, that is, before the FIC and the MSC, and transmits a reference symbol for time synchronization / AFC or differential demodulation. The FIC indicates information such as a multiplex configuration and a label of a service to be transmitted. The MSC expresses data such as music information, dynamic labels, images, and HTML documents.

(2) Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) and transmission Next, digital frequency modulation is performed using each transmission frame Tf generated in (1) above. The digital frequency modulation method is the above-described OFDM. The signal thus generated is transmitted from the terrestrial DAB broadcast station antenna toward the service area as a BANDIII (200 MHz band) or L band band (1.5 GHz band) digital broadcast signal SDB.

(3) An example of a conventional DAB receiver A terrestrial digital audio broadcasting receiver receives a high-frequency analog signal, down-converts it to an intermediate frequency, and passes through a complicated process such as a technique for demodulating the limited digital signal format. Audio signal is played back. Therefore, quality inspection before factory shipment at the manufacturer not only requires time and technology, but it is difficult to repair defects on the production line or at the service center that accepts a failed receiver. In many cases, the receiver or the receiver itself must be replaced with a new one.

(4) Example of conventional patent application Regarding a receiver that supports a data format and modulation system for satellite broadcast signals, diagnoses whether each component constituting the receiver is normal or abnormal and notifies the inspector of the result of the diagnosis As a receiver having a self-diagnosis mode, there is one described in Japanese Patent Laid-Open No. 2000-341160.

In addition, the malfunction of the digital broadcast receiver is monitored, and when the malfunction is determined, the information is stored in the storage unit, the operation history of the user in the past several steps is stored as the operation information, and these information is stored as the billing information for the digital broadcast. JP, 2003-46889, A is mentioned as a system which transmits using a means to transmit etc. to a broadcasting station side.
JP 2000-341160 A JP 2003-46889 A

The DAB receiver reproduces necessary audio or data by performing a processing procedure reverse to that of the broadcast side on the above digital audio broadcast signal _SDB . However, these receivers must ensure a certain level of quality at the factory shipment stage. Therefore, the manufacturer performs a quality inspection (operation state inspection) on the receiver immediately before shipment from the factory. There has been a problem that it is desired that this quality inspection be performed accurately in a short working time.

  In addition, the receiver may break down while being used by the user. In this case, the user brings the failed receiver to a nearby service center or the like. In the service center, in order to find a faulty part of the receiver, the operating state of the receiver is inspected. This operation state inspection also has a problem that it is desired to be accurately performed in a short working time.

In the inspection, various inspection devices are used. One of the inspection devices is a signal generator. Signal generator is connected to the receiver antenna terminal to be inspected to generate a signal S _SUM simulating the digital broadcast signal S _DB as described above. The inspector of the manufacturer or the service center refers to the behavior of the receiver with respect to the simulation signal _SSUM from the signal generator and tries to find an abnormal part of the receiver. However, inspection equipment, especially signal generators, are very expensive. Therefore, depending on the service center, there is a problem that a receiver capable of diagnosing the operation state without requiring a signal generator is desired from the viewpoint of reducing capital investment.

  Therefore, an object of the present invention is to provide a receiver capable of reliably and quickly diagnosing whether or not each component constituting the apparatus is normal, and another object of the present invention is to provide a high capital investment. It is an object of the present invention to provide a receiver capable of diagnosing whether each component is normal or abnormal.

  Each of the above objects is solved by the following inventions. A first invention of a DAB receiver having a self-diagnosis function is a digital audio broadcasting generated by modulating a transmission frame generated based on a plurality of audio data services and then performing OFDM orthogonal frequency division multiplexing) A DAB receiver that performs predetermined processing on a signal and outputs sound, and the DAB receiver detects whether or not synchronization between the PLL circuit and the PLL circuit is established. And using a local oscillation output whose frequency is arbitrarily adjusted by the PLL circuit, down-converting an input signal of an arbitrary reception frequency included in a predetermined DAB frequency band, A tuner that generates a signal, and an intermediate frequency band signal generated by the tuner are OFDM demodulated and transmitted. An OFDM demodulator that reproduces the transmission frame, and a frame synchronization process that detects the beginning of the transmission frame reproduced by the OFDM demodulator, and then a fast information channel that generates the transmission frame and a plurality of audio data A digital signal having a CH decoder for reproducing a main service channel generated from the service, detecting a head of the main service channel and performing a synchronization process, and selecting a predetermined audio data service from the main service channel A processing unit, a DA converter that restores and outputs the audio data service output from the CH decoder of the digital signal processing unit to an original analog audio signal, a control unit that controls a self-diagnosis mode, and the control unit Diagnosis by A notification unit for notifying the result by a display unit, etc., and in the self-diagnosis mode, the control unit diagnoses whether the control data communication system with the OFDM demodulator or the like is normal. After controlling the tuner to have a predetermined reception frequency, it diagnoses whether the PLL circuit is normal or abnormal based on the detection result of the PLL synchronization detector, and if the PLL circuit is normal, the CH decoding When the frame synchronization processing of the detector is diagnosed as normal or abnormal, and the frame synchronization of the CH decoder is diagnosed as normal, the result of the diagnosis is notified to the notification unit, and the control data communication system, PLL circuit, OFDM When the demodulator and the CH decoder are diagnosed as abnormal, the result of the diagnosis is notified to the notification unit.

  A second invention is dependent on the first invention, and further includes a plurality of operation keys for outputting a signal based on the operation to the control unit when operated from the outside, wherein the control unit is in a self-diagnosis mode. In parallel with the diagnosis operation of the control data communication system, the PLL circuit, the OFDM demodulator and the CH decoder, it is diagnosed whether the operation key is normally operated based on the output signal from the operation key. When the abnormality is diagnosed from among the plurality of operation keys, the result of the diagnosis is notified to the notification unit, and when all the operation keys are diagnosed, the result of the diagnosis is displayed. The notification unit is notified.

  A third invention is dependent on the first invention, further includes a Viterbi decoder for detecting an error rate value of a digital signal included in an input signal to the OFDM demodulator, and the control unit includes a self-diagnosis mode Further, after synchronization is established in the OFDM demodulator, the error rate value detected by the Viterbi decoder is fetched a predetermined number of times, and the average value of the fetched error rate values is greater than or equal to a predetermined threshold value. If it is determined that the reception sensitivity is poor after diagnosing whether the reception sensitivity is good or not based on whether or not, the result of the diagnosis is notified to the notification unit, and if the reception sensitivity is determined to be good, the determination The result is notified to the notification unit.

  The fourth invention is dependent on the first invention, and stabilizes the supplied power supply voltage to provide drive voltages for driving the tuner, OFDM demodulator, CH decoder, Viterbi decoder, and the like. In the self-diagnosis mode, the control unit further includes one or more stabilized power supply units to be generated, and each drive voltage value generated by the stabilized power supply unit falls within a predetermined voltage range. Whether or not the stabilized power supply unit is normal or abnormal is diagnosed based on whether or not it is present, and the result is notified to the notification unit.

  The fifth invention is dependent on the first invention, and the diagnosis sequence performed by the control unit in the self-diagnosis mode is the diagnosis of the stabilized power supply unit, the control data communication system, and the PLL circuit. The OFDM demodulator and the CH decoder are diagnosed, and then the reception sensitivity is diagnosed. If all the diagnosis results are normal, the notification unit is informed of the normal notification and at the same time the DA converter is operated. The original voice signal is output, and when the abnormality is diagnosed during the diagnostic sequence, the abnormal part is notified to the notification unit.

  A sixth invention is dependent on the first to fifth inventions, wherein the receiver is configured so that a signal generator that generates a signal simulating a terrestrial digital broadcast signal can be connected to the tuner. In the diagnostic mode, the simulated signal generated by the signal generator is down-converted to generate an intermediate frequency band signal.

  A seventh invention is dependent on the first to fifth inventions, and the receiver is configured so that an antenna can be connected to the tuner in order to receive a terrestrial digital broadcast signal more reliably. In the self-diagnosis mode, the tuner down-converts the digital broadcast signal input through the antenna to generate an intermediate frequency band signal.

  According to the first invention, the receiver receives a digital audio broadcast signal generated based on the OFDM modulation and outputs audio. The control unit diagnoses whether each component of the receiver is normal or abnormal, and the notification unit outputs the diagnosis result of the control unit to the outside. Thus, the receiver can perform the self-diagnosis of each component for receiving the digital audio broadcast signal and outputting the sound, at high speed and with certainty.

  According to the second invention, in the receiver, it is diagnosed whether all the operation keys are normal or abnormal, whereby the receiver can perform a self-diagnosis more finely.

  According to the third invention, the receiver diagnoses whether the reception sensitivity is normal or abnormal. Thereby, the receiver can perform a self-diagnosis more finely.

  According to the fourth invention, the receiver diagnoses whether the stabilized power supply unit is normal or abnormal. Thereby, the receiver can perform a self-diagnosis more finely.

  According to the fifth aspect of the invention, the receiver operates each part in the order of diagnosis of the stabilized power supply unit, then diagnosis of the control data communication system, PLL circuit, OFDM demodulator and CH decoder, and then diagnosis of reception sensitivity. Is diagnosed as normal or abnormal. Thereby, the receiver can perform a self-diagnosis more finely.

  According to the sixth invention, the self-diagnosis mode is performed based on the simulation signal generated by the signal generator capable of generating a wide variety of simulation signals as is well known. As a result, the self-diagnosis mode of the receiver can be performed more strictly.

  According to the seventh aspect, the terrestrial digital broadcast signal is used even in the self-diagnosis mode. Therefore, the receiver can execute the self-diagnosis mode without using the expensive signal generator described in the sixth invention. Thereby, the capital investment required in connection with the receiver can be reduced.

  FIG. 1 is a block diagram showing an overall configuration of a receiver Rx according to an embodiment of the present invention, FIG. 2 is a diagram showing a data structure of the transmission frame, and FIG. 3 is a configuration of a voltage detector of FIG. FIG. 4 is a flowchart showing the procedure of the operation phase diagnostic phase executed by the control unit, FIG. 5 is a flowchart showing the procedure of the stabilized power source diagnostic phase executed by the control unit, and FIG. FIG. 7A is a flowchart showing the processing procedure of the diagnostic phase of the PLL circuit executed by the control unit, FIG. 7B is a diagram showing the frequency range of the DAB receiver, and FIG. 7 is the processing procedure of the signal processing unit executed by the control unit. FIG. 8 is a flowchart showing a processing procedure of a reception sensitivity diagnosis phase executed by the control unit.

  In FIG. 1, a receiver Rx includes an input terminal 1, a tuner 2 that down-converts an input signal having an arbitrary reception frequency included in a predetermined DAB frequency band, and generates a signal in an intermediate frequency band, and a digital signal. A processor 3, a D / A converter 4 that restores and outputs the audio data service output from the digital signal processor 3 to the original analog audio signal, a low-frequency amplifier 5, a speaker 6, and a power source 7 A stabilized power supply unit 8, a plurality of operation keys 9 for outputting a signal based on the operation when operated from the outside, a display 10 for displaying a diagnosis result, a control unit 11 for controlling a self-diagnosis mode, And an operation mode selector 12.

  The tuner 2 includes a PLL circuit 13 whose frequency is arbitrarily adjusted, a PLL synchronization detector 14 that detects whether synchronization of the PLL circuit 13 is established, and the like. In addition, tuner 2 includes a filter for selecting a frequency, a mixer for down-conversion, and a local oscillator. However, the filter, mixer, and local oscillator are not shown because they are not directly related to the nature of the self-diagnostic mode (described later) specific to the present application.

  The digital signal processing unit 3 includes an OFDM demodulator 15 that demodulates an intermediate frequency band signal generated by the tuner 2 and reproduces a transmission frame, a deinterleaver 16, and an input signal to the OFDM demodulator. Information generated by a Viterbi decoder 17 for detecting an error rate value of a digital signal and a frame synchronization process for detecting the head of a transmission frame reproduced by the OFDM demodulator 15 and then generating a transmission frame CH that reproduces a channel and a main service channel generated from a plurality of audio data services, detects the head of the main service channel and performs synchronization processing, and then selects a predetermined audio data service from the main service channel And issue unit 18, and a MPEG Decoder 19.

  The control unit 11 includes a voltage detector 20 and executes a “factory self-diagnosis mode”, a “normal operation mode”, or a “service self-diagnosis mode” according to the selection by the operation mode selector 12.

  Hereinafter, with reference to the flowcharts of FIGS. 4 to 8, the respective modes will be described in the order of the factory self-diagnosis mode, the normal operation mode, and the service self-diagnosis mode.

1. Self-diagnosis mode for factory First, the inspector of the factory prepares for step 401 of the self-diagnosis mode for factory as one process in the quality inspection at the shipping stage in FIG. The inspector connects a signal generator (not shown) to the input terminal 1. Signal generator generates a signal S _SUM simulating the terrestrial digital audio broadcasting signal S _DB mentioned in the description of the prior art. Next, the operation mode selector 12 selects and executes the factory self-diagnosis mode prepared in the receiver mode.

  Here, the operation key 9 will be described. The operation key 9 includes a plurality of various keys, and outputs a signal based on the operation to the control unit 11 when operated from the outside. In order to connect these keys, a connector is used or soldered. However, at the time of factory shipment, connector contact failure may occur or soldering connection failure may occur. The receiver Rx having such an abnormality must not be shipped. Therefore, the control unit 11 needs to diagnose whether the operation key 9 is normal or abnormal. Therefore, the control unit 11 executes a diagnosis phase of the operation key 9 described below.

1-1. Diagnosis Phase of Operation Key 9 In the main diagnosis phase of Step 402, the control unit 11 first displays a predetermined message on the display 10 and prompts the examiner to operate all keys. The inspector operates each key in response to the message. First, in step 403, when the inspection vehicle operates the key (1) of the operation key, the operation key 9 generates a signal for specifying the operated key (1). The control unit 11 takes in the input of the key (1) operated by the operation key 9. When the control unit 11 has received the key input and identifies the key (1) operated in step 404, the control unit 11 causes the display 10 to display that the key (1) is OK in step 405. The operation key (2) operates in the same manner in steps 406 to 408. Similarly, the control unit 11 similarly operates in steps 409 and 410 for the key (n) to capture input in all the operation keys 9. Judge whether or not. If the input of all keys has been taken in, no abnormality has occurred in the operation keys 9, so that all keys are displayed OK in step 411, and the control unit 11 exits from the diagnosis phase and will be described later. Proceed to step.

  On the other hand, when the input of all the keys is not taken in, the control unit 11 continues this diagnosis phase. If it is determined in step 404, 407, and 410 that all the keys have been operated but the key input is not captured, the display 10 inputs the corresponding key as not operated in step 412. Continue waiting display. Such a key has an abnormality such as a contact failure of a connector. Thereby, the inspector can know which operation key 9 is abnormal by referring to the display 10. As a result, the inspector prohibits shipment of the receiver Rx in which the operation key 9 is abnormal and repairs the corresponding key.

1-2. Diagnosis Phase of Stabilized Power Supply Unit 8 By the way, the voltage range in which the tuner 2 operates is predetermined. Now, it is assumed that the lower limit value of the operating voltage of the tuner 2 is V _MIN1 and the upper limit value thereof is V _MAX1 . Under this assumption, the drive voltage Vt supplied to the tuner 2 must satisfy V _MIN1 <Vt <V _MAX1 . Similarly, the lower limit value of the voltage at which the digital signal processor 3 can operate is assumed to be V _MIN2, and the upper limit value is assumed to be V _MAX2 . Under this assumption, the drive voltage Vd must satisfy V _MIN2 <Vd <V _MAX2 . The same applies to Va supplied to the low-frequency amplifier 5.

However, the drive voltage Vt, Vd or Va may not satisfy V _MIN <Vt, Vd, Va <V _MAX . That is, the stabilized power supply unit 8 or the power supply 7, the power switch, etc. may not be able to generate accurate drive voltages Vt, Vd, Va. The receiver Rx having such an abnormality must also not be shipped from the factory. Therefore, when the diagnosis phase of the operation key 9 ends, the control unit 11 transitions to step 501 in FIG. 5 which is the diagnosis phase of the stabilized power supply unit 8.

  In this diagnosis phase, the detection result of the voltage detector 20 is used. Here, the voltage detector 20 will be briefly described. As shown in FIG. 3, the voltage detector 20 includes a switch 21 and an A / D converter 22. The switch 21 is connected to the stabilized power supply unit 8 or the power supply 7. The switch 21 selectively receives the drive voltage Vt, Vd, Va designated by the control unit 11 and outputs it to the A / D converter 22. The A / D converter 22 converts the input analog drive voltages Vt, Vd, and Va into digital values, that is, converts them into digital values and takes them in by the control unit 11. In step 502, the control unit 11 first switches the switch 21 of the voltage detector 20 to designate Vd among the drive voltages Vt, Vd, and Va. The A / D converter 22 digitizes the drive voltage Vd designated at step 503.

The control unit 11 takes in the drive voltage Vd quantified in step 504 and determines whether or not the inequality of V _MIN2 <Vd <V _MAX2 is satisfied. When the inequality is not satisfied, the control unit 11 determines that the voltage Vd has failed in Step 505, and the stabilized power supply unit 8 or the power supply 7, the power switch, and the like are generated in Step 506 like “Vd NG”. The display 10 displays that the drive voltage is abnormal. ,
On the other hand, if the above inequality is satisfied in step 504, the power supply unit Vt is taken in in step 507, the Vt level is digitized in step 508, and it is determined in step 509 whether the inequality of V _MIN1 <Vt <V _MAX1 is satisfied. If the inequality is not satisfied, the control unit 11 determines that the voltage Vt has failed in step 510 and displays the same in step 511.

  When there is an unselected drive voltage Va in step 512, the control unit 11 designates an unselected Va and continues the diagnosis phase in the course of steps 513 to 517 as described above. In this way, it is determined whether or not all the drive voltages Vt, Vd, Va have been selected.

  If all the drive voltages Vt, Vd, and Va have been selected, the stabilized power supply unit 8 is normal in step 518, so the control unit 11 exits from this diagnosis phase and enters the PLL circuit diagnosis phase described later. move on.

As described above, in this diagnosis phase, it is determined in steps 504, 509, and 515 whether or not the drive voltages Vt, Vd, and Va are within a predetermined range. The display device 10 notifies the inspector of the abnormality of the stabilized power supply unit 8 when the drive voltages Vt, Vd, Va outside the proper range are detected. As a result, the inspector prohibits or repairs the shipment of the receiver Rx having an abnormality in the stabilized power supply unit 8 or the power supply 7, the power switch, or the like.
1-3. A signal generator is connected to the diagnostic phase input terminal 1 of the PLL circuit 13. The signal generator generates and outputs a simulation signal SSUM of the digital broadcast signal SDB. The simulation signal SSUM is input to the tuner 2 via the input terminal 1. In the tuner 2, the inputted simulation signal SSUM is down-converted to a signal SIF in the intermediate frequency band. When down-converting, a local oscillation output is used from a voltage controlled oscillator or the like. The frequency and phase of the local oscillation output are adjusted by the PLL circuit 13. That is, the frequency and phase of the local oscillation output are synchronized with the frequency and phase of the reference signal generated by a crystal oscillator (not shown) or the like.

  The PLL circuit 13 may also fail at the quality inspection stage. In addition, the margin of the transmission frequency range may be small. When the margin of the transmission frequency range is small, it is assumed that a failure mode will eventually occur due to ambient temperature and aging. The receiver Rx having the PLL circuit 13 having a failure or a small margin is not suitable for shipping. Therefore, the control unit 11 executes the diagnosis phase 601 of the PLL circuit 13 of FIG. 6A after exiting from the diagnosis phase of the stabilized power supply unit 8 of FIG. If the factory mode is selected by the operation mode selector 12, the process proceeds from step 602 to step 603. In this phase, the detection result of whether or not the synchronization by the PLL synchronization detector 14 is established is used. The PLL synchronization detector 14 is connected to the PLL circuit 13. The result of detecting the establishment of synchronization is output from the PLL synchronization detector 14 and is captured by the control unit 11. The control unit 11 determines whether or not synchronization is established in the PLL circuit 13 based on the acquired detection result after a certain time t. When it is determined to be normal, the control unit 11 sends out PLL data and median data from the control unit 11 that exceed the reception frequency range necessary for the digital broadcast receiver in steps 603, 605, and 607. After a time, it is checked whether PLL synchronization is established in steps 604, 606, and 608. That is, it is confirmed that there is a transmission frequency margin of the PLL circuit 13. FIG. 6B shows an example of the DAB reception frequency range.

  When the synchronization is established, the control unit 11 diagnoses that the PLL circuit 13 is normal and ends the diagnosis phase. The control unit 11 exits from the diagnosis phase and proceeds to the next phase. On the other hand, when the synchronization is not established, the PLL circuit 13 is abnormal. For this reason, the control unit 11 causes the display 10 to display that the PLL circuit 13 is abnormal as “PLL NG” in step 609. As described above, according to this diagnosis phase, it is diagnosed whether the PLL circuit 20 is normal or abnormal. As a result, the inspector prohibits shipment of the receiver Rx having an abnormality in the PLL circuit 20 or sends it to repair.

1-4. Diagnosis Phase of Digital Signal Processing Unit 3 In FIG. 1, signal S _IF is input to OFDM demodulator 15. The baseband signal S _BB , that is, Tf is reproduced by the OFDM demodulator 15. After exiting the diagnostic phase of the PLL circuit 13, the control unit 11 transitions to the diagnostic phase 701 of the digital signal processing unit 3 in FIG. In this diagnosis phase, it is detected whether or not a synchronization signal of Tf has been established. When the communication check is OK in step 703, the IF communication check is OK in step 704, the interrupt check is OK in step 705, and the synchronization is established, the digital signal processing unit 3 detects that it indicates Generate results. The detection result is captured by the control unit 11.

  When synchronization is established, the control unit 11 exits from the diagnosis phase and proceeds to the next phase (described later). If synchronization is not established, in step 706, the display 10 displays that the digital signal processing unit 3 is abnormal as “LSI NG”.

1-5. Reception Sensitivity Diagnosis Phase In the reception sensitivity diagnosis phase 801, the signal _SIF is input to the OFDM demodulator 15 in FIG. When the level of the input signal _SIF decreases or noise increases, the error rate after the Viterbi decoder 18 deteriorates through the deinterleaver. This error rate value by the Viterbi decoder 18 indicates the sensitivity of the received radio wave at that time in the receiver Rx. After synchronization is established in the OFDM demodulator 15, the error rate value detected by the Viterbi decoder 18 is fetched a predetermined number of times, and based on whether the average value of the fetched error rate values is equal to or greater than a predetermined threshold value. If the error rate value is below the standard after diagnosing whether the reception sensitivity is good or bad, the receiver Rx is determined to have some abnormality in the system and becomes unsuitable for shipping. Therefore, the control unit 11 executes the reception sensitivity diagnosis phase 801, monitors the error rate value in step 802, detects whether the reception sensitivity is good or bad, and notifies the inspector.

In step 803, the control unit 11 calculates an average value BER _AVE of i _PRE error rate values. Next, in step 5804, the average value BER _AVE is compared with the reference value BERth, and in step 805, it is determined whether or not the average value BER _AVE is larger than a predetermined reference value BERth. The reference value BERth is a threshold value for determining whether the reception sensitivity of the receiver Rx is good or bad. If the average value BER _AVE is equal to or less than the reference value BERth, the sound output from the receiver Rx contains a lot of noise, and therefore the receiver Rx is not suitable for shipping.

If BER _AVE > BERth is not satisfied in step 805, the control unit 11 causes the display 10 to display that the reception sensitivity is poor as “BER NG” in step 806. As a result, the inspector prohibits shipment of the receiver Rx having poor reception sensitivity or sends it to repair.

On the other hand, if it is determined in step 805 that BER _AVE > BERth, the control unit 19 determines that the reception sensitivity is good. As a result, the control unit 11 shows that there is no abnormality in the reception sensitivity of the operation key 9, the stabilized power supply unit 8, the serial data communication system, the PLL circuit 13, the digital signal processing unit 3, and the receiver Rx. Although not shown, the control unit 11 causes the display 10 to display that the diagnosis result of the receiver Rx is good, such as “CHECK OK”.

  In step 807, the control unit 11 supplies the low frequency amplifier 5 with the voltage Vcc from the power source 7, and the speaker 9 outputs sound. Therefore, the inspector can actually listen to the voice in step 808 after the end of the self-diagnosis mode for the factory and determine whether or not the receiver Rx normally outputs the voice. As a result, the inspector can only permit shipment of the normally operating receiver Rx.

  When the above-described self-diagnosis mode for factories ends, finally, the inspector operates the operation mode selector 12 to set the mode of the receiver Rx to the normal operation mode. Thereafter, a normal receiver Rx is shipped and put in the user's hand.

2. Normal operation mode The user enjoys sound through the receiver Rx. At this time, the normal operation mode is executed in the receiver Rx. As described above, when shipped from the factory, the state of the receiver is set to the normal operation mode. By operating only the operation key 9, the user gives an instruction to the control unit 11, and can know the state of the receiver Rx by sound from the display 10 or the speaker 6.

  In parallel, the control unit 11 performs self-diagnosis even when the user is using the receiver Rx in the normal operation mode, and continues to monitor the failure part. Here, when an abnormality occurs in the stabilized power supply unit 8, the serial data communication system, the PLL circuit 13, and the digital signal processing unit 3 during the normal operation mode, the control unit 11 immediately indicates “***” of the abnormal part. The above message such as “NG” is displayed on the display 10. Further, the display 10 can be equipped with display contents for the user to easily check the error rate of the reception sensitivity.

3. Self-diagnosis mode for service As described above, in the self-diagnosis mode for factories, since a high-accuracy quality inspection is required, the simulated signal _SSUM of the signal generator is used. However, signal generators are expensive. Therefore, some service centers do not have a signal generator. Therefore, the receiver Rx is the fault site in the self-diagnosis mode for services for self-diagnosis, using digital broadcast signals S _DB that is actually delivered from the ground DAB antenna. Hereinafter, the service self-diagnosis mode will be described in detail. However, there are places similar to the self-diagnosis mode for factories. Therefore, in the following description, processing similar to that for the factory will be briefly described.

  An inspector such as a service center prepares to inspect the receiver Rx. First, an optional antenna (not shown) other than the attached antenna is connected to the input terminal 1. The inspector sets the operation mode by the operation mode selector 12 so as to execute the self-diagnosis mode for service.

  When the above preparation is completed, the control unit 11 knows that the mode to be executed at present is the service self-diagnosis mode and executes it.

As described above, the occupied frequency band of the digital broadcast signal _SDB varies from region to region. Therefore, if the receiver Rx is the failure location to the self-diagnosis using a digital broadcast signal S _DB, the examiner reception area, that it is necessary to input the frequency band to be received the receiver Rx is. In FIG. 6A, when service use is selected in step 602, a region is selected using an operation key in step 610. Further, audio data for n services determined in advance is multiplexed on the digital broadcast signal _SDB . Therefore, the inspector needs to select and input one of the services in order to cause the receiver Rx to execute the diagnosis mode. Therefore, the inspector operates the operation key 9 to specify the reception area and the service. The operation key 9 generates a signal S _AREA that specifies a reception area and a signal S _SE that specifies a service.

First, the control unit 11 takes in the signal S _AREA and the signal S _SE generated by the operation key 9. The signal S _AREA and the signal S _SE are held in the storage area of the control unit 11. The signal S _AREA is used in a diagnosis phase of the PLL circuit 13 to be described later. The signal _SSE is used in a diagnostic phase of digital signal processing 3 described later.

3-1. The diagnosis phase of the operation key 9 The service self-diagnosis mode is the same as that for the factory in FIG. 4 described above, and the description of this diagnosis phase is omitted. By this diagnosis phase, the display device 10 can notify the inspector that the operation key 9 is broken in the receiver Rx.

3-2. Diagnosis phase of the stabilized power supply unit 8 When no abnormality is detected in the operation key 9, a transition is made to this diagnosis phase, as in the self-diagnosis mode for factories. Since the same processing as that for the factory in FIG. 5 is performed in this diagnosis phase, description of this diagnosis phase is omitted. By this diagnosis phase, the display 10 can notify the inspector that the stabilized power supply unit 8 has failed in the receiver Rx.

3-3. Diagnosis phase of the PLL circuit 13 When no abnormality is detected in the stabilized power supply unit 8, a transition is made to this diagnosis phase. In the service self-diagnosis mode, a digital broadcast signal _SDB that is actually transmitted toward the service area is used. Therefore, this diagnosis phase is different from that in the factory self-diagnosis mode.

As described at the beginning of this section, the inspector inputs the reception area in step 610 of FIG. 6A, so that the control unit 11 uses the signal S _AREA held in the storage area described above. In step 611, the frequency control data D _FREQ is generated. As described above, the terrestrial digital audio broadcast signal _SDB is currently supplied to the receiver Rx. Digital broadcast signal S _DB are those carrier frequencies fc2 assigned to the receiving area is OFDM modulated in the transmission frame. Therefore, digital broadcast signals S _DB is included in the occupied frequency band Bc2 having a center frequency fc2. The control unit 11 sends the generated frequency control data D _FREQ to set the reception frequency band of the tuner 2 to the occupied frequency band Bc2. As a result, the tuner 2 starts receiving the digital broadcast signal _SDB .

  Thereafter, the control unit 11 executes this diagnosis phase in the same manner as the factory self-diagnosis mode of FIG. When an abnormality of the PLL circuit 13 is detected, the display 10 notifies the inspector accordingly. Thereby, the inspector can know that there is an abnormality in the PLL circuit 13 in the receiver Rx.

3-4. Diagnosis phase of digital signal processing unit 3 When no abnormality is detected in the PLL circuit 13, the control unit 11 shifts to a frame synchronization diagnosis phase of the digital signal processing unit. This diagnosis phase is the same as that in FIG. 7 for the factory, and the description of this diagnosis phase is omitted. Through this diagnosis phase, the display 10 can notify the examiner that an abnormality has occurred in the frame synchronization processing in the digital signal processing unit 3.

3-5. Reception Sensitivity Diagnosis Phase When no abnormality is detected in the frame synchronization processing of the digital signal processing unit 3, the control unit 11 transitions to a reception sensitivity diagnosis phase. This diagnosis phase is the same as that of FIG. 8 for factory use, and description of this diagnosis phase is abbreviate | omitted. Through this diagnosis phase, the display 10 can notify the examiner that the reception sensitivity is abnormal. In this case, care must be taken in a place where the environment of the received radio wave is guaranteed. Whether the reception sensitivity is normal or abnormal is preferably determined by comparing with a receiver that is a reference for which performance is guaranteed.

  When the reception sensitivity is normal, the receiver Rx has an abnormality in the reception sensitivity of the operation key 9, the stabilized power supply unit 8, the serial data communication system, the PLL circuit 13, the digital signal processing unit 3, and the receiver Rx. It turns out that it has not occurred. In this case, the display 10 displays on the display 10 that the diagnosis result of the receiver Rx is good. Thereby, the inspector can know that the receiver Rx is normal.

  By the above self-diagnosis mode for service, the inspector can know where the receiver Rx is out of order. After the found failure part is repaired, the operation mode selector 12 is operated, and the mode of the receiver Rx is set to the normal operation mode. The repaired receiver Rx is then returned to the user.

  As described above, the receiver Rx executes two types of self-diagnosis modes as necessary. In any self-diagnosis mode, the control unit 11 of the receiver Rx diagnoses whether each unit constituting the receiver Rx is normal or abnormal. That is, the receiver Rx performs self-diagnosis. As a result, the work burden on the inspector in the quality inspection or the inspection of the faulty part is reduced. Furthermore, the control unit 11 can reliably determine whether each component is normal or abnormal by each determination step in its own processing procedure.

Further, the receiver Rx is configured to be able to connect a signal generator. In the factory self-diagnosis mode, the simulation signal _SSUM from the signal generator is used. As a result, it is possible to provide a receiver Rx that can cope with a quality inspection at a factory shipment stage in which a strict inspection is required.

  Furthermore, in the service self-diagnosis mode, the digital broadcast signal SDB transmitted from the terrestrial DAB antenna can be used. As a result, the service center or the like can easily and reliably find the failure location without using an expensive signal generator.

  When a service center or the like has a signal generator, a factory self-diagnosis mode may be executed even for finding a fault location.

  Further, in the above embodiment, the display device 10 notifies the inspector of the abnormal part of the receiver Rx. However, it is also easy for the speaker 6 to notify the abnormal part of the receiver Rx by voice. That is, the receiver Rx may include any configuration as long as it is a configuration that notifies the examiner of the diagnosis result of the control unit 11 (a notification unit in the claims).

  In the above embodiment, in both diagnosis modes, the presence or absence of abnormality is diagnosed in the order of the operation key 9, the stabilized power supply unit 8, the PLL circuit 13, the frame synchronization processing of the digital signal processing unit 3, and the reception sensitivity. It was. This is a preferred example and should not be construed as limited to this procedure.

  Furthermore, in the above embodiment, the operation mode selector may use a hidden switch that does not touch the user's eyes when switching to the self-diagnosis mode for the factory and the self-diagnosis mode for the service.

  As described above, according to the DAB receiver having the self-diagnosis function of the present invention, the quality inspection immediately before factory shipment can be performed accurately in a short working time, and while the user is using it. When a failure occurs, it is possible to accurately perform an operation state inspection for finding a failure point of the receiver in the service center in a short work time.

  Further, in the inspection at the service center, it is possible to diagnose the operating state without using an expensive signal generator, and the industrial applicability is high.

The block diagram which shows the whole structure of receiver Rx which concerns on one Embodiment of this invention. Diagram showing data structure of transmission frame Block diagram showing the configuration of the voltage detector of FIG. The flowchart which shows the process sequence of the diagnostic phase of the operation key which a control part performs The flowchart which shows the process sequence of the diagnostic phase of the stabilization power supply part which a control part performs (A) Flowchart showing processing procedure of diagnosis phase of PLL circuit executed by control unit (b) Diagram showing frequency range of DAB receiver The flowchart which shows the process sequence of the signal processing part which a control part performs The flowchart which shows the process sequence of the diagnostic phase of the receiving sensitivity which a control part performs

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna input terminal 2 Tuner 3 Digital signal processing part 4 D / A converter 5 Low frequency amplifier 6 Speaker 7 Power supply 8 Stabilization power supply part 9 Operation key 10 Display 11 Control part 12 Operation mode selector 13 PLL circuit 14 PLL synchronization Detector 15 OFDM demodulator 16 Deinterleaver 17 Viterbi decoder 18 CH decoder 19 MPEG decoder 20 Voltage detector 21 A / D input switch 22 A / D converter

Claims (7)

After a transmission frame generated based on a plurality of audio data services is configured, DAB reception that outputs audio by performing predetermined processing on the digital audio broadcast signal generated by orthogonal frequency division multiplexing modulation Machine,
The DAB receiver has a PLL circuit and a PLL synchronization detector that detects whether synchronization of the PLL circuit is established, and uses a local oscillation output whose frequency is arbitrarily adjusted by the PLL circuit. A tuner for down-converting an input signal of an arbitrary reception frequency included in a predetermined DAB frequency band to generate a signal of an intermediate frequency band;
An OFDM demodulator that reproduces a transmission frame by performing orthogonal frequency division multiplexing demodulation on the intermediate frequency band signal generated by the tuner and a frame synchronization process that detects the beginning of the transmission frame reproduced by the OFDM demodulator After playing the fast information channel generating the transmission frame and the main service channel generated from a plurality of audio data services, detecting the head of the main service channel and performing synchronization processing, A digital signal processor having a CH decoder for selecting a predetermined audio data service from the main service channel;
A DA converter that restores the audio data service output from the CH decoder of the digital signal processing unit to the original analog audio signal and outputs it;
A control unit for controlling the self-diagnosis mode;
A notification unit for notifying the result of diagnosis by the control unit using a display device or the like,
In the self-diagnosis mode, the control unit diagnoses whether the control data communication system with the OFDM demodulator or the like is normal, and if normal, after controlling the tuner to a predetermined reception frequency, Based on the detection result of the PLL synchronization detector, diagnose whether the PLL circuit is normal or abnormal, and if the PLL circuit is normal, diagnose whether the frame synchronization processing of the CH decoder is normal or abnormal, When the frame synchronization of the CH decoder is diagnosed as normal, the result of the diagnosis is notified to the notification unit,
When the control data communication system, the PLL circuit, the OFDM demodulator and the CH decoder are diagnosed as abnormal, the DAB receiver having a self-diagnosis function is characterized in that the result of the diagnosis is notified to the notification unit. . A plurality of operation keys for outputting a signal based on the operation to the control unit when operated from the outside;
In the self-diagnosis mode, the control unit performs the operation key operation based on the output signal from the operation key in parallel with the diagnosis operation of the control data communication system, PLL circuit, OFDM demodulator, and CH decoder. Diagnose whether or not it has been operated normally, and when it is diagnosed that there is an abnormality from among the plurality of operation keys, notify the notification unit of the result of the diagnosis,
2. The DAB receiver having a self-diagnosis function according to claim 1, wherein when all of the operation keys are diagnosed as normal, the result of the diagnosis is notified to the notification unit. A Viterbi decoder for detecting an error rate value of a digital signal included in an input signal to the OFDM demodulator;
In the self-diagnosis mode, after the synchronization is established in the OFDM demodulator, the control unit captures an error rate value detected by the Viterbi decoder a predetermined number of times, and an average value of the captured error rate values is obtained in advance. After determining whether the reception sensitivity is good or not based on whether or not the threshold value is greater than or equal to a predetermined threshold, if the reception sensitivity is determined to be bad, the result of the diagnosis is notified to the notification unit,
2. The DAB receiver having a self-diagnosis function according to claim 1, wherein when it is determined that the reception sensitivity is good, the result of the determination is notified to the notification unit. And further comprising one or more stabilized power supply units that stabilize a supplied power supply voltage and generate a drive voltage for driving each of the tuner, the OFDM demodulator, the CH decoder, the Viterbi decoder, and the like.
In the self-diagnosis mode, the control unit further determines whether the stabilized power supply unit is based on whether the value of each drive voltage generated by the stabilized power supply unit is within a predetermined voltage range. 2. The DAB receiver having a self-diagnosis function according to claim 1, wherein the DAB receiver diagnoses whether it is normal or abnormal, and notifies the result to the notification unit. The diagnosis sequence performed by the control unit in the self-diagnosis mode is firstly diagnosis of the stabilized power supply unit, then diagnosis of the control data communication system, PLL circuit, OFDM demodulator and CH decoder, and then the reception In the order of diagnosis of sensitivity, if all the diagnosis results are normal, simultaneously notify the notification to the notification unit, and simultaneously operate the DA converter to output the original audio signal,
2. The DAB receiver having a self-diagnosis function according to claim 1, wherein, when an abnormality is diagnosed during the diagnostic sequence, the notification unit is notified of the abnormality. The receiver is configured to connect a signal generator that generates a signal simulating a terrestrial digital broadcast signal to the tuner, and the tuner down-converts the simulated signal generated by the signal generator in the self-diagnosis mode. 6. A DAB receiver having a self-diagnosis function according to claim 1, wherein a signal in an intermediate frequency band is generated. The receiver is configured to connect an antenna to a tuner in order to receive a terrestrial digital broadcast signal more reliably. In the self-diagnosis mode, the tuner down-converts the digital broadcast signal input through the antenna. 6. The DAB receiver having a self-diagnosis function according to claim 1, wherein the DAB receiver generates a signal in an intermediate frequency band.

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