JP5177654B2 - Radio receiving terminal apparatus and receiving channel scanning method - Google Patents

Description

  The present invention relates to a radio reception terminal device and a reception channel scanning method, and particularly suitable for use in a radio reception terminal device capable of receiving a plurality of types of broadcast waves and a reception channel scan method executed in the radio reception terminal device. Is.

  In recent years, wireless services for mobile devices such as mobile devices and automobiles are increasing. For example, in addition to or instead of conventional analog broadcasting, recently, there is also provided one capable of receiving digital broadcasting. For example, in Europe, there are digital radio broadcast standards called DAB (Digital Audio Broadcast) and digital television broadcasts called DVB (Digital Video Broadcasting) as digital broadcast standards. An apparatus that can receive these two digital broadcasts by one terminal has also been proposed.

  In addition to the above-mentioned DVB, which is an internationally approved standard, digital television broadcasting includes ISDB (Integrated Services Digital Broadcasting), a standard developed mainly by the Japan Broadcasting Corporation in Japan, There is a wireless service such as ATSC (Advanced Television Systems Committee), which is a standard developed in Japan.

  By the way, with the globalization of the economy, a single manufacturer is increasingly producing radio reception terminal devices for a plurality of countries. In this case, if a wireless receiving circuit corresponding to a plurality of standards (broadcasting systems) is mounted on one wireless receiving terminal device, the manufacturer can enjoy the advantage that it is not necessary to manufacture a product for each destination country.

  Conventionally, in order to receive wireless services of these multiple standards (multiple systems) with a single wireless receiving terminal device, it was necessary to prepare dedicated antennas and wireless receiving circuits designed for each system separately. . For this reason, there has been a problem that the circuit scale increases in accordance with the number of wireless service systems to be implemented, and the cost also increases. In particular, it has been difficult to mount such a large-scale radio receiving circuit on a small terminal such as a mobile phone.

  As one method for solving such a problem, there is a technique called “reconfigurable radio circuit”. The reconfigurable radio circuit is a technology that allows the reception function to be freely switched by updating the applied software. If this technology is used, a set of radio reception circuits using multiband antennas, multiband RF (Radio Frequency) circuits, etc. are prepared for radio reception terminal devices that switch between and use multiple types of radio services as necessary. It can be realized just by doing.

For example, by specifying the modulation method based on the current position of the receiver detected by the GPS receiver and the discrimination result of the television broadcast standard in the received radio wave, and by updating the software so as to correspond to the specified modulation method There has been proposed a reconfigurable receiver that switches a function of a programmable logic circuit and demodulates a received television broadcast standard radio wave (for example, see Patent Document 1). In addition, a technique has been proposed in which a TV signal tuning process using TV channel scanning information is executed, and a demodulation bandwidth is predicted from TV channel scanning information of the channel-scanned TV signal (see, for example, Patent Document 2). ).
JP 2006-86730 A JP 2007-89038 A

  However, if the wireless service to be used is switched by software update, as in a reconfigurable radio circuit, it takes time to update the software and reset the channel (reception frequency) at the tuner, and the response performance There was a problem of getting worse.

  For example, when performing a scan process to create a broadcast system channel list that can be received in an area where a wireless reception terminal device exists, it is necessary to sequentially switch a plurality of systems and perform the scan process one by one. . At this time, not only the software needs to be updated every time the broadcasting system is switched, but also the tuning (reception frequency setting) in the tuner must be repeated using the updated software. For this reason, there is a problem that it takes a long time to complete the scanning process.

  The present invention has been made to solve such a problem. In a wireless reception terminal device capable of receiving a plurality of types of broadcast waves, the circuit scale can be reduced and the plurality of methods can be used. An object of the present invention is to shorten the time required for the scanning process.

In order to solve the above-described problems, the present invention provides a front-end circuit that performs processing from reception of an OFDM-modulated broadcast wave to OFDM demodulation of the received signal and detection of a synchronization signal from the demodulated signal. One set is provided as a circuit common to a plurality of systems. In addition, when performing scan processing across multiple broadcast systems, multiple demodulation parameters corresponding to multiple broadcast systems are sequentially switched and set to the OFDM demodulator, and when OFDM is synchronized (synchronization signals can be detected). A receivable method among a plurality of methods is determined on the basis of the value of the demodulation parameter set in (1) and at least the value of the demodulation parameter of the type of the synchronization signal.

  According to the present invention configured as described above, only one set of front-end circuits is provided as a common circuit for a plurality of broadcasting systems, so that the conventional technique in which a plurality of front-end circuits are provided according to the number of broadcasting systems is provided. In comparison, the circuit scale can be reduced.

  Also, when receiving an OFDM-modulated broadcast wave, the process from receiving the broadcast wave to OFDM demodulating it and detecting the synchronization signal from the demodulated signal is the same regardless of the broadcast system ( That is, it can be executed by a circuit having the same function. For this reason, when performing scan processing over a plurality of broadcasting systems, it is not necessary to update software in order to change the function of the circuit each time the system is switched.

  Further, the difference in the broadcasting system can be determined from at least one of the value of the demodulation parameter set in the OFDM demodulator and the type of the detected synchronization signal. In the present invention, when performing scan processing over a plurality of broadcasting systems, values corresponding to a plurality of broadcasting systems are sequentially set as OFDM demodulation parameters for one reception frequency in the OFDM demodulator, and OFDM Therefore, it is not necessary to change the frequency setting of the tuner one by one when switching the broadcasting system.

  As described above, according to the present invention, it is not necessary to update the software or set the tuner frequency each time the method is switched, so that it is possible to shorten the time required for the scan processing across a plurality of methods.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of a wireless reception terminal device according to the first embodiment. The wireless reception terminal device according to the first embodiment is a device capable of receiving a plurality of OFDM-modulated broadcast waves, and includes one front-end circuit 100 and a plurality of decoding circuits 200 as shown in FIG. And one controller (CPU) 300.

  In the first embodiment, a plurality of decoding circuits 200 are provided in a number corresponding to the number of broadcasting systems that can be received by the wireless reception terminal device. Here, as an example, it is assumed that the wireless receiving terminal device can receive broadcast waves of two broadcasting systems, DAB which is a European digital radio broadcasting standard and DVB which is a European digital television broadcasting standard. In this case, the plurality of decoding circuits 200 includes a DAB decoding circuit 200A and a DVB decoding circuit 200B.

  Only one front-end circuit 100 is provided in the wireless reception terminal device as a circuit commonly used in the two broadcasting systems. As shown in FIG. 1, the front-end circuit 100 includes a tuner 11, an A / D converter 12, an orthogonal demodulation unit 13, an FFT processing unit 14, a synchronization detection unit 15, and a method determination unit 16.

  The tuner 11 receives an OFDM-modulated broadcast wave via an antenna 400 connected to the front end circuit 100 and selects a channel. The tuner 11 is a so-called multiband tuner that supports both the DAB broadcast frequency band and the DVB broadcast frequency band. Specifically, as shown in FIG. 2, the tuner 11 includes an antenna input circuit 21, a high frequency amplification circuit 22, a frequency conversion circuit (mixer) 23, a local oscillation circuit 24, a channel selection circuit 25, an intermediate frequency amplification circuit 26, and the like. It is possible to apply a known technique.

  A broadcast wave signal received by the antenna 400 is OFDM-modulated on the broadcast station side, and is further up-converted to an RF signal by frequency conversion using orthogonal modulation. The antenna input circuit 21 of the tuner 11 performs a process of removing the interference signal from the RF signal received by the antenna 400. The high frequency amplifier circuit 22 performs a process of selectively amplifying an RF signal output from the antenna input circuit 21 only at a specific band at the same frequency.

  The frequency conversion circuit 23 mixes the RF signal output from the high frequency amplifier circuit 22 and the local oscillation signal output from the local oscillation circuit 24, and obtains a signal having a frequency difference between them, thereby converting the RF signal. Convert to IF (Intermediate Frequency) signal. The channel selection circuit 25 sets the frequency of the local oscillation signal (local oscillation frequency) to a value corresponding to the selected reception frequency (broadcast channel). For example, when performing a scanning process in order to create a broadcast system channel list that can be received in an area where a wireless reception terminal device exists, the channel selection circuit 25 outputs a local signal output from the local oscillation circuit 24 in accordance with control from the CPU 300. The local oscillation frequency of the oscillation signal is switched and set sequentially.

  The intermediate frequency amplifier circuit 26 amplifies the IF signal output from the frequency conversion circuit 23 and performs processing for removing signals other than the desired wave. The IF signal amplified by the intermediate frequency amplifier circuit 26 is supplied to the A / D converter 12 of FIG. The A / D converter 12 converts the IF signal output from the intermediate frequency amplifier circuit 26 of the tuner 11 from an analog signal to a digital signal. The orthogonal demodulator 13 demodulates (down-converts) the digital IF signal (orthogonally modulated) output from the A / D converter 12 to baseband.

  The FFT processing unit 14 corresponds to the OFDM demodulation unit of the present invention, and is based on the baseband signal generated by the orthogonal demodulation unit 13 (the frequency of the signal output from the tuner 11 is down-converted). Perform fast Fourier transform (FFT) processing. The FFT processing performed here corresponds to a known OFDM demodulation processing for OFDM modulation (IFFT processing) performed on a broadcast wave signal on the broadcasting station side.

  The FFT processing unit 14 sets a window function for the signal output from the quadrature demodulation unit 13 when performing the FFT processing. That is, the FFT process is performed assuming that only the portion in the window set by the window function is a periodic waveform that repeats forever from the past to the future. Since it is assumed to be a periodic waveform, the signal can be expanded into a Fourier series and harmonics can be analyzed.

  Before setting the window function for the signal output from the quadrature demodulator 13, the frequency (reception frequency) of the signal output from the quadrature demodulator 13 by automatic frequency control such as AFC (Automatic frequency control). You may perform the process which stabilizes. AFC is a process for automatically adjusting the frequency of a signal to the broadcast frequency by feeding back the difference between the reception frequency and the broadcast frequency. By correcting the shift in reception frequency, it is possible to suppress the occurrence of DC offset.

  The FFT processing unit 14 also sets an FFT size (corresponding to an OFDM carrier interval) as a demodulation parameter when performing FFT processing on the signal output from the orthogonal demodulation unit 13. The appropriate FFT size depends on the broadcast wave received by the wireless reception terminal device of this embodiment. That is, the broadcast station side determines a desired FFT size when OFDM modulating a broadcast wave signal. Therefore, the FFT processing unit 14 that performs OFDM demodulation needs to set the same size as the FFT size used in the OFDM modulation and execute the FFT processing.

  When performing a scanning process to create a channel list of broadcast stations that can be received in an area where the wireless reception terminal device of the present embodiment exists, an appropriate FFT size is unknown. After setting the frequency of a certain broadcast channel for the tuner 11, the FFT processing unit 14 sequentially sets FFT values of different values as variable parameters in accordance with control from the controller 300. Then, as a result of the FFT processing performed by the FFT processing unit 14 with each of the set FFT sizes, the synchronization detection unit 15 to be described later determines whether the OFDM carrier has been detected properly, in other words, whether the OFDM has been synchronized. To check whether the broadcast channel can be received.

  When the broadcasting system is DAB, the FFT size that can be set when performing OFDM modulation on the broadcasting station side is any one of 1/4 kHz, 1/2 kHz, 1 kHz, and 2 kHz. When the broadcast system is DVB, the FFT size that can be set when performing OFDM modulation on the broadcast station side is any one of 2 kHz, 4 kHz, and 8 kHz. That is, when performing the scanning process, the FFT processing unit 14 sequentially sets these FFT sizes as variable parameters, and executes the FFT process. As will be described in detail later, the FFT processing unit 14 sequentially switches and sets a plurality of FFT sizes corresponding to the two broadcasting systems for one broadcasting channel (reception frequency).

  The synchronization detection unit 15 detects a synchronization signal from the signal output from the FFT processing unit 14. The type of synchronization signal detected varies depending on the method (standard) of the broadcast wave being received. When receiving a DAB broadcast wave, the synchronization detection unit 15 detects a synchronization signal (hereinafter referred to as an FP signal) called “Frame Preamble”. When receiving a DVB broadcast wave, the synchronization detection unit 15 detects a synchronization signal (hereinafter referred to as an SP signal) called “SP (Scattered Pilot)”.

  The method determination unit 16 is a receivable method among a plurality of methods based on the combination of the FFT size value set as the demodulation parameter in the FFT processing unit 14 and the type of the synchronization signal detected by the synchronization detection unit 15. Determine. Further, as described above, the method determination unit 16 determines whether the OFDM is synchronized as a result of the FFT processing by the FFT processing unit 14 (whether the synchronization signal is detected by the synchronization detection unit 15) or not to the current tuner 11. It is determined whether the set broadcast channel is a receivable channel.

  For example, if any one of the FFT sizes of 1/4 kHz, 1/2 kHz, 1 kHz, and 2 kHz is set in the FFT processing unit 14, and the FP signal is detected by the synchronization detection unit 15, the method determination unit 16 Is determined to be receivable. Further, when any of the 2 kHz, 4 kHz, and 8 kHz FFT sizes is set in the FFT processing unit 14, if the SP signal is detected by the synchronization detection unit 15, the method determination unit 16 can receive the DVB broadcast method. Is determined. In this determination, the method determination unit 16 acquires information indicating which FFT size is set in the FFT processing unit 14 from the controller 300, and acquires information regarding which synchronization signal is detected from the synchronization detection unit 15. .

  Each of the plurality of decoding circuits 200 corresponds to the decoding unit of the present invention, and performs a decoding process corresponding to the broadcast method determined to be receivable by the method determining unit 16. That is, the DAB decoding circuit 200A performs a decoding process corresponding to the DAB broadcasting method to generate a so-called transport stream signal. The DVB decoding circuit 200B performs a decoding process corresponding to the DVB broadcasting method to generate a so-called transport stream signal.

  The controller 300 corresponds to the control unit of the present invention, and includes a channel selection process in the tuner 11 provided in the front-end circuit 100, a demodulation parameter (FFT size) setting process for the FFT processing unit 14, and a decoding circuit 200. Control the decoding process. When the controller 300 performs a scanning process for creating a receivable channel list by sequentially switching reception frequencies to be selected by the tuner 11, an FFT corresponding to a plurality of broadcasting systems is selected for one reception frequency to be selected. Control is performed so that the size value is sequentially switched and set in the FFT processing unit 14.

  In this case, the method determination unit 16 selects the FFT size value when the OFDM is synchronized from the signal output from the FFT processing unit 14 among the different values of the FFT size set by sequentially switching by the controller 300. Based on the combination with the type of the synchronization signal detected by the synchronization detection unit 15, a receivable method is determined from among a plurality of methods.

  For example, the controller 300 sequentially switches the FFT size set in the FFT processing unit 14 to DAB 1/4 kHz, 1/2 kHz, 1 kHz, and 2 kHz with the reception frequency of a certain broadcast channel set in the tuner 11. At this time, if the FP signal is detected by the synchronization detection unit 15, the method determination unit 16 determines that the DAB broadcast method can be received. On the other hand, if the FP signal cannot be detected, the controller 300 next sequentially switches the FFT size set in the FFT processing unit 14 to DVB 2 kHz, 4 kHz, and 8 kHz while keeping the reception frequency set in the tuner 11. . At this time, if the SP signal is detected by the synchronization detection unit 15, the method determination unit 16 determines that the DVB broadcast method can be received.

  Next, the operation of the wireless reception terminal device according to the first embodiment configured as described above will be described. FIG. 3 is a flowchart illustrating an operation example of scan processing of the wireless reception terminal device according to the first embodiment. In FIG. 3, the controller 300 sets a certain broadcast channel (a reception frequency to be selected) in the tuner 11 (step S1). Next, the controller 300 sets an FFT size of a certain broadcasting method in the FFT processing unit 14 for the reception frequency set in step S1 (step S2). When the wireless reception terminal device can receive broadcast waves of two broadcasting systems, DAB and DVB, as in this embodiment, for example, one of the FFT sizes that can be set by the DAB broadcasting system (for example, 1/4 kHz) ) Is first set in the FFT processing unit 14.

  In this state, a series of reception processes of the tuner 11, the A / D converter 12, the quadrature demodulator 13 and the FFT processor 14 are executed (step S3). At this time, the synchronization detection unit 15 tries to detect the synchronization signal from the signal output from the FFT processing unit 14. Here, an attempt is made to detect an FP signal which is a DAB synchronization signal. Then, the synchronization detection unit 15 determines whether or not the FP signal has been detected (step S4). If the FP signal can be detected, the synchronization detection unit 15 notifies the method determination unit 16 of the result (step S5).

  The method determination unit 16 is a combination of the type of the synchronization signal detected by the synchronization detection unit 15 (FP signal in this example) and the FFT size value set in step S2 (in this example 1/4 kHz). Based on the above, a receivable method (a DAB is receivable in the present example) among a plurality of methods is determined (step S6). Then, the method determination unit 16 notifies the controller 300 of the determination result. Upon receiving this notification, the controller 300 holds information on the determination result in a memory (not shown) (step S7). The information of the determination result includes information indicating the broadcast channel (reception frequency), the type of broadcast system that can be received at the reception frequency, and the FFT size.

  Next, the controller 300 determines whether or not the scanning process has been completed for all broadcast channels (step S8). If not completed, the controller 300 returns to the process of step S1 to set the next broadcast channel. On the other hand, when the scanning process is completed for all broadcast channels, the scanning process is terminated. After the end of the scanning process, the controller 300 controls the demodulation circuit 200 based on the determination result information held in a memory (not shown). That is, the controller 300 operates the one corresponding to the receivable broadcasting system among the plurality of demodulation circuits 200A and 200B, and generates a transport stream signal from the OFDM demodulated signal.

  In step S4, if the synchronization detection unit 15 determines that the FP signal has not been detected, the controller 300 returns to step S2 and the controller 300 selects another FFT size (for example, 1/2 kHz) that can be set in the DAB broadcasting method. Set in the FFT processing unit 14. And the process of step S3-S4 is performed, and it is determined again whether the FP signal was detected by the synchronous detection part 15. FIG. If the FP signal cannot still be detected, the process returns to step S2. In the same manner, unless the FP signal is detected by the synchronization detection unit 15, 1 kHz and 2 kHz are sequentially set in the FFT processing unit 14 as other FFT sizes that can be set in the DAB broadcasting system, and the synchronization detection unit 15 sets the FP signal. It is determined whether or not it was detected.

  Even though all the FFT sizes (1/4 kHz, 1/2 kHz, 1 kHz, 2 kHz) that can be set in the DAB broadcasting system are sequentially set in the FFT processing unit 14, the synchronization detection unit 15 cannot detect the FP signal. Then, the controller 300 sets one FFT size (for example, 2 kHz) that can be set in DVB, which is a broadcasting system different from DAB, in the FFT processing unit 14 (step S2).

  In this state, a series of reception processes of the tuner 11, the A / D converter 12, the quadrature demodulator 13 and the FFT processor 14 are executed (step S3). At this time, the synchronization detection unit 15 tries to detect the synchronization signal from the signal output from the FFT processing unit 14. Here, an attempt is made to detect an SP signal which is a DVB synchronization signal. Then, the synchronization detector 15 determines whether or not the SP signal has been detected (step S4).

  Here, when the SP signal cannot be detected, the loop processing of steps S2 to S4 is repeated. That is, as long as the SP signal is not detected by the synchronization detection unit 15, the controller 300 sequentially sets other FFT sizes that can be set in the DVB broadcasting system to 4 kHz and 8 kHz in the FFT processing unit 14, and the synchronization detection unit 15 It is determined whether or not it was detected. In this loop processing, if any of the FFT sizes is set in the FFT processing unit 14 and the SP signal can be detected by the synchronization detection unit 15, the process proceeds to steps S5 to S8.

  As described above in detail, in the first embodiment, the front end circuit 100 including the tuner 11, the A / D converter 12, the quadrature demodulation unit 13, the FFT processing unit 14, the synchronization detection unit 15, and the method determination unit 16 is provided. Only one set is provided as a circuit common to a plurality of systems. Then, the FFT size corresponding to a plurality of broadcasting systems is sequentially switched and set in the FFT processing unit 14, and the value of the FFT size set when OFDM synchronization is established (when a synchronization signal is detected). Based on the combination of the types of synchronization signals, a receivable method among a plurality of methods is determined.

  Thus, according to the first embodiment, since only one set of front end circuits 100 is provided as a circuit common to a plurality of broadcasting systems, a plurality of front end circuits are provided according to the number of broadcasting systems. Compared with the technology, the circuit scale can be reduced.

  In addition, according to the first embodiment, the process from receiving an OFDM-modulated broadcast wave to OFDM demodulating it and detecting a synchronization signal from the demodulated signal is performed regardless of the difference in the broadcast system. The same function of the end circuit 100 can be executed. For this reason, when performing scan processing across a plurality of methods, it is not necessary to update software in order to change the function of the circuit each time the method is switched.

  Furthermore, according to the first embodiment, it is possible to determine the type of broadcasting system from the combination of the FFT size value set in the FFT processing unit 14 and the type of synchronization signal detected by the synchronization detection unit 15. it can. In particular, in the first embodiment, when performing scan processing across a plurality of broadcasting systems, FFT sizes corresponding to a plurality of broadcasting systems are sequentially set in the FFT processing unit 14 for one reception frequency, It may be determined whether or not the OFDM can be synchronized. That is, as shown in the flowchart of FIG. 3, when switching the broadcast system to be scanned, there is no need to return from step S4 to step S1 and set the frequency of the tuner 11 again, and return to step S2 to return to the FFT size. What is necessary is just to determine whether OFDM synchronization can be taken by changing a value.

  As described above, according to the first embodiment, since it is not necessary to update software or set the frequency of the tuner 11 each time the broadcasting method is switched, it is possible to shorten the time required for scanning processing across a plurality of methods. Can do.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram illustrating a configuration example of a wireless reception terminal device according to the second embodiment. The radio reception terminal apparatus according to the second embodiment is an apparatus capable of receiving a plurality of OFDM-modulated broadcast waves, and includes one front-end circuit 100 ′ and a plurality of decoding circuits as shown in FIG. 200 and one controller (CPU) 300.

  Also in the second embodiment, the plurality of decoding circuits 200 are provided in a number corresponding to the number of broadcasting systems that can be received by the wireless reception terminal device. Here, as an example, in addition to DAB and DVB described in the first embodiment, it is assumed that the wireless reception terminal device can receive broadcast waves of three broadcasting systems of ISDB, which is a Japanese digital television broadcasting standard. In this case, the plurality of decoding circuits 200 includes a DAB decoding circuit 200A, a DVB decoding circuit 200B, and an ISDB decoding circuit 200C.

  When the broadcasting system is ISDB, the FFT size that can be set when performing OFDM modulation on the broadcasting station side is the same as DVB, and is either 2 kHz, 4 kHz, or 8 kHz. Therefore, when performing the scanning process, the FFT processing unit 14 sequentially sets these FFT sizes as variable parameters, and executes the FFT process. When the broadcasting system is ISDB, the synchronization signal detected by the synchronization detection unit 15 is the same as DVB and is an SP signal.

  Only one front-end circuit 100 'is provided in the wireless reception terminal device as a circuit commonly used in the above three broadcasting systems. As shown in FIG. 4, the front end circuit 100 ′ includes a tuner 11 ′, an A / D converter 12, an orthogonal demodulation unit 13, an FFT processing unit 14, a synchronization detection unit 15, a method determination unit 16 ′, and a control signal detection. A portion 17 is provided. In FIG. 4, those given the same reference numerals as those shown in FIG. 1 have the same functions, and therefore redundant description is omitted here.

  The tuner 11 'receives and selects an OFDM-modulated broadcast wave via the antenna 400 connected to the front end circuit 100'. The tuner 11 'is a so-called multiband tuner corresponding to the DAB broadcast frequency band, the DVB broadcast frequency band, and the ISDB broadcast frequency band.

  The control signal detector 17 detects a control signal defined for synchronization detection in each broadcasting system from the signal output from the FFT processor 14. When the broadcast system is DVB, a control signal called a TPS (Transmission Parameter Signaling) pilot signal (hereinafter referred to as a TPS signal) is defined. When the broadcasting system is ISDB, a control signal called TMCC (Transmission and Multiplexing Configuration Control) pilot signal (hereinafter referred to as TMCC signal) is defined. That is, the control signal detection unit 17 detects either the TPS signal or the TMCC signal from the signal output from the FFT processing unit 14.

  In addition to the combination of the FFT size value set as a demodulation parameter in the FFT processing unit 14 and the type of synchronization signal (either FP signal or SP signal) detected by the synchronization detection unit 15, the method determination unit 16 ′ Based on the type of control signal detected by the control signal detection unit 17, a receivable system is determined from among the three broadcast systems.

  As described above, DVB and ISDB have the same FFT size value set as a demodulation parameter in the FFT processing unit 14 (both 2 kHz, 4 kHz, and 8 kHz), and the synchronization detected by the synchronization detection unit 15. The types of signals are also the same (both types are SP signals). Therefore, it is not possible to determine whether it is DVB or ISDB only by a combination of the FFT size value and the type of the synchronization signal. On the other hand, the types of control signals detected by the control signal detector 17 are different between DVB and ISDB (TPS signal for DVB, TMCC signal for ISDB). Therefore, if a control signal is added to the determination element of the broadcasting system, it is possible to determine whether it is DVB or ISDB.

  Next, the operation of the radio reception terminal device according to the second embodiment configured as described above will be described. FIG. 5 is a flowchart illustrating an operation example of scan processing of the wireless reception terminal device according to the second embodiment. In FIG. 5, the controller 300 sets a certain broadcast channel (a reception frequency to be selected) in the tuner 11 '(step S11). Next, the controller 300 sets an FFT size of a certain broadcasting system in the FFT processing unit 14 for the reception frequency set in step S11 (step S12). When the wireless reception terminal device can receive broadcast waves of three broadcasting systems of DAB, DVB, and ISDB as in the present embodiment, for example, one of the FFT sizes that can be set in the DAB broadcasting system (for example, 1 / 4 kHz) is first set in the FFT processing unit 14.

  In this state, a series of reception processes of the tuner 11 ′, the A / D converter 12, the quadrature demodulator 13 and the FFT processor 14 are executed (step S 13). At this time, the synchronization detection unit 15 tries to detect the synchronization signal from the signal output from the FFT processing unit 14. Here, an attempt is made to detect an FP signal which is a DAB synchronization signal. Then, the synchronization detector 15 determines whether or not the FP signal has been detected (step S14).

  Here, when the FP signal cannot be detected, the loop processing of steps S12 to S14 is repeated. That is, unless the FP signal is detected by the synchronization detection unit 15, the controller 300 sequentially sets other FFT sizes that can be set in the DAB broadcasting method to 1/2 FFT, 1 kHz, and 2 kHz in the FFT processing unit 14, and the synchronization detection unit 15 determines whether the FP signal has been detected. In this loop processing, if any of the FFT sizes is set in the FFT processing unit 14 and the FP signal is detected by the synchronization detection unit 15, the process proceeds to step S15.

  On the other hand, although all FFT sizes (1/4 kHz, 1/2 kHz, 1 kHz, 2 kHz) that can be set in the DAB broadcasting system are sequentially set in the FFT processing unit 14, the synchronization detection unit 15 detects the FP signal. If not, next, the controller 300 sets one of FFT sizes (for example, 2 kHz) that can be set in DVB and ISDB, which are different broadcasting systems from DAB, in the FFT processing unit 14 (step S12).

  In this state, a series of reception processes of the tuner 11 ′, the A / D converter 12, the quadrature demodulator 13 and the FFT processor 14 are executed (step S 13). At this time, the synchronization detection unit 15 tries to detect the synchronization signal from the signal output from the FFT processing unit 14. Here, an attempt is made to detect an SP signal which is a synchronization signal of DVB and ISDB. Then, the synchronization detector 15 determines whether the SP signal has been detected (step S14).

  Here, when the SP signal cannot be detected, the loop processing of steps S12 to S14 is repeated. That is, as long as the SP signal is not detected by the synchronization detection unit 15, the controller 300 sequentially sets other FFT sizes that can be set in the DVB and ISDB broadcasting schemes to 4 kHz and 8 kHz in the FFT processing unit 14, and the synchronization detection unit 15 It is determined whether the SP signal has been detected. In this loop processing, if any of the FFT sizes is set in the FFT processing unit 14 and the SP signal is detected by the synchronization detection unit 15, the process proceeds to step S15.

  In step S15, the synchronization detection unit 15 notifies the method determination unit 16 'of the detected type of the synchronization signal (either FP signal or SP signal). Next, the synchronization detection unit 15 determines whether or not the detected synchronization signal is an SP signal (step S16). If the detected synchronization signal is an SP signal, the synchronization detection unit 15 notifies the control signal detection unit 17 to that effect.

  Upon receiving this notification, the control signal detector 17 detects a control signal defined for synchronization detection in each broadcasting system from the signal output from the FFT processor 14 (step S17). Then, the control signal detection unit 17 notifies the method determination unit 16 'of the detected type of control signal (TPS signal or TMCC signal) (step S18). Thereafter, the process proceeds to step S19. On the other hand, if it is determined in step S16 that the synchronization signal detected by the synchronization detector 15 is not an SP signal, the process jumps to step S19 without performing the processes of steps S17 and S18.

  In step S19, the method determination unit 16 ′ determines the FFT size value set in the FFT processing unit 14 in step S12, the type of the synchronization signal detected by the synchronization detection unit 15 in step S14, and the control signal detection unit in step S17. Based on the type of the control signal detected in step 17, the receivable broadcasting system is determined from among the plurality of systems (step S19). When the type of the synchronization signal is an FP signal (when the processes of steps S17 and S18 are not performed), as in the first embodiment, the method determination unit 16 ′ determines the FFT size value and the type of the synchronization signal. The broadcasting system that can be received from is determined.

  The system determination unit 16 ′ notifies the controller 300 of the determination result of the broadcast system. Upon receiving this notification, the controller 300 holds information on the determination result in a memory (not shown) (step S20). The information of the determination result includes information indicating the broadcast channel (reception frequency), the type of broadcast system that can be received at the reception frequency, and the FFT size.

  Next, the controller 300 determines whether or not the scan process has been completed for all broadcast channels (step S21). If not completed, the controller 300 returns to the process of step S11 to set the next broadcast channel. On the other hand, when the scanning process is completed for all broadcast channels, the scanning process is terminated. After the end of the scanning process, the controller 300 controls the demodulation circuit 200 based on the determination result information held in a memory (not shown). That is, the controller 300 operates the one corresponding to the receivable broadcasting system among the plurality of demodulation circuits 200A, 200B, and 200C, and generates a transport stream signal from the OFDM demodulated signal.

  As described above in detail, in the second embodiment as well, in the same way as in the first embodiment, the front end circuit 100 ′ is provided with only one set as a circuit common to a plurality of broadcasting systems. Accordingly, the circuit scale can be reduced as compared with the prior art in which a plurality of front-end circuits are provided. Further, according to the second embodiment, since it is not necessary to update the software and set the frequency of the tuner 11 ′ every time the broadcasting system is switched, it is possible to shorten the time required for the scanning process across a plurality of systems. .

  Furthermore, in the second embodiment, the method determination unit 16 ′ uses the control signal detection unit 17 in addition to the FFT size value set in the FFT processing unit 14 and the type of the synchronization signal detected by the synchronization detection unit 15. The broadcasting system is determined based on the type of the detected control signal. Thereby, even if it is a broadcasting system with the same FFT size value and the same kind of synchronization signal, both can be discriminated.

  In the first and second embodiments, three types of broadcasting methods, DAB, DVB, and ISDB, are exemplified, but the broadcasting method to which the present invention is applicable is not limited to this. For example, the wireless reception terminal device of the present invention also supports broadcasting schemes such as DRM (Digital Radio Mondiale), which is a digital radio standard in the short wave and medium wave bands, and MediaFlo, which is a standard for multimedia distribution services for mobile phones. Is possible. Incidentally, in the case of DRM, the settable FFT sizes are 288 Hz, 256 Hz, 176 hz, and 112 Hz, and the detected synchronization signal is an FP signal. In the case of MediaFlo, the settable FFT size is 4 kHz, and the detected synchronization signal is a TDM (Time Division Multiplex) / FDM (Frequency Division Multiplex) signal.

  In the first and second embodiments, the example in which a plurality of decoding circuits 200 are provided in a number corresponding to the number of broadcast systems that can be received by the wireless reception terminal device has been described. Is not limited to this. For example, the decoding circuit may be configured as a reconfigurable circuit, and the decoding function may be freely switched in accordance with the broadcasting system by updating software applied to the decoding circuit. In this way, the circuit scale of the wireless reception terminal device including the decoding circuit can be further reduced.

  Even in this case, the scan processing across a plurality of broadcasting systems in the front-end circuits 100 and 100 'can be performed without updating the software. Further, the software update in the decoding circuit may be performed only for the broadcasting system determined to be receivable by the scan processing of the front-end circuits 100 and 100 ′, and the software for all the broadcasting systems supported by the wireless reception terminal device. There is no need to update.

  In the first and second embodiments described above, at least two of the FFT size set in the FFT processing unit 14 and the type of the synchronization signal detected by the synchronization detection unit 15 are used as broadcast system determination elements. However, the determination may be made based on only one of them. For example, when only two broadcasting systems, DAB and DVB, are supported by the wireless receiving terminal device, two broadcasting systems can be selected only by the type of synchronization signal (FP signal or SP signal) detected by the synchronization detector 15. It is possible to determine. In addition, when the broadcasting system supported by the wireless receiving terminal device is only two systems, DAB and DRM, when the synchronization signal (FP signal) is detected by the synchronization detection unit 15, it is set in the FFT processing unit 14. It is possible to discriminate between the two broadcasting systems based only on the FFT size value.

  In the first and second embodiments, one broadcast channel (reception frequency) is set, and FFT sizes corresponding to a plurality of broadcast systems are sequentially set in the FFT processing unit 14. If a synchronization signal is detected in one broadcasting system, the other broadcasting systems do not perform scanning processing. That is, in the flowcharts of FIGS. 3 and 5, after the synchronization signal is detected in step S4 or step S14, the FFT size of another broadcasting system is set until the broadcast channel is switched after returning to step S1 or step S11. Scan processing is not performed. On the other hand, all the broadcast system scan processes may be performed.

  For example, in the flowchart of FIG. 3, after step S <b> 7, it is determined whether or not scanning processing for all broadcasting systems supported by the wireless reception terminal device has been completed. Then, if all the broadcast system scanning processes have been completed, the process proceeds to step S8. If not, the process returns to step S2. Similarly, in the flowchart of FIG. 5, after step S <b> 20, it is determined whether or not scanning processing for all broadcasting systems supported by the wireless reception terminal device has been completed. Then, if all the broadcast system scanning processes have been completed, the process proceeds to step S21. If not completed, the process returns to step S12.

  In addition, each of the first and second embodiments described above is merely an example of a specific example for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. It will not be. In other words, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

It is a block diagram which shows the structural example of the radio | wireless receiving terminal device by 1st Embodiment. It is a block diagram which shows the structural example of the tuner with which the radio | wireless receiving terminal device by 1st and 2nd embodiment is provided. It is a flowchart which shows the operation example of the scanning process of the radio | wireless receiving terminal device by 1st Embodiment. It is a block diagram which shows the structural example of the radio | wireless receiving terminal device by 2nd Embodiment. 7 is a flowchart illustrating an operation example of scan processing of the wireless reception terminal device according to the second embodiment.

Explanation of symbols

14 FFT processing unit 15 Synchronization detection unit 16, 16 ′ Method determination unit 17 Control signal detection unit 100, 100 ′ Front-end circuit 200 Decoding circuit 300 Controller

Claims (3)

A wireless reception terminal device that supports reception of a plurality of OFDM-modulated broadcast waves,
A tuner that receives the OFDM-modulated broadcast wave and selects a channel;
An OFDM demodulator that performs OFDM demodulation on the signal output from the tuner;
A synchronization detector that detects a synchronization signal from the signal output from the OFDM demodulator;
A method of determining a receivable method among the plurality of methods based on a value of a demodulation parameter set in the OFDM demodulator and at least a value of the demodulation parameter of a type of the synchronization signal detected by the synchronization detector A determination unit;
A decoding unit that performs a decoding process corresponding to the scheme determined by the scheme determination unit on the signal output from the OFDM demodulation unit;
A control unit that controls channel selection processing in the tuner, setting processing of the demodulation parameter for the OFDM demodulation unit, and decoding processing in the decoding unit,
The tuner, the OFDM demodulation unit, the synchronization detection unit, and the method determination unit are provided as a set of front end circuits common to the plurality of methods,
When performing a scan process for creating a receivable channel list by sequentially switching reception frequencies to be selected by the tuner, the control unit performs a plurality of channels corresponding to the plurality of methods for one reception frequency to be selected. The above demodulation parameters are sequentially switched and set in the OFDM demodulator,
The method determination unit includes a value of the demodulation parameter when the synchronization signal is detected by the synchronization detection unit among the plurality of demodulation parameters of the plurality of methods set by sequentially switching by the control unit, A radio receiving terminal apparatus, wherein a receivable scheme is determined from among the plurality of schemes based on at least a value of the demodulation parameter together with a type of the synchronization signal detected by a synchronization detector. A control signal detector for detecting a control signal defined by each of the plurality of methods from a signal output from the OFDM demodulator;
In addition to the value of the demodulation parameter set in the OFDM demodulator and the type of the synchronization signal detected by the synchronization detector, the method determination unit determines the type of the control signal detected by the control signal detector. The wireless receiving terminal device according to claim 1, wherein a receivable method is determined based on the plurality of methods. A radio receiving terminal device that supports reception of a plurality of OFDM modulated broadcast waves, a tuner that receives and selects the OFDM modulated broadcast waves, and an OFDM signal that is output from the tuner An OFDM demodulator that performs demodulation, a synchronization detector that detects a synchronization signal from a signal output from the OFDM demodulator, a value of a demodulation parameter set in the OFDM demodulator, and the detection that is detected by the synchronization detector Based on a combination of synchronization signal types, a method determination unit that determines a receivable method among the plurality of methods, and a control that controls channel selection processing in the tuner and setting processing of the demodulation parameter for the OFDM demodulation unit And the tuner, the OFDM demodulation unit, the synchronization detection unit, and the method determination unit are common to the plurality of methods. A method for performing a scan process of the reception channels in a radio receiving apparatus that includes a set as-end circuit,
A reception frequency setting step in which the control unit sets a reception frequency to be selected in the tuner;
A parameter setting step in which the control unit sequentially sets the plurality of demodulation parameters corresponding to the plurality of schemes in the OFDM demodulation unit with respect to the reception frequency set in the reception frequency setting step;
The demodulation parameter that was set when the synchronization signal was detected by the synchronization detection unit among the plurality of demodulation parameters of the plurality of methods that were sequentially switched and set in the parameter setting step by the method determination unit And a determination step of determining a receivable scheme among the plurality of schemes based on a combination of the value of and the type of the synchronization signal detected by the synchronization detection unit,
A method of scanning a reception channel, wherein the processing of the reception frequency setting step, the parameter setting step, and the determination step is repeatedly performed by sequentially switching values of the reception frequency set in the tuner.