JP5061885B2 - Diversity receiving apparatus and diversity control method - Google Patents

Description

  The present invention relates to a diversity receiver and a diversity control method, and more particularly, to a diversity receiver and a diversity control method suitable for a device that receives a television broadcast, an FM broadcast, or the like in a moving body such as a vehicle.

  In an FM broadcast receiving apparatus and a television broadcast receiving apparatus (hereinafter abbreviated as a TV apparatus or a television) mounted on a moving body such as an automobile, various devices have been made in order to maintain reception quality even when the automobile is moved. For example, the antenna selection method diversity receiver having a plurality of antennas and a selection circuit that selects the antenna having the highest received electric field intensity from among them, and the signals of a plurality of receivers including the antenna and the tuner are combined and received. Phase control diversity receivers that improve quality are used.

  Also, when receiving FM broadcasts or television broadcasts while moving, away from the broadcast radio wave transmitting station that is receiving with movement, or in the shade of buildings or mountains, the received electric field strength decreases and noise is mixed However, there were inconveniences in selecting a channel each time or re-tuning. Conventionally, in order to eliminate such inconvenience, the main tuner and the sub tuner are provided with two systems of receiving circuits, while performing antenna selection method or phase (phase control method) diversity reception control as required, When there is no need for diversity reception or when the electric field strength drops below a certain value, the sub-tuner performs a control (seek) to search for other broadcast radio waves having a large electric field strength while receiving the broadcast. Things are known. In addition, it receives broadcast information superimposed on broadcast radio waves, for example, a service (RDS: Radio Data System) that transmits program information that has the same content as the broadcast that is being received and that has a different channel, frequency, and transmitting station. Thus, a system that automatically switches to a channel with good reception quality is known.

FIG. 4 is a block diagram showing a basic configuration of a conventional phase diversity receiver. In this example, the output signals of two antennas 31 and 32, and the first receiver 33 and the second receiver 34 that receive and demodulate the output signals of the respective antennas (the second receiver 34 in the drawing). A phase shifter 35 for adjusting the phase of the first receiver, a phase difference detector 36 for adjusting the phase of the second receiver output signal by the phase shifter 35 so as to match the phase of the first receiver output signal, and two receivers Is provided in order to prevent the reception quality from being deteriorated even in a weak electric field environment.
FIG. 5 is a block diagram showing an example of a conventional diversity receiving apparatus described in Patent Document 1 in which both phase diversity reception and reception of data multiplexed in broadcast radio waves such as RDS reception are made compatible. The receiving apparatus shown in this example includes two sets of antennas 41 and 42, a main tuner (first tuner) 43 and a sub tuner (second tuner) 44, and two tuners 43 and 44, respectively. A DSP 45 that digitally processes and demodulates the output digital intermediate frequency signal (IF signal), an audio amplifier (amplifier) 46 that amplifies the demodulated and analog-converted signal, and converts the electrical signal into sound. A speaker 47, a microcomputer 48 that controls the tuners 43 and 44, and the DSP 45, and an indicator that displays an image by the output of the microcomputer 48, or a user inputs an instruction to the microcomputer based on the display screen 49 is provided.

In this configuration, the DSP 35 and the microcomputer 48 perform FFT processing (high-speed frequency conversion processing), digital filter processing, frequency synchronization processing, time / frequency de-interleaving processing, audio code processing, data decoding processing in accordance with built-in programs and data. Perform phase diversity processing. During reception of the broadcast, the electric field strength level of the received signal is compared with a preset threshold value. While one main tuner receives and demodulates the broadcast, the other sub-tuner executes a substitute station seek process and the like in the background. On the other hand, when the electric field intensity level being received by the main tuner is below a certain value level, the phase diversity processing function is turned on to match the phases of the two signals to improve the reception state.
JP 2007-60624 A

However, the conventional diversity receiver and method described above have the following problems. For example, as described in Patent Document 1, when switching between the main tuner and the sub-tuner, the process of detecting the phase of each output signal and synchronizing both takes a required time, In many cases, the quality of the output signal was not stable. Therefore, if the synthesized signal is demodulated and output from the speaker during this period, the user will hear a voice with reduced quality. In particular, when the difference in electric field strength level between two tuner output signals is large, the time required to establish synchronization tends to be long as a characteristic of the synchronous system circuit, so that the time for outputting unpleasant sound becomes long. In addition, when a noise component is included in either one, the time required for establishing synchronization further increases.
The present invention has been made to solve such a problem in the conventional phase diversity receiver, and even if there is a large difference in electric field strength or reception quality between the two tuner output signals, the combined output signal is not generated. It is an object of the present invention to provide a diversity receiver and a diversity control method capable of preventing the occurrence of a voice output having a reduced quality before stabilization.

In order to solve such a problem, the present invention provides a diversity receiving apparatus according to claim 1, wherein a plurality of systems of receiving means for receiving and demodulating each of radio signals supplied from a plurality of antennas, and an output of the receiving means. and phase diversity means for synthesizing by adjusting the phase of a signal, a reception situation detecting means for determining the reception quality of the output signal of said receiving means, output for selecting the desired signal from among said receiving means and said phase diversity means Selecting means, setting means for setting a wait time based on the reception quality of the signal to be combined in the phase diversity means, and switching the combined signal as an output signal from the start of the combining process in the phase diversity means based on the wait time. and a wait time control means for controlling the time until the output, the setting Means as the difference of the reception quality of a signal synthesized in the phase diversity means increases, and sets long the wait time.
According to a second aspect of the present invention, in the diversity receiver according to the first aspect, the wait time is preset in a plurality of stages in accordance with the degree of difference in reception quality of signals synthesized by the phase diversity means. And

According to a third aspect of the present invention, there are provided a plurality of systems of receiving means for receiving and demodulating each of radio signals supplied from a plurality of antennas, a phase diversity means for adjusting and combining phases of output signals of the receiving means, and A reception status detection means for judging the reception quality of the output signal of the reception means and the phase diversity means, an output selection means for selecting a required signal from the reception means and the phase diversity means, and a synthesis in the phase diversity means Setting means for setting the wait time based on the reception quality of the signal to be transmitted, and based on the wait time set by the setting means, the synthesized signal is switched and output as an output signal from the start of the synthesis processing in the phase diversity means. a wait time control means for controlling the time to, the Fe Multipath signal combining in's diversity means, noise, associated with at least one level of the adjacent channel signal interference, characterized by comprising means for adding additional time to the wait time.
According to a fourth aspect of the present invention, in the diversity receiver according to any one of the first to third aspects, the phase diversity means synthesizes the intermediate frequency signal output of the receiving means after digital conversion. It is characterized by being.
The invention according to claim 5 relates to a diversity control method, and in a diversity control method for combining a plurality of reception signals supplied from a plurality of antennas, a reception status detection process for determining the reception quality of the reception signals, and reception An output selection process for selecting a required signal from the signal and the phase diversity processing signal, a process for setting the wait time based on the reception quality of the signal combined in the phase diversity process, and a phase based on the wait time look including a wait time control process for controlling the time from diversity processing start to supply by switching a synthesized signal as an output signal, the difference between the reception quality of the process of the setting signal for the synthesis in the phase diversity processing is increased As the above wait time is set longer Characterized in that that.

  According to the present invention, in a phase diversity receiving apparatus that adjusts and combines the phases of radio signals supplied from a plurality of antennas, the weight time is set based on the reception quality of the signals combined in the phase diversity means, and the phase diversity Because it is configured to control the time from the start of the synthesis process to the time when the synthesized signal is switched and output as an output signal, it is caused by the instability of the synthesized output that occurs immediately after the start of phase diversity processing and until synchronization is established. Therefore, it is possible to prevent a signal with degraded sound quality from being output as a demodulated signal, which is effective in improving reception quality.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. . In addition, the same parts and the same matters as those already described are denoted by the same reference numerals and numbers, and redundant description is omitted.

FIG. 1 is a block diagram showing an embodiment of a diversity receiving apparatus in which the present invention is applied to an apparatus for receiving FM broadcast.
The apparatus shown in this example supplies antennas 1 and 2, output signals of the respective antennas, F / E units 3 and 4 for converting the frequency to an intermediate frequency (IF), and amplifies the output signal. Intermediate frequency amplifiers (IF amplifiers) 5 and 6, analog digital converters (ADCs) 7 and 8 for digitally converting the output intermediate frequency signals, and the required frequency from the digitally converted intermediate frequency signals The intermediate frequency filters (IF Filters) 9 and 10 of the variable band frequency type, the phase diversity processing unit 11 (phase diversity means) for performing the phase synthesis processing of the output signal of the intermediate frequency filter, and the above two intermediates FM demodulation for demodulating the outputs of the frequency filters 9 and 10 and the phase diversity processing unit 11 12 to 14 and reception status detectors 15 to 17 (reception status detection means) for detecting reception quality based on the output signals of the respective FM demodulator, as well as RDS data in the three FM demodulator output signals. RDS demodulators 18 to 20 for performing demodulation / synchronization processing and error correction processing to extract channel information, transmitting station information, program information and the like superimposed on the broadcast wave, and three FM demodulator output signals, An FM processing unit 21 to 23 that performs mute processing (mute), stereo blend processing, high cut processing, de-emphasis processing, and the like, and a control unit 24 that incorporates a CPU and a memory that records necessary information and data, and performs overall control. (Wait time control means), an output selector (output selection section: output selection means) 25 for selecting one output from the three FM processing sections 21 to 23, and A DAC (Digital Analog Converter) 26 that converts a selected digital signal into an analog signal and a speaker 27 that converts the converted analog signal into sound are provided. Although not limited to this, for convenience of explanation, the F / E unit 3, IF amplifier 5, ADC 7, and IF filter 9 are replaced with a main tuner (first tuner: receiving means), an F / E unit 4, and an IF amplifier. 6, the ADC 8 and the IF filter 10 are called a sub tuner (second tuner: receiving means).

In the above configuration, basically, both the main tuner and the sub tuner usually receive broadcast waves of the same frequency, turn on the function of the phase diversity processing unit 11, and output the output signal to the speaker 27 via the output selector 25. To supply. At least when the reception state in the main tuner is good and stable, the function of the phase diversity processing unit 11 is turned off, the broadcast is received only by the main tuner, and another alternative channel of the same broadcast is received by the sub tuner. A search process for searching and RDS information is received, and various types of information are extracted and stored. When the series of processing is completed, the sub-tuner returns to the frequency being received again, turns on the function of the phase diversity processing unit 11, and restarts the phase diversity processing. Also, if the reception status deteriorates during reception by phase diversity, the phase diversity processing function is turned off, and the sub tuner detects an alternative station while receiving the broadcast only by the main tuner, or the previous seek as described above. A broadcast channel with good reception quality is searched with reference to the alternative station information stored in the processing.
In this way, when the two output signals of the main tuner and the sub tuner are combined, a signal including noise may be generated until the combined output signal is stabilized as described above. In the invention, control is performed so as to set a waiting time (wait time) so that the synthesized signal is not output until the synthesized signal output is stabilized. This control is performed by the control unit 24. The control unit 24 stores programs and data necessary for executing the control described below, and is configured to perform various processes based on the programs and data. Has been.

FIG. 2 is a flowchart showing a control example of the diversity receiver configured as shown in FIG. In the process shown in this example, when the apparatus is turned on, or when the user operates an operation dial or a key to receive a new broadcast, the control unit 24 sets two Fs so that the specified frequency is obtained. / E units 3, 4 and IF filters 9, 10 are controlled to synthesize the reception quality of the output signals of the FM demodulators 12 and 14 of the respective systems and the outputs of the IF filters 9 and 10 of both tuners. The reception quality of the output signal of the FM demodulator 13 of the unit 11 is detected by the reception status detectors 15 to 17 provided in the respective systems (S1).
As a result of this detection, if at least the reception quality of the main tuner system is very good (S2, Yes), the output selector 25 selects the output of the FM processing unit 21 that is the output of the main tuner, and the DAC is connected via the DAC. The audio signal is guided to the speaker 27 (S3). At the same time, the sub-tuner performs seek processing such as RDS data extraction and alternative station information search (S4), and returns to S2 after the seek processing is completed.

On the other hand, if the reception quality at the main tuner or the sub-tuner is below a certain value in S2 (S2, No), it is determined whether the reception quality of the phase diversity processing system is good or not (S5, Yes). ), Wait time (waiting time) until the phase diversity processing output is turned on by judging the reception quality based on the received electric field strength and C / N (ratio of carrier level to noise level) of both tuner systems at that time Is set (S6).
The wait time is preferably set according to the time until the combined signal of the two signals is stabilized. For example, when the sub tuner side is returned from the seek process to the desired frequency reception and the synthesizing process is performed, the electric field strengths of the main tuner side and the sub tuner side are compared, and if the difference between the two is small (for example, 15 dB or less), When the wait time is 3 msec (millisecond, the same applies below) and the difference between the two electric field strengths is large (for example, 15 dB or more and 30 dB or less), the wait time is 10 msec, and when the difference between the two is large (for example, 30 dB or more) The wait time is set to 15 msec. Needless to say, the set value of the wait time is not limited to this example or the electric field strength, and the reception status of both may be compared by other means.

In addition to the difference in electric field strength, factors such as the presence / absence of multipaths and adjacent channel signal interference can be considered as factors that affect the synthesis processing time. Therefore, the reception status detectors 15 to 17 detect these presences, Depending on the degree, a process of adding a wait time of + α can be performed (S7).
In this way, the necessary wait time is set and the elapse of the set time is monitored (S8, No), and when the set wait time has elapsed (S8, Yes), it is determined that the combined output signal is stable. Then, the demodulated signal of the system of the diversity processing unit 11 is selected by the output selector 25 and is output to the speaker 27 via the DAC 26 (S9). Also, during the synthesis process, the seek process is executed according to the monitoring result of the alternative station seek process and the reception quality degradation of the synthesized signal (S10), and when necessary (S10, Yes), the diversity process is performed. Is turned off, seek processing is performed (S11), and the process returns to S1 or S2.
In addition, in the above process S5, when the reception status of the composite signal (diversity processing unit output signal) is not good (No in S5), it is replaced based on a new seek process or a previous seek process result or RDS information. Station selection and alternative station candidates are displayed (S12). It may be convenient for the user to confirm the displayed screen or prompt the user to change the channel.

The configuration and processing described above are examples of the present invention, and various modifications can be made. For example, it is possible to provide not only two systems but also three or more tuner means (reception means), and select and synthesize two required systems from them, or synthesize three or more systems signals. . In addition, when the modulation method is OFDM (Orthogonal Frequency Division Multiplex), combining processing is performed for a large number of subcarriers, and signals other than FM modulation are similarly performed based on existing techniques. The present invention can be employed.
As another modified embodiment, for example, as shown in FIG. 3, an IF selector 28 is inserted in front of the three FM demodulators 12 to 14 to select only necessary IF signals. May be. According to this configuration, for example, when each processing described above is realized by a CPU or DSP, instead of performing all three systems in parallel, only the necessary processing is performed in the CPU equivalent to the case of selecting for the IF selector. If it is executed by a DSP, the effect of reducing the processing load on the CPU or DSP can be expected. Alternatively, as shown in FIG. 3, if a necessary signal is selected by the IF selector, the output selector 25 can be omitted, and the configuration can be simplified so that three outputs are combined into one and supplied to the DAC. Will.

Further, as shown in FIG. 3, omitting the RDS demodulator added to the system of the phase diversity processor is also useful for simplifying the configuration or simplifying the processing. Furthermore, the setting of the wait time is not limited to the example described above, and various modifications can be made. For example, the reception quality of the phase demodulator processing output FM demodulator 13 is monitored, and after confirming that the reception quality is stable, the composite output signal is selected or controlled by the output selector. Is also possible. At this time, combined with control by the wait time set according to the difference in electric field strength of each system and the presence or absence of noise, the combined signal is obtained by AND processing (logical product output) or OR processing (logical sum output) of both signals. It may also be useful to control the output on and off.
In addition, the means described in Patent Document 1 and the publicly known document described in the same document disclose means related to a diversity antenna and a diversity receiver, and therefore can be referred to when implementing the present invention. .

  If the diversity antenna control method of the present invention is programmed based on an OS that can be controlled by a computer, it can be controlled by the same processing method by a computer equipped with the OS. In recent years, most television systems and the like use a digital processing circuit such as a computer or a DSP. Therefore, if the method of the present invention is stored in a memory as a program or data, a part of these functions are used. The invention can be carried out.

The block diagram which shows one Example of the diversity receiver of this invention. The flowchart which shows one Example of the diversity control method of this invention. The block diagram which shows the other Example of the diversity receiver of this invention. The block diagram which shows an example of the conventional diversity receiver. The block diagram which shows an example of the conventional diversity receiver.

Explanation of symbols

  1, 2 antenna, 3, 4 F / E section, 5, 6 IF amplifier, 7, 8 ADC (analog / digital converter), 9, 10 IF filter, 11 phase diversity processing section, 12 to 14 FM demodulator, 15 to 17 reception status detector, 18 to 20 RDS demodulator, 21 to 23 FM processing unit, 24 control unit, 25 output selector, 26 DAC (digital / analog converter), 27 speaker, 28 IF selector

Claims (5)

A plurality of receiving means for receiving and demodulating each of radio signals supplied from a plurality of antennas;
Phase diversity means for adjusting and synthesizing the phase of the output signal of the receiving means;
Reception status detection means for judging the reception quality of the output signal of the reception means;
An output selecting means for selecting a desired signal from among said receiving means and said phase diversity means,
Setting means for setting a wait time based on the reception quality of the signal combined in the phase diversity means;
Based on the wait time set by the setting means, comprising a wait time control means for controlling the time from the start of the synthesis process in the phase diversity means until the synthesized signal is switched and output as an output signal,
The diversity receiving apparatus according to claim 1, wherein the setting means sets the wait time longer as a difference in reception quality of signals combined in the phase diversity means increases .   2. The diversity receiving apparatus according to claim 1, wherein the wait time is preset in a plurality of stages in accordance with the degree of difference in reception quality of signals synthesized by the phase diversity means. A plurality of receiving means for receiving and demodulating each of radio signals supplied from a plurality of antennas;
Phase diversity means for adjusting and synthesizing the phase of the output signal of the receiving means;
Reception status detection means for judging the reception quality of the output signals of the receiving means and the phase diversity means;
Output selecting means for selecting a required signal from the receiving means and the phase diversity means;
Setting means for setting a wait time based on the reception quality of the signal combined in the phase diversity means;
Based on the wait time set by the setting means, a wait time control means for controlling the time from the start of the synthesis process in the phase diversity means until the synthesized signal is switched and output as an output signal;
A diversity receiving apparatus comprising means for adding an additional time to the wait time in relation to at least one level of multipath, noise, and adjacent channel signal interference of signals to be combined in the phase diversity means. The diversity receiving apparatus according to any one of claims 1 to 3, wherein the phase diversity means synthesizes the intermediate frequency signal output of the receiving means after digital conversion. In a diversity control method for combining a plurality of received signals supplied from a plurality of antennas,
A reception status detection process for determining the reception quality of the received signal;
An output selection process for selecting a required signal from the received signal and the phase diversity processing signal;
A process of setting a wait time based on the reception quality of the signal to be combined in the phase diversity process;
A wait time control process for controlling a time from the start of the phase diversity process to switching and supplying a composite signal as an output signal based on the wait time,
In the diversity control method, the setting process sets the wait time longer as a difference in reception quality of signals to be combined in the phase diversity process increases .

Images