JP2012049945A - Broadcast reception device and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a broadcast reception device and a control method therefor, capable of avoiding mutual interference between local oscillation circuits, in a configuration capable of receiving a broadcast wave of an identical channel simultaneously by a plurality of tuners.SOLUTION: A broadcast reception device includes: a frequency variable unit 33 for switching a local oscillation frequency fc between an upper-side mode to convert into a higher frequency than the reception frequency fa of the reception channel and a lower-side mode to convert into a lower frequency, among frequencies convertible into an intermediate frequency fb; and in case of a reception channel change, a central control unit 32 for allowing the frequency variable unit 33 to switch the mode so that each tuner 11A, 11B has a different local oscillation frequency fc, based on the reception channel and the mode in each tuner 11A, 11B.

Description

  The present invention relates to a broadcast receiving apparatus including a plurality of tuners capable of receiving broadcast waves of the same channel and a control method thereof.

  Conventionally, a superheterodyne radio broadcast receiving apparatus is known. This type of radio broadcast receiving apparatus includes a local oscillation circuit that outputs a local oscillation signal for converting a reception channel signal into an intermediate frequency signal (see, for example, Patent Document 1).

JP 2008-177737 A

  By the way, when a plurality of tuners are built in the radio broadcast receiving apparatus and the broadcast waves of the same channel are simultaneously received by each tuner, a situation occurs in which the local oscillation circuit of each tuner outputs a local oscillation signal of the same frequency at a high frequency, The local oscillation circuit causes mutual interference and causes reception degradation.

  The present invention has been made in view of the above-described circumstances, and has a configuration capable of simultaneously receiving broadcast waves of the same channel with a plurality of tuners, and a broadcast receiving apparatus capable of avoiding mutual interference between local oscillation circuits and the same It is to provide a control method.

  In order to achieve the above object, the present invention includes a plurality of tuners capable of receiving broadcast waves of the same channel, and a signal of a local oscillation frequency for converting a signal of a reception channel into a signal of an intermediate frequency for each tuner. In the broadcast receiving apparatus having the local oscillation circuit that outputs the local oscillation frequency, the local oscillation frequency is set to the upper mode that is higher than the reception frequency of the reception channel among the frequencies that can be converted to the intermediate frequency, and the lower frequency. Switching unit for switching between lower mode and mode switching to the switching unit so that the local oscillation frequency is different for each tuner based on the reception channel and the mode of each tuner when changing the reception channel And a control unit for controlling.

  According to this configuration, among the frequencies that can be converted to the intermediate frequency, the local oscillation frequency is switched between an upper mode that is higher than the reception frequency of the reception channel and a lower mode that is a lower frequency. Since there is a switching unit and a control unit that switches the mode to the switching unit so that the local oscillation frequency is different in each tuner based on the reception channel and the mode of each tuner when changing the reception channel, With a configuration in which a plurality of tuners can simultaneously receive broadcast waves of the same channel, mutual interference between local oscillation circuits can be avoided.

In the above configuration, when the two tuners receive the same reception channel, the control unit may distribute one tuner to the upper mode and the other tuner to the lower mode. According to this configuration, when two tuners receive the same channel broadcast at the same time, mutual interference between the local oscillation circuits can be reliably avoided, and reception degradation can be reliably avoided.
In the above configuration, when the two tuners receive different reception channels, the control unit may set both tuners in the same mode. According to this configuration, when two tuners receive broadcasts of different channels at the same time, mutual interference between the local oscillation circuits can be reliably avoided, and reception degradation can be reliably avoided.

  In addition, the present invention includes a local oscillation circuit that includes a plurality of tuners capable of receiving broadcast waves of the same channel, and outputs a signal of a local oscillation frequency for converting a signal of the reception channel into an intermediate frequency signal for each tuner. In the control method of the broadcast receiving apparatus having the above, when changing the reception channel, the reception channel of each tuner is received from among the reception channels of each tuner and the local oscillation frequency in each tuner that can be converted into the intermediate frequency. Based on whether the upper mode is a higher frequency than the frequency or the lower mode is a lower frequency, the mode is switched so that the local oscillation frequency is different in each tuner. According to this configuration, a plurality of tuners can simultaneously receive broadcast waves of the same channel, and mutual interference between local oscillation circuits can be avoided.

  According to the present invention, a plurality of tuners can simultaneously receive broadcast waves of the same channel, and mutual interference between local oscillation circuits can be avoided.

It is a block diagram which shows the structure of the vehicle-mounted broadcast receiver which concerns on this embodiment. 5 is a flowchart showing reception channel switching control (reception frequency switching control).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the in-vehicle broadcast receiving apparatus according to this embodiment.
This in-vehicle broadcast receiving device 10 is formed in a small size so that it can be mounted on a vehicle that is a moving body, is mounted on the vehicle, receives a broadcast wave that is broadcast by a broadcasting station, and is superimposed on this broadcast wave. This is an in-vehicle device that outputs a signal.
More specifically, the in-vehicle broadcast receiving apparatus 10 is a receiving apparatus that receives a radio broadcast, and has a so-called AV (audio / visual) function navigation apparatus that has an amplifier function and a navigation function for driving a vehicle speaker. Is housed in. This navigation device is a radio mode that listens to the radio according to instructions from the user, displays a map in the display panel, and navigation that guides the vehicle to the destination (the guidance map from the current value to the destination is displayed on the display map). Display and perform route guidance using voice) and operate in each operation mode such as a navigation mode.
Note that the radio mode and the navigation mode can be executed simultaneously, such as displaying a map while emitting radio sound, as in a known AV navigation apparatus.

Radio broadcasts that can be received by the in-vehicle broadcast receiving apparatus 10 include not only radio broadcasts that broadcast music programs but also radio broadcasts that broadcast traffic information. That is, when a music program is received, an audio signal corresponding to the music information is output, and the sound is emitted from the vehicle speaker by the amplifier function of the navigation device. When traffic information of simple figures or characters is received, a signal corresponding to the traffic information is output, and processing for displaying the traffic information on the display panel of the navigation device is performed according to a user instruction or the like.
The in-vehicle broadcast receiving device 10 may be configured as a separate unit from the navigation device and externally connected to the navigation device.

As shown in FIG. 1, this in-vehicle broadcast receiving apparatus 10 includes a plurality of (two in this configuration) tuners 11A and 11B that can receive broadcast waves of the same channel, and an instruction input unit that inputs various instructions from the user. 12 and a control unit 13 for controlling the in-vehicle broadcast receiving apparatus 10 as a whole.
Each of the tuners 11A and 11B is a superheterodyne tuner that converts a reception channel signal (referred to as a reception signal Sa) into an intermediate frequency signal (referred to as an output signal Sb) and outputs it, and has the same configuration. Yes. Each tuner 11A, 11B is configured by sequentially connecting a tuning circuit 21, a frequency conversion circuit 22, an intermediate frequency amplification circuit 23, and a detection circuit 24.

  The tuning circuit 21 tunes with the radio wave in the frequency band corresponding to the reception channel among the received radio waves received via the antenna (not shown), and outputs the radio wave in the frequency band as the reception signal Sa. More specifically, the tuning circuit 21 includes a resonance circuit including a coil and a variable capacitance element (so-called varicap), and is controlled by the control unit 13 to receive channels designated by the user. Accordingly, by changing the capacitance of the variable capacitance element, the resonance frequency of the resonance circuit is changed, whereby the tuning frequency of the tuning circuit 21 is changed.

The frequency conversion circuit 22 is a circuit that converts the frequency fa of the received signal Sa into an intermediate frequency fb and outputs the signal as an output signal Sb. Under the control of the control unit 13, the local frequency that varies the oscillation frequency (local oscillation frequency) fc The oscillation circuit 22A includes a mixer 22B that mixes the received signal Sa and the signal Sc having the local oscillation frequency fc from the local oscillation circuit 22A to generate the signal Sb having the intermediate frequency fb.
The local oscillation circuit 22A has a voltage controlled oscillation circuit (VCO), and controls the oscillation frequency of the voltage controlled oscillation circuit with the control voltage Vc from the frequency variable unit (switching unit) 33 in the control unit 13. The local oscillation frequency fc that is the oscillation frequency of the local oscillation circuit 22A is varied. In this case, the local oscillation circuit 22A is controlled by the mixer 22B so as to output a local oscillation frequency fc that converts the signal of the reception channel into the signal Sb of the intermediate frequency fb.

The mixer 22B outputs a signal Sb having an intermediate frequency fb that is a difference between the local oscillation frequency fc and the frequency fa of the reception signal Sa by the superheterodyne method.
The intermediate frequency amplifier circuit 23 amplifies and outputs the signal Sb of the intermediate frequency fb supplied from the mixer 22B, and the detection circuit 24 detects (demodulates) the broadcast wave of the reception channel from the signal Sb of the intermediate frequency fb. The signal superimposed on the broadcast wave is extracted and output. That is, when a broadcast wave on which an audio signal is superimposed is received, the audio signal is extracted and output.

The control unit 13 includes a memory 31 for storing various data such as programs, a central control unit 32 for executing various control processes by executing programs stored in the memory 31, and a tuner under the control of the central control unit 32. And a frequency variable unit 33 for varying the local oscillation frequency fc of the local oscillation circuit 22A of 11A and 11B.
The memory 31 stores table data in which a plurality of reception channels (reception frequencies) and local oscillation frequencies fc for receiving each reception channel are associated with each other. Based on the table data, a frequency variable unit is stored. 33 variably controls the local oscillation frequency fc of each tuner 11A, 11B according to the reception channel of each tuner 11A, 11B.

  By the way, in this configuration, since a plurality of tuners 11A and 11B capable of receiving broadcast waves of the same channel are provided, one tuner 11A or 11B is receiving an arbitrary reception channel, and the other tuner 11B or 11A is used. Any receiving channel can be received. For this reason, while one tuner 11A or 11B is receiving, a channel search for searching for a reception channel that can be received by the other tuner 11B or 11A, or a music program being received by one tuner 11A or 11B is emitted into the vehicle. While using the other tuner 11B or 11A, various usage modes such as recording the same or different music program in a recording device (not shown) connected to the device are possible. For the channel search, a known process for searching for a reception channel based on the reception intensity may be applied.

However, when a plurality of tuners 11A and 11B are incorporated and broadcast waves of the same channel are simultaneously received by the tuners 11A and 11B, that is, when the reception frequencies are the same, local oscillation of the tuners 11A and 11B. A situation occurs in which the circuit 22A outputs the local oscillation signal Sc having the same frequency. Since each local oscillation signal Sc is a high frequency signal, the local oscillation circuit 22A causes mutual interference and causes reception deterioration.
In particular, since the single in-vehicle broadcast receiving apparatus 10 is formed in a small size, the above problem is likely to occur. On the other hand, in order to avoid this problem, a configuration in which a shield against noise is added can be considered. However, it is difficult not only to increase the number of parts but also to secure a space for arranging the shield.

Therefore, in the present embodiment, when the reception channels of both tuners 11A and 11B are the same, the superheterodyne system of one tuner 11A or 11B is used as the intermediate frequency using the local oscillation frequency fc that is higher than the reception frequency fa. The lower superheterodyne method (upper mode) is set to fb, and the superheterodyne method of the other tuner 11B or 11A is changed to the intermediate frequency fb using the local oscillation frequency fc lower than the reception frequency fa. By performing the mode switching control to the (lower mode), mutual interference of the local oscillation circuit 22A is avoided, and a decrease in reception performance is avoided.
Here, in the upper superheterodyne system, the local oscillation frequency fc is made the sum of the reception frequency fa and the intermediate frequency fb, so that the mixer 22B ((local oscillation frequency fc) − (reception frequency fa)) In the lower superheterodyne system, the local oscillation frequency fc is set to a difference between the reception frequency fa and the intermediate frequency fb, so that the mixer 22B (((local oscillation frequency fc) The intermediate frequency fb of + (reception frequency fa)) is generated and output.

In order to enable switching of the superheterodyne method in this way, the table data in the memory 31 includes local portions corresponding to the upper superheterodyne method and the lower superheterodyne method for the reception channel (reception frequency). The oscillation frequency fc is described, or the local oscillation frequency fc corresponding to either the upper superheterodyne method or the lower superheterodyne method is described in the table data for the reception channel (reception frequency), and the other superheterodyne is written. When switching to the method, the control unit 13 (central control unit 32) uses the reception channel (reception frequency) and the local oscillation frequency fc corresponding to one to change the local oscillation frequency fc of the other superheterodyne method. A configuration that executes a calculation process to calculate It has become.
In addition to the above, a known configuration that enables switching of the superheterodyne method may be used.
And the frequency variable part 33 functions as a switching part which switches a superheterodyne system by controlling the control voltage Vc to 22 A of local oscillation circuits of each tuner 11A, 11B.

Next, the operation of the in-vehicle broadcast receiving apparatus 10 will be described.
In the present embodiment, of the two tuners 11A and 11B, one tuner 11A functions as a main tuner, and the other tuner 11B functions as a sub tuner. The main tuner 11A is used as a tuner that prioritizes reception of the reception channel selected by the user, and the sub-tuner 11B is used as a tuner that prioritizes reception of the traffic information reception channel.

  That is, as a basic operation in the radio mode, when the user selects a reception channel, the fact is input to the control unit 13 via the instruction input unit 12, and the central control unit 32 of the control unit 13 is operated by the frequency variable unit 33. Thus, the local oscillation frequency fc of the local oscillation circuit 22A on the main tuner 11A side is controlled to a frequency corresponding to the reception channel, and is received by the main tuner 11A. In the main tuner 11A, the frequency fa of the reception signal Sa corresponding to the reception channel is converted to the intermediate frequency fb, and an audio signal is detected (demodulated) from the converted signal Sb and output. Thereby, the sound corresponding to the reception channel is emitted from the vehicle speaker or used for recording.

  Further, the sub-tuner 11B performs a known channel search process for searching for a reception channel that can be received from the reception intensity under the control of the central control unit 32 of the control unit 13, and from among the reception channels that can be currently received, A reception channel for broadcasting the registered traffic information is automatically selected and received, and the received information is demodulated and output (traffic information reception processing). The reception channel for broadcasting the traffic information is stored in advance in the memory 31 of the control unit 13. The traffic information reception process of the sub-tuner 11B is also executed in the navigation mode, and the received traffic information is appropriately displayed according to the navigation screen or the user's instruction.

In addition, the central control unit 32 of the control unit 13 determines whether or not the reception intensity of the reception channel being received by the main tuner 11A is equal to or lower than a predetermined threshold that can be determined to be near the boundary of the broadcast area of the reception channel. Judgment. If the central control unit 32 determines that the value is equal to or less than the threshold value, the central control unit 32 performs a known channel search process by the sub tuner 11B while continuing the reception by the main tuner 11A, and the receivable reception searched by this channel search. A preset process for assigning channels to predetermined operation keys, that is, an auto preset process is executed.
By performing this auto-preset process, if the reception channel cannot be received by the main tuner 11A, a receivable reception channel can be selected (tuned) immediately if the user operates the auto-preset operation key. The above is the basic operation.

FIG. 2 is a flowchart showing reception channel switching control (that is, reception frequency switching control) of the control unit 13. This switching control is a process that is repeatedly executed while the in-vehicle broadcast receiving apparatus 10 is in operation (during a radio mode or the like).
First, the central control unit 32 determines whether or not to change the reception channel (step S1). The case where the reception channel is changed is that the user is instructed to change the reception channel of the main tuner 11A, or the reception intensity of the reception channel that the sub-tuner 11B is receiving becomes low. In this case, the reception channel is automatically changed.

When changing the reception channel, the central control unit 32 determines whether the tuners 11A and 11B have the same reception channel (reception frequency) and the superheterodyne system is the same. (Step S2). That is, the central control unit 32 determines whether or not the first condition that the local oscillation frequencies fc are the same when both tuners 11A and 11B receive the same reception channel (reception frequency) is satisfied.
When this first condition is satisfied (step S2: YES), the central control unit 32 performs control to change the reception channel by switching the superheterodyne system by the frequency variable unit 33 to the tuner 11A or 11B that is the reception channel change target. Perform (step S3).

Specifically, when the reception channel of the main tuner 11A is switched, the reception channels (reception frequencies) of the main tuner 11A and the sub tuner 11B are the same after switching, and the main tuner 11A and the sub tuner 11B are the same. In the case of the upper superheterodyne system, the main tuner 11A is switched to the lower superheterodyne system to change the reception channel.
Further, for example, when the reception channel of the sub tuner 11B is switched, the reception channels (reception frequencies) of the main tuner 11A and the sub tuner 11B are the same after switching, and the main tuner 11A and the sub tuner 11B are the same. In the case of the upper superheterodyne system, the reception channel is changed by switching the sub tuner 11B to the lower superheterodyne system.
Therefore, the local oscillation frequency fc differs between the main tuner 11A and the sub tuner 11B, so that mutual interference between the local oscillation circuits of both tuners can be avoided, and reception degradation due to mutual interference when receiving the same channel at the same time is avoided. can do.

On the other hand, when the first condition is not satisfied (step S2: NO), the central control unit 32 changes the reception channel (reception frequency) of both tuners 11A and 11B when the reception channel is changed, and the superheterodyne method. Are different from each other (step S4). Here, when the reception channel is the same, the local oscillation frequency fc is always different if the superheterodyne method is different between the tuners 11A and 11B. However, if the reception channel is different, the superheterodyne method is different. There is a risk that the local oscillation frequencies fc of the tuners 11A and 11B will be the same.
That is, in this step S4, whether or not the central control unit 32 satisfies the second condition including a situation in which the local oscillation frequencies fc when the tuners 11A and 11B are different reception channels (reception frequencies) becomes the same. Judgment.

When this second condition is satisfied (step S4: YES), the central control unit 32 performs control to change the reception channel by switching the superheterodyne system by the frequency variable unit 33 to the tuner 11A or 11B that is the reception channel change target. Perform (step S3).
Specifically, when the reception channel of the main tuner 11A is switched, the reception channels (reception frequencies) of the main tuner 11A and the sub tuner 11B are different after switching, and either the main tuner 11A or the sub tuner 11B is switched. Is the upper superheterodyne method and the other is the lower superheterodyne method, the reception channel is changed by switching the superheterodyne method of the main tuner 11A.
Further, for example, when the reception channel of the sub tuner 11B is switched, the reception channels (reception frequencies) of the main tuner 11A and the sub tuner 11B are different after switching, and either the main tuner 11A or the sub tuner 11B is When the upper superheterodyne method is used and the other is the lower superheterodyne method, the reception channel is changed by switching the superheterodyne method of the sub tuner 11B.
Therefore, the local oscillation frequency fc differs between the main tuner 11A and the sub-tuner 11B, so that mutual interference between the local oscillation circuits 22A of the tuners 11A and 11B can be avoided and reception deterioration due to mutual interference can be avoided. .

When neither the first condition nor the second condition is satisfied (step S4: NO), the central control unit 32 uses the frequency variable unit 33 to supervise the tuner 11A or 11B that is the reception channel change target. Control is performed to change the reception channel without switching the heterodyne system (step S5).
As a result, in this case as well, the local oscillation frequency fc differs between the main tuner 11A and the sub tuner 11B, so that mutual interference between the local oscillation circuits 22A of both tuners 11A and 11B can be avoided, and reception deterioration due to mutual interference can be avoided. can do. The above is the reception channel switching control (reception frequency switching control).

  As described above, according to the present embodiment, when the reception channel is changed, local oscillation is performed in each tuner 11A, 11B based on the reception channel of each tuner 11A, 11B and the superheterodyne system (mode). An upper superheterodyne method (upper mode) in which the local oscillation frequency fc is higher than the reception frequency fa of the reception channel among the frequencies that can be converted to the intermediate frequency fb so that the frequency fc is different, and reception of the reception channel Since the mode is switched between the lower superheterodyne method (lower mode) with a frequency lower than the frequency fa, the tuners 11A and 11B can simultaneously receive broadcasts of the same channel between the local oscillation circuits 22A. Mutual interference and reception degradation can be avoided.

In this case, when each tuner 11A, 11B receives the same reception channel, one tuner 11A or 11B is an upper superheterodyne system (upper mode), and the other tuner 11B or 11A is a lower superheterodyne system (lower Therefore, when the tuners 11A and 11B simultaneously receive broadcasts of the same channel, mutual interference between the local oscillation circuits 22A can be reliably avoided, and reception deterioration can be reliably avoided.
In addition, when each tuner 11A, 11B receives a different reception channel, both tuners 11A, 11B are set to the same upper superheterodyne system or lower superheterodyne system, so that both tuners 11A, 11B broadcast different channels. In the case of simultaneous reception, mutual interference between the local oscillation circuits 22A can be surely avoided, and reception degradation can be reliably avoided.
Further, when the mode is switched, only the tuner 11A or 11B whose reception channel is to be changed is switched, so that only the tuner 11A or 11B on the reception channel change side needs to be controlled, and the reception of the other tuner 11B or 11A is received. Can be continued, and sound interruptions can be avoided.

  Further, in this configuration, the two tuners 11A and 11B are a main tuner and a sub tuner, and whether or not the reception intensity of the reception channel being received by the central control unit 32 is equal to or lower than a predetermined threshold value. If it becomes less than or equal to the threshold value, the reception of the reception channel by the main tuner is searched while the reception of the reception channel by the main tuner is continued. In addition, channels that can be received by the sub-tuner can be searched in advance without searching for channels that can be received by the main tuner. Therefore, by automatically presetting the receivable channels searched by the sub-tuner, if the user operates the preset operation key when reception is difficult, the receivable channels can be selected (tuned) immediately. Can do.

The above-described embodiment is merely one aspect of the present invention, and can be arbitrarily modified within the scope of the present invention. For example, in the above-described embodiment, the case where the present invention is applied to the in-vehicle broadcast receiving apparatus 10 including the two tuners 11A and 11B has been described. You may apply to the apparatus 10. FIG. In this case, based on the reception channel and mode (upper superheterodyne system, lower superheterodyne system) of each tuner, the mode may be switched so that the local oscillation frequency fc is different in each tuner. When this mode switching is performed, if the tuner whose reception channel is to be changed is mode switched, reception by other tuners can be continued, and sound interruptions can be avoided efficiently.
In the above-described embodiment, the case where the present invention is applied to the in-vehicle broadcast receiving apparatus 10 has been described. However, the present invention is not limited to this, and the present invention may be applied to various broadcast receiving apparatuses including a plurality of tuners.

10 In-vehicle broadcast receiver (broadcast receiver)
11A, 11B Tuner 13 Control unit 22A Local oscillation circuit 32 Central control unit (control unit)
33 Frequency variable part (switching part)

Claims (5)

In a broadcast receiving apparatus having a plurality of tuners capable of receiving broadcast waves of the same channel, and having a local oscillation circuit that outputs a signal of a local oscillation frequency for converting a signal of a reception channel into a signal of an intermediate frequency for each tuner ,
A switching unit that switches between an upper mode that is higher than a reception frequency of the reception channel and a lower mode that is a lower frequency among the frequencies that can be converted to the intermediate frequency, the local oscillation frequency,
A broadcast unit characterized by having a control unit that causes the switching unit to switch modes so that the local oscillation frequency is different in each tuner based on the reception channel of each tuner and the mode when the reception channel is changed Receiver device.   2. The control unit according to claim 1, wherein when the two tuners receive the same reception channel, the control unit distributes one tuner to the upper mode and the other tuner to the lower mode. Broadcast receiving device.   The broadcast receiving apparatus according to claim 2, wherein when the two tuners receive different reception channels, the control unit sets both tuners to the same mode.   The broadcast receiving apparatus according to any one of claims 1 to 3, wherein when the mode is switched by the switching unit, the control unit switches the mode of a tuner whose reception channel is to be changed. A broadcast receiving apparatus having a plurality of tuners capable of receiving broadcast waves of the same channel and having a local oscillation circuit that outputs a signal of a local oscillation frequency for converting a signal of a reception channel into a signal of an intermediate frequency for each tuner In the control method,
When changing the reception channel, is the upper mode in which the reception channel of each tuner and the local oscillation frequency in each tuner are higher than the reception frequency of the reception channel among the frequencies that can be converted to the intermediate frequency? A control method for a broadcast receiving apparatus, wherein the mode is switched so that the local oscillation frequency is different in each tuner based on whether the lower mode is a low frequency.

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