JP2007300170A - In-vehicle broadcast receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-vehicle broadcast receiver capable of enhancing channel detection accuracy without considerably extending a channel scan time. <P>SOLUTION: The in-vehicle broadcast receiver provided with a plurality of tuners captures data associated with a set time difference in the case of starting the channel scan, allows the tuners to start broadcast receiving according to the captured data associated with the time differences, and performs reception propriety discrimination of broadcast waves on the basis of a result of the detection of the same channel outputted from the tuners with the time differences. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-vehicle broadcast receiving apparatus including a plurality of tuners that receive a broadcast while moving, perform a channel scan by sequentially changing a reception frequency.

In-vehicle broadcast receivers generally include a plurality of tuners and improve reception performance using diversity reception technology that performs signal synthesis and switching.
In addition, the channel scan (automatically scans the broadcast channel) and records the receivable channel data in the memory, and then reads the selected channel data from the memory and controls the tuner reception frequency to receive the broadcast. Scanning and auto-preset functions are often used.

On the other hand, in digital broadcasting, it takes time to detect a broadcast wave, and for this reason, a scan time when performing a channel scan becomes relatively long.
For example, in digital terrestrial television, it is necessary to scan all 49 channels from channel 13 (ch13) to channel 62 (ch62), as shown in FIGS. There is. In general, the tuner tuning time (the time from when the PLL built-in oscillation circuit that controls the tuner receiving frequency starts up until the PLL converges) takes approximately 100 milliseconds, and it is also necessary to determine whether there is a broadcast signal. It takes 600 milliseconds. Therefore, at least about 35 seconds are required to complete scanning of all channels.

In order to improve scanning accuracy in the in-vehicle broadcast receiving apparatus, the time series data may be subjected to signal determination twice or three times as shown in the operation flowcharts in FIGS. . For this reason, for example, when the signal determination is performed twice, there is a problem that the scan time is approximately twice as long (35 seconds → about 65 seconds).
In order to solve this problem, conventionally, a technique for shortening the scan time by using a plurality of tuners and alternately tuning the scan channels alternately is known (for example, see Patent Document 1).
JP 10-150346 A (paragraph “0004”, FIG. 1)

According to the technique disclosed in Patent Document 1 described above, the time required for scanning is approximately halved and the time required for scanning is reduced, but the channel detection accuracy is not guaranteed.
In particular, when channel scanning is performed while a vehicle is moving in an in-vehicle broadcast receiver, channel misdetection such as misstop may occur due to fluctuations in received radio waves accompanying movement, and improvement in channel detection accuracy is required. It was.

  The present invention has been made to solve the above-described problems. An in-vehicle broadcast receiving apparatus and a channel scan control method capable of improving channel detection accuracy without significantly increasing a channel scan time. The purpose is to obtain.

  The in-vehicle broadcast receiving apparatus according to the present invention determines whether or not reception is possible according to a plurality of tuners that perform channel scanning independently based on a set time difference, and detection results of the same channel output from each tuner with the time difference. And a control means for performing the above.

  According to the present invention, channel scanning is performed independently based on time difference data set in each of the mounted tuners, and the detection result of the same channel is checked a plurality of times without significantly increasing the scanning time. In addition, the channel detection accuracy can be improved.

Embodiment 1 FIG.
1 is a block diagram showing an internal configuration of an in-vehicle broadcast receiving apparatus according to Embodiment 1 of the present invention.
The in-vehicle broadcast receiving apparatus according to the first embodiment of the present invention includes tuner ^{# 11} 1, tuner ^# 22 ² , signal processing device 3 as signal processing means, and control device 4 with a built-in microcomputer as control means. , And an operation input device 5 such as a key switch and a dial as operation input means. Reference numeral 6 denotes a vehicle speed sensor connected to the control device 4 via an ECU (electronic control unit) (not shown) and an in-vehicle LAN (Local Area Network).

The tuner ^{# 1} 1 and the tuner ^{# 2} 2 perform channel scans independently based on the time difference data (delay time) set by the control device 4, and the channel scan results are sent to the signal processing device 3 and the control device. Output to 4.
The signal processing unit 3 has a function of tuner ^{# 1} 1, and the tuner ^{# 2} 2 broadcast waves received by the signal processing, the output to the not shown reproduction system (video, audio). Therefore, the signal processing device 3 includes a detection unit ^{# 1} 31, a detection unit ^{# 2} 32, a diversity combining unit 33, and an image / audio decoding unit 34.

The digital broadcast wave received by the tuner ^{# 1} 1 is converted into an IF (intermediate frequency) signal and input to the detection unit ^{# 1} 31 of the signal processing device 3. The detector ^{# 1} 31 performs A / D (Analog / Digital) conversion of the input IF signal to digital data, and further, performs quadrature modulation and frequency-tuned I component and Q component signals on an FFT (high-speed) basis. The signal is converted into a frequency signal by Fourier calculation and output to the diversity combining unit 33.
On the other hand, the broadcast wave received by tuner ^# 22 ² is converted into an IF (intermediate frequency) signal and input to detector ^{# 2} 32 of signal processing device 3. The detector ^{# 2} 32 converts the input IF signal into digital data by A / D conversion, and further converts it into a frequency signal by FFT of the I component and Q component signals that have been subjected to quadrature modulation and frequency tuning. To the unit 33.

The diversity combiner 33 switches or combines the frequency signals output by the tuner ^{# 1} 1 and the tuner ^{# 2} 2 and detected and output by the detector ^{# 1} 31 and the detector ^{# 2} 32 according to the output of the control device 4. And output to the image / sound decoder 34.
Further, the image / audio decoding unit 34 converts the input frequency signal into, for example, an MPEG2-TS (Moving Picture Experts Group 2-Transport Stream) signal, and the video data, audio data, Broadcast data and the like are separated and output to a reproduction system (not shown).

On the other hand, the control unit 4 has a function of performing determination of reception according tuner ^{# 1} 1, detection results of the same channel output with a time difference from the tuner ^{# 2} 2. Therefore, the control device 4 includes a tuner ^{# 1} control unit 41, a tuner ^{# 2} control unit 42, a signal ^{# 1} determination unit 43, a signal ^{# 2} determination unit 44, a switching unit 45, a main control unit 46, , Memory ^{# 1} 461 and memory ^{# 2} 462.

The tuner ^{# 1} control unit 41 activates the channel scan operation for the connected tuner ^{# 11} 1 based on the time difference data set under the control of the main control unit 46 when the channel scan is executed.
The signal ^{# 1} determination unit 43 receives signal quality information such as C / N (Carrier / Noise) output from the detection unit ^{# 1} 31 of the signal processing device 3 during the channel scan operation by the tuner ^{# 11} 1. The level is determined and recorded in memory ^{# 1} 461.

On the other hand, the tuner ^{# 2} control unit 42 activates the channel scan operation for the connected tuner ^# 22 ² based on the time difference data set under the control of the main control unit 46 when the channel scan is executed.
At this time, the signal ^{# 2} determination unit 44 receives the signal quality information such as C / N output from the detection unit ^{# 2} 32 of the signal processing device 3 during the channel scan operation by the tuner ^# 22 ² , and determines the level. To memory ^{# 2} 462.

Under the control of the main control unit 46, the switching unit 45 outputs the tuner ^{# 11} 1 and tuner ^{# 2} 2 outputs or a switching signal to the diversity combining unit 33.
The main control unit 46 refers to the signal quality levels output from the signal ^{# 1} determination unit 43 and the signal ^{# 2} determination unit 44 and recorded in the memory # 1 (461) and the memory # 2 (462). It is judged whether or not the broadcast wave can be received by comparing with a threshold value indicating the set receivable signal quality level, or by referring to the time-series data and estimating the reception status of the broadcast accompanying movement, and judging whether or not the broadcast wave can be received.

Note that the operation input device 5 and the vehicle speed sensor 6 are connected to the main control unit 46, and when starting the channel scan, the time difference data set and input via the operation input device 5 is taken in, and the tuner ^{# 1} control unit 41 The tuner ^{# 2} control unit 42 controls the channel scan start timing.
At this time, the main control unit 46 calculates the time difference data from the moving speed of the vehicle measured by the vehicle speed sensor 6 (for example, determines the magnitude of the time difference in proportion to the moving speed), and the tuner ^{# 1} control unit 41. The start timing of channel scanning by the tuner ^{# 2} control unit 42 may be controlled.

   The main control unit 46 also fetches a threshold value (receivable signal level) used for determining whether or not broadcast waves can be received via the operation input device 5 operated by the user, and determines whether or not broadcast waves can be received. . Convenience can be provided to the user by changing the above-described threshold according to the use of the channel scan.

2 to 4 are diagrams cited for explaining the operation of the in-vehicle broadcast receiving apparatus according to the first embodiment of the present invention. A schematic diagram (FIG. 2) showing the operations of tuner ^{# 1} and tuner ^{# 2} on the time axis, a flowchart (FIG. 3) showing a flow of basic operation of the in-vehicle broadcast receiver, and a schematic diagram of signal determination processing ( FIG. 4) is shown.
Hereinafter, the operation of the in-vehicle broadcast receiving apparatus according to the first embodiment of the present invention shown in FIG. 1 will be described in detail with reference to FIGS.

In the schematic diagram of FIG. 2, the in-vehicle broadcast receiving apparatus according to the first embodiment of the present invention performs channel scanning of digital broadcasting (ch13 to ch62). At this time, the control device 4 controls the tuner ^{# 1} 1 and the tuner ^{# 2} 2 and starts the scan of the tuner ^{# 2} 2 with a time difference of 700 mS after the start of the scan of the tuner ^{# 1} 1, for example.

At this time, the IF signal output from the tuner ^{# 11} is detected by the detection unit ^{# 1} 31 of the signal processing device 3, and the detection result is output to the signal ^{# 1} determination unit 43 of the control device 4. Here, the detection is the control until the input IF signal is A / D converted into digital data, and further converted into a frequency signal by FFT of the signals of the I component and Q component that have been subjected to quadrature modulation and frequency tuning. Say.
The signal ^{# 1} determination unit 43 receives signal quality information such as C / N (Carrier / Noise) output from the detection unit ^{# 1} 31 of the signal processing device 3 during the channel scan operation by the tuner ^{# 11} 1. The level of the received signal quality information is determined, and the determination result is written into the memory ^{# 1} 461.

Similarly, the signal output from the tuner ^# 22 ² is detected by the detection unit ^{# 2} 32 of the signal processing device 3, and the detection result is output to the signal ^{# 2} determination unit 44 of the control device 3.
Then, the signal ^{# 2} determination unit 44 receives the signal quality information such as C / N output by the detection unit ^{# 2} 32 of the signal processing device 3 during the channel scan operation by the tuner ^# 22 ^2, and receives the received signal quality information. The level of the signal quality information is determined, and the determination result is written into the memory ^{# 2} 462.

As described above, the control device 4 (main control unit 46) performs the channel scan operations of the tuner ^{# 1} 1 and the tuner ^{# 2} 2 independently, and when the scan of the tuner ^{# 2} 2 is finished, the control device 4 4 (main control unit 46) refers to the contents recorded in the memory ^{# 1} 461 and the memory ^{# 2} 462, and compares with a preset threshold value to determine whether or not the broadcast wave can be received. finish.
By controlling as described above, the signal determination was performed twice only by extending the time from the start of the tuner scan of tuner ^{# 1} 1 to the start of the channel scan of tuner ^{# 2} 2 (in this case, 700 ms). The same effect as the case can be obtained.

In the flowchart of FIG. 3, first, it is assumed that a channel scan is instructed by the user operating a specific key switch of the operation input device 5.
First, the main control unit 46 of the control device 4 sets a reception frequency (N value) to the tuner ^{# 1} control unit 41 (step ST301). As a result, tuner ^{# 11} starts channel scan from ch13 and outputs the result to signal processor 4. The signal processing device 4 waits for the convergence (PLL lock) of the PLL (phase synchronization circuit) that controls the reception frequency of the tuner in the detection unit ^{# 1} 31 (step ST302), and determines the signal of the control unit 4 to determine whether or not reception is possible. Output signal quality information such as C / N to the ^{# 1} determination unit 43.

The signal ^{# 1} determination unit 43 determines the level of the signal quality information (steps ST303 and ST304), records information on the presence / absence of broadcast in the memory 461 (steps ST305 and ST306), and transmits the broadcast wave to the main control unit 46. It is entrusted to determine whether or not to receive.
The above-described procedure (step ST301 to step ST306) is repeated until the channel scan is completed for all channels (step ST307).

On the other hand, the main control unit 46 controls the tuner ^{# 2} control unit 43 and activates the channel scan of the tuner ^{# 2} 2 after 700 ms has elapsed from the start of the channel scan of the tuner ^{# 1} 1.
The tuner ^{# 2} control unit 43 sets the reception frequency (N value) of ch13 to the tuner ^{# 2} 2 (step ST311), whereby the tuner ^{# 2} 2 performs channel scan of ch13 and outputs the result as a signal. Output to the processing device 4. The signal processing device 4 waits for the convergence of the PLL that controls the reception frequency of the tuner at the detection unit ^{# 2} 32 (step ST312), and then determines the signal ^{# 2} determination unit 44 of the control unit 4 for C / Output signal quality information such as N. The signal ^{# 2} determination unit 44 determines the level of the signal quality information (steps S313 and ST314), records broadcast presence / absence information in the memory 462 (steps S315 and ST316), and transmits the broadcast wave to the main control unit 46. Entrust reception decision.

Subsequently, the main control unit 46 sets an N value corresponding to the reception frequency of ch14 in the tuner ^# 22 2, and repeats the above-described procedure (steps ST311 to ST316). The above-described procedure is repeated until scanning for all channels from ch15 to ch62 is completed (step ST317).
Then, after the channel scan by the tuner ^{# 2} 2 is completed, the main control unit 46 refers to the reception quality levels recorded in the memory ^{# 1} 461 and the memory ^{# 2} 462 and determines whether or not the broadcast wave can be received (step S318). ). The main control unit 46 uses a signal quality level such as C / N determined by the signal ^{# 1} determination unit 43 and the signal ^{# 2} determination unit 44, a threshold set by the operation input device 5, or the vehicle speed sensor 6. The broadcast wave can be received or not is determined by comparing with a threshold that is dynamically set according to the output moving speed.

Details of the determination of whether or not broadcast waves can be received by the main control unit 46 will be described in detail with reference to FIG. FIG. 4 is a diagram showing detection results and determination results for the broadcast reception status of ch21 in comparison with three examples (a), (b), and (c).
For example, as shown in FIG. 4A, when the detection result of ch 21 is tuner ^{# 11} 1 and quality level “2”, tuner ^{# 2} 2 is quality level “3”, and the threshold is level 3, The control unit 46 determines that ch21 is level “3” (receivable). In the figure, the shaded portion indicates the receivable signal quality level.
The main control unit 46 can also grasp the state of signal change of the broadcast radio wave while the vehicle is moving by using the above-described determination method. For example, if three tuners (tuner ^{# 1} , tuner ^{# 2} , tuner ^{# 3} ) are used and the time difference between the start of scanning is set to 700 ms, the detection results of each tuner are as shown in FIG. 4B, for example. For example, the main control unit 46 can estimate that the signal of ch21 at this time is “there is a weak electric field but there is a received signal”, and as a result, can determine that the signal quality is “3” (receivable). In this case, the channel scan is completed with a delay of about 1400 ms compared to the conventional method.

Furthermore, when three tuners (tuner ^{# 1} , tuner ^{# 2} , and tuner ^{# 3} ) are used and channel scans are performed with a time difference of about 2 seconds each, for example, the detection results of each tuner are shown in FIG. c), the signal quality level of ch21 at this time transitions to “3”, “1”, and “0”. From this, the main control unit 46 determines that the signal is “received”. Therefore, it can be determined that the signal quality is “0” (cannot be received).
In this way, the main control unit 46 can estimate the broadcast reception status based on the time series of the channel scan detection results, and reflect this in the determination of whether or not reception is possible. In this case also, the channel scan is completed with a delay of about 4 seconds compared to the conventional method.

  In FIGS. 4A, 4B, and 4C, the signal quality level “3” is set as the threshold value, and the signal quality level “3” or higher is determined as the receivable signal quality. It can be made variable by the user operating the operation input device 5 according to the usage. Further, the moving speed of the vehicle may be detected by the vehicle speed sensor 6 or the like, and the main control unit 46 may dynamically change the threshold according to the moving speed.

As described above, Embodiment 1 of the present invention performs channel scanning independently based on the time difference data set in each installed broadcast receiving means, and checks the detection result of the same channel a plurality of times. Therefore, the channel detection accuracy is improved without significantly increasing the scan time.
The functions of the tuner ^{# 1} control unit 41, tuner ^{# 2} control unit 42, signal ^{# 1} determination unit 43, signal ^{# 2} determination unit 44, switching unit 45, and main control unit 46 constitute the control unit 4. It is assumed that the microcomputer that performs the processing sequentially reads and executes the program recorded in the built-in ROM. At this time, it is assumed that each of the memory ^{# 1} 461 and the memory ^{# 2} 462 is allocated and recorded in a RAM built in the microcomputer. The above microcomputer is not shown.

It is a block diagram which shows the internal structure of the vehicle-mounted broadcast receiving apparatus concerning Embodiment 1 of this invention. It is the figure quoted in order to demonstrate operation | movement of the vehicle-mounted broadcast receiver concerning Embodiment 1 of this invention. It is a flowchart explaining operation | movement of the vehicle-mounted broadcast receiver concerning Embodiment 1 of this invention. It is the figure quoted in order to demonstrate operation | movement of the vehicle-mounted broadcast receiver concerning Embodiment 1 of this invention. It is the figure quoted in order to demonstrate the operation | movement of the channel scan of the broadcast receiver in a prior art example. It is a flowchart explaining the operation | movement of the channel scan of the broadcast receiver in a prior art example. It is the figure quoted in order to demonstrate the operation | movement of the channel scan of the broadcast receiver in a prior art example. It is a flowchart explaining the operation | movement of the channel scan of the broadcast receiver in a prior art example.

Explanation of symbols

1 tuner ^{# 1} , 2 tuner ^{# 2} , 3 signal processing device, 4 control device, 5 operation input device, 6 vehicle speed sensor, 31 detection unit ^{# 1} , 32 detection unit ^{# 2} , 33 diversity combining unit, 34 image / audio decoding 41, tuner ^{# 1} control unit, 42 tuner ^{# 2} control unit, 43 signal ^{# 2} determination unit, 44 signal ^{# 2} determination unit, 45 switching unit, 46 main control unit, 461 memory ^{# 1} , 462 memory ^{# 2} .

Claims (7)

An in-vehicle broadcast receiving device that receives a broadcast while moving, and sequentially changes a set frequency to execute a channel scan,
A plurality of tuners that independently perform the channel scan based on a set time difference; and
Control means for determining whether or not reception is possible according to the detection result of the same channel output with a time difference from each of the tuners;
An in-vehicle broadcast receiver characterized by comprising: Detection of signals output from the respective tuners with a time difference is performed, and the generated frequency signal is output to the control unit, and diversity combining is performed under the control of the control unit, and multiplexed into the frequency signal. The in-vehicle broadcast receiving apparatus according to claim 1, further comprising: a signal processing unit that separates the data and outputs the separated data to each reproduction system. 3. The vehicle-mounted device according to claim 1, further comprising an operation input unit that takes in data relating to a time difference input for the setting and supplies the data to the control unit when starting the channel scan. 4. Broadcast receiving device. The control means includes
2. The digital broadcast receiving apparatus according to claim 1, wherein data based on the time difference is calculated and set from a moving speed. The control means includes
During the channel scan operation, signal quality information is received from each tuner via the signal processing means, and the received signal quality information is compared with a preset threshold value to determine whether or not the reception is possible. The in-vehicle broadcast receiving apparatus according to claim 1, wherein the in-vehicle broadcast receiving apparatus is performed.   6. The in-vehicle broadcast receiving apparatus according to claim 5, further comprising operation input means that takes in data relating to a threshold value input for operation for the setting and supplies the data to the control means. The control means includes
6. The in-vehicle broadcast receiving apparatus according to claim 5, wherein a reception situation is estimated based on a time series of channel scan detection results recorded in a memory for each of the tuners, and is reflected in the determination of whether or not reception is possible.

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