JP2009232355A - Channel scanning method for tuner unit and broadcast signal receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the channel scanning time of a tuner by shortening the lock-up time by optimizing the tuning order of a channel scan. <P>SOLUTION: A broadcast signal receiver comprises: a tuner unit 1; an oscillation unit 14 which is divided into a plurality of oscillation bands and generates the oscillation signal of an oscillation frequency, corresponding to a tuning channel by varying a tuning voltage for each oscillation band; and a host 4 that switches the tuning voltage to be applied to the oscillation unit 14, to continuously switch the tuning channel, wherein a channel scan is performed by sequentially switching the tuning channel so that the change amount of the tuning voltage in switching the tuning channel becomes smaller than a voltage difference between the tuning voltage in tuning a minimum channel included in the oscillation bands and a tuning voltage in tuning a maximum channel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a channel scanning method and a broadcast signal receiving apparatus in a tuner unit having a plurality of oscillator bands.

  Currently, there are many channels in digital television broadcasting, and channel scanning is performed to determine which channel has a broadcast signal when the tuner is powered on. Note that not only digital television broadcast signals but also broadcast signals having a plurality of channels are received, a channel scan can be performed in advance to confirm the channels containing the broadcast signals.

  The tuner installed in the conventional broadcast signal receiver selects the channel from the first channel (low frequency side) to the maximum channel (high frequency side) when the power is turned on, and the program on the host side broadcasts to any channel. Knows if a signal is present.

  When selecting a channel in the tuner, it is necessary to oscillate an oscillation signal different from the broadcast signal (desired channel) by the baseband frequency from the VCO in order to convert the broadcast signal (desired channel) to be received into a predetermined baseband frequency signal. There is. For example, a tuning voltage Vt having a magnitude capable of setting an oscillation signal from a PLL circuit to the VCO is supplied to determine the oscillation frequency of the VCO (see, for example, Patent Document 1). The PLL circuit described in Patent Document 1 generates a reference signal necessary for oscillating an oscillation signal different from a broadcast signal by a baseband frequency from a VCO based on given data, and is oscillated by the reference signal and the VCO. The oscillation frequency is compared in phase, the charge pump is charged with the phase error signal obtained by the phase comparison to generate the tuning voltage Vt, and the oscillation frequency of the VCO is changed by the tuning voltage Vt.

  By the way, since the broadcast signal subjected to the channel scan is a wide band, the OSC band is divided into a plurality of bands, the variable range of the tuning voltage Vt within one band is suppressed, and the tuning voltage Vt is set to a low voltage (low voltage) in each band. (High-frequency side channel) to high voltage (high-frequency side channel).

  FIG. 4 is a diagram showing the relationship between the tuning voltage Vt and the oscillation frequency when the OSC band is divided into three bands. For example, in the first band, the oscillation frequency of each channel can be selected with a tuning voltage Vt between 1 V and 30 V, and the tuning voltage Vt is 1 V in order to perform channel scanning from the low frequency side channel to the high frequency side channel. From 30 to 30 V in a predetermined step. Tuning is also possible in the second and third bands so that the oscillation frequency of each channel within the band can be selected with a tuning voltage Vt between 1 V and 30 V, and the channel is scanned from the low frequency side channel to the high frequency side channel. The voltage Vt is increased from 1V to 30V in a predetermined step.

  Accordingly, the maximum channel of the first band and the minimum channel of the second band are adjacent channels, but the tuning voltage Vt when selecting the maximum channel of the first band is the maximum voltage (30V). The tuning voltage Vt for selecting the minimum channel of the second band is the lowest voltage (1V).

When channel scanning is performed in a conventional tuner, for example, channel selection is started from the smallest channel of the first band, and the channel number is sequentially increased to the largest band of the third band. Therefore, when switching from the maximum channel of the first OSC band to the minimum channel of the second OSC band, the tuning voltage Vt is changed from the maximum voltage (30V) to the minimum voltage (1V). Similarly, when switching from the maximum channel of the second OSC band to the minimum channel of the third OSC band, the tuning voltage Vt is changed from the maximum voltage (30 V) to the minimum voltage (1 V). Even when the channel scan direction is reversed, the tuning voltage Vt is changed from the lowest voltage (1 V) to the maximum voltage (30 V) at the boundary of the OSC band.
JP 2002-261606 A

  As described above, when the channel scan is performed so that the channel number is increased or decreased in order in one channel step, the tuning voltage Vt is changed from the lowest voltage (1V) to the maximum voltage (30V) when crossing the boundary of adjacent OSC bands. ) Or the maximum voltage (30V) to the minimum voltage (1V).

  However, since the tuning voltage Vt changes greatly during the channel scan, the lockup is the time from when the channel selection command is given to the PLL circuit until the OSC oscillation frequency is fixed and the tuner tuning is completed. There was a problem that time became long.

  The present invention has been made in view of the above points, and a channel scan method for a tuner unit that can reduce the lockup time by optimizing the channel scanning channel selection order and reduce the time required for the channel scan, and An object is to provide a broadcast signal receiving apparatus.

  The channel scan method of the present invention receives a broadcast signal including a plurality of channels, while generating an oscillation signal by applying a tuning voltage corresponding to a selected channel to an oscillation circuit divided into a plurality of oscillation bands, A channel scan method for continuously switching the channel selection by controlling the oscillation band and the tuning voltage by extracting the signal of the channel selection by mixing the oscillation signal with the broadcast signal including the plurality of channels, The amount of change in the tuning voltage when switching the tuning channel is smaller than the voltage difference between the tuning voltage when tuning the minimum channel and the tuning voltage when tuning the maximum channel included in the oscillation band. The channel scanning is performed by sequentially switching the channel selection channel.

  According to this configuration, the amount of change in the tuning voltage when switching the tuning channel is based on the voltage difference between the tuning voltage when tuning the minimum channel included in the oscillation band and the tuning voltage when tuning the maximum channel. Since the tuning order is optimized so that the tuning time becomes smaller, it is possible to prevent the lock-up time from becoming longer due to a large change in the tuning voltage during channel scanning, and to shorten the channel scanning time.

  In the above channel scan method, the present invention also groups all channels over the entire oscillation band according to the tuning voltage at the time of channel selection, and scans from the channel having the lowest tuning voltage within an arbitrary oscillation band. When the channel selection within the group is completed, the tuning voltage of the group selected immediately before is shifted to the next group with the smallest change in tuning voltage, and the channels of the group are sequentially selected. , It is characterized by the fact that it moves to a group with higher tuning voltage.

  With this configuration, channels with the same tuning voltage are selected from all oscillation bands in sequence, and when channel selection within the same group is completed, the next group with a smaller amount of tuning voltage shifts to the same channel selection. As a result, the amount of change in tuning voltage when switching channels can be minimized over the entire period of channel scan, and the lockup time can be prevented from becoming longer due to large changes in tuning voltage. The scanning time can be shortened.

  In the channel scan method, the present invention starts scanning from the channel having the lowest tuning voltage in an arbitrary oscillation band, and the same tuning voltage as the scan start channel in the other oscillation band or the same. When a channel that becomes a tuning voltage within a predetermined range whose change amount is smaller than that at the time of channel selection adjacent in the oscillation band is sequentially selected, and channel selection that is the same or a tuning voltage within the predetermined range is completed. , Select an unselected channel adjacent to the last selected channel in the same oscillation band, and sequentially select channels having the same tuning voltage as that channel or a tuning voltage within the predetermined range from other oscillation bands. Select a station and increase the tuning voltage sequentially in the same manner. To.

  With this configuration, the amount of change in tuning voltage when switching channels can be minimized over the entire period of channel scanning, and when tuning within the group is completed, it is within the same oscillation band as the last selected channel. Since the adjacent unselected channel is selected at, the number of band switching can be suppressed.

  In the above channel scan method, the present invention also groups all channels over the entire oscillation band according to the tuning voltage at the time of channel selection, and scans from the channel having the highest tuning voltage within an arbitrary oscillation band. When the channel selection within the group is completed, the tuning voltage of the group selected immediately before is shifted to the next group with the smallest change in tuning voltage, and the channels of the group are sequentially selected. , It is characterized by a sequential shift to a group having a lower tuning voltage.

  With this configuration, channels with the same tuning voltage are selected from all oscillation bands in sequence, and when channel selection within the same group is completed, the next group with a smaller amount of tuning voltage shifts to the same channel selection. As a result, the amount of change in tuning voltage when switching channels can be minimized over the entire period of channel scan, and the lockup time can be prevented from becoming longer due to large changes in tuning voltage. The scanning time can be shortened.

  In the channel scan method, the present invention starts scanning from a channel having the highest tuning voltage in an arbitrary oscillation band, and the same tuning voltage or the same as the scan start channel in another oscillation band. When a channel that becomes a tuning voltage within a predetermined range whose change amount is smaller than that at the time of channel selection adjacent in the oscillation band is sequentially selected, and channel selection that is the same or a tuning voltage within the predetermined range is completed. , Select an unselected channel adjacent to the last selected channel in the same oscillation band, and sequentially select channels having the same tuning voltage as that channel or a tuning voltage within the predetermined range from other oscillation bands. Select a channel and then gradually reduce the tuning voltage in the same manner. To.

  With this configuration, the amount of change in tuning voltage when switching channels can be minimized over the entire period of channel scanning, and when tuning within the group is completed, it is within the same oscillation band as the last selected channel. Since the adjacent unselected channel is selected at, the number of band switching can be suppressed.

  Further, according to the present invention, in the above channel scan method, scanning is started from the channel having the lowest tuning voltage in the low-frequency oscillation band, and the tuning voltage is sequentially increased so that adjacent channels in the oscillation band are sequentially turned. When the channel with the highest tuning voltage is reached in the oscillation band, the channel with the highest tuning voltage is moved to the oscillation band adjacent to the high frequency side, and the tuning voltage is sequentially lowered to cause the oscillation. Channels adjacent to each other in the band are selected in order, and when the channel with the lowest tuning voltage is reached within the oscillation band, the next transition to the channel with the lowest tuning voltage is made in the oscillation band adjacent to the high frequency side. Similarly, channel selection is repeated for each oscillation band.

  With this configuration, when the channel with the highest tuning voltage is reached within the oscillation band, the next transition is to the channel with the highest tuning voltage in the oscillation band adjacent to the high frequency side, and to the channel with the lowest tuning voltage within the oscillation band. When it reaches, the transition is made to the channel with the lowest tuning voltage in the next oscillation band adjacent to the high frequency side, so that the amount of change in the tuning voltage when the oscillation band is switched can be suppressed. In addition, since the adjacent channels in the oscillation band are selected in order, the number of band switching can be suppressed.

  Further, according to the present invention, in the above channel scan method, scanning is started from the channel having the highest tuning voltage in the high-frequency oscillation band, and the tuning voltage is sequentially decreased, and the adjacent channels in the oscillation band are sequentially switched. When the channel with the lowest tuning voltage in the oscillation band is reached, the channel with the lowest tuning voltage is shifted to the oscillation band adjacent to the lower frequency side, and the tuning voltage is sequentially increased to cause the oscillation. Channels adjacent to each other in the band are selected in order, and when the channel having the highest tuning voltage is reached within the oscillation band, the next transition to the channel having the highest tuning voltage is performed in the oscillation band adjacent to the low frequency side. Similarly, channel selection is repeated for each oscillation band.

  With this configuration, when the channel with the lowest tuning voltage is reached within the oscillation band, the next transition is to the channel with the lowest tuning voltage in the oscillation band adjacent to the low frequency side, and the channel with the highest tuning voltage within the oscillation band. When it reaches, the transition is made to the channel with the highest tuning voltage in the next oscillation band adjacent to the low frequency side, so that the amount of change in the tuning voltage when the oscillation band is switched can be suppressed. In addition, since the adjacent channels in the oscillation band are selected in order, the number of band switching can be suppressed.

  The broadcast signal receiving apparatus according to the present invention includes a tuner unit that extracts a channel selection signal by mixing an oscillation signal with a broadcast signal including a plurality of channels, and a tuning voltage divided for each oscillation band. And an oscillation unit that generates an oscillation signal having an oscillation frequency corresponding to the channel to be selected, and a control unit that performs channel scanning for continuously switching the channel to be selected by switching a tuning voltage applied to the oscillation unit. In the broadcast signal receiving apparatus, the control unit selects a tuning voltage and a maximum channel when selecting a minimum channel included in the oscillation band so that a change amount of the tuning voltage when switching a tuning channel is selected. Channels are switched by switching the channel so that the voltage difference from the tuning voltage at the time becomes smaller. And performing Rusukyan.

  With this configuration, the amount of change in the tuning voltage when switching channels is made smaller than the voltage difference between the tuning voltage when tuning the minimum channel included in the oscillation band and the tuning voltage when tuning the maximum channel. Since the channel selection order is optimized, it is possible to prevent the lockup time from becoming longer due to a large change in the tuning voltage during channel scanning, and to shorten the channel scanning time.

  According to the present invention, the channel scan channel selection order can be optimized to shorten the lock-up time, and the tuner channel scan time can be shortened.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a configuration example of a broadcast signal receiving apparatus that executes a channel scanning method of the present invention. The broadcast signal receiving apparatus includes a tuner unit 1 having a plurality of OSC bands, a demodulator 2 that demodulates a broadcast signal received by the tuner unit 1, and a broadcast signal demodulated by the demodulator 2 as a video signal and an audio signal. The main components are an MPEG decoder 3 that decodes and a host 4 that functions as a control unit that controls a tuning voltage during channel scanning.

  The tuner unit 1 amplifies an RF signal output from an RF unit (not shown) by a high frequency amplifier 11 and then inputs the amplified signal to the mixer 12. The mixer 12 mixes the RF signal and the local oscillation signal to generate a baseband frequency signal. Is amplified by the baseband frequency amplifier 13 and then output to the demodulator 2. The local oscillation signal supplied to the mixer 12 is generated by the local oscillation unit 14. The local oscillating unit 14 includes first, second, and third frequency variable oscillators 14a to 14c for each of the three divided OSC bands. The first variable frequency oscillator 14a is configured to be able to vary the oscillation frequency within the first OSC band. Similarly, the second and third frequency variable oscillators 14b and 14c are configured to be able to vary the oscillation frequency within the second and third OSC bands, respectively. In this way, the local oscillation frequency that covers the entire area of the broadband broadcast signal is supplied with the entire oscillation frequency of the first, second, and third frequency variable oscillators 14a, 14b, and 14c. In this example, the OSC band that covers the entire area of the broadcast signal is divided into three, but the number of divisions is not limited to this. Further, the number of divisions of the OSC band and the number of frequency variable oscillators do not necessarily need to match. A local oscillation signal generated by the local oscillation unit 14 is supplied to the mixer 12 via the switching unit 15. The switching unit 15 includes switching terminals 15a, 15b, and 15c connected to output terminals of the first, second, and third frequency variable oscillators 14a to 14c. Based on a band switching signal given from the host 4 to the switching unit 15, one of the first, second and third frequency variable oscillators 14 a to 14 c is selected and connected to the mixer 12. The oscillation frequency of the first, second and third frequency variable oscillators 14 a to 14 c changes according to the tuning voltage Vt applied from the PLL circuit 16.

FIG. 2 is a schematic configuration diagram of the PLL circuit 16. A reference signal obtained by _{dividing the} reference signal f _OSC output from the reference signal oscillator 21 configured by a crystal oscillator or the like by the frequency divider 22 by the frequency division number R is input to the phase comparator 24. On the other hand, a signal obtained by dividing the oscillation frequency f _VCO output from the variable frequency oscillator (14a, 14b, 14c) by the frequency divider N by the frequency divider N is input to the phase comparator 24. The phase comparator 24 compares the phase of the reference signal with the oscillation frequency f _VCO oscillated by the variable frequency oscillator (14a, 14b, 14), and charges the charge pump 25 with the phase error signal obtained by the phase comparison. A tuning voltage Vt is generated. The generated tuning voltage Vt is taken out by the LPF 26 and only the direct current component is taken out and applied to the variable frequency oscillators (14a, 14b, 14c) to change the oscillation frequency. The tuning voltage Vt is controlled by the frequency division number R set in the frequency divider 22, and the oscillation frequency of each OSC band is determined by the voltage value of the tuning voltage Vt.

  The host 4 gives the frequency division number R set in the frequency divider 22 to the PLL circuit 16 as a channel selection command via the demodulator 2. The ROM 17 stores channel selection order data at the time of channel scanning. The host 4 reads the tuning order data from the ROM 17 and outputs a tuning instruction and a band switching signal in the order according to the tuning order data.

Here, the tuning order optimized to shorten the lockup time will be described.
In the present embodiment, the channel selection order is not determined only by the descending or ascending order of the channel numbers, but the channel selection is performed in the order in which the change in the tuning voltage Vt becomes as small as possible when the channels are switched.

  FIGS. 3A to 3C show an example of the optimized channel selection order. For convenience of explanation, it is assumed that the first OSC band includes 1 to 3 channels, the second OSC band includes 4 to 6 channels, and the third OSC band includes 7 to 9 channels. The present invention is not limited to such channel setting.

  As shown in FIG. 3A, all channels subject to channel scanning can be grouped by tuning voltage Vt. In this example, group 1 = (1Ch, 4CH, 7CH), group 2 = (2Ch, 5CH, 8CH), and group 3 = (3Ch, 6CH, 9CH). In this example, each channel in the same group is exemplified as having the same tuning voltage Vt. However, it is not always necessary to have the same voltage, and the voltage width is within a range where an allowable lock-up time can be realized. It is also possible to have In the channel selection order shown in FIG. 3A, the channel starts from channel 1 which is the lowest frequency channel of the first OSC band. First, the channels constituting group 1 are scanned. The channel selection order is controlled from channel 1 to channel 4, which is the lowest frequency channel of the second OSC band, and channel 4 to channel 7, which is the lowest frequency channel of the third OSC band. Since the lowest frequency channel (1CH, 4CH, 7CH) of each OSC band has the same tuning voltage Vt (1V), the lock-up time is greatly shortened.

  Next to the 7th channel which is the lowest frequency channel of the third OSC band, the 8th channel which is an adjacent channel in the same OSC band is selected. At this time, the tuning voltage Vt is increased by one step when changing the channel selection from the 7th channel to the 8th channel. However, since the voltage change is a minimum step, the lockup time can be shortened.

  Since 8 channels constitute group 2, the channels of group 2 are scanned. The channel selection order is controlled from 8 channels of the third OSC band to 5 channels of the second OSC band and 2 channels of the first OSC band. Since the tuning voltage Vt is the same for each channel (2CH, 5CH, 8CH) of each OSC band, the lock-up time is greatly shortened.

  Next to the 2nd channel of the first OSC band, 3 channels which are adjacent channels in the same OSC band are selected. At this time, the tuning voltage Vt is increased by one step when changing the channel selection from the 2nd channel to the 3rd channel. However, since the voltage change is the minimum step, the lockup time can be short.

  Since the three channels constitute group 3, the channels of group 3 are scanned. The channel selection order is controlled from 3 channels of the first OSC band to 6 channels of the second OSC band and 8 channels of the third OSC band. Since the channels (3CH, 6CH, 9CH) of these OSC bands have the same tuning voltage Vt (30V), the lock-up time is greatly shortened.

  Thus, by selecting the channels in group order as shown in FIG. 3A, the tuning voltage Vt does not change with the change of the channel selection channel, or the voltage changes below the minimum step. As a result, the time required to complete the channel scan can be shortened.

  Further, as shown in FIG. 3B, scanning may be started from group 3 on the high voltage side. Start with channel 9, which is the highest frequency channel of the third OSC band. The channel selection order is controlled from channel 9 to channel 6 which is the highest frequency channel of the second OSC band, and channel 6 to channel 3 which is the highest frequency channel of the first OSC band.

  After 3 channels of the first OSC band, 2 channels that are adjacent channels (group 2) in the same OSC band are selected. The channel selection order is controlled from 2 channels of the first OSC band to 4 channels of the second OSC band and 8 channels of the third OSC band. Further, after 8 channels of the third OSC band, 7 channels (group 1) which are adjacent channels in the same OSC band are selected. Then, the channel selection order is controlled from 7 channels of the third OSC band to 4 channels of the second OSC band and 1 channel of the first OSC band.

  Thus, even if the channel selection order is selected as shown in FIG. 3B, there is no change width of the tuning voltage Vt accompanying the change of the channel selection channel or the voltage change in the minimum step. The time required to complete the channel scan can be shortened.

  Further, as shown in FIG. 3C, the channel selection order can be optimized without grouping the channels with the tuning voltage Vt. Starting from the first channel which is the lowest frequency channel of the first OSC band, the first OSC band is selected in order of 2 channels and 3 channels. Next to channel 3 which is the highest frequency channel of the first OSC band, channel 6 is selected which is the highest frequency channel of the second OSC band having the same tuning voltage Vt. Then, the second OSC band is tuned in the order of 5 channels and 4 channels. Next to the 4th channel which is the lowest frequency channel of the second OSC band, the 7th channel which is the lowest frequency channel of the third OSC band having the same tuning voltage Vt (1 V) is selected. Then, the channel in the third OSC band is selected in order of 8 channels and 9 channels. In addition, after the 3rd channel which is the highest frequency channel of the first OSC band, the 9th channel which is the highest frequency channel of the third OSC band which is another same tuning voltage Vt is not the second OSC band. After selecting the channel and selecting the third OSC band in sequence, it is possible to select from the 7th channel to the 4th channel which is the lowest frequency channel of the second OSC band.

  Although a tuning order other than the above may be used, it is important to optimize the tuning order so that the tuning voltage Vt does not change greatly when the tuning channel changes.

  Next, the operation of the broadcast signal receiving apparatus when performing the above channel scan will be described.

  The host 4 reads channel selection order data from the ROM 17 at the time of power activation and performs channel scanning. For example, it is assumed that the tuning order data shown in FIG. The host 4 sends a tuning command signal for selecting the channel 1 of the first OSC band and a band switching signal for selecting the first OSC band to the tuner unit 1 via the MPEG decoder 3 and the demodulator 2. .

In the tuner unit 1, the channel selection command signal and the band switching signal are input to the PLL circuit 16. Frequency divider numbers R and N corresponding to the oscillation frequency for receiving channel 1 are set in frequency divider 22 of PLL circuit 16 by the channel selection command signal. The switching unit 15 selects the switching terminal 15a so that the first frequency variable oscillator 14a covering the first OSC band is connected to the mixer 12 through the switching terminal 15a by the band switching signal. As a result, the tuning voltage Vt (1 V) is controlled so as to obtain an oscillation frequency for converting the frequency component of one channel in the broadcast signal into the baseband frequency. The first variable frequency oscillator 14a oscillates at an oscillation frequency corresponding to the tuning voltage Vt, and an oscillation signal having this oscillation frequency is input to the mixer 12 via the switching terminal 15a. The mixer 12 mixes the broadcast signal and the oscillation signal and converts the frequency component of one channel in the broadcast signal into a baseband frequency. The host 4 confirms the presence / absence of a signal from the demodulator output at the time of channel selection. When the signal confirmation for one channel is completed, the next channel indicated in the tuning order data is selected in the same manner as described above. In the channel selection order shown in FIG. 3A, four channels of the second OSC band are selected. In the PLL circuit 16 to which the channel selection command signal has been input, the tuning voltage Vt is the same for the immediately previous channel selection channel (1 channel) and the current channel selection channel (4 channels), so the second channel of the second OSC band. The second frequency variable oscillator 14b has already been tuned to the oscillation frequency for receiving four channels. Therefore, the tuning operation is completed simply by the switching unit 15 switching from the switching terminal 15a to the switching terminal 15b based on the band switching signal. Next, the same operation and lock-up time occur when channel 7 of the third OSC band is selected. Next, when the channel selection channel is switched from the 7th channel to the 8th channel, new frequency division numbers R and N are set in the frequency divider 22 of the PLL circuit 16, but the tuning voltage Vt has the smallest change width. Since only one step is up, the lock-up time until the oscillation frequency of the third variable frequency oscillator 14c is set is short. As described above, when channel scanning is performed in the channel selection order shown in FIG. 3A, the tuning voltage Vt does not change or has a minimum change width.

  As described above, according to this embodiment, the channel selection order at the time of channel scanning is optimized so that there is no or minimum change width of the tuning voltage Vt at the time of channel change from the viewpoint of shortening the lock-up time. Therefore, the lock-up time at the time of channel selection can be shortened and the time required for the entire channel scan can be shortened.

  In the above description, the channel selection command signal and the band switching signal are transmitted from the host 4 to the tuner unit 1 via the MPEG decoder 3 and the demodulator 2, but are directly input from the host 4 to the tuner unit 1. It is good also as a structure. Further, the configuration is not limited to the configuration in which the tuning voltage Vt is controlled by the frequency dividing number R as in the PLL circuit 16 shown in FIG. 2, and the tuning voltage (oscillation frequency) can be varied based on a command signal from the host. For example, other configurations may be used. If the broadcast signal is encoded by a method other than MPEG, a decoder corresponding to the encoding method is used. Furthermore, it can be applied not only to television broadcasting but also to channel scanning for FM broadcasting.

  The present invention is applicable to a broadcast signal receiving apparatus that performs channel scanning in a tuner.

The block diagram of the broadcast signal receiver which concerns on one embodiment which performs the channel scan method of this invention Schematic configuration diagram of the PLL circuit shown in FIG. The figure which shows the channel selection order at the time of the channel scan performed in the said one Embodiment The figure which shows the channel selection order at the time of the conventional channel scan

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tuner part 2 ... Demodulation part 3 ... MPEG decoder 4 ... Host 11 ... High frequency amplifier 12 ... Mixer 13 ... Baseband frequency amplifier 14 ... Local oscillation part 14a ... 1st frequency variable oscillator 14b ... 2nd frequency variable oscillator 14c ... Third frequency variable oscillator 15 ... Switching units 15a, 15b, 15c ... Switching terminal 16 ... PLL circuit 21 ... Reference signal oscillator 22 ... Divisor (frequency division number R)
23 ... Frequency divider (frequency division number N)
24 ... Phase comparator 25 ... Charge pump 26 ... LPF

Claims (8)

While receiving a broadcast signal including a plurality of channels, the oscillation signal is generated by applying a tuning voltage corresponding to the selected channel to an oscillation circuit divided into a plurality of oscillation bands, and the broadcast signal including the plurality of channels is generated. A channel scan method for continuously switching the channel selection by controlling the oscillation band and the tuning voltage by extracting the signal of the channel selection by mixing the oscillation signal with
The amount of change in the tuning voltage when switching the tuning channel is smaller than the voltage difference between the tuning voltage when tuning the minimum channel and the tuning voltage when tuning the maximum channel included in the oscillation band. A channel scanning method, wherein channel scanning is performed by sequentially switching channel selection channels.   All channels across all oscillation bands are grouped by tuning voltage at the time of channel selection, scanning is started from the channel with the lowest tuning voltage within any oscillation band, and the channels within that group are selected. When the station is completed, the tuning voltage of the group selected immediately before is shifted to the next group that has the smallest amount of change, the channel of that group is sequentially selected, and the group is sequentially shifted to the group with the higher tuning voltage. The channel scanning method according to claim 1, wherein: Start scanning from the channel with the lowest tuning voltage in any oscillation band, and select the same tuning voltage as the scan start channel in the other oscillation band or the channel selection adjacent in the same oscillation band Select the channel that will be the tuning voltage within a predetermined range with a smaller change amount than
When the channel selection of the tuning voltage within the same range or the predetermined range is completed, the channel that is not selected in the same oscillation band as the last selected channel is selected, and the tuning voltage same as the channel or the above-mentioned channel is selected. 3. The channel scanning method according to claim 1, wherein a channel having a tuning voltage within a predetermined range is sequentially selected from other oscillation bands, and thereafter the tuning voltage is sequentially increased in the same manner. .   All channels across all oscillation bands are grouped by tuning voltage at the time of channel selection, and scanning is started from the channel with the highest tuning voltage in any oscillation band to select the channels in that group. When the station is complete, the tuning voltage of the group selected immediately before is shifted to the next group that has the smallest amount of change, the channel of that group is sequentially selected, and the channel is sequentially shifted to the group with the lower tuning voltage. The channel scanning method according to claim 1, wherein: Start scanning from the channel with the highest tuning voltage in any oscillation band, and select the same tuning voltage as the scan start channel in another oscillation band or the channel selection adjacent in the same oscillation band Select the channel that will be the tuning voltage within a predetermined range with a smaller change amount than
When the channel selection of the tuning voltage within the same range or the predetermined range is completed, the channel that is not selected in the same oscillation band as the last selected channel is selected, and the tuning voltage same as the channel or the above-mentioned channel is selected. 3. A channel scanning method according to claim 1, wherein a channel having a tuning voltage within a predetermined range is sequentially selected from within another oscillation band, and thereafter the tuning voltage is successively lowered in the same manner. .   Start scanning from the channel with the lowest tuning voltage in the low-frequency oscillation band, and gradually increase the tuning voltage to select adjacent channels in that oscillation band in order, and tune within that oscillation band. When the channel with the highest voltage is reached, the next transition to the channel with the highest tuning voltage is performed in the oscillation band adjacent to the high frequency side, and the tuning voltage is sequentially lowered to select the adjacent channels in the oscillation band in turn. When the channel having the lowest tuning voltage is reached in the oscillation band, the channel is shifted to the channel having the lowest tuning voltage in the oscillation band adjacent to the high frequency side, and the channel selection is repeated for each oscillation band in the same manner. The channel scanning method according to claim 1, wherein:   Start scanning from the channel with the highest tuning voltage in the high-frequency oscillation band, and gradually lower the tuning voltage to select the adjacent channels in that oscillation band in order, and tune in that oscillation band. When the channel with the lowest voltage is reached, the next transition to the channel with the lowest tuning voltage is performed in the oscillation band adjacent to the low band side, and the tuning voltage is sequentially increased to select the adjacent channels in the oscillation band in order. When the channel having the highest tuning voltage in the oscillation band is reached, the channel is shifted to the channel having the highest tuning voltage in the oscillation band adjacent to the low frequency side, and the channel selection is repeated for each oscillation band in the same manner. The channel scanning method according to claim 1, wherein: A tuner unit that extracts a channel selection signal by mixing an oscillation signal with a broadcast signal including multiple channels, and is divided into multiple oscillation bands, and the tuning voltage can be varied for each oscillation band to support the channel selection channel. A broadcast signal receiving apparatus comprising: an oscillating unit that generates an oscillation signal having an oscillating frequency; and a control unit that performs a channel scan that switches a tuning channel continuously by switching a tuning voltage applied to the oscillating unit,
The controller is configured such that when the tuning channel is switched, the amount of change in the tuning voltage is based on a voltage difference between the tuning voltage when tuning the minimum channel included in the oscillation band and the tuning voltage when tuning the maximum channel. The broadcast signal receiving apparatus is characterized in that channel scanning is performed by sequentially switching the channel selection so that the channel becomes smaller.

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