JP3050697U - Frequency synthesizer type channel selection device - Google Patents

Abstract

(57) [Summary] [Configuration] When a channel preset is executed, an initial value of the frequency f ₀ is set in step S1. Step S
Until the horizontal synchronizing signal is detected at step 5, the frequency f ₀ is added by 0.5 MHz at step S7. When a horizontal synchronization signal is detected, an AFT search process is performed in step S9. That is, the frequency f ₀ is monitored while monitoring the AFT voltage.
Is added in increments of 0.5 MHz, and it is determined in step S11 whether or not there is a station. Here, if it is determined to be owned,
Preset the channel data of the broadcasting station and execute step S
At 15, 6 MHz is added to the frequency f ₀ , and the process returns to step S 3. By repeating such an operation, the preset is executed over the entire reception band. [Effect] Channel preset can be performed without a PAL channel plan.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention relates to a frequency synthesizer type tuner, and more particularly to a frequency synthesizer type tuner applied to, for example, a PAL type television receiver.

[0002]

[Prior art]

 In such a conventional frequency synthesizer type channel selection device, auto preset is executed according to a predetermined channel plan.

[0003]

[Problems to be solved by the invention]

 However, the PAL system has been adopted in many countries. Therefore, in order to be able to preset in each country, it is necessary to store a channel plan for each country in a nonvolatile memory. For this reason, there has been a problem that the memory capacity is enlarged and as a result, the cost is increased.

On the other hand, in the voltage synthesizer system, auto-preset can be performed regardless of the channel plan, but there is a problem that it takes time to complete the preset. Therefore, a main object of the present invention is to provide a frequency synthesizer type channel selecting device which can be preset in a short time without a PAL type channel plan.

[0005]

[Means for Solving the Problems]

 The idea is to search for a broadcasting station at a first frequency interval from one end of a reception band, and when a station is detected, set a frequency at a second frequency interval larger than the first frequency interval, and then set a third frequency smaller than the second frequency interval. This is a frequency synthesizer type tuning device that searches at intervals.

[0006]

[Action]

 When the channel preset is executed, the initial value of the frequency is set, and the broadcast station at one end (lower end) of the reception band is searched at the first frequency interval. When a broadcast station is detected, the channel data of the broadcast station is preset in the memory, and the frequency is set at a second frequency interval larger than the first frequency interval. The second frequency interval is set to be larger than the first frequency interval, but is set to be smaller than the frequency between PAL broadcast stations. Therefore, a search is made for a broadcast station adjacent to the detected broadcast station. In this case, the frequency is set near the frequency of the adjacent broadcasting station. Then, the broadcast station is searched at a third frequency interval smaller than the second frequency interval. By repeating this operation, the preset is executed up to the broadcast station at the other end (upper end) of the reception band.

[0007]

[Effect of the invention]

 According to this invention, the broadcast station at one end of the reception band is detected and the adjacent broadcast station is searched at a predetermined frequency interval, so that the preset can be executed even without a PAL channel plan. . In addition, since a large frequency interval is set between adjacent broadcasting stations, the time required for auto presetting can be shortened as compared with a voltage synthesizer type tuning apparatus.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

【Example】

 With reference to FIG. 1, a frequency synthesizer type tuning apparatus 10 of this embodiment includes a tuning operation unit 12, and a frequency f according to a channel selected by the tuning operation unit 12.₀Is supplied from the microcomputer 14 to the latch register 16. Frequency f of selected channel₀Is stored (preset) in a memory 14 a provided in the microcomputer 14.₀And the next (other) frequency f ₀ Hold until is given. Output of the latch register 16 (frequency f₀) Is supplied to the phase detection circuit 20 via the variable frequency divider 18.

The frequency synthesizer type tuning apparatus 10 includes a reference oscillator 22, and a clock pulse generation circuit 24 generates a clock pulse based on an output (oscillation frequency) of the reference oscillator 22 and supplies the clock pulse to the microcomputer 14. The oscillation frequency from the reference oscillator 22 is frequency-divided by the fixed frequency divider 26 at a predetermined frequency division ratio, and supplied to the phase detection circuit 20. In the phase detection circuit 20, the detection output is obtained based on the frequency f ₂ given frequency f ₁ supplied from the variable frequency divider 18 from the fixed frequency divider 26. That is, the detection output when the frequencies f ₁ and f ₂ are equal is 0, when the frequency f ₁ is greater than the frequency f ₂ are positive detection output is obtained, the frequency f ₁ is the frequency f If it is smaller than ₂ , a negative detection output is obtained. The low-pass filter 28 outputs a tuning voltage to the tuner 30 based on the output from the phase detection circuit 20. The oscillation frequency of the local oscillator 30a included in the tuner 30 is controlled by the tuning voltage.

In the tuner 30, a high-frequency television signal received by an antenna (not shown) is amplified by a high-frequency amplifier 30b and mixed with an oscillation frequency from a local oscillator 30a to extract a video intermediate frequency signal. This video intermediate frequency signal is amplified by a video intermediate frequency amplification circuit 32 and supplied from a terminal 34 to a video signal processing circuit (not shown). Further, the oscillation frequency from the local oscillator 30 a is divided by the pre-frequency divider 36 at a predetermined frequency division ratio, and is provided to the variable frequency divider 18. Variable frequency divider 1 8 varies the frequency dividing ratio based on the frequency f ₃ which is supplied from the preceding stage frequency divider 36, the peripheral and the wave number f ₁ and frequency f ₂ is adjusted to be equal.

The output from the video intermediate frequency amplification circuit 32 is provided to an automatic frequency adjustment (AFT) circuit 38. In the AFT circuit 38, a video carrier is extracted, and this video carrier is amplified. The amplified signal has a constant amplitude and is subjected to FM detection. Then, a change in the frequency is extracted as a change in the DC voltage. After this voltage is amplified, unnecessary components are removed and applied to the tuner 30. The local oscillation frequency is corrected by the output (AFT voltage) of the AFT circuit 38, and the intermediate frequency of the video intermediate frequency signal is made constant. The AFT voltage is supplied to the microcomputer 14, and the microcomputer 14 determines whether the setting of the frequency has been completed based on the AFT voltage. That is, when the AFT voltage is fluctuating, it is determined that the broadcasting station is being searched because the local oscillation frequency is being adjusted. On the other hand, when the AFT voltage is constant, since the local oscillation frequency is also adjusted to a constant value, it is determined that the search for the broadcast station has been completed, that is, the broadcast station has been detected.

The output of the video intermediate frequency amplification circuit 32 is provided to a synchronization separation circuit 40, and the horizontal synchronization signal (H _sync. ) _Extracted by the synchronization separation circuit 40 is provided to the microcomputer 14. The microcomputer 14 determines whether there is a video signal based on the presence or absence of the horizontal synchronization signal. That is, when there is a horizontal synchronization signal, it is determined that there is a video signal, and when there is no horizontal synchronization signal, it is determined that there is no video signal.

For example, when a channel is preset, an initial value of the frequency f ₀ is set. The initial value of the frequency f ₀ is set to a value smaller than the frequency at the lower end of the reception band of any country. Then, until the broadcasting station of the lower end of the reception band is detected, the frequency f ₀ is set (in this example, the first frequency interval is set to 0.5 MH _Z.) At a first frequency interval, broadcasting A station search is performed.

When the microcomputer 14 detects a horizontal synchronizing signal, an AFT search is executed at a third frequency interval equal to the first frequency interval. That is, the microcomputer 14 monitors the AFT voltage while adding the frequency f ₀ by 0.5 MH _Z, you determine the presence or absence of a broadcasting station. The microcomputer 14 is determines that Yukyoku if the AFT voltage is constant (in this example, 2 MH _Z) AFT voltage is a predetermined frequency width if continue to vary beyond the judges that no station I do. If it is determined that chromatic station may preset the channel data of a broadcast station memory 14a, 6MH _Z (second frequency interval) is added to a frequency f _0. The channel plan of the PAL system, the frequency between broadcasting stations adjacent for a 7～8MH _Z, the second frequency interval in this embodiment is set to 6MH _Z. Therefore, the frequency f ₀ is set near the frequency of the broadcasting station adjacent to the detected broadcasting station. Then, the frequency f ₀ is set again at the third frequency interval, and when the microcomputer 14 detects the horizontal synchronizing signal, the AFT search is executed. By repeating such an operation, the preset can be executed over the entire reception band.

On the other hand, if a horizontal synchronization signal is detected and an AFT search is performed on a broadcast station, but no broadcast is performed, that is, if an AFT search is performed over a predetermined frequency width, the detected horizontal synchronization signal is erroneous. Judge that it was. That is, the microcomputer 14 performs processing according to the flowchart shown in FIG. As shown in FIG. 2, the microcomputer 14 starts the processing channel preset is selected, sets the frequency f ₀ at stearyl-up S1. Followed, the frequency f ₀ In step S3, it is determined whether or exceeds the maximum value of the reception bands of (900MH _Z). Here, if "YES", that is, if the channel preset has been completed over the entire reception band, the process ends. If "NO", it is determined in step S5 whether or not there is a horizontal synchronization signal. Here, "NO" returns to the step S3 to 0.5 MH _Z the summing frequency f ₀ if it processes the AFT search in step S9 if "YES". In step S11 actually determine whether there is a video signal, if "Y ES" records the channel data in the memory 14a, and 6MH _Z added to the frequency f ₀ in the subsequent step S5, the flow returns to step S3 . On the other hand, if "NO" in the step S11, the frequency width to be searched at step S17, it is determined whether exceeds 2 MH _Z. Here, if "YES", it is determined that the horizontal synchronization signal detected in step S5 is incorrect, and the process returns to step S3. If "NO", the process returns to step S9 and the AFT search is continued. .

According to this embodiment, since the broadcast station at the lower end of the reception band is detected and the adjacent broadcast station is searched at a predetermined frequency interval, the preset can be executed even if there is no PAL channel plan. Can be. In addition, since the frequency interval (second frequency interval) between adjacent broadcasting stations is increased, the time required for auto presetting can be reduced as compared to a voltage synthesizer type channel selection device.

In this embodiment, the presetting is performed from the broadcasting station at the lower end of the receiving band. However, the presetting may be performed from the broadcasting station at the upper end of the receiving band. Further, in this embodiment, the first frequency interval and the third frequency interval are set to be equal, but they may be set to different frequency intervals. At this time, by setting the third frequency interval to be small, the AFT search can be executed more accurately.

[Submission date] March 12, 1998

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

[Means for Solving the Problems]

This invention is, first search means for searching broadcasting station in the first frequency interval from one end of the reception band, detecting means for detecting detects the Yukyoku or no station, the frequency of the broadcasting station detected a chromatic station by the detection means the search for next station with a small third frequency interval than the second frequency interval after adding the second frequency interval the summing means for adding a larger first frequency interval second frequency interval, and adding means This is a frequency synthesizer type channel selection device including two search means .

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

[Action]

When the channel preset is executed, the initial value of the frequency is set, and the first search means searches the broadcast station at one end (lower end) of the reception band at the first frequency interval (for example, 2 MHz) . Whether there is a broadcasting station, i.e. Yukyoku or Mukyoku is thus detected in the detection means, in the case of the chromatic station channel data of the broadcast station is stored in the memory (preset). Further, a second frequency interval larger than the first frequency is added to the frequency of the broadcasting station whose station is detected by the adding means . However, it is set smaller than the frequency spacing between the second frequency interval broadcasters adjacent. For example, the PAL system, the frequency interval between broadcast stations in most countries because the a 7MHz or 8 MHz, the second frequency interval is set to 6 MHz. Then, in the case of searching the next station, the search of the next station is performed in the third frequency interval equal to the first frequency interval after adding the second frequency interval. By repeating this operation, the preset is executed up to the broadcasting station at the other end (upper end) of the reception band.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

On the other hand, if a horizontal synchronization signal is detected and an AFT search is performed on a broadcast station, but no broadcast is performed, that is, if an AFT search is performed over a predetermined frequency width, the detected horizontal synchronization signal is erroneous. Judge that it was. That is, the microcomputer 14 performs processing according to the flowchart shown in FIG. As shown in FIG. 2, the microcomputer 14 starts the processing channel preset is selected, sets the frequency f ₀ at stearyl-up S1. Followed, the frequency f ₀ In step S3, it is determined whether or exceeds the maximum value of the reception bands of (900MH _Z). Here, if "YES", that is, if the channel preset is completed over the entire reception band, the process is terminated. If "NO", it is determined in step S5 whether or not there is a horizontal synchronization signal. Here, "NO" returns to the step S3 to 0.5 MH _Z the summing frequency f ₀ if it processes the AFT search in step S9 if "YES". In step S11 actually determine whether there is a video signal, if "Y ES", the channel data recorded in the memory 14a at step S13, 6MH _Z added to the frequency f ₀ Succeeding step S 1 5 Then, the process returns to step S3. On the other hand, if "NO" in the step S11, the frequency width to be searched at step S17, it is determined whether or exceeds 2 MH _Z. Here, if "YES", it is determined that the horizontal synchronization signal detected in step S5 is erroneous, and the process returns to step S3. If "NO", the process returns to step S9 to continue the AFT search.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a part of the processing of the microcomputer shown in FIG. 1 embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Frequency synthesizer type tuning apparatus 14 ... Microcomputer 30 ... Tuner 38 ... AFT circuit

[Procedure amendment]

[Submission date] March 12, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims for utility model registration

[Correction method] Change

[Correction contents]

[Utility model registration claims]

Claims (3)

[Utility model registration claims] 1. Searching for a broadcasting station at a first frequency interval from one end of a reception band, setting a frequency at a second frequency interval larger than the first frequency interval when detecting a station, and thereafter setting a frequency smaller than the second frequency interval. A frequency synthesizer type tuning device that searches at a third frequency interval. 2. The frequency synthesizer type tuning apparatus according to claim 1, wherein said second frequency interval is set smaller than a frequency interval between adjacent broadcasting stations in a PAL type channel plan. 3. The frequency synthesizer type tuning apparatus according to claim 1, wherein said first frequency interval is equal to said third frequency interval.