JPH01305718A - Channel selection device in tuner - Google Patents

Abstract

PURPOSE:To simplify and speed up a channel selecting operation by automatically channel-selecting a frequency until it is tuned in accordance with an offset value. CONSTITUTION:If the listener of a travelling vehicle inputs a part of the frequency by a lead 14 and operates a channel selecting start lead when he does not know an accurate broadcasting frequency, a control circuit 13 judges zero in the offset value, calls frequency-dividing number corresponding to the set frequency from a ROM memory 16, and outputs it to a programmable frequency divider 8. When there is an inputted broadcasting station by the inputted frequency-dividing number, a tuned signal is outputted from a detection circuit 5, and the control circuit 13 receives the tuned broadcasting station if the tuned signal is present. When the tuned signal is not outputted on the other hand, tuning and a reception action are executed by shifting the offset value one by one until the tuned signal is outputted from the detection circuit 5.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tuner in which, by inputting a vague frequency using an operation button, broadcasting of frequencies before and after the frequency can be automatically selected. Regarding a channel selection device.

[Conventional technology]

BACKGROUND ART Conventionally, there has been a tuner called direct tuning in which when a user inputs the frequency of a desired broadcasting station by operating an operation button, the user selects the broadcasting station of that frequency.

[Problem to be solved by the invention]

By the way, with the conventional tuner mentioned above, you cannot select a station unless you remember the exact frequency that corresponds to the station name. When you want to listen to a broadcast station, if you don't know the exact frequency of the local broadcast station, but you remember the approximate frequency (for example, you remember the first two digits of ○OMHz), you can select the broadcast station you want to listen to. There was a problem in that it took a lot of time and effort to select a station.

[Purpose of the invention]

The present invention is intended to solve the above-mentioned problems, and its purpose is to enable users to select the desired frequency by inputting the approximate frequency using operation 10, even if they do not remember the exact frequency of the broadcast station they listened to. It is an object of the present invention to provide a channel selection device for a tuner which enables the selection of broadcast stations in a short time and easily.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention searches for the nearest broadcasting station to the frequency centered on the inputted frequency by inputting the approximate frequency of the broadcasting station that one wishes to listen to using an operation button. The gist of this is that the system allows users to tune in to that broadcasting station.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. The figure shows the case of a digital synthesizer tuner, where l is an antenna, 2 is an RF amplifier, 3 is a mixer, 4 is an IF amplifier,
5 is a detection circuit, 6 is a VCo as a local oscillator, 7 is a prescaler that quarters the output of the VCO, 8 is a programmable frequency divider, 9 is a low-pass filter, 10 is a phase comparator, 11 is a frequency divider, Reference numeral 12 designates a reference crystal oscillator, and the above is a known circuit configuration.

In other words, when trying to receive 80MHz FM broadcast, the VCo6 must oscillate (80-10,7Ml(z)).Therefore, the programmable frequency divider 8
When the frequency division number N = 693 (usually a variable frequency divider is used) is input to the prescaler 7, and the frequency division number of the prescaler 7 is 4, the input to the phase comparator 10 is
One input sets the oscillation frequency of the reference crystal oscillator 12 to 1.
00K7 and the frequency division number of the frequency divider 11 is 4, the frequency component of will be applied, and since a PLL including the VCo6 is configured, the frequency of the VCo6 is controlled so that ft=69.3MHz. It turns out. in this way,
When varying the reception frequency, change the division number of the programmable frequency divider 8 (for the FM band, N = 654 to 79).
2) The reception frequency corresponding to the frequency division number is determined.

Also, in the case of AM broadcasting, the channel space is 9KH.
z, the reference frequency is set to 9KHz, and the VCo
6.

Reference numeral 13 designates a control circuit that performs operations to be described later, into which the output signal from the above-mentioned detection circuit 5 and the signal from the operation button 14 are input, and the signal to the display 15 and the above-mentioned programmable frequency divider 8 are input. The division number is output. Note that the operation button 14 described above is, for example, a numeric keypad for inputting a frequency. Further, the display 15 displays the frequency input by the operation button 14, the frequency being selected, or, if there is a broadcast station corresponding to the input frequency, the name of the broadcast station.

16 is a ROM memory that serves as an offset memory for changing the frequency little by little up and down to the band edge around the frequency input by the operation button 14 described above, and stores a frequency division number corresponding to the frequency; 17 is a selector; When the frequency of a tuned broadcast station is stored using a preset button or the like, it is a memory such as a RAM that stores the selected frequency.

Next, the operation will be explained based on the above-described configuration with reference to the flowchart shown in FIG.

If you are currently listening to a program from a certain FM broadcast station while driving in a car, and the radio waves of that station become weak and it becomes difficult to listen to the program, you can listen to a broadcast station in the area where the listener is driving. If the receiver wants to listen but does not know the positive 6-square frequency, the receiver inputs some of the frequencies stored in the receiver's memory, for example, the first two digits of the frequency, using the operation button 14 (step St). Next, when a channel selection start button provided as a part of the operation buttons 14 is operated (step S2), the control circuit 13
In step S3), it is determined whether all the input frequencies have been input. If all the frequencies have been input (for example, if all three digits of 82.5 MHz are filled), Proceed directly to the next step S4.

Also, if all frequencies are not input (for example, 82 MHz), all remaining digits are assumed to be 0 (
Step S4), proceed to the next Stellar S5.

Then, in step S5, the offset value is set to 0. That is, if all frequencies (82.5MHz) are input, the 82.5MHz frequency is output as is, and if some frequencies (82MHz) are input, the 82.5MHz frequency is output as is. Outputs a frequency of 0MHz. In this way, once the frequency is determined, the control circuit 1
3 has an offset value of 0 in step 6, so
The frequency division number corresponding to the frequency set in step 5 is read from the memory 16 and output to the programmable frequency divider 8. Therefore, if there is a broadcasting station based on the frequency division number input by the above-described operation, a tuned signal is output from the detection circuit 5, so the control circuit 13 determines whether or not this tuned signal is present (step 37). here,
If there is a broadcast station to tune into, the reception state is maintained and all operations are completed. Note that if the frequencies of the broadcasting stations are known and all frequencies are input, unless the input frequencies are incorrect, tuning can be achieved if there is a receiving station, so the operation ends at this point.

On the other hand, if the tuned signal is not output from the detection circuit 5, skip steps 3B and S9, or perform the same processing as steps S6 and 37 described above, and then change the offset value from 0 to 1. Step 5
IO), return to step S6. Then, in step S6, the input frequency is changed to a plus offset value as the reception frequency (step S6). In other words, as in the example above, if only two digits of <82MHz are entered,
82.1 MHz is set as the reception frequency, and the frequency division number corresponding to the frequency is input to the programmable frequency divider 8. As a result, it is determined whether or not a tuned signal is output from the detection circuit 5 (step S7). If a tuned signal is output, the operation ends in the same manner as described above. If the tuned signal is not output, the receiving frequency is changed from the input frequency (82 MHz) to a negative offset value. That is, 81.9 MHz is set as the reception frequency, and the frequency division number corresponding to the frequency is input to the programmable frequency divider 8 (step S8). As a result, it is determined whether or not a tuned signal is output from the detection circuit 5 (step S9), and if a tuned signal is output, the operation is ended. In addition, when the tuned signal is not output, the tuned signal is output to the detection circuit 5.
The above operation is repeated by shifting the offset value by 1 until the output is output.

In the above-mentioned embodiment, the frequency is changed little by little up and down, but in reality, it is sufficient to change the frequency for each country's channel plan. For example, as an offset value, the FM Attendance to broadcast is 25K
Hz (USA), 100KHz (Japan), 200KHz (
Europe), and in the case of AM broadcasting, it is changed at a value of 9 KHz (Japan, Europe) and 10 KHz (United States).

Furthermore, when changing the order of steps S6 and S8, it actually takes time to select the desired broadcasting station due to the tuner's tuned signal detection time and PLL lockup time, so the offset value is As in the case of Japan, if <100KHz, +O, +100
KHz, +200KHz, +300KHz, -100K
Hz, -200KHz.

-300KHz, +400Klfz, +500KH
z, +600KHz, -400KHz, -500Kl
(z, -600KI (z), it is also possible to change both values several steps at a time.

〔Effect of the invention〕

As described above, even if you do not know the exact frequency of a broadcasting station, the present invention automatically offsets the frequency until you are tuned in by operating the operation button and inputting all or part of the vague frequency. Since the channel is selected according to the value, for example, even if the exact frequency is not known when listening on a car stereo, the channel selection can be performed easily and quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a tuning device in a tuner according to the present invention, and FIG. 2 is a flowchart of a control circuit in the same block diagram. 8... Programmable frequency divider, 13... Control circuit,
14...Operation button, 15...Display, 16...RO
M.

Claims (1)

[Scope of Claims] A tuner that is capable of selecting a desired broadcasting station by changing the frequency division number of a programmable frequency divider, comprising: an operation button such as a numeric keypad for inputting a number as a frequency; and the operation button. An offset memory that has data that allows the frequency to be changed little by little up and down around the frequency input using the button, a memory such as a ROM that stores a frequency division number corresponding to the frequency, and a number input using the operation button. a display that displays a certain frequency or a symbol corresponding to the frequency; and a display device that reads from the memory a frequency division number corresponding to a frequency that is slightly shifted around the frequency input by the operation button, and displays the programmable portion of the tuner. 1. A tuning device for a tuner, comprising: a control circuit that repeatedly sends out a tuned signal obtained when tuned to a frequency generator until it is detected.