JPH07101836B2 - Synthesizer Yuna - Google Patents

Description

The present invention relates to a synthesizer tuner capable of receiving all channels of FM band and VHF of television.

[Outline of Invention]

This invention uses FM band and VHF for TV as front end.
Under the FM wide range for 1 to 3 channels of VHF, it is used by switching between those for 4 to 12 channels of TV VHF, but band switching and band display are performed by dividing the frequency of a programmable counter as a variable frequency dividing circuit. The FM band and the TV band are performed based on the N value of the ratio 1 / N, and the FM band and the TV VHF band can be treated as completely different bands in appearance.

[Conventional technology]

Conventionally, the front end that further extends the FM band and the high frequency side to make it a wide band and can receive up to 1 to 3 channels of VHF of a television is integrated into an IC and widely used. Therefore, FM band and TV VHF 1-12
When making a tuner that can receive all bands up to the channel, the front end has the wide range described above.
It is common to switch between the FM front end and the front end that receives channels 4 to 12 of VHF of the television.

Band switching is also performed in accordance with the switching of the front end, as shown in FIG. 3, in a frequency range lower than channel 3 and a frequency range higher than channel 4 of VHF of the television. Then, the band changeover switch (1) provided on the operation panel surface is changed over and displayed as shown in FIG. Further, the same band display is also performed on the liquid crystal display section of the tuner.

[Problems to be solved by the invention]

However, when the FM band and the VHF band of the television can be received, it is natural that the band is switched between the FM band and the VHF band of the television. Therefore, when the band switching is performed according to the front end as described above, the usability is very poor.

The present invention remedies this drawback.

[Means for solving problems]

The present invention provides a synthesizer tuner with a band changeover switch for switching between an FM band and a band of channels 1 to 12 of VHF of a television and switching of the front end with an N value of a frequency division ratio 1 / N and The band switching switch is switched according to the switching.

[Action]

Band switching is performed between the FM band and the TV band.
Therefore, band switching is performed with a natural feeling, and usability is improved.

〔Example〕

In the present invention, as shown in FIG. 1, the front end is a wide-range first front end for FM band capable of covering up to 1 to 3 channels of VHF of a television, and 4 to 12 channels of VHF of a television. And a second front end for switching between them. on the other hand,
Band switching is performed between the FM band and the TV band as shown in the figure.

Then, the N value of the frequency division ratio 1 / N of the variable frequency dividing circuit is changed corresponding to the band switching, and the front end is switched based on this N value. It is possible to switch such as.

That is, FIG. 2 shows an embodiment of the present invention, and (11) is FM.
1st front end for wide band FM band, covering 1 to 3 bands of band and VHF, (1
2) is a second front end that covers channels 4 to 12 of VHF.

The signal received by the antenna (13) is supplied to the first and second front ends (11) and (12) via the distributor (14). These first and second front ends (1
From 1) and (12), the signals obtained by converting the received signal to an intermediate frequency signal are obtained, and these signals are switched circuit (15).
Is supplied to the intermediate frequency amplifier circuit (16) and is selectively selected by a switching signal from a microcomputer (18) which will be described later, and the signal from the switch circuit (15) is supplied to the intermediate frequency amplifier circuit (16).

(17) is a local oscillation circuit that supplies a local oscillation signal to the mixers of the first and second front ends (11) and (12).
It is configured. That is, (171) is a variable frequency oscillating circuit (hereinafter abbreviated as VCO), and its oscillation output signal is supplied to a prescaler (172) and pre-divided,
It is supplied to the variable frequency dividing circuit (173) and divided into 1 / N.
Then, the frequency-divided output is supplied to the phase comparison circuit (174) and phase-compared with the signal of the reference frequency from the reference oscillation circuit (175), and the comparison output signal is supplied to the low-pass filter (17).
It is supplied to the VCO (171) through 6) and the oscillation frequency of the VCO (171) is controlled so as to be a frequency according to the division ratio 1 / N. The oscillation output signal of the VCO (171) becomes the local oscillation signal supplied to the first and second front ends (11) and (12).

The N value of the frequency division ratio 1 / N of the variable frequency dividing circuit (173) is given from the microcomputer (18). The microcomputer (18) has operation buttons (19) and a liquid crystal display (20).
And a band changeover switch (21) are connected. The band selector switch (21) is for FM band and TV band (VHF 1
~ 12 channels) and can be switched.

In this case, the N value supplied from the microcomputer (18) to the variable frequency dividing circuit (173) is assigned in the FM band and the TV band as shown in the following table.

As is clear from this table, when N value is 1305-1585, FM
It is a band, and when the N value is 1650 to 1990 and 1025 and 1055, it is a TV band. Therefore, the switching signal of the switch circuit (15) for switching the outputs of the front ends (11) and (12) can be formed based on this N value.

For example, when the band selector switch (21) is switched to the FM band, the switch circuit (15) is switched to the state shown in the figure by the switching signal from the microcomputer (18) and the first front end (11). The output of is selected. In this state, press the tuning button on the operation button section (19) and the microcomputer (1
The N value is given to the variable frequency dividing circuit (173) from 8),
The local oscillation frequency is changed within the FM band, the search operation is performed, and once the broadcasting station is detected, the search is stopped and the sound is played. If it is the desired station, release the tuning button and end the search. Through the above operation, the user selects the desired station. This operation is the same for TV bands.

At this time, the liquid crystal display (20) displays "F
The letter "M" and the received frequency are displayed.

Next, when the band selector switch (21) is switched to the TV band, when the N values of channels 1 to 3 of the television are supplied from the microcomputer (18) to the variable frequency dividing circuit (173), The switch circuit (15) is switched to the first front end (11) side, and when the N values of channels 4 to 12 are supplied from the microcomputer (18) to the variable frequency dividing circuit (173), the switch circuit (15) is switched. Circuit (15) is the second front end (12)
Switched to the side.

When the N value of this TV band is output from the microcomputer (18), "T" is displayed on the liquid crystal display (20).
The letter "V" and the reception frequency are displayed, indicating that the band is a TV band.

〔The invention's effect〕

As described above, according to the present invention, as the front end for the FM band, 1 to 3 of the FM band and the VHF of the television are used.
Even when using a wide-range one that covers up to the channels, it becomes possible to switch the band between the FM band and the bands of channels 1 to 12 of the television, which improves usability for the user.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIGS. 3 and 4 are diagrams for explaining conventional band switching. (11) and (12) are the first and second front ends,
(15) is its changeover switch, (17) is a local oscillation circuit of PLL configuration, (173) is its variable frequency dividing circuit, (18) is a microcomputer for giving N value to the variable frequency dividing circuit (173), (21) is a band changeover switch.

Claims (1)

[Claims] 1. A first front end for an FM band and a band of VHF channels 1 to 3 of a television, and a second front end for a band of VHF channels 4 to 12; A local oscillation circuit of a PLL configuration having a variable frequency dividing circuit for supplying a local oscillation frequency signal to the first and second front ends, and an N value of the frequency dividing ratio 1 / N is given to the variable frequency dividing circuit. It has an N value setting means and a band switch for switching between the FM band and the VHF band from 1 to 12 channels, and the first and second front ends are set according to the switching N value of the band change switch. A synthesizer tuner adapted to be switched.