JPS6031128B2 - digital synthesizer tuner - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a digital synthesizer tuner, and more specifically, muting, DX/LOCAL cutting,
and a digital synthesizer tuner including signals for controlling each operation of the alarm.

According to the prior art in digital synthesizer tuners, each of the above-mentioned operations is controlled by a number of signals corresponding to the number of operations, and these signals are processed independently of each other.

Therefore, an increase in the number of signals to be processed directly leads to the addition of circuits inside the tuner, complicated signal wiring, and an increase in production costs. This invention is
The main object of the present invention is to provide a digital synthesizer tuner that solves the above-mentioned problems. To summarize the invention, each of the above-mentioned operations is controlled by one type of control signal from an automatic control device such as a microcomputer. Note that other advantages and features of the present invention will become clear from the description below. The drawing is a schematic block diagram of an internal circuit of a tuner according to an embodiment of the present invention.

In the figure, 1 is an RF amplifier, 2 is a mixer, and 3 is a PLL.
VC○ (local oscillator) in the circuit, 4 is an intermediate frequency amplifier,
5 is a detector, 6 is an audio amplifier, 7 is a power supply device for the audio amplifier 6, and 13 is a speaker. Since these are well-known structures in tuners, they will not be explained in this embodiment for the sake of convenience. Next! 8 is a DX/L ratio AL cutter.
The output section of this switch 8 is connected to the gain adjustment signal receiving section of the high frequency amplifier 1. When the signal a, is derived from the output section, the gain of the high frequency amplifier 1 decreases and the LO
The tuner is set to the CAL receiving state. Moreover, when signal a2 is derived from this output section, conversely, this amplifier 1
The gain of the tuner is increased and the tuner is set to the DX reception state. Signal a from the output section of this DX/LOCAL switch
, or a2 is derived depending on the content of the first control signal X, from the timer means 15 in the computer 14 connected to its input. The timer means includes a clock circuit 16 that outputs an ever-changing time signal, and a desired time for outputting the alarm sound, which can be set by an external operation. If such a setting is made, a set time signal corresponding to the set time is output The output time setting circuit 17 compares the time signal from the clock circuit 16 and the set time signal from the time setting circuit 17, and if they match, outputs the first control signal X and the second control signal X2. It consists of a comparison circuit 18 that outputs . For example, the first control signal X,
When the content is "1", the signal a, from the output section of the DX/LOCAL switch 8 is also "0", and the first control signal X, is "0".
It is assumed that a signal a2 is respectively derived from this output when the contents of .

As an example of a specific circuit that follows this assumption, the base electrode and collector electrode of a transistor are connected to DX/L, respectively.
These are defined as the input section and output section of the OCAL switch 8. Then, a DC power source is connected to the emitter electrode of this transistor. On the other hand, it is proposed in this embodiment that the final amplification stage of the high frequency amplifier 1 is constituted by a transistor, and the emitter electrode of the transistor is set in the gain adjustment signal receiving section. Therefore, when the first control signal X has a content of "1", the transistor of the DX/LOCAL gate 8 is turned on. As a result, the DC power source is connected to the emitter electrode of the transistor of the high frequency amplifier 1.
The potential of the emitter electrode of this amplifier 1 rises. As a result, the gain of amplifier 1 decreases. This state of reduced gain is the LOCAL reception state, and ultimately the DX/LOCA reception state is
The L switch 8 is switched to the LOCAL receiving side.

On the other hand, the first control signal X from the computer 14,
Conversely, when the content of is "0", the key of amplifier 1 rises, and as a result, the tuner is switched to the DX receiving state. In this way, computer 4 performs DX/LOCA
The switching operation of the L switch 8 can be controlled by the first control signal X. The first control signal X derived from the computer 4 further controls a muting device 9 and an alarm ON/OFF device 10, which will be described later.

The muting device 9 is configured so that the content of the first control signal X is "1".
”, it is activated to prevent the radio signal from being output from the detector 5. Here, as an example of the configuration of the muting device 9, the base electrode of the transistor is connected to the first control signal X,
It is proposed to connect the collector electrode to the input part of the wave detector 5 and to the output part of the detector 5. According to this example configuration,
When the content of the first control signal X, is "1", the transistor is conductive. As a result, the output of the detector 5 is grounded via the collector-emitter electrode of the transistor. Therefore, the radio signal is not input to the amplifier 6,
muted. Further, when the content of the first control signal X is "0", the transistor is not conducted to the outside,
The radio signal from the detector 5 is output to an amplifier 6.

The first control signal X for the above alarm ON/OFF device 1,
When the content of is "1", the power supply device 7 operates the amplifier 6.
to drive. As a configuration example of the alarm ON/OFF device 10 and the power supply device 7, among the two-stage amplification transistors,
The base electrode of the previous stage transistor is connected to the first control signal X,
It has been proposed to connect the power supply to the input part of the amplifier 6, connect the power supply to the emitter electrode of the transistor in the subsequent stage, and make the collector electrode of the transistor in the latter stage the output to the power supply receiving part of the amplifier 6. Note that the transistor at the front stage is an NPN type, the transistor at the rear stage is a PNP type, and the collector electrode of the transistor at the front stage is connected to the base electrode of the transistor at the rear stage. In the above configuration example, when listening to a certain radio program, if you set the time at which you want the alarm to sound using the time setting circuit 17, the time signal from the clock circuit 16 and the desired time set at the time setting circuit 17 will be synchronized. When they do not match, the comparison circuit 18 sets both the first and second control signals X, X2 to "0".

Therefore, the DX/LOCAL switch 8 outputs the signal a2 to increase the gain of the high frequency amplifier 1, and the tuner
The radio broadcast is emitted from the speaker 3 while the reception state is maintained, and the muting device 9 and alarm ON/OFF device 10 are kept inactive. Now, when the tuner is in the DX receiving state and a radio broadcast is being broadcast from the speaker 3, when time advances and the time signal from the clock circuit 16 matches the desired time set by the time setting circuit 17. , the comparison circuit 18 sets both the first and second control signals X, , X2 to "1", and as a result, the above D
The X/LOCAL switch 8' outputs the signal a, lowering the gain of the high frequency amplifier 1 and putting the tuner in the LOCAL receiving state, and the muting device 9 operates to block the output of the radio signal from the detector 5. In addition, alarm O
The N/OFF device 1 drives the power supply device 7 and the audio amplifier 6
to a state where the alarm signal can be amplified.

At the same time, the AND circuit 12 receives both the first and second control signals X, X2 which have become "1" from the comparator circuit 18, and outputs "1" from the AND circuit 12 to output the alarm signal generator 1.
1 is driven. As a result, an alarm signal is derived from the alarm signal generator 11 and supplied to the speaker 3 via the audio amplifier 11, causing the speaker 13 to sound and notify the time. This sound is an alarm sound and radio broadcasting is not emitted.As mentioned above, the tube of this embodiment has a muting operation that suppresses noise between stations and a DX/LOCAL switching operation during the automatic channel selection operation, and an alarm. The ON/○FF sliding operation can be controlled by one type of control signal.

Note that the DX/LOCAL switching is performed during the automatic channel selection operation period. This is because during this period, LOCAL reception, that is, strong electric field (short distance) reception is performed, and after receiving the desired radio broadcast, the state is switched to DX reception, that is, weak electric field (long distance) reception. As described above, according to the present invention, a single type of control signal in a digital synthesizer tuner includes the functions of multiple signals such as a DX/LOCAL switching signal and a muting signal.
It is possible to simplify the circuit inside the tuner and the signal wiring, and therefore, it is possible to reduce the production cost, which is a unique effect.

[Brief explanation of the drawing]

The drawing is a schematic block diagram of an internal circuit of a tuner according to an embodiment of the present invention. 1...High frequency amplifier, 2...Mixer, 3...
...Local oscillator, 4...Intermediate frequency amplifier, 5...
...Detector, 6...Audio amplifier, 7...
・Power supply device, 8...DX/LOCAL switch, 9.
...Muting device, 10...Alarm ON/○FF switch, 11...Alarm signal generator, 12...AND circuit, 13...Speed −
power, 14""" microcomputer.

Claims (1)

[Claims] 1. In a digital synthesizer tuner including a DX/LOCAL switch, a muting device, and an alarm ON/OFF device, a time limit means is provided that allows the time to be set by external operation and outputs a control signal when the set time elapses, and the above-mentioned A digital synthesizer tuner characterized in that the DX/LOCAL switch is switched to a LOCAL receiving side by a control signal, and the muting device and alarm ON/OFF device are each switched to an operating state.