JPS598086B2 - Self-tuning shortwave receiver - Google Patents

Description

[Detailed Description of the Invention] The present invention is capable of automatically receiving radio shortwave broadcasting, and radio shortwave broadcasting in Japan, automatically scanning the receiving frequency group, and always automatically receiving the best frequency radio waves. This invention relates to a self-tuning shortwave receiver developed for the purpose of

Japanese radio shortwave broadcasting consists of the first group of broadcast programs that simultaneously broadcast the same content, that is, frequency 3.
9 2 5 MHz, 6.0 5 5 MHz, 9.5
A second broadcast program group that simultaneously broadcasts three waves of 9 5 MHz and other same content, that is, frequencies of 3.9 4 5 MHz, 6.1 1 5 MHz, 9
．． Although it consists of three waves of 760 MHz, in areas where there is a lot of fading, even if you tune to one of the six waves, the broadcast content cannot be heard clearly.

The present invention solves the above-mentioned drawbacks, and by selecting whether the first broadcast group is the second broadcast group, the reception frequency of the first broadcast group is 3 waves, or the reception frequency of the second broadcast group is 3 waves. The system automatically scans the radio waves sequentially and automatically selects and receives radio waves with the best frequency.

First, a conventional shortwave receiver will be briefly explained based on Fig. 1. 1 is a receiving antenna for shortwave broadcasting, 2 is a tuning section placed after this receiving antenna, and this tuning section is manually operated. , the radio wave to be received is selected based on the sound heard from the rear speaker 7.

Reference numeral 3 denotes a frequency conversion section arranged after the tuning section 2, and this conversion section converts the oscillation section 32 selected by the tuning section 2 and the signal from the tuning section 2 and the signal from the oscillation section 32. It also serves as a mixer section 31 for mixing.

Reference numeral 4 denotes an intermediate frequency amplification section arranged after the conversion section 3, 5 a detection section arranged after the amplification section, and 6 an audio amplifier connected after the detection section; A speaker 7 is connected to.

FIG. 2 is a block diagram showing an embodiment of the present invention, in which 1 is a receiving antenna for shortwave broadcasting, 21 is a preset tuner section disposed after this receiving antenna, and this tuner section includes, for example, a preset tuner section. Three types of variable capacitors are provided, namely, one for 3 MHz, one for 6 MHz, and one for 9 MHz.

Reference numeral 31 denotes a mixer section arranged after the preset tuner section 21, and numerals 4, 5, 6, and 7 at the latter stage are an intermediate frequency intensifier section, a detection section, an audio amplifier section, and a speaker, respectively, as in FIG.

8 in FIG. 2 is a level setting section, and this setting section is the detection section 5.
It inputs the detection signal a from the detection section 5, and outputs the level signal b when the detection signal is below a desired level.

Reference numeral 9 denotes a detecting section arranged after the setting section 8, and this detecting section outputs a detection signal C when the level signal b is input.

Reference numeral 10 denotes a ring counter placed after the detection section 9, and each time the pulse-like detection signal c is input, this counter
It is counted and output in order to the output terminals 10a, 10bt10c group.

That is, when one detection signal C is input, a signal is output from the output terminal 10b, and when another detection signal C is input, a signal is output from the next output terminal 10c. When yet another detection signal C is input, it operates so that the signal is output from the next output terminal 10a.

Reference numeral 322 denotes an oscillating section disposed after the ring counter 10. This oscillating section is selectively oscillated by a signal from the ring counter 10, and this oscillating signal is input to the mixer section 31.

Note that the preset tuner section 21 also has a ring counter 10.
For example, one of the preset variable capacitor groups is selectively activated by a signal from the variable capacitor.

The electronic circuits shown in FIGS. 3 and 4 are further specific versions of the main parts of the block diagram shown in FIG. 2, and the reference numbers in FIGS. 3 and 4 correspond to the reference numbers in FIG. It is written as follows.

In the preset tuner section 21 of FIG. 3, for example, 3M
Varicon for Hz: M'TC1, Varicon TC for 6MHz
Variable capacitors TC3 for 2 and 9 MHz are each set in advance, and 11 in FIG. 3 is a power supply.

X1, X3, and X5 of the oscillator 322 are a group of crystal oscillators for the first broadcast program, X2, X4, and X6 are a group of crystal oscillators for the second broadcast program, and S3 is a manual switch for controlling the first broadcast, This is for selecting the second broadcast program, and in FIG. 3, the second broadcast program is selected.

Note that D7 and D10 are display devices that indicate whether the selected broadcast is the first broadcast or the second broadcast.

Reference numeral 82 in FIG. 3 is a selection switch for selecting automatic tuning or manual tuning for this automatic tuning type short wave receiver, and in the case shown, the automatic tuning type is set.

S1 outputs a tuning signal C' in the case of a manual tuning type.

The electronic circuits shown in FIGS. 3 and 4 will be briefly described.

First, when a switch (not shown) of the power supply 11 in FIG. 3 is turned on, a signal is output from the already selected output terminal 1 of the counter 111 of the ring counter 10 in FIG. For example, when transistor TR2 is selected and turned on from the group, terminal 1
Transistor TR3 in FIG. 3 is turned on via T, and the preset capacitors TC 3 and C
3 is activated, the oscillation transistor TR5 is activated by the crystal oscillator X6 via the diode D6, and the mixer transistor TR4 is activated. 9 MHz of the program, i.e. 9. 7 6 0 MHz broadcast content is sent as a detection signal a to an audio amplifier 6 (not shown).
is output as

Thus, in the above situation, 9. 7 6 0 MHz
When the broadcast radio wave becomes weaker, that is, when the detected signal a becomes lower than the set level of the setting section 8, the level signal b is sent, the transistor TR7 in FIG. 4 is turned off, the diode D1 oscillates, and the transistor TR8 is turned off. The pulse-like detection signal C is input to the counter 111 via the terminal 3T, and this time, for example, the transistor TR6 is selected and turned on, and the transistor TR1 in FIG. 3 is turned on via the terminal 3T. At the same time, the preset capacitors TC1 and CI are activated, and the oscillation transistor TR5 is activated by the crystal oscillator X2 via the diode D8, and as a result, 3. of the second broadcast program is activated. The broadcast content of 945 MHz is output as a detected signal a to an audio amplifier 6 (not shown).

Similarly, in this state, if the detected signal a becomes lower than the setting level of the setting section 8, 6. of the next second broadcast program. 1
The 15 MHz broadcast content is output as a detection signal a to an audio amplifier 6 (not shown).

The present invention having the above configuration has [a plurality of tuning means TC1, CI, TC2, C2, TC3, C preset to a desired number of shortwave broadcasting frequencies].
3, and a detection section 9 which is disposed after the detection section 5 which is located before the audio amplifier section 6 and sends out a signal when the output of the detection section 5 is below a certain set level. , placed after this detection section,
This is an automatic tuning type shortwave receiver characterized by comprising a counter means 10 that automatically switches the preset tuner section 21 and the oscillation section 322 every time there is a signal from the detection section 9. When the received radio waves become weak due to fading, other received radio waves with the same content can be automatically and electronically selected and received, so the best broadcast is always available without the need for manual tuning. You will be able to receive radio waves automatically.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional example, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are specific electronic circuit diagrams of the embodiment of the present invention. 21: preset tuner section, 6: audio amplifier section, 5: detection section, 9: detection section, 322: oscillation section, 10: counter means (ring counter).

Claims (1)

[Claims] 1. In a shortwave receiver that selectively receives shortwave broadcast waves that transmit the same program using a plurality of different carrier waves, a preset tuner section having a plurality of tuning means preset to a desired number of shortwave broadcast frequencies; an oscillating section that oscillates a signal; a mixer section that mixes this frequency signal with the output of the tuner section to obtain an intermediate frequency;
a detection section that extracts an audio signal from the intermediate frequency signal; a setting section that outputs a level signal when the magnitude of the audio signal extracted from the detection section is below a desired level; and an output level signal of the setting section. The detection section outputs a pulse-like detection signal when the detection signal is input, and the output that is obtained in order by counting the pulses each time the detection signal is input. 1. A self-tuning shortwave receiver comprising a ring counter section that sequentially switches frequencies.