JPS59219056A - Fsk modulator - Google Patents

Abstract

PURPOSE:To attain the cost-down by changing an oscillating constant of an oscillating circuit by the switching of an electronic switch to frequency-modulate the oscillating frequency by an output of a code generating circuit. CONSTITUTION:An output of a code generating circuit 1 is brought into a low level to open an electronic switch 15. A variable capacitor 16 is adjusted to match the oscillating frequency to a higher frequency of the FSK modulation. Then an output of the code generating circuit 1 is brought into a high level to close the electronic switch 15. Then a variable capacitor 17 is adjusted to match the oscillating frequency to a lower frequency of the FSK modulation. The FSK modulator is matched to the modulation frequency of the FSK modulation and the frequency shift width by executing a series of adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to FSX, which can be used for digital communications.
The present invention relates to a modulation device.

Conventional configurations and their problems In recent years, information transmission has gained advantages in that it enables transmission and regenerative relay that is almost unaffected by channel noise, is easy to encode, and allows the combination of transmission and switching functions. Digital communication methods are widely used. Furthermore, among digital communication systems, the FSK system, which is resistant to fading, is often used.

A conventional FSX modulation device will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a conventional FSK modulation device. Reference numeral 1 denotes a code generation circuit comprised of a microcomputer, etc., which outputs a pulse train having binary levels. 2 is a variable resistor for adjusting the voltage applied to the variable capacitance diode 8, 3 is a high resistance\, 4 is an oscillation circuit, 6 is an oscillation element group that determines the oscillation constant of the oscillation circuit, 6 is a DC bias resistor, 7 is 0
An inverter such as MO8, 8 a variable capacitance diode, 9 a DC blocking capacitor, 10 a variable capacitor, 11 a crystal oscillator, and a 120''i capacitor. It is determined by the oscillator 11, the variable capacitance diode 8 which is a capacitive element, and the capacitor 10°12.

Regarding the conventional FSK modulator configured as described above, 'tJ!' will be described below. 4. Use the parent method as the parent method. First, the output of the code generation circuit 1 is set to low level. In this case, the capacitance of the variable capacitance diode 8 increases, so the variable capacitor 10 is adjusted to match the oscillation frequency to the lower frequency of FSX modulation. Next, the output of the code generating circuit 1 is set to a no-y level. When the variable resistor 2 is adjusted, the voltage applied to the variable capacitance diode 8 changes.
The capacity will change. Therefore, by adjusting the variable resistor 2, the oscillation frequency of the oscillation circuit 4 can be changed, and the oscillation frequency is matched to the higher frequency of FSK modulation. The above adjustment procedure allows the FSX modulation device to perform the desired FSX modulation.

However, in the above configuration, a variable capacitance diode 8, which is a highly curved element, is used, and there is a problem in that the cost becomes high when a system using an FSK modulator is created. However, variable capacitance diodes had many unsatisfactory characteristics, such as large variations and poor temperature characteristics.

OBJECTS OF THE INVENTION An object of the present invention is to provide an FSX modulator that enables cost reduction of the FSX modulator.

Structure of the Invention The FSK modulation device of the present invention comprises an oscillation circuit including an inductive element and a capacitive element, a code generation circuit, and an electronic switch whose opening and closing are controlled by the output of the code generation circuit. The oscillation constant of the oscillation circuit is changed, and the oscillation frequency of the excavation circuit is FSX-modulated by the output of the code generation circuit.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a circuit diagram of an FSK modulation device according to an embodiment of the present invention. In FIG. 2, the same numbers as in FIG. 1 are added, and explanations are omitted. In FIG. 2, 13 is an oscillation circuit, 14 is a group of oscillation elements that determines the oscillation constant of the oscillation circuit, and 15 is a transistor that serves as an electronic switch. Although this electronic switch can be composed of a diode or the like, here Now, as an example, a case where a transistor is used is shown. 16 is a variable capacitor that determines the higher frequency of FSK modulation, 17il-1:
This is a variable capacitor that determines the lower frequency of FSK modulation.

The adjustment method for the FSX modulation device of this embodiment constructed as described above will be described below.0 First, the output of the code generation circuit 1 is set to a low level and the electronic switch 16 is opened. At this time, the oscillation elements that determine the oscillation constant of the oscillation circuit are three elements: the crystal oscillator 11, the capacitor 12, and the variable capacitor 16, and the variable capacitor 17 does not affect the oscillation frequency. Therefore, the variable capacitor 16 is adjusted to match the oscillation frequency to the higher frequency of FSK modulation. Next, the output of the code generation circuit 1 is set to a noise level and the electronic switch 16 is closed. At that time, the capacitance of the variable capacitor 17 also affects the oscillation constant of the oscillation circuit. Therefore, this time, adjust the variable capacitor 17 to
Adjust the oscillation frequency to the lower frequency of K modulation. By performing this series of adjustments, the FSK modulation device can be matched to the target modulation frequency and frequency shift width of FSX modulation.

As described above, according to this embodiment, cost reduction is achieved by replacing the variable capacitance diode with a variable capacitor and using an electronic switch.

Next, three examples of other embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows a circuit diagram of an FSX modulator according to another embodiment of the present invention. In FIG. 3, 18 is an oscillation circuit, one is a group of oscillation elements that determines the oscillation constant of the oscillation circuit,
2o and 21 are variable capacitors that determine the modulation frequency of FSX modulation.

The adjustment method for the FSK modulation device of this embodiment configured as described above will be explained below. The difference between this embodiment and the previous embodiment is that the two variable capacitors are connected in series instead of in parallel. The adjustment method is to set the output of the code generation circuit 1 to low level, close the electronic switch 16, adjust the variable capacitor 20 to match the lower frequency of FSK modulation, and then set the output of the code generation circuit 1 to low level. Then, adjust the variable capacitor 21 to match the higher frequency of the modulation to FS.

FIG. 4 shows a circuit diagram of an FSX modulator according to a third embodiment of the present invention. In FIG. 4, 1 is a code generation circuit;
22 is an oscillation circuit; 23 is an oscillation element group that determines the oscillation constant of the oscillation circuit; 24 and 26 are variable coils that determine the modulation frequency of FSK modulation; 26, 27, 28, and 29 are capacitors that determine the oscillation constant; 31 is a bias setting resistor, and 32 is an oscillation transistor.

The adjustment method for the FSX modulator of this embodiment configured as described above will be explained below.The difference between this embodiment and the embodiments shown in FIGS. 2 and 3 is that the variable capacitor 2 for applying modulation is 2 variable coils and C-rJ
The difference is that the Os inverter 7 is replaced with a transistor 32. The adjustment method in this embodiment starts with the code generation circuit 1.
The output of FSX is set to high level and the variable coil 24 is adjusted.
Then, the output of the code generation circuit 1 is set to a low level, and the variable coil 25 is adjusted to match the lower frequency of the FSX modulation.

FIG. 6 shows another embodiment of the FSX modulation device according to the present invention. In FIG. 6, 33 is an oscillation circuit, 34 is a group of oscillation elements that determines the oscillation constant of the oscillation circuit, 16 is a transistor that serves as an electronic switch, 36 and 36 are variable coils that determine the modulation frequency of FSX modulation, and 26 and 36 are variable coils that determine the modulation frequency of FSX modulation. 27 and 28 and 2
9 is a capacitor that determines the oscillation constant.

The adjustment method for the FSX modulation device of this embodiment configured as described above will be explained below. The difference between this embodiment and the embodiment shown in FIG. 4 is that the two variable coils are connected in parallel instead of in series. The adjustment method is to first set the output of the code generation circuit 1 to a low level, adjust the variable coil 36, and then
Adjusting to the lower frequency of the SX modulation, then set the output of the code generation circuit 1 to high level and adjust the variable coil 36 to generate the FS.
Tune to the higher frequency of K modulation.

As described above, according to these embodiments, cost reduction is achieved by replacing the variable capacitance diode and variable resistor with an electronic switch and a variable capacitor or variable coil. In the above embodiments, the electronic switch is constructed using a transistor, but the electronic switch is not limited to a transistor, and may be any switch as long as it has the function of opening and closing in response to an electric signal. For example, a diode switch can be used.

Effects of the Invention As is clear from the above explanation, the present invention comprises an oscillation circuit including an inductive element and a capacitive element, a code generation circuit, and an electronic switch whose opening and closing are controlled by the output of the code generation circuit. The oscillation constant of the oscillation circuit is changed by opening and closing the switch, and the oscillation frequency of the oscillation circuit is FSX-modulated by the output of the code generation circuit, so not only can costs be reduced, but also the capacitor or Setting the value of the coil has the excellent effect of providing a modulation device with very excellent temperature characteristics.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional FSK modulation device, Fig. 2 is a circuit diagram of an FSK modulation device according to an embodiment of the present invention, and Figs. 3, 4, and 6 are FS- modulation according to the present invention. FIG. 3 is a circuit diagram showing another embodiment of the device. 1... Code generation circuit, 2... Variable resistor, 3... Resistor, 4... Oscillation circuit, 5...
...Oscillation element group, 6...Bias resistance, 7
...Inverter, 8...Variable capacitance diode, 9...Capacitor, 1o...
Variable capacitor, 11...Crystal resonator, 12.
... Capacitor, 13 ... Oscillation circuit, 14
...Oscillation element group, 16 ... Transistor, 16 ... Variable capacitor, 17 ... Variable capacitor, 18 ... Oscillation circuit, 19 ...・
...Oscillation element group, 20...Variable capacitor, 21
--- Variable capacitor, 22 --- Oscillation circuit, 23 --- Oscillation element group, 24 --- Variable coil, 26 --- Variable "l" 26... Capacitor, 27... Capacitor, 28...
・・Capacitor, 29・・・・−Capacitor, 30・・
... Resistor, 31 ... Resistor, 32 ... - ... Transistor, 33 ... Oscillation circuit, 34 ... Oscillation element group, 35 ... Variable Koinope 36 ...・Variable coil O

Claims (1)

[Claims] An oscillation circuit consisting of an inductive element and a capacitive element, a code generation circuit, and an electronic switch whose opening and closing are controlled by the output of the code generation circuit, and the oscillation constant of the oscillation circuit is determined by opening and closing of the electronic switch. An FSK modulation device configured to frequency-modulate the oscillation frequency of the oscillation circuit with the output of the code generation circuit.