JPH0779267B2 - Modulation wave switching circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used in a modulator of a communication device. The present invention was developed for a communication device for a meeting line of a microwave satellite communication device,
Not limited to this application, it can be widely used as a switching circuit of a modulator.

The present invention is used for switching modulated waves. The present invention relates to a modulated wave switching circuit that can save power and can avoid an output level overshoot phenomenon that occurs when power is turned on.

[0003]

2. Description of the Related Art The prior art, as shown in FIG. 6, has a modulation circuit 13 for modulating a modulated signal and an automatic gain control circuit 14 for keeping the amplitude of the output modulation signal constant. The gain control circuit 14 includes an automatic attenuator 15 that controls the level of the input modulation signal by the control signal S13, an amplifier 16 that amplifies the signal, and an AM detector 17 that detects the amplitude of the amplified modulation signal S14. When the modulation signal S14 is turned off, the power supply of the amplifier 16 is turned off by the output power supply control signal S12 of the power supply control circuit 18.

[0004]

In such a conventional modulation wave switching circuit, since the power of the amplifier at the final stage is turned off, the amplitude of the final output signal becomes 0. At this time, if AM detection is performed, the detection level becomes the minimum. As a result, the amount of attenuation of the automatic attenuator is also minimized, and when the power source of the final stage amplifier is turned on again, an overshoot phenomenon in which the signal amplitude increases for a moment as shown in FIG. 7 occurs. Further, even when the output signal is turned off for a long time, the power supply of the circuits other than the amplifier at the final stage is turned on, so that there is a problem that the power is significantly consumed.

The present invention solves such a problem, and it is an object of the present invention to provide a modulation wave switching circuit capable of eliminating overshoot when the power is turned on and reducing power consumption. To aim.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a modulator circuit,
A modulation wave switching circuit comprising an automatic gain control circuit for controlling the amplitude of a modulation signal from the modulation circuit to be constant, and a switching device for switching the output of the automatic gain control circuit, A power supply control circuit for turning on / off the power supply of the gain control circuit according to a control signal, and a delay circuit for delaying the control signal of the power supply control circuit to serve as a switching control signal for the switching unit are provided.

The delay circuit is an integrator circuit. The delay circuit is provided with a level detector which sends out an output as the switching control signal when the output voltage of the integrator circuit reaches a certain level, and is provided with a plurality of modulators. A combiner may be provided for combining the outputs.

[0008]

The automatic gain control circuit keeps the output level from the modulation circuit constant, and the output signal is turned on by the output signal of the level detector ("1" when on, "0" when off).・ Turn off, and if off, terminate with a terminator. The control signal from the control signal generator is sent to the power supply control circuit of each modulator to turn on / off the power supply of the modulation circuit, the automatic gain control circuit, and the level detector. In this case, the power supply of the level detector shows "1" even in the level detection (that is, the output signal of the detector always shows "1" when the power is turned on). The delay circuit delays the output of the level detector from becoming "1" at the moment when the power is turned on. Therefore, when the power is off, the power of the modulator is turned off and the output signal is terminated. When turned on, the output signal level of the automatic gain control circuit becomes sufficiently stable, and then the control signal of the switching device becomes “1”, which is output to the combiner. When it is desired to obtain one modulation signal from two modulators, A signal (one is a no signal state) is synthesized.

As a result, it is possible to avoid the overshoot phenomenon of the output signal amplitude that occurs at the moment when the power is turned on, and it is possible to reduce the power consumption.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a block diagram showing the overall configuration of an embodiment of the present invention,
FIG. 2 is a diagram showing the configurations of the delay circuit and the level detector in the embodiment of the present invention.

The embodiment of the present invention comprises a first modulator 1 and a second modulator 2, and a control signal generator 11 for providing a control signal to the first modulator 1 and the second modulator 2. And a combiner 10 for combining the modulated signals from the first modulator 1 and the second modulator 2, and modulation for modulating the modulated signal in each of the first modulator 1 and the second modulator 2. Circuit 3
And an automatic gain control circuit 4 for controlling the amplitude of the modulation signal from the modulation circuit 3 to be constant, and a switch 9 for switching the output of the automatic gain control circuit 4.
As a feature of the present invention, a level detector 7 that detects a signal level, a terminator 8 that terminates a signal, a power supply control circuit 5 that turns on / off the power supplies of the modulation circuit 3 and the automatic gain control circuit 4 by a control signal. And a delay circuit 6 for delaying the control signal of the power supply control circuit 5 to obtain a switching control signal of the switch 9. The delay circuit 6 is an integrating circuit, and the output voltage of the integrating circuit is at a constant level. A level detector 7 is provided for sending the output as a switching control signal when the level is reached.

Next, the operation of the embodiment of the present invention thus constructed will be described.

The modulation circuit 3 modulates the input modulated signal and outputs it to the automatic gain control circuit 4. The automatic gain control circuit 4 makes the level of the output signal constant and sends it to the switch 9 as the output signal S5. The switch 9 outputs this output signal S5
Is turned on / off by the output signal S4 from the level detector 7, which is "1" when turned on and "0" when turned off,
If it is off, the termination unit 8 is switched to terminate.

A control signal S1 (a signal for controlling ON / OFF of the modulator output) sent from the control signal generator 11 is sent to the power supply control circuit 5 of the first and second modulators 1 and 2 and modulated. The power sources S2 and S3 of the circuit 3, the automatic gain control circuit 4, and the level detector 7 are turned on / off. In this case, the power supply S3 of the level detector 7 shows "1" even in the level detection (that is, the output signal of the detector always shows "1" when the power is turned on). The delay circuit 6 arranged on the input side of the level detector 7 is provided at the moment when the power is turned on.
Delays the output of "1". As a result, when turned off, the power supply of the first and second modulators 1 and 2 is turned off, and at the same time, the output signal S7 is terminated. When turned on, after the level of the output signal of the automatic gain control circuit 4 is sufficiently stabilized, the control signal S4 of the switch 9 becomes "1" and is output to the combiner 10. When it is desired to obtain one modulation signal S8 from the modulation signals S6 and S7 of the first and second modulators 1 and 2, two signals (one of which is a no signal state) are combined.

As described above, when one modulated wave output is obtained from the modulated waves of the first modulator 1 and the second modulator 2, all the modulated waves other than the desired modulated wave are turned off and combined. Combine with vessel 10. Therefore, even when it is turned off, the output signal from the first modulator 1 is always terminated and the level of the modulated wave output signal S8 of the combiner 10 is always constant.

The control signal S1 for switching the modulated wave is sent from the control signal generator 11 to the power supply control circuit 5 of the first modulator 1 and the second modulator 2. The first and second modulators 1 and 2 have a level of the modulation signal kept at a constant amplitude by a modulation circuit 3 for modulating the input modulated signal and an automatic gain control circuit 4 for keeping the amplitude of the modulation signal constant. The switch 9 is turned on or off by the output signal S4 from the detector 7. The output signal S4 has a level "1" in the on-state and a level "0" in the off-state, and thus is terminated by the terminator 8 in the off-state. Modulation circuit 3,
Power supply S for automatic gain control circuit 4 and level detector 7
2 and S3 are supplied through the power supply control circuit 5, and the timing is linked to the control signal S1 for switching the modulation wave.

That is, when the modulated wave output is on, power is supplied to each circuit, and when it is off, each circuit is powered off. When the state shifts from the off state to the on state, the amplitude of the output signal causes an overshoot phenomenon as shown in FIG. 7 due to the operating characteristics of the automatic gain control circuit 4. However, it is the delay circuit 6 that the output level of the level detector 7 becomes "1" (ON state).
Therefore, the output signal amplitude of the automatic gain control circuit 4 is stabilized and the switch 9 is turned on after a certain time delay. This state is shown in FIG. FIG. 4 shows the relationship between the output voltage and the input voltage of the level detector 7, and FIG. 5 shows the time from the moment when the control signal S1 is turned on, the power supply of each circuit, the output signal of the delay circuit 6, and the level detector. 7 shows the relationship of the output signals of 7.

[0018]

As described above, according to the present invention, by turning on / off the power source of the entire modulator to switch the modulation wave, it is possible to save extra power when the power is off.
In addition, by delaying the on state of the changeover switch for a certain time when turned on, there is an effect that the overshoot phenomenon peculiar to the automatic gain control circuit can be avoided.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing configurations of a delay circuit and a level detector according to the embodiment of the present invention.

FIG. 3 is a diagram showing a signal state when a modulated wave is switched in the embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation of the level detection circuit in the embodiment of the present invention.

FIG. 5 is a diagram illustrating timings of a power-on signal and a modulated wave switching signal according to the embodiment of the present invention.

FIG. 6 is a block diagram showing an overall configuration of a conventional example.

FIG. 7 is a diagram showing a signal state when a modulated wave is switched in a conventional example.

[Explanation of symbols]

 1 1st modulator 2 2nd modulator 3, 13 Modulation circuit 4, 14 Automatic gain control circuit 5, 18 Power supply control circuit 6 Delay circuit 7 Level detector 8 Terminator 9 Switcher 10 Combiner 11 Control signal generation 12 Modulator 15 Auto Attenuator 16 Amplifier 17 AM Detector

Claims (3)

[Claims] 1. A modulation wave switch comprising a modulation circuit, an automatic gain control circuit for controlling the amplitude of a modulation signal from the modulation circuit to be constant, and a switcher for switching the output of the automatic gain control circuit. In the circuit, a power supply control circuit that turns on / off the power supply of the modulation circuit and the automatic gain control circuit by a control signal, and a delay circuit that delays the control signal of the power supply control circuit to be a switching control signal of the switcher. A modulation wave switching circuit characterized by comprising: 2. The delay circuit is an integrator circuit, and the delay circuit comprises a level detector that sends an output as the switching control signal when the output voltage of the integrator circuit reaches a certain level.
Modulated wave switching circuit described. 3. The modulated wave switching circuit according to claim 1, further comprising a plurality of modulators and a combiner for combining outputs of the modulators.