JPS603219A - Automatic power controlling amplifier - Google Patents

Abstract

PURPOSE:To eliminate the transient fluctuation of transmission power generated at the switching of an automatic power control loop by using an automatic power control amplifier in which a simple switching timing circuit is added to an automatic power control loop and a fixed bias loop. CONSTITUTION:The automatic power control amplifier (ALC) consists of an automatic power control loop comprising a comparator 2, an amplifier 3 and a contact 10a of a relay 10, a fixed bias loop comprising a comparator 6 and an analog switch 11, relays 10 and 12 on/off-controlling both loops, a timer 18 and NAND gates 15, 16 and 17, and has a relay driving circuit 20 deciding the relay 10 and the drive timing, the power level detection circuit comprising a comparator 13 and a transistor 14, and a switch 19 on/off-controlling the ALC manually.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic power control amplifier used for controlling the transmission power of, for example, a satellite communication earth station, which requires high stability against fluctuations in the transmission power level.

In a power control device for an earth station transmission system that has a protection system in addition to a working system, particularly high stability is required with respect to transient fluctuations in power level that occur when switching from the working system to the protection system.

FIG. 1 shows a transmission power control device using a conventional automatic power control amplifier. In fig.

100 is a transmission system, 200 is an automatic power control amplifier (hereinafter A
It is abbreviated as LCAMP. ), lNi1'']: RF multiplied signal input terminal, OUT is RF multiplied signal output terminal.

1 is a detector installed at the output of the transmitting system 1(]D,
Detects the transmission power level and converts the DC signal into ALCAMP 20
Give to 0. 5 is a PIN diode attenuator. Furthermore, A and B are input terminals and output terminals of ALCAMP200. The ALCAMP 200 receives the detected DC signal from the detector 1 through the comparator 2, compares it with the reference voltage (ref) from the reference voltage setter 8, and further amplifies it through the amplification device 6 and then sends it through the switch 4. and is fed back to the PIN diode attenuator 5. This main signal system automatic power control loop (hereinafter abbreviated as ALC loop) is controlled on and off by a switch 4. The ALC loose on/off control modes include a so-called automatic mode in which the ALC loop is automatically turned off when an abnormality in the transmission system (for example, an output cutoff) is detected, and then turned on after returning to the standby system, and a manual mode in which the ALC loop is turned on after returning to the standby system. It has a manual mode that can be turned on and off. moreover.

When the ALC loop is off, the operating point of the attenuator 5 is fixed at a fixed bias point (Vrix) by the fixed bias setter 9, and it is composed of a comparator 6 and a switch 7 to prevent excessive transmission power when the ALC loop is on. A fixed bias loop was provided to match the output point of the amplifier 6 with a fixed bias point ("fix") set by the fixed bias setter 9, and the ALC loop was turned on from this fixed bias point.

However, with such a configuration, in the automatic mode mentioned above, when the active transmission system is switched to the backup system due to an abnormality and the transmission power returns to a certain level, the ALC loop is turned on at the same time. However, if the operating speed of switch 7 is faster than switch 4, the fixed bias loop will be turned off first, and then the ALC loop will be turned on.

There is a drawback that the ALC loop is turned on when the output of the amplifier 3 deviates from the Vfix in the direction of increasing the transmission power, resulting in an excessive power level. Next, even in the manual mode, the reference voltage (■ref) is set to the fixed bias point (Vfix
), if the transmission power is adjusted in the direction of increasing the transmission power, this is due to the operation timing difference between the fixed bias loose and ALC loose.

There was also the drawback that an excessive transient occurred when the ALC was turned on.

It is an object of the present invention to provide an automatic power control amplifier capable of eliminating transient fluctuations in the transmit power level that occur when switching on the ALC loop.

According to the present invention, there is provided an automatic power control amplifier connected between an output and an input of a transmission system to form an automatic power control loop, the automatic power control amplifier being inserted into and connected to the automatic power control loop to open and close the automatic power control loop. and when the automatic power control loop is in an open state, both the input side and output side levels of the first switching means match a fixed bias voltage applied to the transmission system side. a fixed bias loop; inserted and connected to the fixed/bias loop;
In the automatic power control amplifier having a second opening/closing means for opening and closing the fixed bias loop, there is obtained an automatic power/control amplifier characterized in that it is equipped with an automatic power control device.

Next, nine embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 2, an automatic power control amplifier (hereinafter abbreviated as ALCAMP) according to an embodiment of the present invention includes a comparator 2. An automatic power control loop (hereinafter referred to as AL
C loop) and a comparator 6. It consists of a fixed bias loop consisting of an analog switch (second opening/closing means) 11, relays 10 and 12 that control on/off of both of these loops, a timer (timekeeping means) 18, and NAND gates 15, 16, and 17, as described above. Relays 10 and 12
A relay drive circuit 20 that determines the drive timing of the relay 1, a power level detection circuit that supplies an input signal to the relay 1 drive circuit, a power level detection circuit consisting of a comparator 16 and a transistor 14, and a switch 19 that manually controls the ALC on/off. It has

In this embodiment, the difference from the conventional one shown in FIG. The use of the contact 12a, the provision of a switch 19 having the same function as switches 4 and 7 outside the 9-car loop, and the use of the relay drive circuit 20 using the timer 18 to turn on the relay 10 at the same time as the ALC is turned on. Turn it on to close the ALC loop.

The relay 12 is turned on after a certain time delay to open the fixed bias loop.

Now, if the transmission power is cut off due to an abnormality in the current transmission system during operation with the switch 19 in the ALC ON state, the comparator 16 detects this abnormality and turns on the transistor 14, so that the input level of the NAND gate 16 becomes L level, output becomes H level, relay 10 turns off and AL
C loop opens automatically. On the other hand, the input of timer 18 is also low.
This timer 18 is configured to perform a delay operation only when the input changes from L level to H level, so the output goes to L level at the same time as the input goes to L level. Therefore, the output of the NAND gate 17 becomes H level, the relay 12 is turned off, and its contact 12a turns on the analog switch 11, closing the fixed bias loop. That is, if the ALC loop opens and the fixed bias transmit power returns to a certain level.

The comparator 16 automatically detects this and turns off the transistor 14, so the input of the NAND gate 16 goes high.
level, the output becomes L level, relay 10 is turned on, and A
LC loop closes.

On the other hand, the input of timer 18 also becomes H level, and timer 1
8 starts the delay operation from this point and sets the output to H level after a certain set time. Since the switch 19 id ALC is selected to be on, when the output of the timer 18 becomes H level, the two inputs of the NAND gate 17 both become H level and the output becomes L level. Therefore, the relay 12 turns on, and its contacts connect the cyan analog switch 11.
turns off and opens the fixed bias loop.

That is, since the ALC loop is closed when the level difference between the input and output sides of the contact 10a of the relay 10 that directly opens and closes the ALC loop is always zero, transients in the transmission power level when the ALC is on can be completely eliminated. I can do it.

In addition, switch 19 in 1 manual mode turns on ALC.
Even when the circuit is turned off, the opening and closing of the ALC loop and the fixed bias loop are delayed by the timer 18 as described above, so there is no concern that transients will occur.

That is, in this embodiment, relay 10° relay 12.
A portion including the contact 12a of the relay 12, the relay, and the drive circuit 20 constitutes an opening/closing timing circuit, and the opening/closing timing circuit uses a signal to turn on the ALC (a signal when the transistor 14 is off or a signal when the switch 19 is turned on to ALCON).
When the timer 18 receives a signal when switching to the side, the set time of the first timer (timer 18) has elapsed.

This opens the second opening/closing means (analog switch 11).

As explained above, when using the automatic power control amplifier according to the present invention in which a simple opening/closing timing circuit is added to the automatic power control loop and the fixed bias loop, the problem that occurs when the automatic power control loop opens and closes, especially when closing. It becomes possible to completely eliminate transient fluctuations in transmission power.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transmission power control device using a conventional automatic power control amplifier, and FIG. 2 is a block diagram. 1 is a block diagram of one embodiment of an automatic power control amplifier according to the present invention. FIG. 1...Detector, 2...Comparator, 6...Amplifier, 4
...Switch, 5...PIN diode attenuator, 6
...Comparator, 7...Switch, 8...Reference voltage setter. 9...Fixed bias setting device, 10...Relay, 10
a...Contact of relay 10, 11...Semiconductor analog switch, 12...Relay, 12a...Contact of relay 12, 13...Comparator, 14...Transistor, 15.16 and 17.・NAND gate,
18...Timer, 19...Switch, 20...Relay, drive circuit. 100...Transmission system, 200...Automatic power control amplifier (
ALCAMP), A... ALCAMP input, B...
・ALC Amp output, v, v...power supply + "da"
t...Detection voltage + Vref...Reference voltage + Vf
ix...Fixed bias voltage.

Claims (1)

[Claims] 1. An automatic power control amplifier connected between an output and an input of a transmission system to form an automatic power control loop, the first automatic power control amplifier being inserted into and connected to the automatic power control loop to open and close the automatic power control loop. opening/closing means, and a fixed bias loop that matches the levels of the input side and output side of the first switching means with a fixed bias voltage applied to the transmission system side when the automatic power control loop is in an open state. and a second opening/closing means inserted and connected to the fixed bias loop for opening and closing the fixed bias loop, after a signal setting time for turning on the automatic power control has elapsed. , an automatic power control amplifier comprising an opening/closing timing circuit for opening the second opening/closing means.