JPS607215A - Alc circuit - Google Patents

Abstract

PURPOSE:To obtain proper response characteristics in applying this ALC circuit to a transmission circuit where the transmission state is changed suddenly in a mobile radio or the like by providing an ALC voltage detecting means corresponding to individual causes and providing plural time constant circuits holding individually each ALC voltage. CONSTITUTION:When overdrive is caused in a mobile radio or the like during transmission and the 1st and 2nd ALC voltage are outputted respectively from the 1st and 2nd time constant circuits 7 and 12 because of deterioration in the SWR, a variable gain amplifier 2 is controlled according to them. Since the 2nd ALC voltage is restored in a comparatively shorter time constant than the conventional time constant when the SWR becomes normal, the variable gain amplifier 2 receives the control only at the 1st ALC voltage. When an antenna mismatching detector 10 is actuated with a transmission final stage section 3 at normal state and the 2nd ALC voltage is generated, since the 2nd ALC voltage is kept by the 2nd time constant circuit 12 having a comparatively shorter time constant, when the mismatching is cancelled, the operating characteristics of the variable gain amplifier 2 follow up it and the circuit is restored to the normal state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ALC circuit, and more particularly to an ALCl circuit applied to a transmitting circuit in which the SWR of an antenna changes, such as in a mobile radio.

Normally, in order to incorporate the transmission final stage section 3 shown in FIG. 1 into an ALC loop, the gains of the circuits at each stage, such as the variable gain amplifier 2 provided before the transmission final stage section 3, are automatically adjusted. Information necessary for adjustment is generated by the transmission final stage section 3 or the overdrive detector 4. The generated information is called an ALC voltage, and the ALC voltage obtained from the overdrive detector 4 is generated from the forward power sent from the transmission final stage 3 to the overdrive detector 4. When forward power is input to the overdrive detector 4, a part of this forward power is rectified and sent to the comparator 5 as a forward voltage. Comparator 5 has reference voltage V! is provided, and when the forward voltage exceeds the reference voltage 71, the AL
Outputs C voltage. When the circuits at each stage, such as the variable gain amplifier 2, receive the ALC voltage at the terminal 2a, the operating characteristics of the output signal level relative to the input signal level change. Since the ALC circuit is a type of feedback loop circuit, a time constant circuit 7 is provided to obtain response characteristics according to the signals handled. The time during which the ALC voltage is held by the time constant circuit 7 is called the ALC holding time. It is determined by taking into consideration the cycle of the envelope of the ALC retention signal, distortion, etc. Antenna 6 for mobile radio etc.
If the state of SwR changes suddenly, the p-transmission final stage may be degraded or damaged due to antenna mismatch.

To deal with this case, as shown in FIG. 1, the chain line connection between the overdrive detector 4 and the antenna 6 is cut, and xl, x,.

The antenna mismatch detector 10 is provided by connecting the wires of X3. The antenna mismatch detector 10 rectifies a part of the reflected power to obtain a reflected voltage, and a comparator 11 compares this reflected voltage with a reference voltage V2. A signal is generated according to the comparison, and this signal, ie, ALC% and pressure, is output to the terminal 7a of the time constant circuit 7. Note that the heat generated in each part of the power supply circuit and transmission circuit is
E? (Differences in the final stage 3); (This is often caused by operation, so in order to prevent damage to various circuits due to heat generation, it is recommended to use a PT notification means such as a buzzer connected to the temperature sensor. It is better to suppress the abnormal behavior in 3.For the sake of
Newspaper related to temperature sensors etc. installed in each part, ie ALC
The voltage is applied to the terminal 2a of the variable gain amplifier 2 or the time constant circuit 7.
The above-mentioned conventional A
When an LC circuit is provided in a mobile radio transmission circuit, a signal is sent from the antenna mismatch detector 1o to the terminal 7a of the time constant circuit 7 when the SWR of the antenna 6 suddenly deteriorates due to movement. Since this signal is held for a holding time determined by the time constant of the time constant circuit 70, the variable gain amplifier 2 continues to be controlled by the ALC voltage even after the SWR returns to normal. Therefore, a phenomenon occurs in which the output power remains reduced until the holding time elapses, which has the disadvantage of impairing the original function of the ALC circuit.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide an ALC circuit that can obtain appropriate response characteristics when applied to a transmission circuit such as a mobile radio where transmission conditions change suddenly.

The present invention provides ALC cylinder detection means corresponding to each cause, and furthermore, each ALC71! , it has a 1fIi configuration in which a plurality of time constant circuits are provided to hold the pressures separately.

The ALC voltage is controlled by a first time constant circuit, a second time constant circuit,
...Each is retained at an independent retention time.

Hereinafter, the ALC circuit according to the present invention will be described in detail with reference to FIG. 2. Since the same parts in FIG. 2 and FIG. 1 are given the same reference numerals, the explanation will be omitted.

In FIG. 2, 7 and 12 are a first time constant circuit and a second time constant circuit, respectively.

The second time constant circuit 12 is composed of a resistor 14 and a capacitor 13 connected in parallel. The time constant of the 14° resistor and capacitor 13 is set to a value that provides a holding time that can follow sudden changes in SWR. Antenna mismatch detector 1
0 terminal 10a to the terminal 12a of the second time constant circuit 12
The signal sent to the diode 15, ie the ALC voltage,
The signal is output to terminal 2a of variable gain amplifier 2 via. Note that the diodes 15 and 16 are used to prevent interference in the first and second time constant circuits 7 and 12.

At this point, while transmitting with mobile radio etc., it becomes overdrive,
In addition, the swR deteriorates, and the first and second time constant circuits 7
．． When the first and second ALC voltages are output from 12, respectively, the variable gain amplifier 2 is controlled according to the first and second ALC voltages. When the SWR becomes normal, the second ALC voltage returns with a relatively short time constant compared to the conventional time constant, so the variable gain amplifier 2 uses the first ALC voltage.
Controlled only by voltage. When the transmission final stage 3 is normal, the antenna mismatch detector 10 operates and the second ALC voltage is generated, the second time constant circuit 1 having a relatively short time constant is activated.
Since the second ALC voltage is maintained by 2, when the mismatch state is eliminated, the operational inertia of the variable gain amplifier 2 follows this and returns to normal.

In addition, in the present invention, dedicated time constant circuits are provided for each cause such as antenna mismatch and temperature rise in each part (not shown), so there is no cassette between the transmitting final stage section 3 and the antenna 6. It has the advantage of being easier to set and adjust than the conventional V.

Since the ALC circuit according to the present invention has a configuration including a plurality of ALC voltage detection means and a plurality of time constant circuits that determine the holding time of the ALC voltage, it is possible to
Each has a special feature in that it has a dedicated time constant circuit. Therefore, it is easy to set each quantifiable constant related to the time constant, and an appropriate response characteristic can always be obtained for various phenomena.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional ALC circuit, and Fig. 2 is a block diagram showing an embodiment of the ALC circuit of the present invention. In Fig. 6, 1 is a terminal, 2 is a variable gain amplifier, and 3 is a transmission final stage. 4 is an overdrive detector, 5.11 is a comparator, 6 is an antenna, 7 is a first time constant circuit, 8.13 is a capacitor, 9.14 is a resistor, 10 is an antenna mismatch detector, 1
2 is a second time constant circuit. Patent Applicant: Yaesu Musen Co., Ltd. Figures 1 and 2

Claims (1)

[Claims] A variable gain means and a signal for controlling the gain of the variable gain means (
The transmitter is equipped with an ALC voltage detection means for outputting an ALC voltage (hereinafter referred to as an ALC voltage) and a transmission final stage section, and is configured to control a variable gain means according to the ALC voltage to protect the transmission final stage section. In an ALC circuit related to a transmitter or a transmitter/receiver, the plurality of ALC voltage detection means and each ALC detected by the plurality of ALC voltage detection means
A plurality of time constant circuits provided to form a holding time corresponding to a voltage, and having a plurality of holding times.
An ALC circuit characterized in that the variable gain means is controlled by a C voltage.