JPS6048608A - Alc circuit - Google Patents

Abstract

PURPOSE:To obtain an ALC voltage capable of coping with the form of a radio wave by providing plural time constant circuits generating different time constants and a time constant circuit selecting means selecting a time constant circuit in response to the selecting operation by a mode selecting means. CONSTITUTION:The plural time constant circuits Tn (n=5 in this case) are provided to an ALC circuit 15. The input side of the time constant circuits T1- T5 is connected to slave contacts P1-P5 of a time constant changeover dial 16, and the output side is connected in parallel and to a terminal to be controlled of a circuit to be controlled of each stage via a terminal 15b. When an FSK is selected by operating a mode selection dial 13, a master contact Pa and the slave contact P2 of the time constant changeover dial 16 are connected, and the time constant circuit T2 changed over to the time constant circuit T2 corresponding to an FM (sound and code) has a time constant smaller than that of the time constant circuit T1, an ALC voltage capable of following sufficiently the output voltage change at mark/space is transmitted to the circuit to be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ALC circuit, and particularly to an ALC circuit according to a radio wave type.
This relates to an ALC circuit that can change the holding time of the LC voltage.

Usually, the ALC circuit is provided in a transmitting circuit of a wireless communication device or the like for protecting the transmitting final stage section 6 shown in FIG. Transmitting circuit company transmitting device 1, front stage transmitting circuit 4, variable gain amplifier 5,
It is composed of a transmission final stage section 6 and an antenna 7. The transmission signal generated by the telephone key 2 (including the automatic transmission device), microphone 3, etc. of the transmitting device 1 is sent to the front stage so that the radio wave type high frequency transmission power corresponding to the mode selected by the mode selection dial 13 can be transmitted from the antenna 7. The transmitting circuit 4 performs waveform processing such as amplification, modulation, and band selection. A transmission output control circuit such as a variable gain amplifier 5 outputs a transmission signal that has undergone waveform processing to a transmission final stage section 6. The transmission final stage unit 6 generates high-frequency transmission power from the input transmission signal and radiates it into the air from the antenna 7 as a radio wave.

This radio wave type has attributes related to modulation type (amplitude, phase, pulse, etc.) and transmission type (telegraph, telephone, video, facsimile, etc.) In amateur radio, AM, FM,
88B (upper sideband or lower sideband) CW, FSK
(Frequency shift keying using 88B, AM, etc., that is, audio FSK...including AFSK), etc. Further, a vacuum tube or a semiconductor element is used for the power amplification provided in the transmission final stage section 6, and the design goal is to prevent the overlevel of the power amplification and its maximum duration from burning out, deterioration, etc. of the transmission final stage section 6. It becomes. (to audio signal (
(The probability of appearance of a signal is different between the analog waveform) and the telephone key signal (digital waveform)) Especially in SSB, where no carrier wave is emitted in the radio wave when there is no signal, the frequency of the signal appearing in the final stage 6 of the transmission by the AI and C voltage generation circuit 9 is・The detection time of each level and the ALC voltage rise time and the ALC voltage generated by the ALC voltage generation circuit 9 suppress the gain of the variable gain amplifier 5, etc. until the over level is released and the original state is restored. The ALC voltage holding time is an important factor in ensuring proper continuous transmission.

In order to efficiently operate the transmission final stage section 6, a controlled circuit such as a variable gain amplifier 5 controlled by the ALC voltage is provided at each stage, so that the level distribution in each stage during normal times and at the time of ALC start is appropriate. It is planned that way. Figure middle mark 12
The drive control is performed by a volume controller, and this drive control circuit is sometimes provided between the ALC circuit 8 and the transmission final stage section 6. In addition, in order to control the high frequency transmission power of the transmission final stage section 6, a control unit (including an automatic microphone control circuit) and the like are provided.

Normally, the design conditions for the ALC [ball holding time] are more complicated than those of other waveforms when SSB has an analog waveform signal.Therefore, the time constant of the conventional ALC circuit 60 is determined to be compatible with SSB. For this reason, AFSK using SSB, which has a different probability of occurrence of a signal, has drawbacks such as extremely poor response.Furthermore, FSK using FM has the difference between the mark frequency and the space frequency (usually 17011z
~850 Hz) and Pantono? This method has the disadvantage that non-negligible filter rizzol occurs due to filter loss for each frequency that passes through the filter.

The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide an ALC circuit that can obtain an ALC voltage compatible with radio wave types.

An embodiment of the ALC circuit according to the present invention will be described below with reference to FIG.

In FIG. 2, 16 is a time constant switching dial. The time constant switching dial 16 is a rotating switch, and when the mode selection dial 13 is rotated, it contacts the parent contact PIL and the child contacts P, -P5 in conjunction with the rotation of the mode selection dial 13.

The ALC circuit 15 is provided with a plurality of time constant circuits Tn (n is assumed to be 5 for explanation). Time constant circuit T, ~
The input side of T5 is the child contact P, ~P of the time constant switching dial 16.
5, and the output side is connected in parallel to the controlled terminal of the controlled circuit of each stage via the terminal 15b. When the transmission final stage section 6 reaches an overlevel, the overlevel voltage is outputted to the terminal 5a via the x-x' connection, the drive control volume 12, and the y-y' connection. AL
The voltage generating circuit 9 detects the overlevel voltage and outputs the ALC voltage to the parent contact P& of the mode selection dial 13.

Here, the time constant circuit T connected to the child contact P1 has the same time constant as the conventional time constant circuit IO, and the child terminals P, ~
P5 is SSB (voice), FM (voice, code), AM
(voice), SSB (code), and AM (code), the SSB (voice) operates with the same time constant as the conventional one.

When FSK is selected by operating the mode selection dial 13, the master contact Pa and slave contact P2 of the time constant switching dial 16 are connected, and the time constant circuit T2 corresponding to FM (voice, code) K is connected.
Since the time constant circuit T2 which is switched to has a smaller time constant than the time constant circuit T1, it sends out to the controlled circuit an ALC voltage that can sufficiently follow changes in output voltage during marks and spaces. In addition, each time constant circuit T, -T5 is independent of the radio wave type, and has an independent circuit configuration, so by operating the drive control zlJ, -12, it is possible to obtain the optimum high frequency transmission power for the radio wave type. This improves responsiveness compared to a conventional ALC circuit that controls a single time constant circuit in response to a drive control polygon.

The allocation of radio wave types to the time constant circuits T, ~T5 is not limited to the above embodiments, for example, FM (sound, code) SS
B (sign) and AM (sign) may be configured to use the same time constant circuit T2.

The switching information by the time constant switching dial 16 may be obtained from the mode switching circuit 14, and the time constant switching dial 16 may be omitted.

Since the ALC circuit according to the present invention includes a plurality of time constant circuits that generate different time constants and a time constant selection means that selects the time constant circuit in response to a selection operation by the mode selection means, It has the feature that different time constant circuits can be selected by the mode selection means. Therefore, the ALC voltage holding time can be selected according to the radio wave type, and the optimum transmission power can be obtained when used in conjunction with a drive control circuit. Furthermore, the degree of freedom in design regarding time constants is improved, and the circuit configuration can be simplified, such as by being able to share the same bandpass filter between different voltage types.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional ALC circuit, and FIG. 2 is a block diagram showing an embodiment of the ALC circuit according to the present invention. In the figure, 1 is a transmitter, 2 is a telephone key, 3 is a microphone, 4 is a pre-transmission circuit, 5 is a variable gain amplifier, 6 is a transmission final stage, 7 is an antenna, 8°15 is an ALC circuit, and 9 is an AL
C voltage generation circuit, 10°T, ~T5 is time constant circuit, 11
12 is a drive control dial, 13 is a mode selection dial, 14 is a mode control circuit, and 16 is a time constant selection dial. Patent applicant Yaesu Musen Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. variable gain amplification means, ALC voltage generation means for outputting an ALC voltage for controlling the gain of the variable gain amplification means, mode selection means for selecting the radio wave type of high frequency transmission power output from the transmission final stage; ALC related to a transmitting circuit, comprising: controlling the gain of the variable gain amplifying means according to the ALCt pressure to protect the transmitting final stage section;
A selected time constant circuit comprising: a plurality of time constant circuits that generate different time constants; and time constant circuit selection means that selects the time constant circuit in response to a selection operation by the mode selection means. An ALC circuit characterized in that the ALC circuit is configured to control the variable gain amplification means with an ALC voltage via the ALC voltage.