JP2002271214A - Transmission output control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a drawback in that a user is forced to interrupt transmission during transmitting, due to temperature rise caused by self-heating in a small high-power transmitter/receiver. SOLUTION: In a transmission output control system, in which the output level of a transmitting power amplifier 5 is detected by an output detector 4, and the detected level is compared with the reference level by an error amplifier 6 to control a transmission output so that the difference between the levels is reduced, a reference input is varied according to the detected temperature on a high-frequency output circuit board of the amplifier 5. The transmission output level is lowered, when the temperature is high, and is returned to the original output, when the temperature falls.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission output control method for a wireless communication device, and more particularly to a transmission output control method for changing a transmission output according to a temperature rise due to self-heating during continuous transmission.

[0002]

2. Description of the Related Art In general electronic equipment, high-frequency application equipment, or wireless transceivers, if the temperature rises due to continuous operation after turning on the power, the performance of the equipment will be reduced, and parts will be damaged, resulting in failure. Designed to reduce temperature rise. For example, there are many air-cooling systems in which three windows are provided on the side surface or the rear surface of the device, and a cooling fan by a small motor is attached to dissipate heat due to internal temperature rise by convection of air.

In the case of a wireless device, for example, the UHF band or V
When the high-output transceiver in the HF band is used continuously, the temperature of the high-frequency output circuit board and the housing increases due to the self-heating of the components of the transmission power amplifier. If the internal temperature rises, the performance may deteriorate and the required specifications may not be met or a failure may occur.Therefore, a heat sink is attached, a heat dissipation sheet such as a silicon sheet is attached to a high temperature part, A device has been devised that is fixed to a metal housing with a large number of metal screws to release heat by heat conduction.

FIG. 4 is a block diagram of a conventional transceiver to which the present invention is applied. This wireless device is of a transmission / reception switching type (using a PTT switch), and is configured to perform communication by switching between transmission and reception. In the figure, 1 is an antenna, 2 is a low frequency pass filter (LPF), 3 is a transmission / reception switch, 4 is an output detector, 5 is a power amplifier (PA), 2
0 is an error amplifier (APC circuit). Since the transmission / reception switching method (press-to-talk method) is used, the transmission / reception switch 3 is switched to the transmission side and the output of the transmission power amplifier 5 is input to the LPF 2 via the output detector 4 and transmitted from the antenna 1 when transmitting. Transmit radio waves.

[0005] The output detector 4 always monitors the transmission output, detects the transmission level, and inputs it to the error amplifier 20. The error amplifier 20 compares the transmission level with the reference input level, and when the transmission level exceeds the reference input level, operates so as to lower the amplification degree of the PA 5 to lower the transmission level, so that the transmission power is always constant. (APC: automatic power control).

[0006]

However, in the case of the above-mentioned conventional radio equipment, a problem has arisen that the conventional heat radiating means cannot sufficiently radiate heat as the transmission output remains high and the miniaturization is advanced. Was.

As a countermeasure, there is a case where a circuit called a "timeout timer" for switching to a reception state at a fixed time after the start of transmission is provided in order to mitigate a rise in temperature during continuous transmission. If the user manually stops the transmission every time or before the timeout, transmission interruption is inevitable even if no failure occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a means for solving the above-mentioned conventional problems, so that the conventional heat radiating means can avoid the disadvantage that the temperature rise cannot be suppressed and the transmission must be interrupted. It is another object of the present invention to provide a transmission power control method.

[0009]

According to a transmission output control method of the present invention, an output level of a transmission power amplifier is detected and compared with a reference input level by an error amplifier so that the difference is reduced. In the transmission output control method for controlling the power amplifier, a temperature detector attached to the high-frequency output circuit board of the power amplifier, and reference input control means for changing the reference input level of the error amplifier by a temperature detection signal of the temperature detector, Wherein the reference input control means reduces the reference input level given to the error amplifier when the temperature detection signal level of the temperature detector exceeds a threshold value corresponding to a preset allowable temperature, and the transmission output And when the temperature detection signal level becomes lower than the threshold value, the reference input level is increased to increase the transmission output. It is an. Further, the threshold value is controlled to lower the reference input level by a first threshold value corresponding to an allowable upper limit temperature and to control the reference input level to be lower than the allowable upper limit temperature. And a second threshold value corresponding to the allowable lower limit temperature is set.

[0010]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, the same parts as those of the conventional configuration of FIG. In the configuration of the present invention, a temperature detector 7 and a reference input controller 8 for changing a reference input level input to the error amplifier 6 according to the output thereof are provided.
It is characterized in that control by the detected temperature is taken into account.

That is, when a temperature sensor such as a thermistor is mounted as a temperature detector 7 on a circuit board of a high-frequency output section of a power amplifier whose temperature rises remarkably, for example, when the allowable temperature is 65 ° C. and the temperature exceeds 65 ° C. , The transmission output, for example, 4
The transmission is continued as it is until the temperature decreases from 0 W to about 25 W or from 50 W to 25 W. Then, when the temperature drops below the allowable temperature, the transmission output is returned to the original output, for example, 40 W or 50 W. In this way, even if the output level drops, transmission is not interrupted, so that the telephone conversation can be continued.

FIG. 2 is a flowchart showing the control of the present invention. Is a step number. When the mode is switched to transmission, the temperature of the substrate of the transmission high-frequency output circuit is monitored, for example, whether or not a preset allowable temperature of 65 ° C. is exceeded (step). The transmission output is lowered by lowering the reference input given to the amplifier 6 (step). It monitors whether or not the temperature has fallen below the set temperature in a state where the transmission output is lowered (step).
Raises the reference input given to the error amplifier 6, raises the transmission output, and returns to the original output.

FIG. 3 is a block diagram showing a second embodiment of the present invention. In the figure, the same reference numerals are given to the same components as those of the conventional configuration and the first embodiment of the present invention. This second
In this embodiment, a microcomputer is used as a controller 10, and an A / D converter 9 for converting a temperature detection signal into a digital value and a D / A converter 11 for converting a digital output into an analog value are input and output. Is provided, and control is performed by software. The operation is the same as that in the flowchart of FIG. 2 of the first embodiment. For example, in the first embodiment shown in FIG. 1, if the reference input controller 8 is provided with hysteresis, the circuit becomes complicated. In the second embodiment, however, control having hysteresis can be easily performed by a microcomputer. .

The above-mentioned hysteresis control means that when transmission is continued and the temperature of the transmitter rises, the allowable upper limit temperature (for example, 65) for performing control to lower the transmission output level.
° C) and an allowable lower limit temperature (for example, 55 ° C) at which it is determined that the temperature may be reduced by lowering the transmission output to increase the transmission output level and return to the original output. This means setting and controlling two corresponding threshold values.

[0015]

As described in detail above, by implementing the present invention, it is possible to prevent problems such as deterioration of characteristics due to heat and breakage of circuit elements, even when transmission is continuously performed. Even if the transmission output is reduced by the present invention, the transmission is not interrupted, so that the communication is not interrupted, and the effect is extremely large in practical use. Further, the present invention has a great effect that the size of the wireless device can be further reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a control flowchart of the embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional circuit configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 LPF 3 Transmission / reception switch 4 Output detector 5 PA 6 Error amplifier 7 Temperature detector 8 Reference input controller 9 A / D converter 10 Controller 11 D / A converter

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tsukasa Ishigo 43-224 Tsunonuma, Tenno-cho, Tenno-cho, Minami-Akita-gun, Akita Prefecture Inside Kokusai Denki Engineering Co., Ltd. 43- 224 Kokusai Denki Engineering Co., Ltd. Tsurumumadai 43-224 Kokusai Electric Engineering Co., Ltd. F term (reference) 5J100 JA01 JA09 LA10 LA11 5K060 BB03 CC04 HH06 LL01

Claims (2)

[Claims] 1. A transmission output control method for detecting an output level of a transmission power amplifier and controlling an amplification degree of the power amplifier so as to reduce a difference between the output level and a reference input level by an error amplifier. A temperature detector attached to the high-frequency output circuit board; and reference input control means for changing a reference input level of the error amplifier according to a temperature detection signal of the temperature detector. When the temperature detection signal level of the detector exceeds a threshold value corresponding to a preset allowable temperature, the reference input level given to the error amplifier is lowered to lower the transmission output, and the temperature detection signal level is lower than the threshold value. A transmission output control method, wherein the reference output level is increased when the transmission output is lowered, thereby increasing the transmission output. 2. The method according to claim 1, wherein the threshold value is a first threshold value corresponding to an allowable upper limit temperature when controlling to reduce the reference input level, and the reference input level is lower than the allowable upper limit temperature. 2. The transmission output control method according to claim 1, wherein a second threshold value corresponding to the allowable lower limit temperature when the control is performed is set.