JPH07303049A - Emergency shutdown device for transmitter - Google Patents

Abstract

PURPOSE:To prevent the needless radiation of a radio transmitter from being applied. CONSTITUTION:An input signal is amplified by the power amplifier 2 of a transmitter, and is outputted to an output terminal 4, and a part of the output is distributed by a signal distribution circuit 3, and is inputted to a distortion level detector 5. When intermodulation distortion between two frequencies decided in advance occurs due to the deterioration of linearity of the amplifier 2, the level of the intermodulation distortion by the distortion level detector 5 is increased, and when it exceeds a prescribed value, a control signal is generated from a control circuit 11, and a shutdown circuit 8 is set in a shutdown state by the control signal, then, the supply of operating power source power to the amplifier 2 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter having an active circuit such as a signal generator, an amplifier, a frequency converter, etc., when a failure such as an abnormal distortion component represented by spurious is output. , An emergency stop device for stopping the output in an emergency.

[0002]

2. Description of the Related Art Conventionally, in a high-power transmitter or the like used in the fields of communication and broadcasting, when the transmission output of a power amplifier is monitored and a gain abnormality of the power amplifier is detected, the input signal of the power amplifier is detected. The output was stopped by attenuating the level. However, when an unnecessary distortion component is generated in the output signal of the transmitter, conventionally, the output spectrum is measured using a measuring instrument such as a spectrum analyzer in periodic inspections, and it is said that the distortion component is generated. If found, the transmitter output was artificially stopped.

[0003]

In the transmitter, for example, the transmission amplifier, when the gain is normal but the fault such that the linearity of the input / output is deteriorated, the output level is not changed. Regardless, a phenomenon in which the distortion component in the output signal increases may occur. Due to this increase in distortion component, the quality of the output signal itself may deteriorate, and in some cases spurious other than the normal signal may occur. When such a failure occurs, it is necessary to immediately stop the operation of the corresponding amplifier, but in the past, it was necessary to connect a measuring instrument to measure the output signal spectrum or to perform a periodic inspection However, there is a problem in the operation of the device that it is difficult to deal with this request because the failure location cannot be identified until the time comes. Although the example of the amplifier has been described here, a similar failure may occur in the signal generator, and even in that case, there is a similar problem that it is difficult to deal with the failure promptly by the conventional technology. It was

[0004]

In any of the inventions of claims, the output of the active circuit of the transmitter is distributed by the signal distribution circuit, and the level of the distortion component is detected by the distortion level detector from the distributed output. Output cutoff means for cutting off the output of the active circuit is also provided. In the invention of claim 1, the detection level of the distortion level detector is further supplied to the display. According to the second aspect of the invention, the detection level of the distortion level detector is sent to the outside, and the output cutoff means is controlled by a control signal from the outside. According to the invention of claim 3, when the detection level of the distortion level detector further exceeds a predetermined level, an alarm signal is output from the control circuit to the outside, and the output cutoff means is controlled by the control signal from the outside. Has been done. Further, in the invention of claim 4, when the detection level of the distortion level detector becomes equal to or higher than a predetermined level, the control circuit outputs a control signal to operate the output cutoff means.

The output cutoff means is a means for cutting off the operating power supply supplied to the active circuit, or a means for being inserted in the input path of the active circuit and for cutting off an input signal, or a means for being inserted in the output path of the active circuit to output the output signal. It is a means of shutting off. According to the invention of claim 8, in each of the above inventions, a plurality of pilot signals are further inserted into the input path of the active circuit by the pilot injection circuit, and the level of intermodulation distortion of the plurality of pilot signals is increased by the distortion level detector. To be detected.

[0006]

According to the first aspect of the present invention, when the display of the display is viewed by the maintenance person and the detected distortion level is high, the output cutoff means can be directly turned off by a manual operation. In the invention of claim 2, when the sent distortion detection level is viewed on the display,
If it is larger, a control signal can be sent to remotely control the output cutoff means to put it in the cutoff state. According to the invention of claim 3, when an alarm signal is sent, a control signal can be sent to remotely control the output cutoff means. Claim 4
In the invention described above, when the detected distortion level is large, the output cutoff means is automatically turned off.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the invention of claim 1 is shown in FIG. In this embodiment, the present invention is applied to an amplifier as an active circuit of a transmitter. The signal input to the signal input terminal 1 is power-amplified by the amplifier 2 and output to the signal output terminal 4 via the signal distribution circuit 3. The signal distribution circuit 4 is composed of, for example, a directional coupler, and the distribution output on the side other than the output terminal 4 side is input to the distortion level detector 5.
As the distortion level detector 5, for example, a narrow band level detector represented by a selective level meter is used. The output of the distortion level detector 5 is input to the display 6 composed of an LED or the like. The output of the power supply circuit 7 is input to the power supply input terminal 9 of the amplifier 2 via the cutoff circuit 8. Of course, a power distributor may be used as the signal distribution circuit 3, the signal distribution circuit 3 may be included in the distortion level detector 5, and the cutoff circuit 8 may be included in the power supply circuit 7.

The operation of this embodiment will be described below.
The amplifier 2 is a linear amplifier, and if its characteristics are deteriorated, a distortion component is generated in the output signal. Especially when the input signal is a multi-frequency signal having different frequencies, intermodulation distortion of a frequency different from the input frequency occurs. FIG. 2A shows an example in which the frequencies of the input signal are two frequencies of f1 and f2. When the linearity of the amplifier 2 is deteriorated, third-order intermodulation distortion having frequencies 2f1-f2 and 2f2-f1 as shown in FIG. 2B is generated at the output. By detecting and monitoring the level of this intermodulation distortion using a narrow band level detector, the distortion component level in the output signal can be monitored. Further, when the use band of the frequency of the transmitter is limited, a band stop filter having a characteristic of passing a level other than the use band shown in FIG. 3A and a characteristic of passing a frequency higher than the use band shown in FIG. 3B. After passing through the high-pass filter and the low-pass filter having the characteristic of passing a frequency lower than the used band shown in FIG. 3C, a narrow band level detector may be used to detect a distortion component outside the used band. Good.

In this embodiment, the signal input to the signal input terminal 1 is input to the amplifier 2, and this signal is power-amplified and then input to the signal distribution circuit 3. Signal distribution circuit 3
One output is output to the signal output terminal 4, and the other output is output to the distortion level detector 5. The distortion level detector 5 detects the level of intermodulation distortion in the output signal. The amplifier 2 does not output the distortion in a steady state, but when the amplifier 2 is distorted due to the deterioration of the linearity of the input / output of the amplifier 2, the distortion level detector 5 detects this level and displays it on the display 6. Output.

The display 6 is composed of, for example, an array of a plurality of LEDs (light emitting diodes), and the number of light emitted from one end of the array is changed according to the magnitude of the input detection level, or the array is arranged. L separated from one end of
EDs are made to emit light or LEs of different emission colors
Either D may be made to emit light, or the detection level may be displayed in the form of a numeric character in the shape of a day, or a normal meter type indicator may be used. When the operator or maintenance person sees the display on the display 6 and recognizes that the detected distortion level is higher than a predetermined value, the interruption circuit 8 is cut off by an artificial operation to cut off the power supply current supplied to the amplifier 2. This prevents distortion from being output to the signal output terminal 4. The display 6 may be lit and displayed only when the input detection level is equal to or higher than a predetermined value.

FIG. 4 shows a second embodiment of the invention according to claim 1, and parts corresponding to those in FIG. 1 are designated by the same reference numerals. In this embodiment, the present invention is applied to an oscillator as an active circuit of a transmitter, and an oscillator 10 is connected instead of the amplifier 2 in FIG. The oscillator 10 is composed of a frequency synthesizer or the like, and is an oscillator capable of outputting signals having a plurality of predetermined frequencies. Although the oscillator 10 does not output distortion in a steady state, when the oscillator 10 starts to generate distortion due to deterioration of the linearity of the oscillator 10 or the like, the distortion level detector 5 outputs a large level distortion detection output.
Output to. The display of the display 6 indicates that the output is abnormal, and the operator or maintenance person recognizes the abnormal output and operates the cutoff circuit 8 by an artificial operation to supply it to the oscillator 10. Power output current is cut off and signal output terminal 9
Prevents distortion from being output.

An embodiment of the present invention as claimed in claims 3, 4 and 5 is shown in FIG. 5 in which parts corresponding to those in FIG. This figure applies to the case where the active circuit is the amplifier 2 and the operator or maintenance person is far from the transmitter. The output of the distortion level detector 5 is supplied to the control circuit 11. An electrical cutoff circuit having an external control input terminal 13 as the cutoff circuit 8 and capable of executing a cutoff function by the control input is used.

The control circuit 11 comprises an A / D converter, a microprocessor, and a D / A converter as a basic circuit, monitors the detection level input from the distortion level detector 5, and outputs the distortion level detector 5. Changes from the normal state and becomes larger than a specific level, an alarm signal is output to the external alarm output terminal 12. The external alarm output terminal 12 and the external control input terminal 13 are wired via a communication line to a monitoring room that is remotely monitored by an operator or a maintenance person. When the operator or maintenance person recognizes the alarm signal from the external alarm output terminal 12, it outputs a control signal to the external control input terminal 13. Breaking circuit 8
Operates by receiving a control signal from the external control input terminal 13 and shuts off the power supply current supplied to the amplifier 2 to prevent distortion from being output to the signal output terminal 4.

As shown by the dotted line 18 in FIG. 5, the detection output of the strain level detector 5 is sent to the monitoring room through the external alarm output terminal 12, and the strain detection level output sent in the monitoring room is displayed on the display. By observing this, it may be recognized that the distortion level has become higher than the predetermined value, and the control signal may be output to the external control input terminal 13. Further, when the control circuit 11 detects the state of outputting the alarm signal, it outputs a control signal instead of the alarm signal and supplies it to the control input terminal 13 of the cutoff circuit 8 as shown by the dotted line 19 to automatically cut off the power supply. It may be done. In this case, an alarm signal may also be sent to the external alarm output terminal 12 to notify the monitoring room.

In the above description, when the detected distortion level is large, the power supply is cut off. However, as shown in FIG. 6 by attaching the same reference numerals to the portions corresponding to FIG. A signal cutoff circuit 14 may be inserted to cut off the input signal supplied to the amplifier 2. In this case, the signal cutoff circuit 14
The shutoff action of may be performed manually or as shown in FIG.
Similar to the case described in (1), it may be performed by an external control signal or automatically by a control signal from the control circuit 11.

An embodiment of the invention of claim 8 is shown in FIG. 7 by attaching the same symbols to the portions corresponding to FIG. In this embodiment, the pilot injection circuit 15 is provided between the signal input terminal 1 and the amplifier 2.
Is provided and a pilot generator 16 for outputting to the pilot injection circuit 15 is added. The plurality of pilot signals output from the pilot generator 16 have the same level and are output to the pilot injection circuit 15 at the maximum level at which intermodulation distortion is not output even after passing through the amplifier 2. The pilot injection circuit 15 injects a plurality of pilots into the signal supplied to the signal input terminal 1, and inputs the pilot 2 into the amplifier 2. The distortion level detector 5 is set so as to detect a specific harmonic of a plurality of pilot signals, for example, the level of third-order intermodulation distortion. The amplifier 2 does not output distortion in the steady state, but the amplifier 2
When the amplifier 2 becomes distorted due to the deterioration of the input / output linearity, the distortion level detector 5 detects this level and outputs it to the display 6. That is, by injecting a plurality of pilot signals into the input path and monitoring the level of intermodulation distortion, the distortion component in the output signal is detected without depending on the input signal.

Injecting a plurality of pilot signals into the input path of the amplifier 2 and detecting the inter-modulation distortion by the distortion level detector 5 as described above is shown in FIGS. 1, 5, and 6 described above. Examples can also be applied. Further, in the embodiment of FIGS. 5 and 6, the oscillator 1 is used as the active circuit instead of the amplifier 2.
It can also be applied when 0 is used. Further, in the above description, the signal cutoff circuit 14 may be inserted not into the input path of the active circuit but into the output path and cut off so that the output signal is not output to the output terminal 4 when a large distortion is output from the active circuit. Good.

[0018]

As described above, according to this description, when a small distortion component is output from the active circuit of the transmitter, it is detected and the output of the active circuit is cut off. , In particular radio transmitters do not give rise to abnormal spurious emissions, and therefore do not require special expensive measuring instruments.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention of claim 1;

FIG. 2 is a spectrum diagram showing a dual frequency input signal and its intermodulation output.

FIG. 3 is a diagram showing an example of filter characteristics for extracting a mutual cross modulation distortion component.

FIG. 4 is a block diagram showing another embodiment of the invention of claim 1;

FIG. 5 is a block diagram showing an embodiment of each invention of claims 2, 3 and 4.

FIG. 6 is a block diagram showing an embodiment of the invention of claim 6;

FIG. 7 is a block diagram showing an embodiment of the invention of claim 8;

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Shoichi Narahashi, Shoichi Narahashi 2-10-1 Toranomon, Minato-ku, Tokyo NTT Mobile Communications Network Co., Ltd. (72) Makoto Maeda Toranomonji, Minato-ku, Tokyo Chome 10-1 NTT Mobile Communications Network Co., Ltd. (72) Inventor Hironori Sakamoto 5-1-1 Shimorenjaku, Mitaka City, Tokyo Japan Radio Co., Ltd.

Claims (8)

[Claims] 1. A signal distribution circuit for distributing the output of an active circuit of a transmitter, a distortion level detector for detecting the level of a distortion component from the output distributed by the signal distribution circuit, and detection of the distortion level detector. An emergency stop device for a transmitter, comprising: an indicator for displaying an output; and an output interruption means for interrupting an output signal of the active circuit. 2. A signal distribution circuit for distributing the output of an active circuit of a transmitter, and a distortion level detector for detecting the level of a distortion component from the output distributed by the signal distribution circuit and transmitting the detected output to the outside. And an output cutoff means for cutting off the output signal of the active circuit by operating according to a control signal from the outside, and an emergency stop device for a transmitter. 3. A signal distribution circuit for distributing the output of an active circuit of a transmitter, a distortion level detector for detecting the level of a distortion component from the output distributed by the signal distribution circuit, and detection of the distortion level detector. A control circuit for detecting an alarm signal when the level becomes a predetermined level or more and sending an alarm signal to the outside; and an output cutoff means for cutting off the output signal of the active circuit by operating according to a control signal from the outside. Emergency stop of transmitter. 4. A signal distribution circuit for distributing an output of an active circuit of a transmitter, a distortion level detector for detecting a level of a distortion component from an output distributed by the signal distribution circuit, and a detection of the distortion level detector. When the level exceeds a predetermined level, a control circuit that detects this and outputs a control signal, and an output cutoff unit that operates according to the control signal to cut off the output signal of the active circuit Stopper. 5. The emergency stop device for a transmitter according to claim 1, wherein the output cutoff means is means for cutting off the supply of operating power supply to the active circuit. 6. The emergency stop device for a transmitter according to claim 1, wherein said output cutoff means is means for being inserted into an input path of said active circuit to cut off an input signal. . 7. The emergency stop device for a transmitter according to claim 1, wherein the output cutoff unit is a unit that is inserted into an output path of the active circuit and cuts off an output signal. . 8. A pilot injection circuit for injecting a plurality of pilot signals is provided in an input path of the active circuit, and the distortion level detector detects the level of intermodulation distortion of the plurality of pilot signals. The emergency stop device of the transmitter according to claim 1, wherein the emergency stop device is a transmitter.