JP2018098673A - Amplifying device and demodulating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress rising of a level of a signal output from an amplifying device.SOLUTION: An amplifying device 2 comprises: a variable attenuator 22 that adjusts a level of an input signal; a second amplifier 23 that amplifies a signal output from the variable attenuator 22 and outputs the amplified signal; a detection circuit 25 that extracts the signal output from the second amplifier 23, detects the extracted signal and converts the detected signal to a voltage; and a microcontroller 26 that causes the variable attenuator 22 to adjust the level of the input signal on the basis of the level of the signal detected in the detection circuit 25 when the level of the signal detected in the detection circuit 25 is a predetermined level or less, and causes the variable attenuator 22 to reduce the level of the input signal by a predetermined amount when the level of the signal detected in the detection circuit 25 exceeds a predetermined level.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an amplifying device and a demodulating device that make the level of an input signal constant.

  In a base station for wireless communication, an IF (Intermediate Frequency) signal received at an antenna and converted to an intermediate frequency is input to an amplifying device of a modem. Thereafter, the input signal input to the amplifying device is converted into a digital signal by the AD converter, and then signal processing is performed by the signal processing unit.

  The level of the input signal input to the amplifying device changes due to fading or the like. For this reason, the amplification device is provided with an automatic level control (ALC) function for controlling the level of the input signal. In automatic level control, the level of an input signal is controlled by using a variable attenuator that attenuates the input signal based on control by the control unit and an amplifier that amplifies the attenuated signal (for example, Patent Document 1). reference).

JP 2000-101374 A

  If an excessive signal is input to the amplifying apparatus or the amount of attenuation in the variable attenuator of the amplifying apparatus is not appropriate, the level of the signal output from the amplifying apparatus may be excessive. When an excessive signal is input to the circuit at the subsequent stage of the amplifying device, there arises a problem that the circuit at the subsequent stage is destroyed.

  Therefore, the present invention has been made in view of these points, and an amplification device capable of suppressing an increase in the level of a signal output from itself, and an increase in the level of a signal output from the amplification device are suppressed. An object of the present invention is to provide a demodulator capable of performing the above.

  An amplification device according to a first aspect of the present invention includes a variable attenuator that adjusts the level of an input signal, an amplifier that amplifies and outputs a signal output from the variable attenuator, and a signal output from the amplifier. When the level of the signal extracted in the detection circuit is equal to or lower than a predetermined level, the level of the signal extracted in the detection circuit is detected by the variable attenuator. And a control unit for attenuating the level of the input signal by a predetermined amount in the variable attenuator when the level of the input signal is adjusted based on the above.

  When the control unit detects that the level of the signal detected by the detection circuit exceeds the predetermined level, a control mode for controlling the variable attenuator is determined based on the level of the signal extracted by the detection circuit. Then, the first mode in which the level of the input signal is adjusted may be switched to the second mode in which the level of the input signal is attenuated by a predetermined amount.

  When the level of the signal extracted in the detection circuit exceeds the predetermined level, the control unit sets the level of the input signal to the variable attenuator and the maximum level at which the variable attenuator can attenuate. May be attenuated by the amount of attenuation.

  A demodulating device according to a second aspect of the present invention includes the amplifying device and a signal processing unit that generates control information indicating an adjustment amount of the input signal based on a level of a signal extracted in the detection circuit. In the demodulator, the control unit adjusts the level of the input signal based on the control information when the level of the signal extracted in the detection circuit is equal to or lower than a predetermined level.

  According to the present invention, it is possible to suppress an increase in the level of a signal output from an amplification device.

It is a figure which shows the structure of the demodulation apparatus which concerns on this embodiment.

  FIG. 1 is a diagram illustrating a configuration of a demodulation device 1 according to the present embodiment. The demodulating device 1 includes an amplifying device 2 and a signal processing circuit 3. The demodulating device 1 performs detection by adjusting the level of an intermediate frequency signal (hereinafter referred to as IF signal) as an input signal input from the outside in the amplifying device 2, and the signal processing circuit 3 performs signal detection of the IF signal. Process.

  The amplifying device 2 includes a first amplifier 21, a variable attenuator 22, a second amplifier 23, a directional coupler 24, a detection circuit 25, a microcontroller 26, and a DA converter 27. The signal processing circuit 3 includes an AD converter 31 and a signal processing unit 32.

The first amplifier 21 amplifies the IF signal input from the outside, and outputs the amplified IF signal to the variable attenuator 22.
The variable attenuator 22 adjusts the level of the IF signal output from the first amplifier 21 and outputs it to the second amplifier 23. The adjustment amount of the IF signal in the variable attenuator 22 changes based on the voltage value of the control voltage output from the DA converter 27.

The second amplifier 23 amplifies the IF signal output from the variable attenuator 22 and outputs the amplified IF signal to the directional coupler 24.
The directional coupler 24 outputs the IF signal output from the second amplifier 23 to the detection circuit 25 and the AD converter 31 of the signal processing circuit 3.
The detection circuit 25 extracts and detects the IF signal output from the directional coupler 24 and converts it into a voltage. The detection circuit 25 outputs the voltage converted from the IF signal to the microcontroller 26.

The AD converter 31 converts the input IF signal into a digital signal and outputs the digital signal to the signal processing unit 32.
The signal processing unit 32 is, for example, an FPGA (Field-Programmable Gate Array), specifies the level of the IF signal input to the signal processing circuit 3 based on the digital signal output from the AD converter 31, and Based on the control information, control information indicating the attenuation amount of the IF signal in the variable attenuator 22 is generated. For example, the signal processing unit 32 transmits control information to the microcontroller 26 via a serial communication transmission terminal (not shown) provided in the signal processing circuit 3. Here, the number of bits of the control information is, for example, 10 bits. The signal processing unit 32 determines the attenuation amount based on the bit error rate of the received signal and the reception sensitivity corresponding to the modulation sensitivity corresponding to the signal modulation method, and generates control information indicating the attenuation amount. Also good.

  The microcontroller 26 includes a CPU and a storage unit including a ROM and a RAM, and functions as a control unit. The voltage detected by the detection circuit 25 is input to the microcontroller 26. In addition, the microcontroller 26 receives control information from the signal processing unit 32. The microcontroller 26 controls the variable attenuator 22 based on the voltage input from the detection circuit 25 or the control information received from the signal processing unit 32. A state in which the variable attenuator 22 is controlled based on the voltage input from the detection circuit 25 is referred to as a local loop. A state in which the variable attenuator 22 is controlled based on the control information received from the signal processing unit 32 is referred to as a signal processing loop.

  The storage unit of the microcontroller 26 stores the attenuation amount of the IF signal in the variable attenuator 22, the value of the control voltage applied to the variable attenuator 22, the bit value indicated by the control information output from the signal processing unit 32, The microcontroller 26 stores a control table that associates bit values of information (second control information) converted from the control information. Here, the bit amount of information converted from the control information is 14 bits.

  When the level of the signal extracted in the detection circuit 25 is equal to or lower than a predetermined level during the signal processing loop, the microcontroller 26 sets the control mode for controlling the variable attenuator 22 to the level of the signal extracted in the detection circuit 25. Is set to the first mode in which the level of the IF signal is adjusted, and the variable attenuator 22 attenuates the level of the IF signal based on the extracted signal level. In the first mode, the microcontroller 26 controls the variable attenuator 22 based on control information received from the signal processing unit 32, for example. Here, in the first mode, the time taken from when the microcontroller 26 receives the control signal until the level control of the IF signal is performed is about 1 millisecond.

  Specifically, when the microcontroller 26 receives control information from the signal processing unit 32 when the level of the extracted signal is equal to or lower than a predetermined level, the microcontroller 26 refers to the control table and sets the control value of the 10-bit control information. , And converted into a 14-bit control value indicated by the second control information. If the control value indicated by the control information is not included in the control table, the microcontroller 26 corresponds to the control value (approximate value) close to the control value and the approximate value included in the control table. The control value indicated by the control information is converted to a 14-bit control value by performing linear interpolation based on the 14-bit control value. Then, the microcontroller 26 specifies a 14-bit control value. Thereby, the amplifying apparatus 2 can increase the resolution of the control value of the variable attenuator 22.

  The microcontroller 26 outputs a digital signal indicating the specified 14-bit control value to the DA converter 27. The DA converter 27 converts the digital signal output from the microcontroller 26 into an analog signal, and applies the analog signal, that is, a control voltage to the variable attenuator 22. Thereby, the variable attenuator 22 can adjust the level of the IF signal to an appropriate level based on the level of the signal detected by the signal processing unit 32.

  The microcontroller 26 includes an AD converter, and converts the signal output from the detection circuit 25 into a digital value. When the microcontroller 26 sets the control mode of the variable attenuator 22 to the first mode, if the microcontroller 26 detects that the level of the signal extracted by the detection circuit 25 exceeds a predetermined level, the microcontroller 26 A signal indicating an over-output error for notifying that the signal level has exceeded a predetermined level is notified to the signal processing unit 32 via a serial communication receiving terminal (not shown).

  In addition, when notifying the signal indicating the error, the microcontroller 26 sets the control mode for controlling the variable attenuator 22 to the second mode in which the level of the IF signal is attenuated by a predetermined amount.

  The microcontroller 26 controls the variable attenuator 22 without receiving control information from the signal processing unit 32 in the second mode. As a result, the microcontroller 26 can reduce the level of the amplified IF signal to a level that does not cause the signal processing unit 32 to be destroyed when the level of the signal extracted in the detection circuit 25 exceeds a predetermined level. The variable attenuator 22 is attenuated. Here, in the second mode, the time taken from when the microcontroller 26 receives the signal extracted by the detection circuit 25 until the level control of the IF signal is performed is about 1 millisecond.

  For example, the microcontroller 26 outputs to the variable attenuator 22 an IF signal by outputting to the DA converter 27 a digital signal indicating the value of the control voltage corresponding to the maximum amount of attenuation that the variable attenuator 22 can attenuate. Is attenuated by the maximum level attenuation. By doing so, the level of the IF signal can be suppressed, and the level of the signal output to the AD converter 31 of the signal processing circuit 3 can be suppressed. Thereby, the amplification device 2 can suppress an increase in the level of the signal output to the signal processing unit 32.

  The microcontroller 26 may notify the signal processing unit 32 of information indicating that the variable attenuator 22 has been switched to the second mode in response to the switch from the first mode to the second mode. Good.

  In addition, when the control mode of the variable attenuator 22 is operating in the second mode, the microcontroller 26 sets the level of the signal when the level of the signal extracted by the detection circuit 25 becomes a predetermined level or less. Based on this, the attenuation amount of the variable attenuator 22 may be changed.

  The microcontroller 26 controls the variable attenuator 22 in the first mode or the second mode to control the level of the IF signal, but the present invention is not limited to this. For example, the time taken to control the level of the IF signal is longer than that in the first mode and the second mode, and the variable attenuator is controlled by the third mode for measuring the internal temperature of the demodulator 1 and checking the setting information. 22 may be controlled to control the level of the IF signal. By doing in this way, the demodulator 1 operates in the third mode at the time of start-up, operates in the first mode after necessary settings are made, and thereafter, the control abnormality in the signal processing unit 32 or the abnormality of the control data When there is, it is possible to switch to the second mode.

[Effect of this embodiment]
As described above, when the level of the signal extracted by the detection circuit 25 is equal to or lower than the predetermined level, the amplification device 2 according to the present embodiment sets the level of the signal extracted by the detection circuit 25 to the variable attenuator 22. Based on this, the level of the IF signal is adjusted. When the level exceeds the predetermined level, the variable attenuator 22 attenuates the level of the IF signal by a predetermined amount. By doing so, the amplifying apparatus 2 can detect that the level of the input IF signal is excessive, and suppress an increase in the level of the signal output to the signal processing unit 32.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Demodulator, 2 ... Amplifier, 21 ... 1st amplifier, 22 ... Variable attenuator, 23 ... 2nd amplifier, 24 ... Directional coupler, 25 ...・ Detection circuit, 26... Microcontroller, 27... DA converter, 3... Signal processing circuit, 31... AD converter, 32.

Claims (4)

A variable attenuator that adjusts the level of the input signal;
An amplifier that amplifies and outputs the signal output from the variable attenuator;
A detection circuit that extracts and detects a signal output from the amplifier and converts it into a voltage;
When the level of the signal extracted in the detection circuit is equal to or lower than a predetermined level, the variable attenuator adjusts the level of the input signal based on the level of the signal extracted in the detection circuit, and the predetermined level A control unit that attenuates the level of the input signal by a predetermined amount to the variable attenuator,
An amplification device comprising: When the control unit detects that the level of the signal detected by the detection circuit exceeds the predetermined level, a control mode for controlling the variable attenuator is determined based on the level of the signal extracted by the detection circuit. Switching from the first mode in which the level of the input signal is adjusted to the second mode in which the level of the input signal is attenuated by a predetermined amount;
The amplification device according to claim 1. When the level of the signal extracted in the detection circuit exceeds the predetermined level, the control unit sets the level of the input signal to the variable attenuator and the maximum level at which the variable attenuator can attenuate. Attenuate by the amount of attenuation
The amplification device according to claim 1 or 2. A demodulator comprising: the amplifying device according to any one of claims 1 to 3; and a signal processing unit that generates control information indicating an adjustment amount of the input signal based on a level of the signal extracted in the detection circuit. A device,
The control unit adjusts the level of the input signal based on the control information when the level of the signal extracted in the detection circuit is equal to or lower than a predetermined level.
Demodulator.

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