JP4809002B2 - Signal amplifier - Google Patents

Description

  The present invention relates to a signal amplifier for amplifying various signals such as a television signal.

  2. Description of the Related Art Conventionally, signal amplifiers that amplify television signals received by antennas have been widely used in television signal receiving systems in ordinary homes (see, for example, Patent Document 1). In particular, in a hearing system that distributes a television signal received by one antenna to each of a plurality of dwelling units such as a condominium, the television signal by a signal amplifier is used to compensate for the attenuation of the television signal due to the distribution or the like. Amplification becomes even more important.

  A block diagram of such a conventional signal amplifier is shown in FIG. As shown in FIG. 5, a conventional signal amplifier 100 includes an input terminal 101, a high-pass filter (hereinafter, HPF) or a band-pass filter (hereinafter, BPF) 102, an input attenuator (hereinafter, input ATT) 103, and an amplifier (hereinafter, referred to as “amplifier”). , AMP) 104, gain controller (hereinafter referred to as GC) 105, AMPs 106, 107, output ATT 108, AMP 109, 110, HPF or BPF 111, and output terminal 112 are connected in sequence. A lightning arrester 113 is connected between the input terminal 101 and the HPF or BPF 102, and a lightning arrester 114 and a monitor terminal 115 are connected between the HPF or BPF 111 and the output terminal 112, respectively.

  In such a configuration, the television signal input to the input terminal 101 is limited to a certain band by the HPF or BPF 102 and noise is removed, and then adjusted to a predetermined input level by the input ATT 103, and the AMP 104, Amplified by the GC 105 and the AMPs 106 and 107. The TV signal is further adjusted to a predetermined output level by the output ATT 108, and then amplified by the AMPs 109 and 110, and is limited to a certain band by the HPF or BPF 111 to remove noise. Is output.

  Here, when the signal amplifier is installed in an apartment house or the like, the installer has adjusted the signal amplifier so that optimum signal amplification can be performed according to the installation environment. Specifically, the installer measures the status of the input TV signal (the level and waveform of the TV signal) using a level analyzer such as a spectrum analyzer, and determines the optimal adjustment method based on this status. Thus, the input ATT 103, the GC 105, or the output ATT 108 is adjusted.

JP 7-184185 A

  However, in such a conventional signal amplifier, the adjustment depends on the experience and knowledge of the installer, so if the installer does not fully understand the specification of the signal amplifier, the optimum adjustment should be performed. I could not.

  For example, if the input level of the TV signal is high, the input signal of the first stage AMP 104 may not be lowered by setting the input ATT 103 to about 10 dB, which may cause distortion in the TV signal. . Conversely, when the input level of the TV signal is low, the C / N (Carrier to Noise Ratio) may be lowered unless the input level of the first stage AMP 104 is increased by setting the input ATT 103 to about 0 dB. . Further, when the wave number of the television signal is higher than the rating, it is necessary to reduce the output level from the rating, and it is necessary to calculate the adjustment amount. In this way, the judgment of the contractor for adjusting the signal amplifier to the optimum state is diverse, and when the inexperienced contractor adjusts, the output level is appropriate, but the image of the television is deteriorated. It was difficult to make appropriate adjustments. Moreover, it has become a cause of causing variation in the image receiving state of the television by the installer. Furthermore, in order to educate a contractor who can perform adjustment, problems such as time and cost are caused.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a signal amplifier capable of easily and accurately adjusting according to installation conditions.

In order to solve the above-mentioned problems and achieve the object, the present invention according to claim 1 is a signal amplifier for amplifying a signal, and amplifying means for performing at least one of amplification and adjustment of the signal; An adjustment value for adjusting the amplification means is determined, an adjustment control means for outputting an adjustment signal corresponding to the adjustment value to the amplification means, and a setting device connected to the signal amplifier is input by the installer. The input level and the output level, which are input levels and output levels for the signal amplifier, which are used only for determining the adjustment value, are received from the setting device. The adjustment control means includes an input means based on the input level received by the input means or the input level received by the input means. Based on Le and said output level, and determines the adjustment value.

According to a second aspect of the present invention, in the first aspect of the present invention, the adjustment of the amplifying unit can be performed without changing a connection state between the amplifying unit and a connection destination of the amplifying unit. The value is adjusted based on the adjustment signal.

Also, in the present invention described in claim 3 according to the present invention described in claim 1 or 2 , the amplification means is an ATT, and the adjustment control means determines the input level received by the input means. When this input level is determined to be a distorted level by determining whether or not this input level is a level at which the amplifying means provided at a stage subsequent to the ATT is distorted inside the signal amplifier. Determines the adjustment value of the ATT to a predetermined adjustment level, generates an adjustment signal according to the adjustment value, outputs the adjustment signal to the ATT, and determines that the adjustment value of the ATT is not a distorting level. A predetermined adjustment level having an attenuation smaller than the predetermined adjustment level is determined, and an adjustment signal corresponding to the adjustment value is generated and output to the ATT.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the amplifying means is an ATT, and the adjustment control means is the input level received by the input means and Based on the output level and the predetermined maximum gain of the signal amplifier, the range in which adjustment is required in the GC provided before the ATT in the signal amplifier exceeds the predetermined variable range of the GC. If it is determined that the adjustment value exceeds the predetermined value, the adjustment value of the ATT is determined to be a predetermined adjustment level, and an adjustment signal corresponding to the adjustment value is generated and output to the ATT. If it is determined that the value does not exceed the predetermined value, the ATT adjustment value is determined to be a predetermined adjustment level whose attenuation is smaller than the predetermined adjustment level, and an adjustment signal corresponding to the adjustment value is generated to generate the adjustment signal. And outputs to the TT.

According to the first aspect of the present invention , since the amplification means can be automatically adjusted, accurate and appropriate adjustment can be efficiently performed regardless of the skill level of the installer. Therefore, the reliability and stability of signal amplification by the signal amplifier can be improved. Furthermore, the time and cost for educating the installer can be reduced.

  Hereinafter, embodiments of a signal amplifier according to the present invention will be described in detail with reference to the accompanying drawings. First, [I] after explaining the basic concept common to each embodiment, [II] explains the specific contents of each embodiment, and [III] finally, modifications to each embodiment of the present invention An example will be described. However, the present invention is not limited by these embodiments.

[I] Basic concept common to the embodiments First, the basic concept common to the embodiments will be described. The signal amplifier according to each embodiment relates to a signal amplifier for amplifying various signals including a television signal in an apartment house or the like, for example, amplifying a television signal received by an antenna in a common hearing system. The present invention relates to a signal amplifier. As in the prior art, this signal amplifier includes various signal amplification or signal adjustment components such as input ATT, GC, and output ATT. In the following description, a configuration that is conventionally adjusted by a contractor so that optimum signal amplification can be performed according to the installation environment of the signal amplifier, such as the input ATT, GC, and output ATT. The element is referred to as an unadjusted element.

  Here, in each embodiment, one of the features is that this non-adjustment element is automatically adjusted. In general, this adjustment is performed by automatically determining an adjustment value based on the input level (reception level) and the output level by the installer, and providing an adjustment signal corresponding to the adjustment value to the non-adjustment element. Is called. Therefore, it is not necessary for the installer to determine the adjustment value, and uniform adjustment can be performed regardless of the adjustment skill of the installer.

  Furthermore, in each embodiment, the adjustment value once determined is stored in the storage unit, and is called immediately after the signal amplifier is turned on and used for adjustment. Therefore, once the adjustment value is determined, it is not necessary to determine the adjustment value again unless the installation environment changes, and the adjustment can be performed more quickly.

[II] Specific Contents of Embodiment Next, specific contents of each embodiment of the signal amplifier according to the present invention will be described.

[Embodiment 1]
First, the first embodiment of the present invention will be described. Here, after describing the configuration of the signal amplifier, the contents of adjustment processing performed using the signal amplifier will be described.

(Configuration of signal amplifier)
FIG. 1 is a block diagram of a signal amplifier of the signal amplifier according to the first embodiment. As shown in FIG. 1, the signal amplifier 1 according to the first embodiment is basically configured in the same manner as the conventional with respect to its signal amplification system. That is, the signal amplifier 1 is configured by sequentially connecting the input terminal 2, HPF or BPF3, input ATT4, AMP5, GC6, AMP7, 8, output ATT9, AMP10, 11, HPF or BPF12, and output terminal 13. Yes. A lightning arrester 14 is connected between the input terminal 2 and the HPF or BPF 3, and a lightning arrester 15 and a monitor terminal 16 are connected between the HPF or BPF 12 and the output terminal 13, respectively.

  In such a configuration, the television signal input to the input terminal 2 is limited to a certain band by the HPF or BPF 3 and noise is removed, and then adjusted to a predetermined input level by the input ATT 4, AMP 5, It is amplified by GC6 and AMP7 and 8. This TV signal is further adjusted to a predetermined output level at the output ATT 9, then amplified by the AMPs 10 and 11, is limited to a certain band by the HPF or BPF 12, and noise is removed. Is output.

  Here, the inputs ATT4, GC6, and the output ATT9 are non-adjusting elements that need to be adjusted according to the installation environment of the signal amplifier 1, and correspond to amplification means in the claims. The input ATT4 and the output ATT9 are provided with a switching unit (not shown). The switching unit switches the settings of the input ATT4 and the output ATT9 based on an adjustment signal from the adjustment control unit 20 described later.

  In FIG. 1, the signal amplifier 1 includes an adjustment control unit 20 and a storage unit 21.

  Among these, the adjustment control unit 20 determines an adjustment value for adjusting the non-adjustment element, and outputs an adjustment signal corresponding to the adjustment value to the non-adjustment element. Corresponding to Specifically, the adjustment control unit 20 is configured to include a CPU (Central Processing Unit), and adjusts non-adjustment elements by loading, interpreting and executing a program stored in the storage unit 21 as necessary. I do. The specific contents of this adjustment process will be described later.

  The storage unit 21 is a storage unit that stores information necessary for adjusting the non-adjustment element in a nonvolatile manner. Specifically, the storage unit 21 stores an adjustment processing program that is interpreted and executed by the adjustment control unit 20. Furthermore, the adjustment value determined by the adjustment control unit 20 is stored in the storage unit 21. In this sense, the storage unit 21 corresponds to the storage unit in the claims. The specific configuration of the storage unit 21 is arbitrary, but can be configured by, for example, an EEPROM (Electronically Erasable and Programmable Read Only Memory).

  The signal amplifier 1 is provided with a connection terminal 22. The connection terminal 22 enables the setting device 30 to be detachably connected to the signal amplifier 1. In particular, the connection terminal 22 receives input of an input level and an output level to the signal amplifier 1, and in this sense, the connection terminal 22 corresponds to input means in the claims. Although the specific configuration of the connection terminal 22 is arbitrary, for example, it is configured as a 9-pin or 25-pin serial port or a parallel port. The connection terminal 22 configured as described above is electrically connected to the adjustment control unit 20, and the input level and the output level input through the connection terminal 22 are input to the adjustment control unit 20.

  Next, the setting device 30 connected to the signal amplifier 1 will be described. The setting device 30 is an input device for inputting an input level and an output level to the signal amplifier 1. For example, a display monitor, a numeric keypad, an execution key, and a connection terminal 31 (illustrations other than the connection terminal 31 are illustrated. (Omitted). Then, the installer removably connects the connection terminal 31 to the connection terminal 22 of the signal amplifier 1 and inputs an input level or an output level numerically using a numeric keypad. At this time, the installer measures the input level in the environment where the signal amplifier 1 is installed with a level measuring instrument such as a spectrum analyzer, and inputs this as the input level. In addition, the installer inputs a required output level to be output from the signal amplifier 1 as the output level. When the input level and the output level are input in this way, the input numerical values are displayed on the display monitor. When the operator operates the execution key while confirming the display content of the display monitor, the input level and output level that have been input are input to the signal amplifier 1 via the connection terminals 31 and 22.

(Adjustment process)
Next, the content of the adjustment process performed using the signal amplifier 1 configured as described above will be described. 2 and 3 are flowcharts of the adjustment process. As shown in FIGS. 2 and 3, the adjustment control unit 20 determines whether or not the signal amplifier 1 is immediately after power-on (step SA-1). This determination can be made by determining flag information stored in the storage unit 21, for example.

  If it is immediately after turning on the power (step SA-1, Yes), the adjustment control unit 20 determines whether or not an adjustment value is stored in the storage unit 21 (step SA-2). When the adjustment value is stored (step SA-2, Yes), the adjustment control unit 20 performs adjustment using the adjustment value (step SA-3). That is, the adjustment control unit 20 acquires from the storage unit 21 and generates an adjustment signal according to the adjustment value so that the adjustment value is set to the input ATT4, GC6, and the output ATT9. The adjustment signals are output to the input ATT4, GC6, and the output ATT9, respectively (step SA-2).

  The input ATT4, GC6 and output ATT9 that have received this adjustment signal set the adjustment value specified by this adjustment signal to itself. In this case, the adjustment process ends here. Therefore, when the adjustment value is stored in the storage unit 21 (when the adjustment value is determined by the adjustment process performed before the adjustment process), the adjustment value is not newly determined and the non-adjustment is not performed. Element adjustments are made.

  On the other hand, if it is determined in step SA-1 that it is not immediately after power-on (step SA-1, No), if it is determined in step SA-2 that no adjustment value is stored in the storage unit (step SA-2, No) ), The adjustment control unit 20 monitors whether the input of the input level and the output level is received via the connection terminal 22 (step SA-4). When there is an input (step SA-4, Yes), the adjustment control unit 20 sets the input level to x and the output level to y (step SA-5), and adjusts based on the input level and the output level. It is determined whether or not it is possible.

  Specifically, the adjustment control unit 20 calculates “output level y−input level x” and determines whether or not the calculation result is equal to or less than the maximum gain (step SA-6). This maximum gain can be stored in advance in the storage unit 21 or can be stored in advance as a program parameter in the adjustment control unit 20 (hereinafter, the same applies to other numerical data in the adjustment process). ). If the subtraction result is not less than or equal to the maximum gain (if the maximum gain is exceeded, step SA-6, No), the adjustment control unit 20 determines that the amplification range by the signal amplifier 1 is exceeded, and connects. A signal (NG signal) indicating that adjustment is impossible is output to the terminal 22 (step SA-7). This NG signal is input to the setting device 30 via the connection terminal 31, and a predetermined NG display is performed on the display monitor of the setting device 30. Therefore, the contractor can grasp that the adjustment is impossible, can avoid the waste of continuing the adjustment even though the adjustment is impossible, and can review the input level and the output level.

  On the other hand, if the subtraction result is less than or equal to the maximum gain in step SA-6 (if the maximum gain is not exceeded, SA-6, Yes), the adjustment control unit 20 adjusts the input ATT4, GC6, and the output ATT9. I do. That is, by comparing the input level x with a predetermined level, it is determined whether or not the input level x is a level at which the first stage AMP 5 is distorted (step SA-8). If the level is distorted (step SA-8, Yes), it is determined that the input level x needs to be lowered, and the adjustment value of the input ATT4 is determined to be a predetermined adjustment level (for example, 10 dB). An adjustment signal corresponding to the adjustment value (for example, a switching signal for switching the level of the input ATT4 to 10 dB) is generated and output to the input ATT4 (step SA-9). If the level is not distorted (No in step SA-8), it is determined that it is not necessary to lower the input level x, and the adjustment value of the input ATT4 is determined to be a predetermined adjustment level (for example, 0 dB). An adjustment signal corresponding to the value is generated and output to the input ATT4 (step SA-10). As a result, the input ATT4 is automatically adjusted.

  Further, the adjustment control unit 20 determines whether or not the output ATT9 needs to be turned on. Specifically, the adjustment control unit 20 calculates “input level x + predetermined maximum gain of signal amplifier 1−output level−adjustment value of input ATT 4 determined in steps SA-9 and SA-10” and calculates It is determined whether or not the result exceeds a predetermined variable range of GC6 (step SA-11). If it exceeds the variable range (step SA-11, Yes), it is determined that output adjustment is necessary at the output ATT9, and the adjustment value of the output ATT9 is set to a predetermined adjustment level (for example, 10 dB). And an adjustment signal (for example, a switching signal for switching the level of the output ATT9 to 10 dB) corresponding to the adjustment value is generated and output to the output ATT9 (step SA-12). If the variable range is not exceeded (step SA-11, No), it is determined that there is no need to perform output adjustment at the output ATT9, and the adjustment value of the output ATT9 is set to a predetermined adjustment level (for example, 0 dB). And an adjustment signal corresponding to the adjustment value is generated and output to the output ATT9 (step SA-13). As a result, the output ATT9 is automatically adjusted.

  Furthermore, the adjustment control unit 20 adjusts the GC 6 so that the output level of the signal amplifier 1 becomes the previously input output level y. Specifically, the adjustment control unit 20 determines that “input level x + predetermined maximum gain of signal amplifier 1−output level−adjustment value of input input ATT4 determined in steps SA-9 and SA-10−step SA-12, The adjustment value of the output ATT9 determined in SA-13 "is calculated, and the calculation result is determined as the adjustment value of GC6 (step SA-14). Then, an adjustment signal corresponding to the adjustment value (for example, a voltage signal having a voltage corresponding to the adjustment value) is generated and output to the GC 6. As a result, the GC 6 is automatically adjusted.

  Next, the adjustment control unit 20 causes the storage unit 21 to store the adjustment values of the input ATT4, the output ATT9, and the GC6 determined in the processes so far (step SA-15). Therefore, immediately after the next power-on, the adjustment value can be adjusted using this adjustment value.

  Thereafter, the adjustment control unit 20 outputs a signal (OK signal) indicating that the adjustment is completed to the connection terminal 22 (step SA-16). This OK signal is input to the setting device 30 via the connection terminal 31, and a predetermined OK display is performed on the display monitor of the setting device 30. Therefore, the installer can grasp that the adjustment is completed and can finish the adjustment work promptly. This completes the adjustment process.

(Effect of Embodiment 1)
As described above, according to the first embodiment, the input ATT4, GC6, and output ATT9 can be automatically adjusted, so that accurate and appropriate adjustment can be efficiently performed regardless of the level of skill of the installer. It can be carried out. Further, when the adjustment value is stored in the storage unit 21, the adjustment of the non-adjustment element is performed without newly determining the adjustment value, so that the efficiency of the adjustment work can be further increased. In addition, the installer can grasp that adjustment is not possible, avoid waste that continues adjustment even though adjustment is not possible, and review the input level and output level. The work efficiency can be further increased. Furthermore, the installer can grasp that the adjustment is completed, and can finish the adjustment work promptly.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. In the second embodiment, the connection between the signal amplifier and the setting device can be executed without using a dedicated connection terminal. FIG. 4 is a block diagram of a signal amplifier of the signal amplifier according to the second embodiment. As shown in FIG. 4, the signal amplifier 40 according to the second embodiment generally includes an input terminal 2, HPF or BPF3, input ATT4, AMP5, GC6, AMP7, 8, output ATT9, AMP10, 11, An HPF or BPF 12, an output terminal 13, a lightning arrester 14, a lightning arrester 15, a monitor terminal 16, an adjustment control unit 20, a storage unit 21, a low-pass filter (hereinafter referred to as LPF) 23, and an interface (hereinafter referred to as I / F) 24 are provided. ing. Further, the connection terminals 22 and 31 of the embodiment 1 are omitted. In addition, about the component similar to Embodiment 1, the code | symbol same as used in Embodiment 1 is attached | subjected as needed, and the description is abbreviate | omitted.

  Among these, the input terminal 2 not only receives the input of the signal to be amplified, but also receives the input level and the output level from the setting device 30 as necessary, and corresponds to the input means in the claims. . The input terminal 2 is configured as a coaxial terminal for connecting a coaxial cable for transmitting a television signal, for example.

  The LPF 23 separates the input level and the output level from the signal input to the input terminal 2, and corresponds to the signal separation means in the claims. The LPF 23 is branched and connected between the input terminal 2 and the HPF or BPF 3, and separates the input level and the output level from the signal input to the input terminal 2. The I / F 24 is a signal interface for converting a signal output from the LPF 23 into an input signal to the adjustment control unit 20.

  In such a configuration, when the installer connects the setting device 30 to the input terminal 2 via the coaxial cable and sets the input level and the output level, the input level and the output level are set via the input terminal 2 in the low frequency band. To the signal amplifier 40. Since the input level and the output level are in a low frequency band, they are not passed through the HPF or BPF 3, but are separated by passing through the LPF 23. The separated input level and output level are converted by the I / F 24 and input by the adjustment control unit 20. Then, by using these input levels and output levels, the same adjustment processing as in the first embodiment is performed, thereby adjusting the inputs ATT4, GC6, and the output ATT9.

(Effect of Embodiment 2)
As described above, according to the second embodiment, the basic effect of the first embodiment can be obtained, and the signal amplifier 40 and the setting device 30 can be connected without providing a dedicated connection terminal. The device configuration of the signal amplifier 40 and the setting device 30 is further simplified.

[III] Modifications to Each Embodiment While the embodiments of the present invention have been described above, the specific configuration and means of the present invention are within the scope of the technical idea of each invention described in the claims. It can be arbitrarily modified and improved within. Hereinafter, such a modification will be described.

(About problems to be solved and effects of the invention)
In addition, the problems to be solved by the invention and the effects of the invention are not limited to the above-described contents, and the present invention solves the problems not described above or has the effects not described above. There are also cases where only some of the described problems are solved or only some of the described effects are achieved. For example, even when the signal amplifier cannot be adjusted to an optimal state in all installation environments, the object of the present invention is achieved as long as the adjustment is possible in at least one installation environment.

(About the object and method of adjustment)
Only a part of the input ATT4, GC6, or the output ATT9 may be the non-adjustment element, or other components may be included in the non-adjustment element. The specific method of adjustment is not limited to the above-described method, and other known adjustment methods may be converted into logic and automatically executed by the adjustment control unit 20. In the above embodiment, the setting device 30 is connected to the input terminal 2 of the signal amplifier 1. However, the present invention is not limited to this, and communication may be performed by connecting to the output terminal 13 or the monitor terminal 16. good.

  The present invention is useful when adjusting a signal amplifier according to installation conditions, and is particularly suitable for performing this adjustment simply and accurately.

It is a block diagram of the signal amplifier of the signal amplifier which concerns on Embodiment 1 of this invention. 3 is a flowchart of adjustment processing according to the first embodiment. FIG. 3 is a flowchart of adjustment processing following FIG. 2. FIG. 6 is a block diagram of a signal amplifier of a signal amplifier according to a second embodiment. FIG. It is a block diagram of the conventional signal amplifier.

Explanation of symbols

1, 40, 100 Signal amplifier 2, 101 Input terminal 3, 12, 102 HPF or BPF
4, 103 input ATT
5, 7, 8, 10, 11, 104, 106, 107, 109, 110 AMP
6, 105 GC
9, 108 Output ATT
13, 112 Output terminal 14, 15, 113, 114 Arrester 16, 115 Monitor terminal 20 Adjustment control unit 21 Storage unit 22, 31 Connection terminal 23 LPF
24 I / F
30 Setting device

Claims (4)

A signal amplifier for amplifying a signal,
Amplifying means for performing at least one of amplification and adjustment of the signal;
An adjustment control means for determining an adjustment value for adjusting the amplification means, and outputting an adjustment signal corresponding to the adjustment value to the amplification means;
The input level and output level input by the installer for the setter connected to the signal amplifier, and the input level and output level input to the signal amplifier, only to determine the adjustment value Provide input means to accept the input of the input level and output level to be used from the setter ,
The adjustment control means determines the adjustment value based on the input level received by the input means or based on the input level and the output level received by the input means;
A signal amplifier characterized by. Adjusting the adjustment value of the amplification means based on the adjustment signal without changing the connection state between the amplification means and the connection destination of the amplification means;
The signal amplifier according to claim 1. The amplification means is ATT;
The adjustment control means includes
By comparing the input level received by the input means with a predetermined level, it is determined whether or not the input level is a level at which the amplification means provided at the subsequent stage of the ATT in the signal amplifier is distorted. And
If it is determined that the level is distorted, the adjustment value of the ATT is determined to be a predetermined adjustment level, an adjustment signal corresponding to the adjustment value is generated and output to the ATT,
If it is determined that the level is not distorted, the adjustment value of the ATT is determined to be a predetermined adjustment level having an attenuation amount smaller than the predetermined adjustment level, and an adjustment signal corresponding to the adjustment value is generated to the ATT. Output,
The signal amplifier according to claim 1 or 2. The amplification means is ATT;
The adjustment control means includes
On the basis of the input level and the output level received by the input means and the predetermined maximum gain of the signal amplifier, adjustment is required in the GC provided before the ATT inside the signal amplifier. Determine whether the range exceeds the predetermined variable range of the GC;
If it is determined that the value is higher, the adjustment value of the ATT is determined to be a predetermined adjustment level, an adjustment signal corresponding to the adjustment value is generated and output to the ATT,
If it is determined that the value does not exceed the predetermined value, the ATT adjustment value is determined to be a predetermined adjustment level whose attenuation is smaller than the predetermined adjustment level, an adjustment signal corresponding to the adjustment value is generated, and the ATT is Output,
The signal amplifier according to claim 1 or 2.

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