KR20070052200A - Automatic gain control - Google Patents

Abstract

The present invention provides an automatic gain control apparatus capable of acquiring both high-speed following of input signal fluctuations and target signal quality when reducing disturbance and noise without using complicated processing. The present invention provides an automatic gain control response that operates with high-speed coefficients when the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and a specific reference value exceeds a predetermined value, that is, when the variation of the automatic gain control of the front end is large. Select a nonlinear transponder. Also, when the difference between the absolute value of the differential value of the automatic gain control voltage of the front end and the specific reference value is less than the predetermined value, that is, when the variation of the automatic gain control of the front end is small, the nonlinear responder of the automatic gain control response operated by the low speed coefficients. Select.

Automatic gain control device

Description

Automatic Gain Control

1 is an explanatory diagram showing a configuration of an automatic gain control device according to a first embodiment;

Fig. 2 is an explanatory diagram showing a graph of an example of BER characteristics of a target signal when CW is applied as an out-of-target signal to a receiver provided with the automatic gain control device of the first embodiment.

Fig. 3 is an explanatory diagram graphically showing an example of BER characteristics of an object signal when burst CW is applied as an off-signal signal to a receiver provided with the automatic gain control device of the first embodiment.

4 is an explanatory diagram showing a configuration of an automatic gain control device according to a second embodiment;

Fig. 5 is an explanatory diagram showing a graph of an example of BER characteristics of an object signal when CW is applied as an out-of-object signal to a receiver provided with the automatic gain control device of the second embodiment.

Fig. 6 is an explanatory diagram graphically showing an example of the BER characteristic of the target signal when the burst CW is applied as the off-target signal to the receiver with the automatic gain control device of the second embodiment.

FIG. 7 is an explanatory diagram showing a response control transition of a digital unit of FIG. 4; FIG.

FIG. 8 is an explanatory diagram graphically illustrating time-base response characteristics when a burst CW is applied as an off-target signal to a conventional example. FIG.

Fig. 9 is an explanatory diagram graphically illustrating time-base response characteristics when burst CW is applied as an off-signal signal to the second embodiment.

10 is an explanatory diagram showing a configuration of an automatic gain control device according to a third embodiment;

Fig. 11 is an explanatory diagram showing a characteristic when a burst CW is applied as an off-signal signal to the third embodiment with a trap;

12 is an explanatory diagram showing a configuration of a receiver according to a fourth embodiment;

Fig. 13 is an explanatory diagram showing a configuration of a receiver using a conventional automatic gain control device.

Fig. 14 is an explanatory diagram showing a graph of an example of BER characteristics of a target signal when CW is applied as an out-of-target signal of a conventional automatic gain control apparatus.

Fig. 15 is an explanatory diagram showing a graph of an example of BER characteristics of a target signal when burst CW is applied as an out-of-purpose signal of a conventional automatic gain control apparatus.

16 is an explanatory diagram showing a table of simulation conditions.

<Description of the code>

10, 20, 30, 40: automatic gain control

100: analog front end 102: RF / IF terminal

104: bandpass filter 106: AGC amplifier

108: antialiasing filter (AAF) 110: AD converter (ADC)

111: AGC control unit 112: detector

114: reference value register 116: subtractor

118: nonlinear transponder 120: subtractor

122: delay unit 123: response speed control signal generator

124: differential circuit 126: reference value register

128: operation circuit 130: AD converter

200: digital front end 210: quadrature converter

212: I-side AGC amplifier 214: Q-side AGC amplifier

220: full complex mixer 230: AGC control unit

232: detector 234: reference register

236: subtractor 238, 240 nonlinear transponder

242: switch 244: limiter

246: subtractor 248: delay

252: nonlinear transponder 254: coefficient register (for high speed)

256: count register (for low speed) 258: count register

260: multiplier 262: switch

264: comparator 266: subtractor

268: delay 270: adder

The present invention relates to an automatic gain control apparatus for inputting and processing a wideband signal from an output signal.

Regarding an automatic gain control device which inputs and processes a wideband signal from an output signal, there is a technique disclosed in Japanese Patent No. 3086080 (Patent Document 1) and Japanese Patent Laid-Open Publication No. 2005-192060 (Patent Document 2). The conventional automatic gain control device disclosed in these documents will be described with reference to FIGS. 13 to 15.

The automatic gain control device 1 is composed of an analog front end 11 at the front end and a digital front end 34 at the rear end. The front analog front end 11 extracts a signal of a predetermined frequency band from the signal input from the RF / IF terminal 12 using the band pass filter 14. Since the bandpass filter 14 has a wider band than the filter of the rear stage that passes only the target signal, the extracted signal includes the non-target signal in addition to the target signal. In addition, a signal having a constant level by the AGC (Automatic Gain Control) amplifier 16 The signal of the predetermined frequency band converted into is input to the AD converter 19 through an antialiasing filter (low pass filter that prevents aliasing), and becomes a digital signal quantized by the AD converter 19.

A signal of a predetermined frequency band converted into a signal of a constant level by the AGC amplifier 16 is also input to an automatic gain control unit (hereinafter referred to as an "AGC control unit") 21. The AGC control unit 21 appropriately manages the level of the wideband signal to prevent saturation of the signal processing unit. The AGC control unit 21 includes a detector 22, a reference value register REF1 24, a subtractor 26, a nonlinear responder (ax ³ + cx) 28, a multiplier 29, and a delay 32. The signal output from the AGC control unit 21 is input to the AGC amplifier 16 as an AGC control signal.

On the other hand, in the rear digital front end 34, the signal of the target band digitized by the AD converter 19 is represented by the I-axis signal and the Q-axis signal through an orthogonal detection process by an orthogonal converter 50 composed of a complex coefficient filter. The complex signal is converted into a complex baseband frequency. The converted complex signal is converted into a signal of a constant level by the I-side AGC amplifier 52 and the Q-side AGC amplifier 54, and the converted target band signal is a full complex composed of multipliers 61 to 64, a subtractor 65, and an adder 66. The mixer 60 converts the complex signals BB.I and BB.Q of the baseband frequency and outputs them from the automatic gain control device 1.

The target band signal converted into a signal of a constant level by the I-side AGC amplifier 52 and the Q-side AGC amplifier 54 is also input to the AGC control unit 70. The AGC control unit 70 suppresses unnecessary band signals, restricts them to only signals in the destination band, and outputs the signals of the destination band constantly. The AGC control unit 70 includes a detector 72, a reference value register REF2 74, a subtractor 76, a nonlinear responder (ax ³ + bx ² + cx) 80, a limiter 84, a subtractor 86, and a delay 88. The output signal of the AGC control unit 70 is output to the I side AGC amplifier 52 and the Q side AGC amplifier 54 as AGC control signals.

As mentioned above, in the automatic gain control apparatus of patent document 1 and patent document 2 shown in FIG. 13, the two AGC control parts 21 and 70 connected to a vertical column manage the level of a broadband signal appropriately by the AGC control part 21 of the previous stage. This aims to prevent saturation of the signal processing section. In addition, the AGC control unit 70 at the next stage suppresses an unnecessary band signal to produce only a signal in the target band, and outputs a constant band signal.

In this case, when the response characteristic of the AGC controller 21 in the front end is slow, saturation occurs in the front end due to insufficient tracking of the change in the input signal, or a short period of gain for the target signal occurs. In order to avoid this, the AGC control unit 21 in the front end speeds up the response. In this way, if the AGC control unit 21 responds quickly, a large level change in the front end signal may occur when the signal level fluctuation other than the target signal is large. . Accordingly, in order to compensate for this, the AGC controller 70 in the rear stage requires a faster response characteristic.

In other words, when the signal level fluctuation other than the target signal is large, the large level fluctuation with respect to the target signal is large when the gain of the AGC amplifier 16 fluctuates due to the action of the AGC. This is because a change in signal level occurs without discriminating out-of-purpose signals. Therefore, when the signal level of the non-target signal is larger than the target signal, the AGC performs the gain adjustment of the AGC amplifier in accordance with the level of the non-target signal so as to keep the signal level within a predetermined range, and thus the target signal is subject to unnecessary level adjustment. do. For this reason, when the level difference between the non-target signal and the target signal is large, and the level variation of the non-target signal is large, the level variation received by the target signal also increases.

Automatic gain control is essential when dealing with signals with large level fluctuations, since distortion due to signal saturation and S / N degradation due to lack of gain can be avoided. However, an automatic gain control device having a high speed response characteristic is an amplitude compressor that compresses the amplitude of a signal, and has a problem in that a large distortion can be generated for the target signal. Here, BER (Bit) is obtained when π / 4QPSK is applied as a target signal and a CW (continuous wave) signal is applied as an adjacent out-of-object signal to a receiver using the automatic gain control apparatus shown in FIGS. 13 and 2. Error Rate) is shown in FIG. 14, and BER when burst CW is applied is shown in FIG. 15. 14 and 15 are examples when the simulation is performed under the conditions of FIG. 16.

In addition, since a high speed response characteristic is required of the AGC control unit at the rear stage, distortion occurs in the target signal by the AGC control unit at the rear stage, the signal outside the target is weak, and the noise energy spectral density (Eb) / N0 is small. Deterioration occurs. This deterioration is improved by slowing down the response of the AGC control unit in the rear stage. In order to slow down the response, it is necessary to slow down the front end response characteristic, and slowing down the front end response characteristic reduces the follow-up of the input signal variation. .

Since it is impossible to obtain both the response characteristics when the disturbance and the noise are reduced and the followability when the interference is weak and the level fluctuation is large, the response characteristic corresponding to the purpose is inevitably set between the two.

In order to solve this problem, Patent Publication No. 2004-274210 (Patent Document 3) is based on a method of controlling the gain of the automatic gain control device in accordance with the general output level, and the fluctuation of the out-of-object signal or the out-of-object signal level In the signal level detection for automatic gain control at the device output, such as larger than the target signal level, the problem is solved by detecting the signal level at the front end only when the input signal fluctuation cannot be coped with.

As described above, the prior arts in References 1 and 2 cannot satisfy both the response characteristics when the interference and the noise are reduced and the high speed followability when the interference is weak and the level fluctuation is large. In response, the response characteristic corresponding to the purpose is inevitably set. In addition, in the reference document 3, the problem is solved by detecting the signal level at the front end only when the detection of the signal level for automatic gain control at the output of the device cannot cope with the input signal variation, but the problem is that a very complicated process is required. There is.

Accordingly, the present invention has been made in view of the problems of the prior art, and it is necessary to secure both high-speed tracking of input signal fluctuations and target signal quality when reducing disturbance and noise without using complicated processing. It is possible to provide an automatic gain control device.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, according to the 1st viewpoint of this invention, in the automatic gain control apparatus 10 which inputs and processes a wideband signal from an output signal, the wideband input signal containing a target signal band is in a fixed amplitude range. A first signal processor 100 having a first AGC controller 111 for controlling, a second signal processor 200 for extracting a target signal from the output of the first signal processor 100, and an output of the second signal processor 200 at a constant amplitude Response speed control signal for generating a response speed control signal for controlling the response speed of the second AGC control unit according to the response state (the magnitude of variation, etc.) of the second AGC control unit 230 and the first AGC control unit 111 to be outputted. It characterized in that it comprises a generator 123.

In the present invention as described above, the response speed control signal generator 123 generates the response speed control signal for controlling the response speed of the second AGC controller 230 according to the response state (the magnitude of the change) of the first AGC controller 111. It features. Since the fast response is required for the second AGC controller 230 only when a fast response occurs in the first AGC controller (the AGC controller in the preceding stage) 111, the response speed control signal generator 123 is in response to the response state of the first AGC controller 111. Therefore, the response characteristics of the second AGC control unit 230 (the AGC control unit later) 230 can be switched. In this way, it is possible to obtain both high-speed tracking of input signal fluctuations and target signal qualities when interference and noise are reduced by simple processing.

In addition, in the above, the reference numerals denoted for the components are shown only as an example the corresponding components in the embodiments and drawings to be described later for ease of understanding, the present invention is not limited thereto. The same applies to the following.

Various applications can be considered as the application examples of the present invention.

The response speed control signal generation unit 123 changes the first AGC controller when the difference between the absolute value of the derivative value of the automatic gain control voltage output from the first AGC controller 111 and the predetermined reference value REF3 exceeds a predetermined value. It is determined that the size is large, and it is possible to generate a response speed control signal for increasing the response speed of the second AGC controller.

In addition, various configurations can be considered as the second AGC controller 230. For example, a first responder 238 for speeding up the response speed of the second AGC controller and a response speed of the second AGC controller are described. A second responder 240 for slowing down and a switch 242 for switching the first and second responders according to the response speed control signal may be used.

Alternatively, the second AGC control unit 230 may include a responder 252 for controlling the response speed of the second AGC control unit, a high speed coefficient register 254 for holding a high speed coefficient used in the responder, and a low speed used in the responder. It is also possible to employ a configuration including a low speed coefficient register 256 that holds a low coefficient.

The second AGC control section 230 can also continuously change the response speed (dynamic control or the like) in accordance with the response state (the magnitude of the change) of the first AGC control section 111. In this case, when switching the response speed of the rear stage from high speed to low speed, the performance can be further improved by gradually changing the continuous speed instead of instantaneously switching. Specifically, in order to avoid a slow response even though the response state of the front end converges rapidly and does not converge the response of the rear end, the change of the response speed when changing from the high speed response to the low speed response is smooth. You can also

In order to solve the said subject, according to the 2nd viewpoint of this invention, the automatic gain control apparatus provided with one 2nd AGC control part with respect to one 1st AGC control part is provided. That is, in the automatic gain control apparatus for inputting and processing a wideband signal from an output signal, the automatic gain control device comprising: a first signal processor 100 having a first AGC controller for controlling a wideband input signal including a target signal band within a predetermined amplitude range; A plurality of second signal processing units for extracting a target signal from the output of the first signal processing unit, and corresponding to each of the second signal processing units, and outputting the output of the second signal processing unit at a constant amplitude; 2 AGC controllers and a response speed control signal generator 123 for generating a response speed control signal for controlling the response speed of each of the second AGC controllers according to the response state (the magnitude of the change) of the first AGC controller. It provides an automatic gain control device characterized in that.

According to such a structure, in addition to the effect of the automatic gain control apparatus which concerns on the said 1st viewpoint of this invention, it is possible to process the signal of a different frequency by providing a some 2nd signal processing part. In addition, since it can be divided into two stages or multiple stages before and after a large delay element such as a filter, the delay in the automatic gain control loop is reduced and a high speed response is possible.

Also for the automatic gain control apparatus according to the second aspect of the present invention, various application examples can be considered as the automatic gain control apparatus according to the first aspect of the present invention (claims 7 to 10 as some application examples).

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the automatic gain control device of the present invention will be described in detail. In addition, in this specification and drawing, duplication description is abbreviate | omitted by using the same code | symbol about the component which has a substantially same functional structure.

<First Embodiment>

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 shows a receiver using an automatic gain control device according to a first embodiment of the present invention. In addition, in FIG. 2, the characteristic example of BER when CW is added as an off-signal signal having a frequency close to the target signal frequency in the first embodiment is shown in FIG. 2, and the characteristic example of BER when burst CW is applied to FIG. Indicates. 2 and 3 show the case where the simulation conditions shown in FIG. 16 are used.

(Configuration of First Embodiment)

1 is a block diagram showing the configuration of the automatic gain control apparatus 10 according to the present embodiment. The automatic gain control apparatus 10 according to the present embodiment is largely divided into an analog front end for processing an analog signal and a digital front end for processing a digital signal. Hereinafter, it demonstrates in order.

(Analog Front End 100)

First, the analog front end 100 for processing analog signals will be described.

In FIG. 1, the signal input from the RF / IF terminal 102 is input to the band pass filter 104 to extract a signal of a predetermined frequency band. Here, since the bandpass filter 104 has a wider band than the filter of the rear stage that passes only the target signal, the extracted signal includes the non-target signal in addition to the target signal. The AGC amplifier 106 is a variable gain amplifier for converting the output signal of the bandpass filter 104 into a signal of a constant level. The predetermined frequency band signal converted by the AGC amplifier 106 into a signal of a constant level is input to the AD converter 110 through antialiasing (a low pass filter that prevents aliasing), and is a digital signal quantized by the AD converter 110. Becomes

The signal of a predetermined frequency band converted by the AGC amplifier 106 into a signal of a constant level is input to the detector 112 of the AGC control unit 111. The AGC control unit 111 properly manages the level of the wideband signal to prevent saturation of the signal processing unit. The AGC control unit 111 includes a detector 112, a reference value register REF1 114, a subtractor 116, a nonlinear responder (ax ³ + cx) 118, a multiplier 120, and a delay 122.

In order to generate a signal for controlling the gain of the AGC amplifier 106, the output signal of the detector 112 is subtracted by the reference value REF1 output from the reference value register 114 by the subtractor 116 and input to the nonlinear responder (ax ³ + cx) 118. do. The output signal of the nonlinear responder 118 is input to the delay unit 122 through the subtractor 120. The subtractor 120 subtracts the output signal of the delayer 122 from the output signal of the nonlinear responder 118. The output signal of the AGC control unit 111 is an AGC control signal for controlling the gain of the AGC amplifier 106 and is input to the AGC amplifier 106.

(Response speed control signal generator 123)

The AGC control signal for controlling the gain of the AGC amplifier 106 is input to the differential circuit 124 of the response speed control signal generator 123, which is a characteristic component of the present embodiment. In the differential circuit 124, the absolute value of the derivative of the voltage value of the AGC control signal is calculated. The output signal of the differential circuit 124 is compared with the reference value REF3 output by the reference value register 126, and an arithmetic circuit (x1-x2) which generates a signal for controlling the gains of the I-side AGC amplifier 212 and the Q-side AGC amplifier 214 described later. <a?) is entered as 128. Specifically, the arithmetic circuit 128 is composed of a subtractor and a comparator, and the output signal of the differential circuit 124 (voltage value of the AGC control signal) input to the terminal X2 from the reference value REF3 output from the reference value register 126 input to the terminal X1. Absolute value of the derivative value of is subtracted and compared with the predetermined value a.

The output signal of the calculation circuit 128 is a response speed control signal and is input to the AGC controller 230 in the digital front end 200 described later. In the AGC control unit 230, when the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and the reference value REF3 exceeds a predetermined value, that is, when the variation of the automatic gain control of the front end is large, the fast coefficients a1, b1, c1) is used to select a nonlinear responder of automatic gain control response. Further, when the difference between the absolute value of the derivative value of the automatic gain control voltage of the front end and the reference value REF 3 is equal to or less than a predetermined value, that is, when the variation of the automatic gain control of the front end is small, the low speed coefficients a2, b2 and c2 are adjusted. Select the nonlinear transponder with the auto gain control response used. Such a configuration and operation will be described later again.

(Digital Front End 200)

Next, a digital front end 200 for processing digital signals will be described.

The signal digitally signaled by the AD converter 110 is orthogonally detected by, for example, an orthogonal converter 210 that is a complex coefficient filter, and is converted into a complex signal of the baseband frequency indicated by the I-axis signal and the Q-axis signal.

As for the complex signal of the converted baseband frequency, the I-axis signal is limited in band by the I-side channel filter Re and the Q-axis signal by the Q-side channel filter Im, and converted into a signal of the target band, and the I-axis signal The I side AGC amplifier 212 is input to the Q axis signal to the Q side AGC amplifier 214.

The I-side AGC amplifier 212 and the Q-side AGC amplifier 214 are variable gain amplifiers for converting the output signals of the I-side channel filter Re and the Q-side channel filter Im into a signal at a constant level. The signal of the target band converted by the I-side AGC amplifier 212 and the Q-side AGC amplifier 214 into a signal of a constant level is, for example, a complex signal of the baseband frequency (BB. I, BB.Q) through the complex mixer 220. As an output, the automatic gain control device 10 outputs the signal.

The full complex mixer 220 is for frequency conversion and is composed of multipliers 221, 222, 223, 224, a subtractor 225, and an adder 226. The real complex local signal (cos) is input from the local signal generator (Local2), and the imaginary axis local signal (-sin) is input from the local complex generator 220. The full complex mixer 220 is input from the local signal generator. Frequency conversion is performed on the complex signal so that the frequency becomes zero or near zero, and the complex signal is output.

The signals of the target band converted by the I-side AGC amplifier 212 and the Q-side AGC amplifier 214 into signals of a constant level are input to the detector 232 of the AGC controller 230.

The AGC control unit 230 suppresses unnecessary band signals, restricts them to signals in the target band, and outputs the signals of the target band constantly. The AGC control unit 230 includes a detector 232, a reference value register REF2 234, a subtractor 236, a nonlinear responder using fast coefficients (a1x ³ + b1x ² + c1x) 238, a nonlinear responder using slow coefficients (a2x ³ + b2x). ² + c2x) 240, switch 242, limiter 244, subtractor 246, and delayer 248.

In the detector 232, in order to generate a signal for controlling the gain of the I-side AGC amplifier 212 and the Q-side AGC amplifier 214, the square value of the I-axis signal and the Q-axis signal of the input target band signal is added, and By calculating the square root and integrating this, variations in the output signals of the I-side AGC amplifier 212 and the Q-side AGC amplifier 214 are detected.

In order to generate a signal for controlling the gains of the I-side AGC amplifier 212 and the Q-side AGC amplifier 214, the output signal of the detector 232 is subtracted from the reference value REF2 output from the reference value register 234 by the subtractor 236, and the nonlinear responder ( a1x ³ + b1x ² + c1x) 238 and a nonlinear responder (a2x ³ + b2x ² + c2x) 240.

The switch 242 selects either the output signal of the nonlinear responder 238 or the output signal of the nonlinear responder 240 based on the response speed control signal from the computing circuit 128 in the analog front end 100. The switch 242 is used for the high speed coefficients a1, b1, when the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and the reference value REF3 exceeds a predetermined value, that is, the variation of the automatic gain control of the front end is large. select the nonlinear responder of the auto gain control response using c1). In addition, when the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and the reference value REF3 is less than or equal to a predetermined value, that is, when the variation of the automatic gain control of the front end is small, the low speed coefficients a2, b2 and c2 are used. Select a nonlinear transponder with automatic gain control response. Here, the response speed of the subsequent stage when the nonlinear responder of the automatic gain control response with the coefficient values of a1, b1 and c1 is selected is the response speed when the nonlinear responder of the automatic gain control response consisting of a2, b2 and c2 is selected. It is set faster.

The output signal selected by the switch 242 (either the output signal of the nonlinear responder 238 or the output signal of the nonlinear responder 240) is input to the limiter 244 provided to suppress the excessive signal level below a predetermined level. The output signal of the limiter 244 is input to the delay unit 248 through the subtractor 246. The subtractor 246 subtracts the output signal of the delayer 248 from the output signal of the limiter 244. The output signal of the AGC control unit 230 is an AGC control signal for controlling the gains of the I-side AGC amplifier 212 and the Q-side AGC amplifier 214 and is input to the I-side AGC amplifier 212 and the Q-side AGC amplifier 214.

(Operation of the First Embodiment)

In the first embodiment, when the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and the reference value REF3 exceeds a predetermined value, that is, when the variation of the AGC control unit 111 of the front end is large, the coefficients for high speed a1, b1, c1) selects non-linear responder 238 of auto gain control response. In addition, when the difference between the absolute value of the derivative value of the automatic gain control voltage of the front end and REF3 is less than or equal to a predetermined value, that is, when the variation of the AGC control unit 111 of the front end is small, the automatic gain using the slow speed coefficients a2, b2, and c2 is used. Select the nonlinear transponder 240 of the control response. Here, the response speed when the nonlinear responder of the automatic gain control response consisting of the coefficient values of a1, b1 and c1 is selected is the response speed when the nonlinear responder of the automatic gain control response consisting of the a2, b2 and c2 is selected. It is set faster.

Moreover, the response modifier is a simple counter. By non-linearizing the response characteristic, both the high speed response characteristic and the distortion are easily facilitated.

(Effect of the first embodiment)

As described above, according to the present embodiment, when the difference between the absolute value of the derivative value of the automatic gain control voltage of the front end and the reference value REF3 exceeds a predetermined value, that is, when the variation of the AGC control unit 111 of the front end is large, the coefficient for high speed is used. Select a non-linear responder of automatic gain control response using the fields a1, b1, c1. Further, when the difference between the absolute value of the derivative value of the automatic gain control voltage of the front end and the reference value REF3 is less than or equal to a predetermined value, that is, when the variation of the AGC control unit 111 of the front end is small, the low speed coefficients a2, b2 and c2 are set. Select the nonlinear transponder with the auto gain control response used. In this way, it is possible to obtain both high-speed tracking of input signal fluctuations and target signal qualities when interference and noise are reduced without using complicated processing. In addition, since the change information of the front end can be obtained with a digital value of 0 or 1, the increase of the interface between the rear end and the front end in this embodiment is slight. In the present embodiment, a characteristic example of BER when CW is added as an off-signal signal having a frequency close to the target signal frequency is shown in FIG. 2, and an example of the characteristic of BER when burst CW is applied. . 2 and 3 use the simulation conditions shown in FIG.

Second Embodiment

4 shows a receiver using an automatic gain control apparatus according to a second embodiment of the present invention. In addition, in Example 2, the characteristic example of BER when CW is added as an undesired signal is shown in FIG. 5, and the characteristic example of BER when burst CW is added is shown in FIG. 5 and 6 show the case where the simulation conditions shown in FIG. 16 are used.

(Configuration of Second Embodiment)

4 is an explanatory diagram showing an automatic gain control device 20 according to the present embodiment. In addition, since this embodiment is an application of the above-mentioned first embodiment, in FIG. 4, the components which have substantially the same functional configuration as this first embodiment (FIG. 1) are denoted by the same reference numerals, and redundant description is omitted. do.

As shown in FIG. 4, the automatic gain control device 20 according to the present embodiment replaces the nonlinear responders 238 and 240 that are components of the automatic gain control device 10 (FIG. 1) according to the first embodiment. ³ + bx ² + cx) 252, and the coefficient registers 254, 256, and 258. The coefficient register 254 is a register for storing the fast coefficients a1, b1, and c1 (hereinafter, C1) described in the first embodiment. The coefficient register 254 is a register for storing the low speed coefficients a2, b2, and c2 (hereinafter, C2) described in the first embodiment. The nonlinear responder 252 calculates (ax ³ + bx ² + cx) by applying coefficients stored in any one of the coefficient registers 254 and 256. The nonlinear responder 252 makes C2 the lower limit and makes the coefficient small by using the value of Cdec held in the coefficient register 258.

(Operation of the second embodiment)

The operation of this embodiment will be described with reference to the state transition diagram shown in FIG.

In the present embodiment, when the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and the reference value REF3 exceeds a predetermined value, the nonlinear responder of the automatic gain control voltage uses the coefficient of C1 (S1). When the difference between the absolute value of the derivative of the automatic gain control voltage of the front end and the reference value REF3 exceeds the predetermined value and becomes less than the predetermined value, the nonlinear responder 252 of the automatic gain control response sets the value of Cdec as C2 as the lower limit. The coefficient is made small (S1? S2? S3). Here, when the difference between the absolute value of the derivative value of the automatic gain control voltage of the front end and the reference value REF3 exceeds the predetermined value again, the value of C1 is used (S2 or S3? S1).

(Effect of 2nd Example)

As described above, according to the present embodiment, it is possible to obtain a faster response than conventional automatic gain control while acquiring both low distortion and followability. In the conventional automatic gain control device, since distortion occurs when the response speed is high, it is set to a slower response than the automatic gain control device according to the present embodiment. For this reason, as shown in Fig. 8, in the ADC output, the target signal cannot be observed at the time of the disturbing file applied by the burst, and the predetermined signal level is not reached even at the output of the automatic gain control device. On the other hand, in the present embodiment showing the response waveform in Fig. 9, the signal level is not large, but the gain of the front end increases to the level at which the target signal can be observed at the ADC output, although it is not a large level due to the high speed followability even in the case of disturbing files. do. At the output of the automatic gain control device, the target signal controlled at the target level can be observed.

Further, a large improvement can be obtained only by making slight modifications to the first embodiment.

Third Embodiment

10 shows a receiver using an automatic gain control apparatus according to a third embodiment of the present invention. 11 shows a characteristic example of BER when burst CW is applied as an out-of-purpose signal in the third embodiment. 11 is a case where the simulation condition shown in FIG. 16 is used.

(Configuration of Third Embodiment)

10 is an explanatory diagram showing an automatic gain control device 30 according to the present embodiment. In addition, since the present embodiment is an application of the second embodiment, the same reference numerals are used for the components having the same functional configuration as those of the second embodiment (Fig. 4) in Fig. 10. Omit.

As shown in FIG. 10, the automatic gain control device 30 according to the present embodiment changes the automatic gain control device 20 (FIG. 4) according to the second embodiment to both sides of the analog front end 100 and the digital front end 200. It adds and demonstrates below.

In the analog front end 100, an AD converter 130 is provided in place of the reference value register REF3 126 and the calculation circuit 128 of the second embodiment. The AD converter 130 receives an output signal from the differential circuit 124 and outputs an analog response state signal to the digital front end 200. In general receivers, the AD converter for the control voltage of the analog automatic gain control is provided to know the received signal level. Therefore, after digital conversion of the automatic gain control voltage of the analog part, the digital part is differentiated and an absolute value is obtained. Interface increase can be avoided.

On the other hand, in the digital front end 200, a configuration for responding to the analog response state signal described above is adopted. In addition to the configuration of the second embodiment, the digital front end 200 of the present embodiment includes a multiplier 260, a switch 262, a comparator 264, a subtractor 266, a delayer 268, and an adder 270.

The multiplier 260 inputs an analog response state signal, which is an output signal of the AD converter 130 in the analog front end 100, and high-speed coefficients a1, b1, and c1 stored in the coefficient register (for high speed) 254 to perform multiplication processing. The output signal of multiplier 260 is input to switch 262 and comparator 264. The switch 262 inputs an output signal of the multiplier 260 and a signal subjected to predetermined delay processing to the coefficient Cdec held by the coefficient register 258, and switches them in accordance with the output signal from the comparator 264. The subtractor 266 receives the coefficient Cdec held by the coefficient register 258 and the output signal of the delay unit 268 to perform the subtraction process.

The signal switched and output by the switch 262 is output to the delay unit 268. The output signal of the delayer 268 is input to the comparator 264, the subtractor 266, and the adder 270. The comparator 264 receives the output signal X1 of the multiplier 260 and the output signal X2 of the delayer 268 and compares them. The output signal which is a result of comparison of the comparator 264 is input to the switch 262.

The adder 270 inputs the output signal of the delayer 268 and the low speed coefficients a2, b2, and c2 stored in the coefficient register (for low speed) 256 to perform the addition process. The output signal of the adder 270 is input to the nonlinear responder 252.

(Operation of the third embodiment)

The coefficient of the nonlinear responder of the automatic gain control response of the rear stage is set to the minimum values of the coefficients for low speed a2, b2, c2 used at low speed by the absolute value of the derivative value of the automatic gain control voltage of the front stage. The high speed coefficients a1, b1, c1 to be used are varied with the maximum value therebetween. In addition, as in the improvement from the first embodiment to the second embodiment, although the response state of the front end converges rapidly and the response of the rear end is not converged, in order to avoid that the response speed becomes slow, from the high speed response to the low speed response, It is possible to smoothly change the response speed when changing. In this embodiment, the value obtained by multiplying the high-speed coefficient and the response state of the front end is compared with the value before one sample, and when the value is smaller than the value before one sample, the value obtained by subtracting Cdec from the value before one sample is nonlinear. It is realized by updating as a control value controlling the coefficient of the transponder.

(Effect of 3rd Example)

In the configuration of this embodiment, as shown in Fig. 10, when the rear end is digital processing, an AD converter 130 is required to obtain the information of the front end. In a general receiver, the control voltage of the analog automatic gain control is used to know the reception signal level. AD converter is provided. Therefore, after the digital conversion of the automatic gain control voltage of the analog unit from the AD conversion unit, the derivative of the digital unit is differentiated and the increase of the separate interface can be avoided.

Fourth Example

12 shows a receiver using an automatic gain control apparatus according to a fourth embodiment of the present invention.

(Configuration of the fourth embodiment)

12 is an explanatory diagram showing an automatic gain control device 40 according to the present embodiment. In addition, since a present Example is an application of the said 1st-3rd Example, in FIG. 12, the same code | symbol is used about the component which has a functional structure substantially the same as the said 1st-3rd Example. The redundant description is omitted.

In this embodiment, a plurality of target signals are simultaneously processed. A plurality of digital units are connected in parallel to the same analog unit, and each digital unit processes signals of different frequencies.

In the example shown in FIG. 12, the analog front end 100 uses the response speed control signal generator 123 (differential circuit 124, reference value register REF3) 126, and arithmetic operation in the analog front end 100 of the configuration (FIG. 1) of the first embodiment. Circuit 128). The case where the response speed control signal generator 123 is shared by each digital front end 200-1, 200-2, and 200-3 is shown. Here, each of the digital front ends 200-1, 200-2, and 200-3 has the same configuration as the digital front end 200 in the first embodiment. That is, in the automatic gain control device 40 according to the present embodiment, when there is only one digital front end, the same configuration as that of the automatic gain control device 10 according to the first embodiment (Fig. 1) is obtained.

In addition, the configuration shown in FIG. 12 is only one example, and based on the configuration of the second embodiment (FIG. 4) or the configuration of the third embodiment (FIG. 10), a plurality of digital parts are connected in parallel to the same analog part as described above. It is also possible to use a connected configuration. In addition, although three cases are shown in FIG. 12 about the number of digital parts, it is not limited to this, It may be two, or may be four or more.

(Effect of 4th Example)

As described above, according to the present embodiment, the fast response is required for the AGC control unit at the rear stage only when the fast response occurs at the AGC control unit at the front end. Therefore, since the automatic gain control apparatus described in the first to third embodiments switches the response characteristics of the AGC control unit at the rear end in accordance with the response state of the AGC control unit at the front end, the high-speed tracking and interference with the input signal fluctuations are simplified by simple processing. And target signal quality when noise is reduced.

Also, in the automatic gain control device of Japanese Patent Laid-Open No. 2004-274210 (Patent Document 3), if the signal transmission delay between the input and the output is large, the control speed of the gain control of the input side variable gain amplifier is slowed. Saturation and S / N (Signal / Noise) deficiency tend to occur, but the automatic gain control device according to the present embodiment can be divided into two stages or multiple stages before and after a large delay element such as a filter. The delay in the loop is small and fast response is possible.

As mentioned above, although preferred embodiment of the automatic gain control apparatus concerning this invention was described referring an accompanying drawing, this invention is not limited to this example. It is obvious to those skilled in the art that various modifications or examples of modifications can be anticipated within the scope of the technical idea described in the claims, and they also belong to the technical scope of the present invention.

For example, in the said embodiment, although the nonlinear responder was demonstrated as an example of the responder for controlling the response speed of an AGC control part, the responder of this invention may be a linear thing which is not limited to being nonlinear.

The present invention can be used for an automatic gain control device that inputs and processes a wider signal than an output signal.

As described above, the present invention can achieve both high-speed following of input signal fluctuation and object signal quality when interference and noise are good by simple processing. In addition, other effects and the like of the present invention have been described in the above detailed description of the invention.

Claims (10)

An automatic gain control apparatus for inputting and processing a wideband signal from an output signal, A first signal processor having a first automatic gain controller for controlling a wideband input signal including a target signal band within a predetermined amplitude range; A second signal processor extracting an object signal from an output of the first signal processor; A second automatic gain controller which outputs the output of the second signal processor at a constant amplitude; And a response speed control signal generator for generating a response speed control signal for controlling the response speed of the second automatic gain control unit according to the response state of the first automatic gain control unit. The method of claim 1, The response speed control signal generation unit is said to have a large variation in the first automatic gain controller when the difference between the absolute value of the differential value of the automatic gain control voltage which is the output of the first automatic gain controller and a predetermined reference value exceeds a predetermined value. And determine and generate a response speed control signal for speeding up the response speed of the second automatic gain control unit. The method according to claim 1 or 2, The second automatic gain control unit, A first responder for speeding up the response speed of the second automatic gain controller; A second responder for slowing the response speed of the second automatic gain control unit; And a switch for switching the first and second responders according to the response speed control signal. The method according to claim 1 or 2, The second automatic gain control unit, A transponder for controlling a response speed of the second automatic gain controller; A high speed coefficient register for holding a high speed coefficient used in the transponder; And a low speed coefficient register for holding a low speed coefficient used in said transponder. The method according to claim 1 or 2, And the second automatic gain control unit continuously changes the response speed according to the response state of the first automatic gain control unit. An automatic gain control apparatus for inputting and processing a wideband signal from an output signal, A first signal processor having a first automatic gain controller for controlling a wideband input signal including a target signal band within a predetermined amplitude range; A plurality of second signal processing units for extracting a target signal from an output of the first signal processing unit; A second automatic gain control unit provided corresponding to each of the second signal processing units and outputting the output of the second signal processing unit at a constant amplitude; And a response speed control signal generator for generating a response speed control signal for controlling the response speed of each of the second automatic gain controllers according to the response state of the first automatic gain controller. The method of claim 6, The response speed control signal generator, When the difference between the absolute value of the differential value of the automatic gain control voltage that is the output of the first automatic gain control unit and the predetermined reference value exceeds a predetermined value, it is determined that the variation of the first automatic gain control unit is large, and the second automatic gain Automatic gain control device, characterized in that for generating a response speed control signal for increasing the response speed of the control unit. The method according to claim 6 or 7, The second automatic gain control unit, A first responder for speeding up the response speed of the second automatic gain control unit; A second responder for slowing the response speed of the second automatic gain control unit; And a switch for switching the first and second responders according to the response speed control signal. The method according to claim 6 or 7, The second automatic gain control unit, A transponder for controlling a response speed of the second automatic gain controller; A high speed coefficient register for holding a high speed coefficient used in the transponder; And a low speed coefficient register for holding a low speed coefficient used in said transponder. The method according to claim 6 or 7, And each of the second automatic gain control units gradually changes the response speed according to the response state of the first automatic gain control unit.

Images