JPH09159748A - Alc circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct variation caused in a device by temperature with high accuracy by using only one set value. SOLUTION: A distributor 2 distributes pilot signals supplied through a digital controlled variable attenuator 1 and a linear detector 3 converts the pilot signals into video signals. A corrector 5 which converts the video signals outputted from the detector 3 into digital signals and corrects the digital signals in accordance with frequency and temperature information is provided. Then a subtractor 7 which finds the difference between the corrected digital signals logarithmically converted by means of a logarithmic converter 6 and a set value and a comparator 8 which compares the logarithmically converted corrected digital signals with the set value are provided. In addition, an up/down counter 10 which sets the attenuation amount of the attenuator 1 with a count value by using the output of the subtractor 7 as an initial value and the output of the comparator 8 as an up/down control signal is provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to ALC (Aut).
o Level Control) circuit,
The present invention relates to an ALC circuit used in a radar device or the like.

[0002]

2. Description of the Related Art FIG. 12 shows an automatic gain control device (Auto Gain) conventionally used in a receiver of a radar device.
Control device: hereinafter referred to as AGC device). This AGC device includes a variable attenuator 20 that changes a gain of a receiver, a logarithmic conversion circuit 21 that converts a received signal into a logarithmic value, and a subtraction circuit 22 that subtracts a gain setting value from an output value of the logarithmic conversion circuit 21. Depending on the transmission pulse width and the transmission frequency number, the addition circuit 23 that adds the previous gain correction amount (attenuation setting amount of the variable attenuator 20) to the output value of the subtraction circuit 22, the hold circuit 24 that holds the gain correction amount, It is configured by a set value selection circuit 25 that selects one of the gain set values 26a to 26c.

Next, the operation of this AGC device will be described. During the gain correction period, the AGC pilot signal is input to the variable attenuator 20 in accordance with the AGC timing signal instead of the received signal. The pilot signal passing through the variable attenuator 20 is converted into a video signal, and then the logarithmic conversion circuit 2
Converted to logarithmic value at 1. The converted logarithmic value is subtracted in the subtraction circuit 22 by the gain setting value selected by the transmission pulse width and the transmission frequency.

The output value of the subtraction circuit 22 is added to the previous gain setting value by the addition circuit 23. The value after the addition becomes the attenuation amount (gain correction amount) of the variable attenuator 20. This control amount is held by the hold circuit 24 until the next AGC timing signal is input.

[0005]

The conventional AGC device is
Because of the above-described configuration, it is not possible to compensate for gain fluctuations in the AGC device due to temperature, and if there are many types of frequency numbers and pulse widths, the required number of gain setting values increases and the circuit scale increases. growing.

Also, a subtraction circuit, an addition circuit, a hold circuit,
There is a problem that the correction accuracy is lowered due to the error of the variable attenuator.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to correct fluctuations in the apparatus due to temperature, only one set value is required, and the correction can be performed with high accuracy. Aim to get the circuit.

[0008]

In order to achieve the above object, an ALC circuit according to the present invention distributes a digital control variable attenuating means for attenuating a pilot signal and a pilot signal passed through the digital control variable attenuating means. Distribution means, linear detection means for converting the pilot signal distributed by the distribution means into a video signal, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, and frequency and temperature information. A correction means for correcting the digital signal, a logarithmic conversion means for converting the digital signal corrected by the correction means into a logarithmic value, and a difference between the digital signal logarithmically converted by the logarithmic conversion means and a set value. Subtraction means, the digital signal logarithmically converted by the logarithmic conversion means, and the set value Comparing means for comparing the output of the subtraction means as an initial value UP / DOW an output of the comparing means
An UP / DOWN counter for setting the attenuation amount of the digitally controlled variable attenuator by using an N control signal and a count value.

In the ALC circuit according to the present invention, the pilot signal is converted into the video signal by the linear detector,
The corrector corrects the digitally converted video signal based on the temperature / frequency information, and the attenuation amount of the digital control variable attenuator is corrected and set accordingly. Further, the subtractor gives an initial attenuation amount, and thereafter, the UP / DOWN counter corrects with an accuracy equal to or less than the minimum attenuation amount of the digital control variable attenuator by comparing the level with a set value.

In the ALC circuit according to the next invention, a digital control variable attenuating means for attenuating the pilot signal, a distributing means for distributing the pilot signal passed through the digital controlling variable attenuating means, and a pilot signal distributed by the distributing means are provided. Linear detection means for converting into a video signal, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, and correction means for correcting the digital signal according to frequency and temperature information,
Storage means for outputting the difference from the set value as a logarithmic value from the digital signal corrected by the correcting means, comparing means for comparing the digital signal corrected by the correcting means with the set value, and output of the storing means Is set as an initial value, the output of the comparison means is used as an UP / DOWN control signal, and the UP / DOWN counter for setting the attenuation amount of the digital control variable attenuation means by the count value is provided.

In the ALC circuit according to the present invention, the pilot signal is converted into the video signal by the linear detector,
The corrector corrects the digitally converted video signal based on the temperature / frequency information, and the attenuation amount of the digital control variable attenuator is corrected and set accordingly. Further, the initial attenuation amount is given by the memory, and thereafter, the UP / DOWN counter corrects with an accuracy equal to or less than the minimum attenuation amount of the digital control variable attenuator by comparing the level with the set value.

In the ALC circuit according to the next invention, the voltage control variable attenuating means for attenuating the pilot signal, the distributing means for distributing the pilot signal passing through the voltage controlling variable attenuating means, and the pilot signal distributed by the distributing means are provided. Linear detection means for converting into a video signal, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and the correction means Logarithmic conversion means for converting the digital signal corrected by the above into a logarithmic value, and subtraction means for obtaining the difference between the digital signal logarithmically converted by the logarithmic conversion means and the set value,
Comparing means for comparing the digital signal logarithmically converted by the logarithmic converting means with a set value; and an UP / DOWN counter having the output of the subtracting means as an initial value and the output of the comparing means as a UP / DOWN control signal, UP / D
D / A conversion means for converting the output of the OWN counter into a voltage value and setting the attenuation amount of the voltage control variable attenuation means.

In the ALC circuit according to the present invention, the pilot signal is converted into the video signal by the linear detector,
The corrector corrects the digitally converted video signal based on the temperature / frequency information, and the attenuation amount of the voltage controlled variable attenuator is corrected and set accordingly. In addition, the subtractor gives the initial attenuation amount, and then the level is compared with the set value.
The output of the P / DOWN counter is converted into a voltage value and corrected with an accuracy not higher than the minimum attenuation amount of the voltage controlled variable attenuator.

In the ALC circuit according to the next invention, a digital control variable attenuating means for attenuating the pilot signal, a distributing means for distributing the pilot signal passed through the digital controlling variable attenuating means, and a pilot signal distributed by the distributing means. Logarithmic detection means for converting into a logarithmic video signal, A / D conversion means for converting the logarithmic video signal output by the logarithmic detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and the correction Subtracting means for obtaining a difference between the digital signal corrected by the means and the set value, comparing means for comparing the digital signal corrected by the correcting means with the set value, and an output of the subtracting means as an initial value The output of the comparison means is used as an UP / DOWN control signal, and the count value is used for the digital control. U to set the attenuation of the variable attenuating means
And a P / DOWN counter.

In the ALC circuit according to the present invention, the pilot signal is converted into a logarithmic video signal by the logarithmic detector, the digitally converted logarithmic video signal is corrected by the corrector by the temperature / frequency information, and digitally controlled accordingly. The attenuation amount of the variable attenuator is corrected and set. Further, the subtractor gives an initial attenuation amount, and thereafter, the UP / DOWN counter corrects with an accuracy equal to or less than the minimum attenuation amount of the digital control variable attenuator by comparing the level with a set value.

In the ALC circuit according to the next invention, a digital control variable attenuation means for attenuating the pilot signal, a distribution means for distributing the pilot signal which has passed through the digital control variable attenuation means, and a pilot signal distributed by the distribution means. Linear detection means for converting into a video signal, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, and correction means for correcting the digital signal according to frequency and temperature information,
A logarithmic conversion means for converting the digital signal corrected by the correction means into a logarithmic value, and a difference between the digital signal logarithmically converted by the logarithmic conversion means and a set value is obtained, and the difference is used as the digital control variable attenuation means. And a subtraction unit for setting the attenuation amount.

In the ALC circuit according to the present invention, the pilot signal is converted into the video signal by the linear detector,
The corrector corrects the digitally converted video signal based on the temperature / frequency information, and the attenuation amount of the digital control variable attenuator is corrected and set accordingly.

In the ALC circuit according to the next invention, the voltage control variable attenuating means for attenuating the pilot signal, the distributing means for distributing the pilot signal passed through the voltage controlling variable attenuating means, and the pilot signal distributed by the distributing means are provided. Linear detection means for converting into a video signal, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and the correction means Logarithmic conversion means for converting the digital signal corrected by the logarithmic value, subtraction means for obtaining the difference between the digital signal logarithmically converted by the logarithmic conversion means and the set value, and the output of the subtraction means to a voltage value. D / A conversion means for converting and setting the attenuation amount of the voltage control variable attenuation means.

In the ALC circuit according to the present invention, the pilot signal is converted into the video signal by the linear detector,
The corrector corrects the digitally converted video signal based on the temperature / frequency information, and the attenuation amount of the voltage controlled variable attenuator is corrected and set accordingly.

In the ALC circuit according to the next invention, a digital control variable attenuating means for attenuating the pilot signal, a distributing means for distributing the pilot signal passed through the digital control variable attenuating means, and a pilot signal distributed by the distributing means are provided. Linear detection means for converting into a video signal, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, and correction means for correcting the digital signal according to frequency and temperature information,
The control means controls the digital control variable attenuation means according to the digital signal corrected by the correction means and the set value.

In the ALC circuit according to the present invention, the pilot signal is converted into the video signal by the linear detector,
The corrector corrects the digitally converted video signal based on the temperature / frequency information, and the attenuation amount of the digital control variable attenuator is corrected and set accordingly. Also, the controller corrects with a precision less than the minimum attenuation of the digitally controlled variable attenuator.

In the ALC circuit according to the next invention, the digital control variable attenuating means for attenuating the pilot signal, the distributing means for distributing the pilot signal passing through the digital controlling variable attenuating means, and the pilot signal distributed by the distributing means are provided. Logarithmic detection means for converting into a logarithmic video signal; A / D conversion means for converting the logarithmic video signal output by the logarithmic detection means into a digital signal; correction means for correcting the digital signal according to frequency and temperature information; The control means controls the digital control variable attenuation means according to the digital signal corrected by the correction means and the set value.

In the ALC circuit according to the present invention, the pilot signal is converted into a logarithmic video signal by the logarithmic detector, the digitally converted logarithmic video signal is corrected by the corrector by the temperature / frequency information, and digitally controlled accordingly. The attenuation amount of the variable attenuator is corrected and set. Also, the controller corrects with a precision less than the minimum attenuation of the digitally controlled variable attenuator.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a first embodiment of an ALC circuit according to the present invention. This ALC circuit includes a digital control variable attenuator 1 for attenuating a pilot signal, a distributor 2 for distributing a pilot signal that has passed through the digital control variable attenuator 1, and a pilot signal distributed by the distributor 2 for conversion into a video signal. Linear detector 3 and an A / D for converting the video signal of the linear detector 3 into a digital signal
A converter 4, a corrector 5 for correcting the digital signal according to the frequency and temperature information, a logarithmic converter 6 for converting the digital signal corrected by the corrector 5 into a logarithmic value, and a logarithmic conversion by the logarithmic converter 6. A subtracter 7 for obtaining the difference between the digital signal and the level set value, a comparator 8 for comparing the digital signal logarithmically converted by the logarithmic converter 6 with the level set value, and a level setter 9 for setting the level set value.
And the output value of the subtractor 7 as an initial value (initial attenuation amount), and the output of the comparator 8 as an UP / DOWN control signal.
It has a UP / DOWN counter 10 that counts down and sets the amount of attenuation of the digitally controlled variable attenuator 1 with the count value.

FIG. 2 shows changes in the level of the pilot signal according to the first embodiment of the present invention. In FIG. 2, P is a pilot signal, and Pl is an example of the level change of the pilot signal.

Next, the operation of the first embodiment of the present invention will be described.

The pilot signal input to the ALC circuit and passed through the digitally controlled variable attenuator 1 is distributed by the distributor 2, one of which is sent to the processing circuit of the next stage and the other of which is a video signal by the linear detector 3. Is converted to.

This video signal is converted into a digital signal by the A / D converter 4, and the compensator 5 corrects the gain fluctuation in the ALC circuit by the temperature / frequency information.
The corrected signal is converted into a logarithmic value by the logarithmic converter 6, the signal converted into a logarithmic value is input to the subtractor 7, and the subtractor 7 obtains the difference from the level set value by the level setter 9. The output value of the subtractor 7 is given to the UP / DOWN counter 10 as an initial value (initial attenuation amount).

The UP / DOWN counter 10 includes a subtractor 7
The attenuation amount of the digital control variable attenuator 1 is given by the initial value (initial attenuation amount) given by the above.

Next, the pilot signal P whose level has been changed by the amount of attenuation given by the UP / DOWN counter 10 is processed in the same manner as described above, and next inputted to the comparator 8. In the comparator 8, the level setter 9 judges the magnitude of the level set value, and if the level set value is larger than the pilot signal, the UP / DOWN counter 10 is set to "DOWN".
The control signal for "N" is output. This control signal causes U
The P / DOWN counter 10 decrements the 1-bit output value. As a result, the digital control variable attenuator 1 reduces the attenuation amount by the minimum attenuation amount. These series of processing,
This is repeated while the pilot signal P is being input.

Since this ALC circuit is provided with the corrector 5 for correcting the digitally converted video signal based on the temperature / frequency information, the temperature / frequency in the ALC circuit is reduced.
Frequency fluctuations are corrected and the set value can be set to one.

Further, since the subtractor 7 gives an initial attenuation amount, and thereafter, the attenuation amount of the digital control variable attenuator 1 is adjusted by level comparison with the level set value, it is possible to correct with an accuracy equal to or less than the minimum attenuation amount. it can.

(Second Embodiment) FIG. 3 shows an ALC circuit according to a second embodiment of the present invention. This ALC circuit includes a digital control variable attenuator 1 for attenuating a pilot signal, a distributor 2 for distributing a pilot signal that has passed through the digital control variable attenuator 1, and a pilot signal distributed by the distributor 2 for conversion into a video signal. Linear detector 3
An A / D converter 4 for converting the video signal of the linear detector 3 into a digital signal, a corrector 5 for correcting the digital signal according to frequency and temperature information, and a digital signal corrected by the corrector 5 and level setting Comparator 8 for comparing with the value and level setter 9 for setting the level set value
And a memory 13 for outputting the difference between the digital signal corrected by the corrector 5 and the level setting value in a logarithmic value, and the output value of the memory 13 as an initial value (initial attenuation amount).
UP / DOWN counter 10 which counts up / down the output of the UP / DOWN control signal and sets the attenuation amount of the digital control variable attenuator 1 by the count value.
And

The memory 13 is provided with data for outputting the initial attenuation amount from the corrected digital signal and the level setting value, and the initial attenuation amount is UP / DOWN counter 1
Output to 0. In the first embodiment, the comparator 8 compares the logarithmic value, whereas the second embodiment compares the true value.

Also in this embodiment, since the corrector 5 for correcting the video signal digitally converted by the temperature / frequency information is provided, the temperature / frequency in the ALC circuit is reduced.
Frequency fluctuations are corrected and the set value can be set to one.

Further, since the memory 13 gives an initial attenuation amount, and thereafter, the attenuation amount of the digitally controlled variable attenuator 1 is adjusted by level comparison with the level setting value, it is possible to correct the attenuation amount with the minimum attenuation amount or less. .

(Third Embodiment) FIG. 4 shows an ALC circuit according to a third embodiment of the present invention. Embodiment 3
Is a modification of the first embodiment, in which the voltage control variable attenuator 14 is used in place of the digital control variable attenuator 1,
Output signal of UP / DOWN counter 10 (count value)
Is converted into an analog signal (voltage value) by the D / A converter 15 and given to the voltage controlled variable attenuator 14.

Other than this, the configuration is the same as that of the first embodiment, and therefore, in FIG. 4, the portions corresponding to FIG. 1 are denoted by the same reference numerals as those in FIG. 1 and the description thereof is omitted.

Also in this embodiment, since the compensator 5 for compensating the digitally converted video signal with the temperature / frequency information is provided, the temperature / frequency in the ALC circuit is reduced.
Frequency fluctuations are corrected and the set value can be set to one.

Further, the subtractor 7 gives an initial attenuation amount, and thereafter, the attenuation amount of the voltage control variable attenuator 14 is adjusted by level comparison with the level set value, so that the correction can be performed with an accuracy equal to or less than the minimum attenuation amount. it can.

(Fourth Embodiment) FIG. 5 shows an ALC circuit according to a fourth embodiment of the present invention. In the fourth embodiment, a logarithmic detector 16 is used instead of the linear detector 3 in the first embodiment, and the logarithmic converter 6 is omitted accordingly.

The logarithmic detector 16 converts the pilot signal distributed by the distributor 2 into a logarithmic video signal, and A / D
The converter 4 converts the logarithmic video signal into a digital signal.

The corrector 5 corrects the above digital signal according to the frequency and temperature information, and inputs the corrected digital signal to the subtractor 7 and the comparator 8.

Therefore, also in this embodiment, since the compensator 5 for compensating the digitally converted logarithmic video signal by the temperature / frequency information is provided, the temperature / frequency fluctuation in the ALC circuit is compensated and the setting is performed. It can have one value.

Further, since the subtractor 7 gives an initial attenuation amount, and thereafter, the attenuation amount of the digital control variable attenuator 1 is adjusted by level comparison with the level setting value, it is possible to correct with an accuracy of the minimum attenuation amount or less. it can.

(Fifth Embodiment) FIG. 6 shows an ALC circuit according to a fifth embodiment of the present invention. In the fifth embodiment, the comparator 8 and the UP / DOWN counter 10 in the first embodiment are omitted, and the output of the subtractor 7 is directly applied to the digitally controlled variable attenuator 1 as the attenuation amount.

This embodiment is useful in a system in which the setting error of the digitally controlled variable attenuator 1 is allowed and the level setting with high accuracy is not required. By omitting the comparator 8 and the UP / DOWN counter 10, the circuit is omitted. The scale can be reduced.

Also in this embodiment, since the compensator 5 for compensating the digitally converted video signal by the temperature / frequency information is provided, the temperature / frequency fluctuation in the ALC circuit is compensated and the set value is set to 1. Can be one.

(Sixth Embodiment) FIG. 7 shows an ALC circuit according to a sixth embodiment of the present invention. Embodiment 6
Is an embodiment in which the fifth embodiment in which the comparator 8 and the UP / DOWN counter 10 are omitted is applied to the third embodiment in which the voltage controlled variable attenuator 14 is used.

Therefore, in this embodiment, the output of the subtractor 7 is converted into an analog signal (voltage value) by the D / A converter 15 and given to the voltage controlled variable attenuator 14.

This embodiment is also useful in a system in which the setting error of the digitally controlled variable attenuator 1 is allowed and the level setting with high accuracy is not required, and the circuit is omitted by omitting the comparator 8 and the UP / DOWN counter 10. The scale can be reduced.

Also in this embodiment, since the compensator 5 for compensating the digitally converted video signal by the temperature / frequency information is provided, the temperature / frequency in the ALC circuit is reduced.
Frequency fluctuations are corrected and the set value can be set to one.

(Embodiment 7) FIG. 8 shows an ALC circuit according to Embodiment 8 of the present invention. In this embodiment, the subtractor 7, the comparator 8, the UP / DOWN counter 1
When 0 is implemented by software by a program executed by the controller 17 and the amount of attenuation of the digitally controlled variable attenuator 1 is n, the minimum amount of attenuation of the digitally controlled variable attenuator 1 is equal to or less than the minimum amount of attenuation of n times of processing. The level can be set with accuracy.

The controller 17 controls the digital control variable attenuator 1 and sets the attenuation amount of the digital control variable attenuator 1 by the processing flow shown in FIG.

FIG. 9 shows an AL according to the seventh embodiment of the present invention.
FIG. 10 is a processing flow chart of the C circuit, and FIG. 10 shows a level change of the pilot signal when this processing flow is executed.

In the processing flow of FIG. 9, first, the initial attenuation amount N
Is the maximum attenuation amount M (step S10), and the attenuation amount ATT
-Enter NdB (step S20) and compare the set value with the measured value level (step 30).

If set value <measured value level, attenuation amount A
Leave TT / NdB turned on (step 4)
0). On the other hand, if the setting value <measured value level is not satisfied, it is determined whether or not the attenuation amount ATT · NdB is the minimum attenuation amount ATT · 0 (step S50). Attenuation ATT / Nd
If B is the minimum attenuation amount ATT · 0, this processing flow is ended, but the attenuation amount ATT · NdB is the minimum attenuation amount ATT.
If not 0, N = N-1 (step S60),
Returning to step S20, the attenuation amount ATT · NdB is reduced and corrected.

As a result, similarly to the case of the first embodiment, the initial attenuation amount is given, and thereafter, the attenuation amount of the digital control variable attenuator 1 is adjusted by the level comparison with the level setting value. It can be corrected with accuracy.

Also in this embodiment, since the compensator 5 for compensating the digitally converted video signal by the temperature / frequency information is provided, the temperature / frequency in the ALC circuit is reduced.
Frequency fluctuations are corrected and the set value can be set to one.

(Embodiment 8) FIG. 11 shows an ALC circuit according to Embodiment 8 of the present invention. This embodiment is a modification of the seventh embodiment, and a logarithmic detector 16 is used instead of the linear detector 3. Other than this, the configuration is the same as that in the seventh embodiment, and therefore, FIG.
In FIG. 1, the portions corresponding to those in FIG. 8 are denoted by the same reference numerals as those in FIG. 8 and their description is omitted.

Therefore, also in this embodiment, since the initial attenuation amount is given and thereafter the attenuation amount of the digital control variable attenuator 1 is adjusted by the level comparison with the level setting value, it is necessary to correct the attenuation amount with the minimum attenuation amount or less. In addition, since the compensator 5 for compensating the digitally converted video signal with the temperature / frequency information is provided, the temperature / frequency fluctuation in the ALC circuit is compensated, and the set value can be made one. it can.

[0062]

As can be understood from the above description, according to the ALC circuit of the present invention, since the ALC circuit is provided with the corrector for correcting the digitally converted video signal by the temperature / frequency information, The temperature and frequency fluctuations of are corrected, and the set value can be set to one,
Further, since the initial attenuation amount is given by the subtractor and thereafter the attenuation amount of the digitally controlled variable attenuator is adjusted by level comparison with the level setting value, it is possible to correct with an accuracy equal to or less than the minimum attenuation amount.

According to the ALC circuit of the next invention, since the ALC circuit is provided with the compensator for compensating the video signal digitally converted by the temperature / frequency information, the ALC circuit
Temperature and frequency fluctuations in the circuit are corrected, and the set value is set to 1
Since the initial attenuation amount is given by the memory and then the attenuation amount of the digitally controlled variable attenuator is adjusted by comparing the level with the level setting value, it is possible to correct with an accuracy less than the minimum attenuation amount. it can.

According to the ALC circuit of the next invention, the ALC circuit is provided with the compensator for compensating the digitally converted video signal based on the temperature / frequency information.
Temperature and frequency fluctuations in the circuit are corrected, and the set value is set to 1
The initial attenuation amount can be given by the subtractor, and the attenuation amount of the voltage-controlled variable attenuator can be adjusted by comparing the level with the level setting value. You can

According to the ALC circuit of the next invention, since the ALC circuit is provided with the corrector for correcting the digitally converted logarithmic video signal by the temperature / frequency information,
The temperature and frequency fluctuations in the LC circuit are corrected, the set value can be set to one, and the initial attenuation amount is given by the subtractor, and then the level comparison with the level set value is performed to make the digital control variable attenuator. Since the amount of attenuation is adjusted, it can be corrected with an accuracy equal to or less than the minimum amount of attenuation.

In the ALC circuit according to the next invention, since the compensator for compensating the digitally converted video signal by the temperature / frequency information is provided,
Temperature and frequency fluctuations in the circuit (digitally controlled variable attenuator) are corrected, and the set value can be set to one.
Further, the circuit scale can be reduced by omitting the comparator and the UP / DOWN counter.

According to the ALC circuit of the next invention, the ALC circuit is provided with the compensator for compensating the digitally converted video signal based on the temperature / frequency information.
Temperature / frequency fluctuations (voltage-controlled variable attenuator) in the circuit can be corrected, the set value can be made one, and the circuit scale can be reduced by omitting the comparator and the UP / DOWN counter.

According to the ALC circuit of the next invention, since the corrector for correcting the video signal digitally converted through the linear detector by the temperature / frequency information is provided, the temperature in the ALC circuit is controlled by the controller. -Frequency fluctuations can be corrected, the set value can be set to one, and the correction can be performed with an accuracy of the minimum attenuation amount or less.

In the ALC circuit according to the next invention, since the compensator for compensating the video signal digitally converted through the logarithmic detector by the temperature / frequency information is provided, the temperature in the ALC circuit is controlled by the controller. -Frequency fluctuations can be corrected, the set value can be set to one, and the correction can be performed with an accuracy of the minimum attenuation amount or less.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an ALC circuit according to the present invention.

FIG. 2 is a graph showing changes in pilot signal level in the ALC circuit according to the present invention.

FIG. 3 is a block diagram showing an ALC circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing an ALC circuit according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing an ALC circuit according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing an ALC circuit according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram showing an ALC circuit according to a sixth embodiment of the present invention.

FIG. 8 is a block diagram showing an ALC circuit according to a seventh embodiment of the present invention.

FIG. 9 is a flowchart showing a processing flow in the seventh embodiment of the ALC circuit according to the present invention.

FIG. 10 is a seventh embodiment of the ALC circuit according to the present invention.
5 is a graph showing changes in pilot signal level in FIG.

[Embodiment 8] An eighth embodiment of an ALC circuit according to the present invention.
FIG.

FIG. 12 is a block diagram showing a conventional ALC circuit.

[Explanation of symbols]

1 digital control variable attenuator, 2 distributor, 3 linear detector, 4 A / D converter, 5 corrector, 6 logarithmic converter, 7 subtractor, 8 comparator, 9 level setter,
10 UP / DOWN counter, 13 memory, 14
Voltage controlled variable attenuator, 15 D / A converter, 16 logarithmic detector, 17 controller

Claims (8)

[Claims] 1. A digital control variable attenuation means for attenuating a pilot signal, a distribution means for distributing the pilot signal that has passed through the digital control variable attenuation means, and a linear for converting the pilot signal distributed by the distribution means into a video signal. Detection means, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and a digital signal corrected by the correction means. To a logarithmic conversion means, a subtraction means for obtaining a difference between the digital signal logarithmically converted by the logarithmic conversion means and the set value, and a digital signal logarithmically converted by the logarithmic conversion means and the set value. The output of the comparing means is compared with the output of the subtracting means as an initial value. An ALC circuit comprising: an UP / DOWN counter, which sets an attenuation amount of the digitally controlled variable attenuator by using a count value as an UP / DOWN control signal. 2. A digital control variable attenuation means for attenuating a pilot signal, a distribution means for distributing the pilot signal which has passed through the digital control variable attenuation means, and a linear for converting the pilot signal distributed by the distribution means into a video signal. Detection means, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and a digital signal corrected by the correction means. Storage means for outputting the difference from the set value as a logarithmic value, comparing means for comparing the digital signal corrected by the correcting means with the set value, and the output of the comparing means with the output of the storing means as an initial value. UP / DO
An ALC circuit, comprising: a UP / DOWN counter for setting the attenuation amount of the digitally controlled variable attenuator by using a count value as a WN control signal. 3. A voltage control variable attenuation means for attenuating a pilot signal, a distribution means for distributing the pilot signal that has passed through the voltage control variable attenuation means, and a linear for converting the pilot signal distributed by the distribution means into a video signal. Detection means, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and a digital signal corrected by the correction means. To a logarithmic conversion means, a subtraction means for obtaining a difference between the digital signal logarithmically converted by the logarithmic conversion means and the set value, and a digital signal logarithmically converted by the logarithmic conversion means and the set value. The output of the comparison means and the output of the subtraction means are used as initial values, and the output of the comparison means is UP / DOW. An UP / DOWN counter that uses an N control signal, and a D / A conversion unit that converts the output of the UP / DOWN counter into a voltage value and sets the attenuation amount of the voltage control variable attenuation unit, are provided. ALC circuit. 4. A digitally controlled variable attenuating means for attenuating a pilot signal, a distributing means for distributing a pilot signal passed through the digitally controlled variable attenuating means, and a pilot signal distributed by the distributing means for conversion into a logarithmic video signal. Logarithmic detection means, A / D conversion means for converting the logarithmic video signal output by the logarithmic detection means into a digital signal, correction means for correcting the digital signal in accordance with frequency and temperature information, and digital corrected by the correction means. A subtracting means for obtaining a difference between the signal and the set value, a comparing means for comparing the digital signal corrected by the correcting means with the set value, an output of the subtracting means as an initial value, and an output of the comparing means is UP. / DOWN control signal is used to set the amount of attenuation of the digitally controlled variable attenuator with the count value. UP / DOWN counter according to the present invention. 5. A digital control variable attenuator for attenuating a pilot signal, a distributor for distributing the pilot signal that has passed through the digital control variable attenuator, and a linear for converting the pilot signal distributed by the distributor to a video signal. Detection means, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and a digital signal corrected by the correction means. A logarithmic conversion means for converting into a logarithmic value, and a subtraction means for obtaining a difference between the digital signal logarithmically converted by the logarithmic conversion means and a set value and setting the attenuation amount of the digital control variable attenuation means by the difference. An ALC circuit characterized by being provided. 6. A voltage-controlled variable attenuator for attenuating a pilot signal, a distributor for distributing the pilot signal that has passed through the voltage-controlled variable attenuator, and a linear device for converting the pilot signal distributed by the distributor to a video signal. Detection means, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal in accordance with frequency and temperature information, and the digital corrected by the correction means. A logarithmic conversion means for converting a signal into a logarithmic value, a subtraction means for obtaining a difference between a digital signal logarithmically converted by the logarithmic conversion means and a set value, and an output of the subtraction means is converted into a voltage value for the voltage control variable. An ALC circuit comprising: a D / A conversion means for setting an attenuation amount of the attenuation means. 7. A digitally controlled variable attenuating means for attenuating a pilot signal, a distributing means for distributing a pilot signal passed through the digitally controlled variable attenuating means, and a linear for converting the pilot signal distributed by the distributing means into a video signal. Detection means, A / D conversion means for converting the video signal output by the linear detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and the digital corrected by the correction means. An ALC circuit comprising: control means for controlling the digitally controlled variable attenuation means according to a signal and a set value. 8. A digitally controlled variable attenuating means for attenuating a pilot signal, a distributing means for distributing a pilot signal that has passed through the digitally controlled variable attenuating means, and a pilot signal distributed by the distributing means for converting into a logarithmic video signal. Logarithmic detection means, A / D conversion means for converting the logarithmic video signal output by the logarithmic detection means into a digital signal, correction means for correcting the digital signal according to frequency and temperature information, and correction means An ALC circuit comprising: a control means for controlling the digitally controlled variable attenuation means according to the digital signal and a set value.