JP2003218651A - Automatic gain controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic gain controller compatible with diversified modulation systems, having excellent response characteristics with respect to a burst signal and high gain control accuracy. <P>SOLUTION: The automatic gain controller is provided with: a variable gain amplifier for amplifying a burst signal with a prescribed gain; a feedforward control section for controlling the gain on the basis of an input signal to the variable gain amplifier; and a feedback control section for controlling the fain on the basis of an output signal from the variable gain amplifier, the operation of the feedforward control section and the feedback control section is switched on the basis of the detection of the received burst signal to control the gain of the variable gain amplifier. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic gain control device for controlling the amplification gain of a received burst signal.

[0002]

2. Description of the Related Art Generally, in a receiver used in a wireless communication system, the level of its received input signal constantly changes depending on the distance from the communication partner station and weather conditions. On the contrary,
Since the quality of the demodulated signal cannot be maintained unless the signal amplitude input to the demodulator has a predetermined constant level, it is necessary to control the reception gain so as to supply the demodulator with a reception signal having a constant amplitude. FIG. 7 is a block diagram showing a first prior art receiving apparatus which supplies a signal having a constant amplitude to a demodulator.

In the figure, a high frequency signal received from an antenna 1 is amplified by a high frequency amplifier circuit 2 and then converted into an intermediate frequency signal by a frequency conversion circuit 3. The amplitude of the intermediate frequency signal is limited by the limiting amplifier circuit 41 so that the signal amplitude is kept constant. As a result, the quadrature detector 4 and the demodulation circuit AD converter 5, which are demodulators, receive the received signals of constant amplitude. The demodulated signal is decoded by the digital decoder 6.

The limiting amplifier circuit 41 is
The received signal is amplitude-limited and envelope detection is performed, and the received signal strength information is expressed as received signal strength indication (RSSI) data 22 using the envelope detected signal output from the limiting amplifier circuit 41.

Next, the second conventional technique will be described with reference to FIG. FIG. 8 shows a block diagram of a conventional receiving apparatus. In the figure, a high frequency signal received from an antenna 1 is amplified by a high frequency amplifier circuit 2 and then converted into an intermediate frequency signal by a frequency conversion circuit 3. The intermediate frequency signal is amplified by the variable gain AGC amplifier circuit 4 so as to keep the signal amplitude constant, and is input to the quadrature detection circuit 5 which is a demodulator.
The received signal converted into the baseband signal by the quadrature detection circuit 5 is converted into digital information by the AD converter 6,
It is input to the digital decoder 7 and converted into a received data string, and is also input to the amplitude estimating section 16. Amplitude estimation unit 1
In 6, the amplitude information of the received signal is generated from the input signal, and this amplitude information is compared with the reference amplitude 17 in the error comparator 15, and the error signal for the reference amplitude is output. This error signal is input to the digital integrator 14, and after averaging the errors, it is input to the gain control terminal of the AGC amplifier circuit 4 via the DA converter 12 as a control signal.

As a result of the above operation, the gain of the AGC amplifier circuit 4 is feedback-controlled so that the amplitude of the output signal of the AD converter 6 becomes a constant magnitude, and the quadrature detection circuit 5 and the demodulation circuit AD which are demodulators. The amplitude of the signal input to the converter 6 becomes constant.

Regarding the information on the received signal strength,
The received signal strength indication (RSSI) data 22 is obtained by converting the gain control signal of the GC amplifier circuit 4 by the RSSI conversion unit 23.

Further, a third conventional technique will be described with reference to FIG. FIG. 9 shows a block diagram of a conventional receiving device. In the figure, a high frequency signal received from an antenna 1 is amplified by a high frequency amplifier circuit 2 and then converted into an intermediate frequency signal by a frequency conversion circuit 3. The intermediate frequency signal is amplified by the variable gain AGC amplifier circuit 4 so as to keep the signal amplitude constant, and is input to the quadrature detection circuit 5 which is a demodulator.
The gain of the AGC amplifier circuit 4 is controlled via the DA converter 12 by the control signal generated by the feedforward control amount estimation circuit 11 as follows. That is, the feedforward control amount estimation circuit 11 inputs the intermediate frequency signal branched from the output of the frequency conversion circuit 3 and detected by the envelope detection circuit 8, and a predetermined gain based on the amplitude information of the intermediate frequency signal. Generate a control signal that sets

As a result of the above operation, the amplitude of the intermediate frequency signal input to the quadrature detection circuit 5 which is a demodulator has a constant magnitude.

Regarding the information on the received signal strength, the output signal of the envelope detection circuit 8 is displayed as the received signal strength (R
SSI) data 22.

[0011]

In a wireless system for performing multiple access relay, represented by the TDMA system,
Communication with each partner station is carried out using burst signals transmitted in bursts. This burst signal is transmitted and received at extremely short time intervals, and the reception level on the receiving side fluctuates greatly depending on the partner station of the communication.Therefore, a circuit for controlling the input signal of the demodulator (gain control) Circuit) is required to have high-speed response performance.

In response to such a demand, the first conventional technique using the limiting amplifier circuit as the gain control circuit can realize an extremely excellent constant amplitude characteristic with respect to a change in the reception level occurring in a short time. However, since the limiting amplifier circuit limits the amplitude, it cannot be applied to a multi-level modulation system of an amplitude modulation system such as an n-QAM system in which the amplitude has information. Further, there is a problem that it is difficult to apply to a system such as a CDMA system or an OFDM system in which demodulation becomes difficult when the amplitude is limited.

Further, in the second conventional technique using the feedback control type AGC amplifier circuit, unlike the first conventional technique, since amplitude information of the modulated wave is not deleted, there is a problem that the modulation system cannot be applied. Resolve. However, in order to secure high control accuracy, it is necessary to secure the number of stages of the digital integrator for a period in which the amplitude fluctuation component of the signal due to the modulation can be sufficiently averaged. This is equivalent to increasing the loop response time constant (loop response time), and it becomes difficult to make a fast response to the reception level that varies for each burst. On the contrary, if a time constant that can sufficiently respond to the fluctuation for each burst is selected, the amplitude information of the modulated wave is deleted as in the first conventional technique, and burst rise, which is a phenomenon peculiar to feedback control,
Vibration due to transient response at the time of falling deteriorates the modulation accuracy at the beginning of the burst, and there is a problem that the optimum design is difficult for application to burst signals.

Further, a feedforward control type AG
In the third conventional technique using the C amplifier circuit, the problem that the optimum design of the step response becomes difficult due to the delay of the feedback loop as in the second conventional technique does not occur. Is easy to design. However, in order to ensure the modulation accuracy of the received signal, it is necessary to sufficiently average the amplitude fluctuation components of the signal due to the modulation and input them to the feedforward control amount estimation unit, which causes a control delay. Further, in the feedforward control type AGC amplifier circuit, it is difficult to secure sufficient control accuracy due to error in control due to characteristic variations of the peripheral circuit due to the ambient temperature and the frequency of the received signal, and the demodulator input amplitude is difficult to secure. There is a problem that the ability to keep constant is poor.

Further, there is a conventional AGC amplifier circuit combining a feedforward control system and a feedback control system, which is disclosed in Japanese Unexamined Patent Publication No. 2000-295181, in which a feedforward circuit and a feedback circuit are simultaneously operated. AGC detected and detected
The peak of the input signal of the amplifier circuit is compared with the peak of the output signal, and the gain of the AGC amplifier circuit is controlled by the ratio, and the gain control cannot be appropriately performed for the signal that fluctuates in a burst.

The present invention has been made to solve the above problems on the premise that it can be applied to various modulation methods. The object of the inventions of claims 1 and 2 is to provide bursting. An object of the present invention is to provide an automatic gain control device having good response characteristics to signals and high gain control accuracy.

A third object of the present invention is to provide an automatic gain control device having good response characteristics to burst signals and always high gain control accuracy.

An object of the invention of claim 4 is to provide an automatic gain control device which has a good response characteristic to a burst signal and a higher gain control accuracy.

A fifth object of the present invention is to provide an automatic gain control device which has a good response characteristic to a burst signal and a higher gain control accuracy.

It is another object of the present invention to provide an automatic gain control device having good response characteristics to burst signals and high gain control accuracy.

An object of the invention of claim 7 is to provide an automatic gain control device having a good response characteristic to a burst signal and capable of easily detecting a control timing and having a high gain control accuracy.

It is another object of the present invention to provide an automatic gain control device having a high response characteristic with respect to a burst signal and capable of easily detecting a control timing with high precision and having a high gain control precision.

It is another object of the present invention to provide an automatic gain control device which has a good response characteristic to a burst signal and can detect a control timing with high accuracy, and which has high gain control accuracy.

Further, an object of the invention of claim 10 is to provide an automatic gain control device having a high response accuracy with respect to a burst signal and capable of obtaining reception signal strength information with high accuracy and having high gain control accuracy.

[0025]

An automatic gain control apparatus according to the invention of claim 1 is a variable gain amplifier for amplifying a received burst signal with a predetermined gain, and based on the burst signal input to the variable gain amplifier. A feedforward control unit for controlling the gain, a feedback control unit for controlling the gain based on the burst signal output from the variable gain amplifier, a burst detection unit for detecting the burst signal, and the burst detection unit A control unit is provided that controls switching between operations of the feedforward control unit and the feedback control unit based on detection of a burst signal.

An automatic gain control device according to a second aspect of the present invention is the automatic gain control device according to the first aspect, in which the control section feeds the feed for a predetermined time after the burst signal is detected by the burst detection section. The forward control unit is operated and then stopped, and switching control is performed so as to operate the feedback control unit.

An automatic gain control device according to a third aspect of the present invention is the automatic gain control device according to the second aspect, wherein the variable gain amplifier is the feedforward control unit during operation of the feedforward control unit. The gain is controlled on the basis of the control value from, and the gain is controlled on the basis of the control value from the feedback control section and the control value held by the feedforward control section during the operation of the feedback control section.

An automatic gain control device according to a fourth aspect of the present invention is the automatic gain control device according to the second aspect, wherein the variable gain amplifier is the feedforward control unit during operation of the feedforward control unit. The gain is controlled based on the control value from the feedback control unit and the control value held by the feedback control unit, and the control value from the feedback control unit and the feedforward control unit hold the gain while the feedback control unit is operating. The gain is controlled based on the control value.

An automatic gain control device according to a fifth aspect of the present invention is the automatic gain control device according to the fourth aspect, wherein the feedback control unit has a response time longer than a burst time of the burst signal. The control value is determined by averaging over a plurality of burst times.

An automatic gain control device according to a sixth aspect of the present invention is the automatic gain control device according to the fifth aspect, wherein the control value from the feedback control unit is updated at a timing at which the burst signal is not received. It

An automatic gain control device according to a seventh aspect of the present invention is the automatic gain control device according to the first aspect, wherein the burst detection unit detects envelope signals of burst signals input to the variable gain amplifier. Presence or absence of a burst signal is detected based on the level.

An automatic gain control device according to an eighth aspect of the invention is the automatic gain control device according to the seventh aspect, wherein the burst detection section detects envelope signals of burst signals input to the variable gain amplifier. Presence or absence of a burst signal is detected based on the differential value of the level.

An automatic gain control device according to a ninth aspect of the present invention is the automatic gain control device according to the first aspect, wherein the burst detection unit detects a burst signal based on detection of a predetermined code included in the burst signal. The presence of is detected.

Further, the automatic gain control device according to the invention of claim 10 is the automatic gain control device according to claim 1, in which the level of the burst signal input to the variable gain amplifier and the feedback control section are determined. An intensity display signal generation unit that generates a received signal intensity display signal based on the control value is provided.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to FIGS. 1 and 2. Figure 1
FIG. 3 is a block diagram showing a circuit configuration of a receiving device having the automatic gain control device according to the first embodiment of the present invention, which receiving device is used in a TDMA communication system. In the figure, 1 is an antenna, and 2 is a high-frequency amplifier circuit for amplifying a high-frequency signal received from the antenna 1. Reference numeral 3 is a frequency conversion circuit for converting the high frequency signal amplified by the high frequency amplification circuit 2 into an intermediate frequency signal, and the output signal thereof is branched and input to the AGC amplification circuit 4 and the envelope detection circuit 8.

The AGC amplifier circuit 4 is a circuit for amplifying the intermediate frequency signal with a gain controlled so as to keep the signal amplitude input to the demodulator in the subsequent stage constant, and the quadrature detection circuit which is the demodulator for the amplified signal. Output to 5.

Further, the envelope detection circuit 8 performs envelope detection on the input signal of the AGC amplifier circuit 4, and outputs the obtained signal amplitude information to the AD converter 9 and the RSSI correction section 21. R
The SSI correction unit 21 corrects the input signal amplitude information with a signal from a digital integrator 14 described later, and outputs it as received signal strength indication (RSSI) data 22 indicating the received signal strength. The AD converter 9 also performs analog / digital conversion of the input signal amplitude information, quantizes it, and outputs it.

Reference numeral 11 is a feedforward control amount estimation unit, which generates a control value of the AGC amplifier circuit 4 based on an input signal from the AD converter 9, and which is supplied via an adder circuit 13 and a DA converter 12. Output to the gain control terminal of the AGC amplifier circuit 4. That is, the feedforward control amount estimation unit 11 outputs a control value for performing feedforward control for controlling the gain of the AGC amplifier circuit 4 based on the amplitude information of the input signal of the AGC amplifier circuit 4. Further, the operation is activated / stopped under the control of the switching control unit 18 which will be described later, and when stopped, the control value immediately before is held and stopped in the output state. The adder circuit 13 adds the output of the feedforward control amount estimation unit 11 and the output of a digital integrator 14 to be described later, and outputs the added signal.
Performs digital / analog conversion of this added signal and outputs it.

Reference numeral 10 denotes a burst detection unit, which indicates that the input signal from the AD converter 9 has reached a predetermined level, for example, a value corresponding to the minimum reception level defined by the system in which this receiver is used. It detects and determines that there is a received burst signal, and outputs a burst detection signal 25. Further, instead of the above, the burst detection unit 10 determines that the received burst signal is present when the differential value of the input signal reaches a predetermined level, for example, the minimum signal-to-noise power ratio equivalent value defined by the system. May be.

The burst detection unit 10 and the feedforward control amount estimation unit 11 perform processing for averaging the quantized detection signal over several symbol intervals in order to remove the amplitude fluctuation component due to the modulation on the signal. As a result, the gain control accuracy for the AGC amplifier circuit 4 is improved. As the processing for removing the modulation component, the root mean square processing may be performed instead of the above averaging processing, and the same effect can be obtained. Although the length of the averaging section is set to a few symbol sections, it is set to the minimum necessary length according to the modulation method and burst format. For example, if the modulation method is a frequency modulation system and a modulation component hardly appears in the amplitude, the averaging section may be short. In the burst format, if the data is known to be constant or is known data in advance, the averaging interval may be short. As a result, the loop delay does not pose a problem in the feedforward control, and the control capable of responding to the burst signal can be speeded up.

On the other hand, the quadrature detection circuit 5 quadrature-detects the input intermediate frequency signal and converts it into a baseband signal.
Output the Q signal. Reference numeral 6 is an AD converter for converting the I and Q signals into digital information, and 7 is a digital decoder for decoding the digital information and converting it into a received data string.

Reference numeral 16 denotes an amplitude estimation unit which receives the digital information output from the AD converter 6 and generates amplitude information of the burst signal on the output side of the AGC amplifier circuit 4. The generated amplitude information is used for error comparison. It is compared with the reference amplitude 17 in the instrument 15. The error comparator 15 outputs an error of the amplitude information with respect to the reference amplitude 17 as an error signal.

The digital integrator 14 inputs the error signal, can sufficiently attenuate the amplitude fluctuation component due to the modulation, and performs the averaging process over a section that is sufficiently short for the length of the reception burst. Generates the control value of. It is desirable that the sampling frequency for inputting the error signal is two or more times for one data symbol period, especially in the case of the modulation method in which the envelope curve changes. The accuracy of the control value is improved by averaging the error signals sampled multiple times. Then, this control value is added to the output of the feedforward control amount estimation unit 11 by the addition circuit 13, and the DA converter 12
Is input to the gain control terminal of the AGC amplifier circuit 4 via. That is, the digital integrator 14 outputs a control value for performing feedback control for controlling the gain of the AGC amplifier circuit 4 based on the amplitude information of the output signal of the AGC amplifier circuit 4. Since the response time of the feedback control is dominated by the averaging time, it is long enough to sufficiently attenuate the amplitude fluctuation component due to the modulation and short for the length of the reception burst. In addition, the switching control unit 1 described later
The operation is started / stopped by the control from 8, and the integrated value up to that point is reset when stopped.

The switching control section 18 receives the burst detection signal 25 output from the burst detection circuit 10 and, after a predetermined time, stops the operation of the feedforward control amount estimating section 11 and operates the digital integrator 14. Switching control is performed. Further, the input TDMA timing signal 19 is counted, and after a predetermined time has elapsed after switching, the operation of the digital integrator 14 is stopped and the operation of the feedforward control amount estimation unit 11 is operated. It should be noted that instead of counting the TDMA timing signal 19, the disappearance of the burst detection signal 25 of the burst detection circuit 10 is detected, and at the end timing of the data section 1034, which will be described later, from the digital integrator 14 to the feedforward control amount estimation unit 11. Switching control may be performed.

FIG. 2 is a diagram showing the operation timing of the automatic gain control apparatus of the first embodiment and the TDMA frame format and reception burst format used in the TDMA communication system. The system has a synchronization channel section 101 and a random access channel section 10
2, signals are transmitted and received according to a TDMA frame 100 composed of an upstream user channel section 103 and a downlink user channel section 104. This figure shows an example in which the receiving apparatus according to the present invention is provided on the base station side, and the timing at which the receiving apparatus operates is a random access channel section 102 and an upstream user channel section 103.

This random access channel section 10
2. In the upstream user channel section 103, there are a plurality of reception channels used by a plurality of communication partner stations at respective timings. Each reception channel becomes a burst-shaped reception signal, and the reception level varies depending on the communication partner station for each reception channel. There are also receive channels where there is no receive burst signal. Reference numeral 1030 denotes a burst signal of one reception channel existing in the uplink user channel section 103.
Preamble section 1032, unique word section 103
3, a payload (data) section 1034, and a ramp-down section 1035.

Next, the gain control operation of the AGC amplifier circuit 4 will be described with reference to FIG. First, in the initial state in which no signal is received, the switching control unit 18 controls the operation of the digital integrator 14 to be in a stopped state and the operation of the feedforward control estimation unit 11 to be in a stopped state or an operating state. .

When the burst signal 1030 is received, the burst detection circuit detects that the input signal has reached a predetermined level, and outputs the burst detection signal 25 at the beginning of the ramp amplifier section 1031 (burst detection 200).
Upon receiving this burst detection signal 25, the switching control unit 1
When the feedforward control amount estimation unit 11 is in the operating state, 8 is operated as it is, and when the feedforward control amount estimating unit 11 is in the stopped state, it is operated (operating section 201). At the same time, the counting of the TDMA timing signal 19 is started, and a predetermined time is counted, and the operation of the feedforward control amount estimation unit 11 is stopped. At this time, the feedforward control amount estimation unit 1
In No. 1, the operation is stopped in the state in which the control value immediately before the stop is output (stop (hold) section 202). Further, during the predetermined time, the ramp-up section 1031 ends, and the feedforward AGC including the envelope detection circuit 8, the AD converter 9, the feedforward control amount estimation unit 11, the addition circuit 13, and the DA converter 12 is performed. The time (convergence time 203) corresponds to the elapse of the convergence time of the part.

Usually, the preamble section 1032 of the received burst signal is a signal section provided for the demodulator of the receiving apparatus to perform the synchronization operation with the burst signal, and the signal received in this section has a constant amplitude, Alternatively, it is a signal modulated with known data. The feed-forward control amount estimation unit 11 to which the signal is input predicts the average value of the signal amplitude based on this characteristic of the received signal, shortens the averaging section, and determines the control value of the AGC amplifier circuit 4 at high speed. The determined control value is input to the gain control terminal of the AGC amplifier circuit 4 via the adder circuit 13 and the DA converter 12, and
The gain of the amplifier circuit 4 is controlled.

Therefore, during the operation of the feedforward control amount estimation unit 11, the AGC amplifier circuit 4 performs gain control at high speed in response to the burst-like fluctuation of the input signal, and the demodulator at the subsequent stage outputs the burst signal. It is possible to demodulate without deterioration.

Next, the switching control unit 18 puts the feedforward control amount estimation unit 11 into the stopped state, and at the same time,
The digital integrator 14 is switched to the operating state, and the feedback AGC unit including the amplitude estimating unit 16, the error comparator 15, the digital integrator 14, the adding circuit 13, and the DA converter 12 is activated.

Digital integrator 14 to which a signal is input
In the operation section 301, the amplitude fluctuation component due to the modulation can be sufficiently attenuated as described above, and the averaging is performed over a section that is sufficiently short with respect to the length of the reception burst.
The control value of the C amplifier circuit 4 is determined. At this time, the feedforward control amount estimation unit 11 holds the control value and stops in a state where the control value is output.
The gain of the amplifier circuit 4 is preset. Therefore, the control value output from the digital integrator 14 is A
It becomes a correction value for correcting the error between the level of the output signal of the GC amplifier circuit 4 and the desired value. This correction value is added to the control value held by the feedforward control amount estimation unit 11 in the addition circuit 13, and is added via the DA converter 12 to the AG.
It is input to the gain control terminal of the C amplifier circuit 4 and controls the gain of the AGC amplifier circuit 4.

Therefore, during the operation of the digital integrator 14, the gain of the AGC amplifier circuit 4 is set by the control value inherited from the feedforward AGC section, so that stable gain control is performed immediately after switching. Further, by correcting the error due to the temperature and the frequency of the received signal caused by the feedforward control with the control value from the feedback AGC unit, it is possible to always ensure high control accuracy. Further, since the gain control is performed with an appropriate response time, it is possible to prevent the modulation component from being removed from the reception signal modulated by the unknown data received in the data section 1034, and maintain the quality of the demodulation signal.

Next, the switching controller 18 causes the TDM
Based on the count of the A timing signal 19, the operation of the digital integrator 14 is stopped at the end timing of the data section 1034 (stop (reset) section 302), the feedforward control amount estimating unit 11 is operated, or the operation is stopped. As it is, it prepares to receive the next burst signal. The digital integrator 14 resets the integrated value up to that point. In the above, when the feedforward control amount estimation unit 11 is left in the stopped state, it is activated when the next burst signal is detected, that is, when the burst detection signal 25 is input from the burst detection unit 10 (operation / stop 204). .

On the other hand, the envelope detection circuit 8 operates during the reception of the burst signal even when the operation of the feedforward control amount estimation unit 11 is stopped, and the signal amplitude information is sent to the RSSI.
Output to the correction unit 21. Regarding the information on the received signal strength, the output signal of the envelope detection circuit 8 is corrected by the output of the digital integrator 14 by the RSSI correction section 21, and then output as received signal strength indication (RSSI) data 22. Therefore, it is possible to obtain accurate received signal strength information while the digital integrator 14 is operating.

Embodiment 2. Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a block diagram showing a circuit configuration of a receiving device having an automatic gain control device according to a second embodiment of the present invention. In the figure, the same symbols as those in FIG. 1 indicate the same or equivalent components.

Similar to the first embodiment, the switching control unit 18 receives the burst detection signal 25 output from the burst detection circuit 10 and, after a predetermined time, stops the operation of the feedforward control amount estimation unit 11 and performs digital integration. The operation of the digital integrator 14 is stopped at the end timing of the data section 1034, and the operation of the feedforward control amount estimation unit 11 is operated. Also, a timing signal is output to an integrator output latch 24 described later so as to latch the output of the digital integrator 14 at a known timing when the receiver does not operate, for example, in the synchronization channel section 101 in the receiving device on the base station side. . The output timing of this timing signal may be the receiver stop period, and may be the timing of the downlink user channel section 104, for example.

The digital integrator 14 inputs the error signal from the comparison circuit 15 and performs an averaging process to generate a gain control value for the AGC amplifier circuit 4. It is desirable that the sampling frequency for inputting the error signal is two or more times for one data symbol period, especially in the case of the modulation method in which the envelope curve changes.
Here, the section in which the averaging process is performed is a section shorter than the length of the reception burst in the first embodiment, but in the second embodiment, it is a section over a plurality of reception bursts. By averaging the sampled error signals over a plurality of reception bursts, the amplitude fluctuation component due to modulation can be sufficiently attenuated to improve the control value accuracy, and the reception burst length can be reduced as in the case of user transmission rate variable TDMA. Even in a system that becomes extremely short, the accuracy of gain control can be improved.

Under the control of the switching controller 18, the integrator output latch 24 latches the correction value generated by the digital integrator 14 at the timing when the receiver is not operating, and outputs it to the adder circuit 13.

That is, the digital integrator 14 uses the AG
Feedback control for controlling the gain of the AGC amplifier circuit 4 is performed based on the amplitude information of the output signal of the C amplifier circuit 4. The control value is latched by the integrator output latch 24 at the timing when the receiver is not operating and added. It is output to the circuit 14. The response time of the feedback control is longer than one burst time due to the averaging over the plurality of bursts. Further, as described above, in order to enable the control value to be latched at the timing when the receiver is not operating, the integration operation is interrupted while the integrated value up to that time is held when stopped.

FIG. 4 is a diagram showing the operation timing of the automatic gain control apparatus of the second embodiment, the TDMA frame format, and the reception burst format. In the figure, the same symbols as those in FIG.

The gain control operation of the AGC amplifier circuit 4 will be described with reference to FIG. First, in the initial state in which no signal is received, the switching control unit 18 controls the operation of the digital integrator 14 to be in a stopped state and the operation of the feedforward control estimation unit 11 to be in a stopped state or an operating state. .

Upon receiving the burst signal 1030, the burst detection circuit detects that the input signal has reached a predetermined level, and outputs the burst detection signal 25 at the beginning of the ramp amplifier section 1031 (burst detection 200).
Upon receiving this burst detection signal 25, the switching control unit 1
When the feedforward control amount estimation unit 11 is in the operating state, 8 is operated as it is, and when the feedforward control amount estimating unit 11 is in the stopped state, it is operated (operating section 201). At the same time, the counting of the TDMA timing signal 19 is started, and a predetermined time is counted, and the operation of the feedforward control amount estimation unit 11 is stopped. At this time, the feedforward control amount estimation unit 1
1 holds the control value immediately before the stop, and stops the operation in the output state (stop (hold) section 202). Further, during the predetermined time, the ramp-up section 1031 ends, and the feedforward AGC including the envelope detection circuit 8, the AD converter 9, the feedforward control amount estimation unit 11, the addition circuit 13, and the DA converter 12 is performed. The time corresponding to the passage of the convergence time of the part
3).

Normally, the preamble section 1032 of the received burst signal is a signal section provided for the demodulator of the receiving apparatus to perform the synchronization operation with the burst signal, and the signal received in this section has a constant amplitude, Alternatively, it is a signal modulated with known data. The feed-forward control amount estimation unit 11 to which the signal is input predicts the average value of the signal amplitude based on this characteristic of the received signal, shortens the averaging section, and determines the control value of the AGC amplifier circuit 4 at high speed. The determined control value is input to the gain control terminal of the AGC amplifier circuit 4 via the adder circuit 13 and the DA converter 12, and
The gain of the amplifier circuit 4 is controlled.

Therefore, during the operation of the feedforward control amount estimation unit 11, the AGC amplifier circuit 4 performs gain control at a high speed in response to the burst-like fluctuation of the input signal, and the demodulator in the subsequent stage outputs the burst signal. It is possible to demodulate without deterioration.

Next, the switching control unit 18 puts the feedforward control amount estimation unit 11 into the stopped state, and at the same time,
The digital integrator 14 is switched to the operating state, and the feedback AGC unit including the amplitude estimating unit 16, the error comparator 15, the digital integrator 14, the adding circuit 13, and the DA converter 12 is activated.

Digital integrator 14 to which a signal is input
In the sampling / averaging section 401, an integration operation is performed so as to perform averaging over a plurality of reception burst sections, and the gain control value of the AGC amplifier circuit 4 is determined.
Specifically, the loop response time of the feedback AGC unit is set to be longer than one burst time, and the feedforward control amount estimation unit 11 switches and operates every time it stops to sample and integrate the error signal at a predetermined timing. . Then, the operation of stopping the reception while the feedforward control amount estimation unit 11 is operating and holding the integrated value is repeated. This integrated value becomes the control value of the AGC amplifier circuit 4.

Here, this control value is not latched in the integrator output latch 24 during the operation of the digital integrator 14. Therefore, while the digital integrator 14 is in operation, the AGC amplifier circuit 4 is already in the integrator output latch 2
The gain is controlled by the added value of the control value from the feedback AGC unit latched in No. 4 and the control value held by the feedforward control amount estimation unit 11. As in the first embodiment, since the gain of the AGC amplifier circuit 4 is set by the control value inherited from the feedforward AGC unit, stable gain control is performed immediately after switching. Further, by correcting the error due to the temperature and the frequency of the received signal in the feedforward control with the control value latched in the integrator output latch 24, it becomes possible to secure high control accuracy.

Next, the switching controller 18 causes the TDM
Based on the count of the A timing signal 19, the operation of the digital integrator 14 is stopped at the end timing of the data section 1034 (stop (hold) section 402), the feedforward control amount estimation unit 11 is operated, or the operation is stopped. As it is, it prepares to receive the next burst signal. The digital integrator 14 holds the accumulated value up to that point. In the above, when the feedforward control amount estimation unit 11 is left in the stopped state, it is activated when the next burst signal is detected, that is, when the burst detection signal 25 is input from the burst detection unit 10 (operation / stop 204). .

Further, the switching control section 18 outputs a timing signal to the integrator output latch 24 in the synchronization channel section 101 in which the receiver does not operate. In response to this timing signal, the integrator output latch 24 latches the control value held by the digital integrator 14. As a result, the control value (correction value) output from the feedback AGC unit is regularly updated (control value update 40
3).

Therefore, since the gain of the AGC amplifier circuit 4 is not frequently controlled during the operation of the digital integrator 14, that is, during the data reception, the demodulation due to the frequent fluctuation of the level input to the demodulator. It is possible to prevent signal quality deterioration. Further, since averaging is performed over a plurality of bursts, in demodulation of a reception signal modulated with unknown data received in the data section 1034, it is possible to prevent the modulation component from being removed and maintain the quality of the demodulation signal.

When the burst signal 1030 is received next time, the AGC amplifier circuit 4 latches the control value from the feedforward AGC unit in the integrator output latch 24 while the feedforward control amount transition constant unit 11 is operating. The gain is controlled by the control value corrected by the corrected value. Therefore, it is possible to realize gain control with high accuracy and high speed response.

On the other hand, the envelope detection circuit 8 operates during the reception of the burst signal even if the operation of the feedforward control amount estimation unit 11 is stopped, and the signal amplitude information is sent to the RSSI.
Output to the correction unit 21. Regarding the information on the received signal strength, the output signal of the envelope detection circuit 8 is corrected by the output from the integrator output latch 24 in the RSSI correction section 21, and then output as received signal strength indication (RSSI) data 22. Therefore, it is possible to always obtain accurate received signal strength information.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 is a block diagram showing a circuit configuration of a receiving apparatus having an automatic gain control apparatus according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG. 3 indicate the same or equivalent elements.

The received data string converted by the digital decoder 7 is input to the unique word detector 20. The unique word detector 20 detects a unique word that is a known code included in the received data string and outputs a unique word detection signal 26. This unique word detection signal 2
6 is used for TDMA frame synchronization, and at the same time, is input as a timing signal to the switching control unit 18. Since the unique word is a code that is always included in the received burst signal, the received burst signal can be detected by detecting the unique word. Therefore, the unique word detection unit 20 operates as a burst detection unit that detects a burst signal.

Reference numeral 27 denotes an averaging circuit for averaging the amplitude information output from the amplitude estimating section 16, which outputs the amplitude information obtained by averaging one or more data symbol intervals and removing the amplitude fluctuation component due to modulation. The error comparator 15 compares the averaged amplitude information with the reference amplitude 17 and outputs an error signal.

Upon receiving the unique word detection signal 26 output from the unique word detector 20, the switching control unit 18 stops the operation of the feedforward control amount estimating unit 11 and switches the operation of the digital integrator 14. The operation of the digital integrator 14 is stopped at the end timing of the data section 1034, and the operation of the feedforward control amount estimation unit 11 is operated. In addition, immediately before stopping the operation of the digital integrator 14,
A sampling signal indicating the timing for sampling the error signal is output to the digital integrator 14. Further, a timing signal is output to the integrator output latch 24 so as to latch the output of the digital integrator 14 at a known timing when the receiver does not operate.

The digital integrator 14 averages the error signal from the comparison circuit 15 in the section over a plurality of reception bursts to generate the gain control value of the AGC amplifier circuit 4. The averaging process is performed on the error signal sampled over a plurality of bursts based on the sampling signal from the switching control unit 18. Since the error signal to be sampled is a signal from which the amplitude fluctuation component due to modulation is removed in the averaging circuit 27, an accurate error signal can be sampled even if sampling is performed once for one reception burst. Then, by sampling just before the stop, the control value can be generated based on the error signal in a more stable state, and the gain control accuracy can be further improved.

FIG. 6 is a diagram showing the operation timing of the automatic gain control apparatus of the third embodiment, the TDMA frame format, and the reception burst format. In the figure, the same reference numerals as those in FIG.

The operation of gain control of the AGC amplifier circuit 4 will be described with reference to FIG. First, in the initial state where no signal is received, the switching control unit 18 controls the operation of the digital integrator 14 to be in a stopped state and the operation of the feedforward control estimation unit 11 to be in an operating state.

When the burst signal 1030 is received, the feedforward control amount estimator 11 which is already in the operating state.
Determines the control value of the AGC amplifier circuit 4 based on the input signal (operation section 501). The determined control value is input to the gain control terminal of the AGC amplifier circuit 4 via the adder circuit 13 and the DA converter 12, and controls the gain of the AGC amplifier circuit 4. As in the first and second embodiments, AGC amplifier circuit 4 can perform demodulation without degrading the burst signal because gain control is performed at high speed in response to the burst-like fluctuation of the input signal.

Next, the switching control unit 18 receives the unique word detection signal 26 from the unique word detector 20 (unique word detection 601), puts the feedforward control amount estimation unit 11 into the stopped state, and at the same time, performs digital integration. The amplitude estimation unit 1 is switched to the operating state of the instrument 14.
6. The feedback AGC unit including the averaging circuit 27, the error comparator 15, the digital integrator 14, the adding circuit 13, and the DA converter 12 is operated. The feedforward control amount estimation unit 11 holds the control value immediately before the stop, and stops the operation in the output state (stop (hold)).
Section 502).

Digital integrator 14 to which a signal is input
Performs an integrating operation in the averaging section 602 so as to perform averaging over a plurality of reception burst sections. Specifically, the loop response time of the feedback AGC unit is set to 1
It is set to be longer than the burst time, and the feedforward control amount estimation unit 11 switches and operates every time it stops, and the error signal is sampled once per burst based on the sampling signal (error signal sampling 60
3). Then, while the reception is stopped and the feedforward control amount estimation unit 11 is operating, the operation of stopping in a state of holding the integrated value obtained by integrating the sampled error signal is repeated. This integrated value becomes the control value of the AGC amplifier circuit 4.

This control value is not latched in the integrator output latch 24 while the digital integrator 14 is operating, as in the second embodiment. Therefore, during the operation of the digital integrator 14, the AGC amplifier circuit 4 is configured so that the integrator output latch 24 has already added the control value from the feedback AGC unit and the control value held by the feedforward control amount estimation unit 11. The gain is controlled by. As in the first and second embodiments, the gain of the AGC amplifier circuit 4 is set by the control value inherited from the feedforward AGC unit, so that stable gain control is performed immediately after switching. Further, by correcting the error due to the temperature and the frequency of the received signal in the feedforward control with the control value latched in the integrator output latch 24, it becomes possible to secure high control accuracy.

Next, the switching controller 18 causes the TDM
Based on the count of the A timing signal 19, the operation of the digital integrator 14 is stopped at the end timing of the data section 1034 (stop (hold) section 605), the feedforward control amount estimation unit 11 is operated, and the next burst signal is generated. To prepare for reception (operation section 501).

Further, the switching control section 18 outputs a timing signal to the integrator output latch 24 in the synchronization channel section 101 in which the receiver does not operate. In response to this timing signal, the integrator output latch 24 latches the control value held by the digital integrator 14. As a result, the control value (correction value) output from the feedback AGC unit is regularly updated (control value update 60
4).

Therefore, since the gain of the AGC amplifier circuit 4 is not frequently controlled during the operation of the digital integrator 14, that is, during the data reception, the demodulation due to the frequent fluctuation of the level input to the demodulator. It is possible to prevent signal quality deterioration. Further, since the error signal is generated using the averaged amplitude information, in demodulation of the reception signal modulated by unknown data received in the data section 1034, the modulation component is prevented from being removed, and the demodulation signal of the demodulation signal Quality can be maintained. Furthermore, since the error signal is sampled immediately before the end of the data section 1034, the control value can be determined based on the error signal in a more stable state, and the accuracy of gain control is improved.

When the burst signal 1030 is received next time, the AGC amplifier circuit 4 latches the control value from the feedforward AGC unit in the integrator output latch 24 while the feedforward control amount transition constant unit 11 is operating. The gain is controlled by the control value corrected by the corrected value. Therefore, it is possible to realize gain control with high accuracy and high speed response.

On the other hand, the envelope detection circuit 8 operates during the reception of the burst signal even when the operation of the feedforward control amount estimation unit 11 is stopped, and the signal amplitude information is sent to the RSSI.
Output to the correction unit 21. Regarding the information on the received signal strength, the output signal of the envelope detection circuit 8 is corrected by the output from the integrator output latch 24 in the RSSI correction section 21, and then output as received signal strength indication (RSSI) data 22. Therefore, it is possible to always obtain accurate received signal strength information.

[0090]

As described above, the automatic gain control device according to the first aspect of the present invention is configured to switch the operations of the feedforward control unit and the feedback control unit based on the detection of the burst signal. The response characteristics are good and the gain can be controlled with high accuracy.

According to a second aspect of the present invention, in the automatic gain control device according to the first aspect, the feedforward control section is operated for a predetermined time after detection of the burst signal and then stopped, and the feedback control section is operated. Since the switching is performed so that the burst signal has a good response characteristic, the gain can be controlled with high accuracy.

According to the third aspect of the present invention, in the automatic gain control device according to the second aspect, the gain is controlled based on the control value from the feedforward control unit during the operation of the feedforward control unit, and the feedback control is performed. Since the gain is controlled based on the control value from the feedback control unit and the control value held by the feedforward control unit during the operation of the unit, the response characteristic to the burst signal is good and the gain can always be controlled accurately.

According to a fourth aspect of the present invention, in the automatic gain control apparatus according to the second aspect, the control value from the feedforward control unit and the control held by the feedback control unit during the operation of the feedforward control unit. The gain is controlled based on the value, and the gain is controlled to be constant based on the control value from the feedback control unit and the control value held by the feedforward control unit while the feedback control unit is operating. And the gain can be controlled with higher accuracy.

According to a fifth aspect of the present invention, in the automatic gain control device according to the fourth aspect, the response time of the feedback control section is made longer than the burst time of the burst signal and averaged over a plurality of burst times. Since the control value is determined, the response characteristic to the burst signal is good, and the gain can be controlled more accurately.

Further, the automatic gain control device according to claim 6 of the present invention has the structure of claim 5 in which the control value from the feedback control unit is updated at a timing at which a burst signal is not received. It is possible to control the gain with good response characteristics to the signal and to accurately control the gain, and further, it is possible to avoid the adverse effect on the received signal due to the variable gain during burst reception.

According to a seventh aspect of the present invention, in the automatic gain control apparatus according to the first aspect, the burst signal is detected based on the envelope detection level of the burst signal input to the variable gain amplifier. Therefore, the response characteristic to the burst signal is good, the control timing can be easily detected, and the gain can be controlled with high accuracy.

In the automatic gain control device according to claim 8 of the present invention, in the configuration of claim 7, burst signal detection is performed based on the differential value of the envelope detection level of the burst signal input to the variable gain amplifier. Since it is configured to do so,
The response characteristic to the burst signal is good, the control timing thereof can be easily and accurately detected, and the gain can be accurately controlled.

Further, since the automatic gain control device according to claim 9 of the present invention has a structure in which the burst signal is detected based on the detection of a predetermined code included in the burst signal in the structure of claim 1, the burst signal is detected. The response characteristic to the signal is good, the control timing can be detected with high accuracy, and the gain can be controlled with high accuracy.

Further, according to a tenth aspect of the present invention, in the automatic gain control device according to the first aspect, the received signal is received based on the level of the burst signal input to the variable gain amplifier and the control value determined by the feedback control section. Since the intensity display signal is generated, the response characteristic to the burst signal is good, the gain can be controlled with high precision, and the intensity information of the received signal can be obtained with high precision.

[Brief description of drawings]

FIG. 1 is a block diagram of a receiving device that is Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a control timing of the automatic gain control device according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a receiving device which is Embodiment 2 of the present invention.

FIG. 4 is a diagram showing a control timing of the automatic gain control device according to the second embodiment of the present invention.

FIG. 5 is a block diagram of a receiving device that is Embodiment 3 of the present invention.

FIG. 6 is a diagram showing a control timing of an automatic gain control device according to a third embodiment of the present invention.

FIG. 7 is a block diagram of a receiving device according to a first conventional technique.

FIG. 8 is a block diagram of a receiving device according to a second conventional technique.

FIG. 9 is a block diagram of a third conventional receiving device.

[Explanation of symbols]

4 AGC amplifier circuit 8 Envelope detection circuit 9 AD converter 10 Burst detection circuit 11 Feedforward control amount estimation unit 12 DA converter 13 Adder circuit 14 Digital integrator 15 Error comparator 16 Amplitude estimation unit 17 Amplitude reference 18 Switching control unit 19 TDMA slot timing signal 20 Unique word detector 21 RSSI correction unit 22 RSSI data 24 Integrator output latch 25 Burst detection signal 26 Unique word detection signal 27 Averaging circuit 100 TDMA frames 1030 burst signal 1032 preamble section 1033 Unique word section 1034 Payload (data) section 200 burst detection 201 Working section 202 Stop section 203 Convergence time 204 operation / stop section 301 working section 302 Stop (reset) section 401 Sampling / averaging interval 402 Stop (hold) section 403 Control value update 601 Unique word detection 602 Averaging section 603 Error signal sampling 604 Update control value 605 Stop (hold) section

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5J100 JA01 LA00 LA08 LA09 LA11                       QA01 SA02                 5K028 AA01 AA06 BB04 HH04 KK33

Claims (10)

[Claims] 1. A variable gain amplifier that amplifies a received burst signal with a predetermined gain, a feedforward control unit that controls the gain based on the burst signal input to the variable gain amplifier, and an output from the variable gain amplifier. A feedback control unit for controlling the gain based on the burst signal generated, a burst detection unit for detecting the burst signal, and the feedforward control unit and the feedback control unit based on detection of the burst signal by the burst detection unit. Automatic gain control device including a control unit for switching and controlling the operation of the above. 2. The control unit performs switching control so that the feedforward control unit is operated for a predetermined time after the burst signal is detected by the burst detection unit and then stopped, and the feedback control unit is operated. The automatic gain control device according to claim 1. 3. The variable gain amplifier is controlled in gain based on a control value from the feedforward control unit during operation of the feedforward control unit, and is controlled from the feedback control unit during operation of the feedback control unit. The automatic gain control device according to claim 2, wherein the gain is controlled based on a control value and a control value held by the feedforward control unit. 4. The variable gain amplifier is controlled in gain based on a control value from the feedforward control unit and a control value held by the feedback control unit during operation of the feedforward control unit, 3. The automatic gain control device according to claim 2, wherein the gain is controlled based on the control value from the feedback control unit and the control value held by the feedforward control unit during operation of the control unit. 5. The automatic control according to claim 4, wherein the feedback control unit has a response time longer than a burst time of the burst signal and averages a plurality of burst times to determine the control value. Gain control device. 6. The automatic gain control device according to claim 5, wherein the control value from the feedback control unit is updated at a timing when the burst signal is not received. 7. The automatic gain according to claim 1, wherein the burst detection unit detects the presence or absence of a burst signal based on the envelope detection level of the burst signal input to the variable gain amplifier. Control device. 8. The burst detection unit detects the presence or absence of a burst signal based on a differential value of an envelope detection level of the burst signal input to the variable gain amplifier. Automatic gain control device. 9. The automatic gain control device according to claim 1, wherein the burst detection unit detects the presence of a burst signal based on detection of a predetermined code included in the burst signal. 10. An intensity display signal generation unit for generating a received signal intensity display signal based on a level of a burst signal input to the variable gain amplifier and a control value determined by the feedback control unit. Item 2. The automatic gain control device according to item 1.