CN109787656B - Automatic gain control device for OFDM power line communication - Google Patents
Automatic gain control device for OFDM power line communication Download PDFInfo
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- CN109787656B CN109787656B CN201910075475.XA CN201910075475A CN109787656B CN 109787656 B CN109787656 B CN 109787656B CN 201910075475 A CN201910075475 A CN 201910075475A CN 109787656 B CN109787656 B CN 109787656B
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Abstract
The invention discloses an automatic gain control device for OFDM power line communication, which comprises: analog front end, gain controller, digital filter. The analog front end is used for amplifying or reducing and filtering the received power line carrier analog signals and carrying out analog-to-digital conversion on the power line carrier analog signals. The gain controller is used for generating gain control words so as to control the amplification factor of the analog front end to the power line carrier analog signals, and is also used for detecting and inhibiting pulse interference to the received power line carrier digital signals. The digital filter is used for filtering out-of-band noise and narrow-band interference of the power line carrier digital signal. The gain controller comprises a first digital gain amplifier, an impulse interference detection and suppression device, a first power estimator, a first loop filter and a gain decomposer. The automatic gain control device can greatly reduce the operation complexity of gain control, improve the anti-pulse interference capability, has small processing time delay, and is very suitable for power line communication engineering application.
Description
Technical Field
The present invention relates to the field of OFDM power line communication, and more particularly, to an automatic gain control device for OFDM power line communication.
Background
The power line communication is a communication mode for transmitting data and media signals by using a power line, and has the advantages of low construction cost, wide coverage range and the like, so that the power line communication is widely applied to the fields of intelligent home, power utilization information acquisition, electrical equipment monitoring and the like. However, power lines were originally designed to carry electrical power, and the channel characteristics were far from ideal, manifested as significant noise, severe signal degradation, and time-varying characteristics. Therefore, the power line carrier communication system which is the mainstream at present adopts the OFDM (orthogonal frequency division multiplexing) technology, effectively resists frequency selective fading, multipath interference and various noises on the power line by adopting long-cycle pre-dropping and combining diversity copying and channel coding technologies, and realizes high-speed and reliable data transmission on the power line.
The performance of the OFDM communication system is easily influenced by the power of a received signal, when the power of the received signal is overlarge, the output signal of the analog-to-digital converter overflows, a truncation effect is generated, and the performance of a receiver is reduced; if the signal is too small, quantization distortion increases, and the sensitivity of the receiver decreases. Therefore, automatic gain control is required to adjust the gain amplifier of the receiver, so that the amplitude of the input signal of the ADC (analog-to-digital converter) is adjusted to the optimal position suitable for demodulation, the dynamic range of the ADC is fully utilized, quantization distortion is reduced, and the performance of the receiver is improved.
Most of the currently used power line communication automatic gain control technologies pay attention to the gain adjustment precision and the dynamic range, and do not consider the factors of significant environmental noise of a power line, short burst transmission frame length (mostly in a few milliseconds, and generally only 20-30 milliseconds at most) and slow channel change, so that the problems of high operation complexity, long processing time delay and the like are caused, and the power line communication automatic gain control technologies are not suitable for engineering application.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide an automatic gain control device for OFDM power line communication, which can greatly reduce the operation complexity of gain control, improve the anti-pulse interference capability, has small processing time delay and is very suitable for power line communication engineering application.
In order to achieve the above object, the present invention provides an automatic gain control apparatus for OFDM power line communication, the automatic gain control apparatus being configured to perform gain control on a power line carrier signal received by an OFDM receiver, the automatic gain control apparatus comprising: analog front end, gain controller, digital filter. The analog front end comprises a programmable gain amplifier, a low-pass filter and an analog-to-digital converter, and is used for amplifying, reducing and filtering the power line carrier analog signal received by the analog front end, and performing analog-to-digital conversion on the power line carrier analog signal. The input end of the gain controller is connected with the output end of the analog front end, the output end of the gain controller is connected with the input end of the analog front end, and the gain controller is used for generating gain control words so as to control the amplification factor of the analog front end to the power line carrier analog signals and is also used for detecting and inhibiting pulse interference on the power line carrier digital signals received by the gain controller. The input end of the digital filter is connected with the output end of the gain controller and is used for filtering out the out-of-band noise and the narrow-band interference of the power line carrier digital signal received by the digital filter.
Wherein the gain controller comprises: the device comprises a first digital gain amplifier, an impulse interference detection and suppression device, a first power estimator, a first loop filter and a gain decomposer. The first digital gain amplifier is used for selecting a corresponding amplification factor according to the gain value input by the gain controller, and then amplifying the power line carrier digital signal received by the first digital gain amplifier according to the amplification factor and outputting the amplified signal. The input end of the impulse interference detection and suppression device is connected with the output end of the first digital gain amplifier and is used for carrying out impulse interference detection and suppression on the power line carrier digital signals received in real time. The input end of the first power estimator is connected with the output end of the impulse interference detection and suppressor and is used for subtracting the signal power of each sampling point of the power line carrier digital signal received by the input end of the first power estimator from the target adjusting power set by the automatic gain control device so as to obtain the power error of each sampling point. And the input end of the first loop filter is connected with the output end of the first power estimator and is used for performing integration operation on the power error of each sampling point, performing proportion operation on the power error, shifting the value after the proportion operation, removing the gain value of the fraction part and finally obtaining an integer gain value. The input end of the gain decomposer is connected with the output end of the first loop filter, the output end of the gain decomposer is respectively connected with the input end of the first digital gain amplifier and the input end of the programmable gain amplifier at the analog front end, the gain decomposer is used for generating a first gain value and a second gain value according to the gain value output by the first loop filter, the gain decomposer directly outputs the first gain value to the first digital gain amplifier, the gain decomposer converts the second gain value into the gain control word and then outputs the gain control word to the programmable gain amplifier, and the programmable gain amplifier selects a corresponding amplification factor according to the gain control word to adjust the power line carrier analog signal received by the programmable gain amplifier.
In a preferred embodiment, the first loop filter performs an integration operation on the power error of each sampling point, and the integration operation adopts the following relation: pacc(n)＝Pacc(n-1)+Perr(n)*KIWherein P isacc(n) represents the power integral value, P, of the nth sample pointerr(n) represents the power error of the nth sample point, KIRepresenting a custom integral coefficient; then, performing a scaling operation, then shifting a value after the scaling operation, removing a gain value of a fractional part, and finally obtaining an integer gain value, wherein the operation adopts the following relational expression: pgain(n)＝(Pacc(n)+Perr(n)*Kp)>>LfracWherein P isacc(0)＝0，KpFor a custom scale factor, LfracIs a fractional word length.
In a preferred embodiment, the generating the first gain value and the second gain value by the gain decomposer comprises: the gain decomposer judges whether an integer gain value output by the first loop filter is within an effective gain range of the programmable gain amplifier, if so, the first gain value is 0dB, and the second gain value is the gain value output by the first loop filter; if the first gain value is not in the effective gain range, the first gain value is a value of a part of the gain value output by the first loop filter, which exceeds the effective gain range, and the second gain value is a value of a part of the gain value output by the first loop filter, which does not exceed the effective gain range.
In a preferred embodiment, the automatic gain control apparatus further comprises a digital gain compensator, an input terminal of the digital gain compensator is connected to an output terminal of the digital filter, and the digital gain compensator is configured to compensate for signal power loss caused by the digital filter.
In a preferred embodiment, the digital gain compensator includes: a second digital gain amplifier, a second power estimator, and a second loop filter. And the input end of the second digital gain amplifier is connected with the output end of the digital filter and is used for amplifying the power line carrier digital signal received by the second digital gain amplifier according to the amplification factor of the second digital gain amplifier and then outputting the power line carrier digital signal. The input end of the second power estimator is connected with the output end of the second digital gain amplifier and is used for subtracting the target adjusting power of the automatic gain control device from the signal power of each sampling point of the power line carrier digital signal received by the second power estimator so as to obtain the power error P 'of each sampling point'err(n) of (a). The input end of the second loop filter is connected with the output end of the second power estimator and is used for calculating the power error P 'of each sampling point'err(n) performing weighted averaging and integration operations, namely adopting the following relational expression: p'avg(n)＝P′avg(n-1)*(1-Ka)+P′err(n)*KaAnd P'acc(n)＝P′acc(n-1)+P′avg(n)*KI'wherein, P'avg(0)＝0，P′acc(0)＝1；KaRepresents a custom weighted average coefficient, K'IIs a custom integral coefficient, the P'avg(n) represents a weighted average of the power of the nth sample point of the power line carrier digital signal received by the second power estimator, P'acc(n) represents a weighted average integrated value of the power of the nth sampling point of the power line carrier digital signal received by the second power estimator, and the weighted average integrated value is finally output to the second digital gain amplifier as the amplification factor of the second digital gain amplifier.
In a preferred embodiment, the automatic gain control apparatus further includes: a timing synchronization module, an input end of which is connected to the digital gain compensator, and an output end of which is connected to both the input end of the gain controller and the input end of the digital gain compensator, wherein the timing synchronization module is configured to determine a starting position of a frame received by the receiver, perform coarse synchronization first, and then perform fine synchronization, and when the initial starting position of the frame is detected during the coarse synchronization, the gain controller and the digital gain compensator stop gain updating, that is, the first power estimator and the first loop filter stop working, and the second power estimator and the second loop filter stop working.
In a preferred embodiment, the glitch detection and suppression device is further configured to set a pulse detection flag after the glitch is detected, otherwise, reset the pulse detection flag, and when the pulse detection flag is set, the first power estimator and the first loop filter of the gain controller stop operating.
In a preferred embodiment, the glitch detection and suppression circuit is further configured to set a pulse detection flag after a glitch is detected, otherwise, to reset the pulse detection flag, and when the pulse detection flag is set, the first power estimator and the first loop filter of the gain controller are disabled, and the second power estimator and the second loop filter of the digital gain compensator are software configurable to be disabled.
In a preferred embodiment, the automatic gain control apparatus further includes: and the input end of the demodulation and decoding module is connected with the output end of the timing synchronization module and is used for carrying out time-frequency transformation, frequency domain processing and bit level processing on the power line carrier digital signals received by the demodulation and decoding module.
In a preferred embodiment, the analog front end is implemented by an analog circuit, the gain controller, the digital filter, the digital gain compensator, the timing synchronization module, and the demodulation and decoding module are implemented by a digital circuit, and each module can be integrated into an OFDM power communication baseband chip.
Compared with the prior art, the automatic gain control device for OFDM power line communication is provided with the gain controller, the automatic gain control is realized by controlling the integral proportion of the sampling points in the gain controller, the process is calculated in real time, the received data does not need to be cached, and complicated operations such as logarithm operation and the like are not needed, the automatic gain control device greatly reduces the operation complexity and improves the operation efficiency, in the OFDM power line communication, the processing time delay of the received frame is shortened, the device is simpler to realize, and the cost is saved; a digital gain compensator is also arranged on the basis of the gain controller, and the signal power caused by the digital filter is compensated, so that the stability of the output signal can be further improved; in addition, a pulse detection and suppression device and a timing synchronization device are arranged, so that the jitter of pulse interference on gain adjustment is reduced, and the automatic gain control is faster and more stable.
Drawings
Fig. 1 is a schematic diagram of an automatic gain control apparatus for OFDM power line communication according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of the connection relationship between the analog front end and the internal structure of the gain controller according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of a digital gain compensator according to an embodiment of the present invention.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Aiming at the problems of high operation complexity, large processing time delay and the like commonly existing in the existing power line communication automatic gain control technology, the inventor makes the following thought: at present, the frame structure of the domestic and foreign power line communication standard is basically composed of a preamble, a frame control and load data. The preamble is a special periodic sequence with excellent correlation and is usually composed of a plurality of repeated forward synchronization Symbols (SYNCP) and reverse synchronization Symbols (SYNCM). The power line communication is a burst transmission mode, and considering that the power channel is a slowly varying channel, there is generally no pilot or reference signal in the OFDM symbols of the frame control and payload data, and the automatic gain control, timing synchronization and channel estimation in the receiver are all performed through the preamble. The power line has the characteristics of remarkable environmental noise, short burst transmission frame length (mostly in a few milliseconds, and the longest transmission frame length is generally only 20-30 milliseconds) and slow channel change. Therefore, the inventor provides the automatic gain control device for power line communication by utilizing the characteristics, the anti-noise capability is strong, the calculation delay is small, the complexity is low, and the automatic gain control device is more suitable for engineering application.
Fig. 1 is a schematic diagram of an automatic gain control apparatus for OFDM power line communication according to an embodiment of the present invention. Fig. 2 shows a connection relationship between the analog front end and the internal structure of the gain controller according to this embodiment. The automatic gain control device comprises an analog front end 10, a gain controller 11, a digital filter 12, and preferably a digital gain compensator 13, a timing synchronization module 14, and a demodulation and decoding module 15.
The analog front end 10 comprises a programmable gain amplifier 10a, a low pass filter 10b, an analog to digital converter 10 c. The typical effective gain range of the programmable gain amplifier 10a is-20 dB to 63dB, and the actual gain range thereof can be set externally, and if the input gain exceeds the actual gain range, the maximum or minimum value is selected. The programmable gain amplifier 10a amplifies or reduces an input analog signal by a gain control word. The low pass filter 10b is used to filter out-of-band high frequency signals. The analog-to-digital converter 10c converts the power line analog carrier signal into a digital signal, which facilitates subsequent complex digital signal processing.
The gain controller 11 generates corresponding gain control information to adjust the amplification factor of the programmable gain amplifier 10a according to the difference between the input signal power and the set target power, and performs the impulse interference detection and suppression operation on the input signal. Specifically, the gain controller 11 includes a first digital gain amplifier 11a, an impulse interference detector and suppressor 11b, a first power estimator 11c, a second loop filter 11d, and a gain decomposer 11 e.
The typical input effective gain range of the first digital gain amplifier 11a is 0-63 dB, the actual gain range can be set externally, if the input gain exceeds the actual gain range, the maximum or minimum value is selected, and a fixed lookup table is used to realize the conversion from the gain value to the amplification factor. The input signal is multiplied by the amplification factor and then subjected to saturation operation, which is the output of the first digital gain amplifier 11 a.
The pulse interference detecting and suppressing unit 11b performs pulse counting based on the input real-time sampling data, detects pulses in real time according to the pulse amplitude and width and corresponding thresholds, and performs corresponding amplitude limiting or zeroing. The pulse interference can be spread to all subcarriers of the frequency domain, the amplitude of the pulse interference is far higher than that of background noise, the requirement on the time-frequency transform FFT word length in demodulation and decoding is increased, the probability of FFT transform saturation can be effectively reduced by limiting or setting zero to the pulse interference, and the performance of a receiver is improved. The pulse detect flag will be set once a pulse disturbance is detected, and reset otherwise.
First power estimator 11c target power PtargetWith power P of each input sample pointsig(n) subtracting to obtain the power error Perr(n) is: perr(n)＝Ptarget-Psig(n)。
First loop filter 11d for power error Perr(n) performing an integration operation, and applying P to the integration resultacc(n) performing a proportional operation, shifting the gain value after the proportional operation, and removing the fractional part of the gain to obtain an integer gain value Pgain(n) is: pacc(n)＝Pacc(n-1)+Perr(n)*KIAnd Pgain(n)＝(Pacc(n)+Perr(n)*Kp)＞＞Lfrac. Wherein, Pacc(0)＝0，KI、KpRespectively configurable loop integral coefficient and proportional coefficient, LfracIs a fractional word length.
The gain decomposer 11e outputs P to the first loop filter 11dgain(n) decomposition, e.g. Pgain(n) within the effective gain range of the programmable gain amplifier 10a, the digital gain is 0dB, otherwise, the excess is the digital gain value. The digital gain value is directly output to the first digital gain amplifier 11 a. The analog gain value is converted to a gain control word of the programmable gain amplifier 10a by a programmable lookup table and then output to the programmable gain amplifier 10a of the analog front end 10.
In the control process of the gain controller 11, the gain controller 11 realizes automatic gain control by controlling the integral proportion of the sampling points, and the process carries out calculation in real time without buffering received data and carrying out complex operations such as logarithm operation and the like, so that the automatic gain control device greatly reduces the operation complexity, improves the operation efficiency and reduces the frame processing time delay. And in the control process of the gain controller 11, if the pulse detection flag is 1, the first power estimator 11c and the second loop filter 11d stop working, the output of the gain decomposer 11e is kept unchanged, interference and noise in the normal receiving process are prevented from influencing the stability of the automatic gain controller, and signal noise is effectively resisted.
The digital filter 12 is composed of a digital bandwidth/low pass filter and a cascaded second order lattice IIR notch bank. The method is used for filtering out-of-band noise and narrow-band interference, so that the signal-to-noise ratio of an output signal is improved.
Optionally, the automatic gain control apparatus further comprises a digital gain compensator 13 for compensating for the signal power loss caused by the digital filter 12. Specifically, the internal structure of the digital gain compensator 13 is shown in fig. 3, and includes a second digital gain amplifier 13a, a second power estimator 13b, and a second loop filter 13 c.
The digital gain compensator 13 mainly compensates for the signal power loss caused by the digital filter 12, and the gain compensation range is relatively small. The second digital gain amplifier 13a and the second power estimator 13b have similar structures to the first digital gain amplifier 11a and the first power estimator 11c of the gain controller 11, and the second loop filter 13c has a two-stage structure of weighted average plus integral, which is good in stability.
The algorithm of the second loop filter 13c is as follows: p'avg(n)＝P′avg(n-1)*(1-Ka)+P′err(n)*KaAnd P'acc(n)＝P′acc(n-1)+P′avg(n)*KI'wherein, P'avg(0)＝0，P′acc(0)＝1；KaRepresents a custom weighted average coefficient, K'IRepresents a custom integral coefficient, P'avg(n) represents a weighted average of the power of the nth sampling point of the power line carrier digital signal received by the second power estimator 13b, P'acc(n) represents a weighted average integrated value of the power of the nth sampling point of the power line carrier digital signal received by the second power estimator 13b, which is finally output to the second digital gain amplifier 13a as the amplification factor of the second digital gain amplifier.
Optionally, the automatic gain control apparatus further comprises a timing synchronization module 14 for determining a start position of a frame, and performing coarse synchronization and fine synchronization. In order to obtain better performance and reduce calculation delay, a cross-correlation mode is adopted; in order to reduce the complexity of the sliding cross-correlation calculation, a compressed local cross-correlation sequence is adopted during coarse synchronization, and the representation mode of the compressed local cross-correlation sequence adopts a binary exponential mode.
The demodulation and decoding module 15 includes a time-frequency transform (FFT) and subsequent frequency-domain processing and bit-level processing.
In the gain control process of the automatic gain control device for OFDM power line communication, if the coarse synchronization of the timing synchronization module 14 is found, or the impulse interference detection and suppression device 11b detects impulse interference, that is, the impulse detection flag is 1, the first power estimator 11c, the first loop filter 11d, the second power estimator 13b, and the second loop filter 13c stop working, and the outputs of the first loop filter 11d and the second loop filter 13c are kept unchanged, so that the stabilization of interference and noise influence signals in the normal receiving process is prevented, and the automatic gain can be made fast and stable.
In summary, according to the automatic gain control device for OFDM power line communication of the present embodiment, a gain controller is provided, and automatic gain control is implemented in the gain controller by performing integral-proportional control on a sampling point, and the process is performed in real time without buffering received data and performing complex operations such as logarithmic operation, so that the automatic gain control device greatly reduces the operation complexity and improves the operation efficiency, and in OFDM power line communication, the processing delay for a received frame is shortened, and the device is simpler to implement and saves the cost; a digital gain compensator is also arranged on the basis of the gain controller, and the signal power caused by the digital filter is compensated, so that the stability of the output signal can be further improved; in addition, a pulse detection and suppression device and a timing synchronization device are arranged, so that the jitter of pulse interference on gain adjustment is reduced, and the automatic gain control is faster and more stable.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (10)
1. An automatic gain control apparatus for OFDM power line communication, the automatic gain control apparatus performing gain control on a power line carrier signal received by an OFDM receiver, comprising:
the analog front end comprises a programmable gain amplifier, a low-pass filter and an analog-to-digital converter and is used for amplifying, reducing and filtering the power line carrier analog signals received by the analog front end and performing analog-to-digital conversion on the power line carrier analog signals;
the input end of the gain controller is connected with the output end of the analog front end, the output end of the gain controller is connected with the input end of the analog front end, and the gain controller is used for generating gain control words so as to control the amplification factor of the analog front end to the power line carrier analog signals and is also used for detecting and inhibiting pulse interference on the power line carrier digital signals received by the gain controller; and
a digital filter, the input end of which is connected with the output end of the gain controller and is used for filtering out the out-of-band noise and the narrow-band interference of the power line carrier digital signal received by the digital filter,
wherein the gain controller comprises:
the first digital gain amplifier is used for selecting a corresponding amplification factor according to the gain value input by the gain controller, and then amplifying the power line carrier digital signal received by the first digital gain amplifier according to the amplification factor and outputting the amplified signal;
the input end of the pulse interference detection and suppression device is connected with the output end of the first digital gain amplifier and is used for carrying out pulse interference detection and suppression on the power line carrier digital signals received in real time;
the input end of the first power estimator is connected with the output end of the pulse interference detection and suppressor and is used for subtracting the signal power of each sampling point of the power line carrier digital signal received by the first power estimator from the target adjusting power set by the automatic gain control device so as to obtain the power error of each sampling point;
the input end of the first loop filter is connected with the output end of the first power estimator and is used for performing integration operation on the power error of each sampling point, then performing proportion operation, shifting the value after the proportion operation, removing the gain value of the fraction part and finally obtaining an integer gain value;
the input end of the gain decomposer is connected with the output end of the first loop filter, the output end of the gain decomposer is respectively connected with the input end of the first digital gain amplifier and the input end of the programmable gain amplifier at the analog front end, the gain decomposer is used for generating a first gain value and a second gain value according to an integer gain value output by the first loop filter, the gain decomposer directly outputs the first gain value to the first digital gain amplifier, the gain decomposer converts the second gain value into the gain control word and then outputs the gain control word to the programmable gain amplifier, and the programmable gain amplifier selects a corresponding amplification factor according to the gain control word to adjust the power line carrier analog signal received by the programmable gain amplifier.
2. The automatic gain control apparatus for OFDM power line communication according to claim 1, wherein the first loop filter performs an integration operation on the power error of each sampling point, the integration operation using the following relation: pacc(n)＝Pacc(n-1)+Perr(n)*KIWherein P isacc(n) represents the power integral value, P, of the nth sample pointerr(n) represents the power error of the nth sample point, KIRepresenting a custom integral coefficient; and
then carrying out proportion operation, shifting the value after the proportion operation, removing the gain value of the fraction part, and finally obtaining the gain valueInteger gain values, the operation using the following relationship: pgain(n)＝(Pacc(n)+Perr(n)*Kp)＞＞LfracWherein P isacc(0)＝0，KpFor a custom scale factor, LfracIs a fractional word length.
3. The apparatus for automatic gain control of OFDM power line communication of claim 1 wherein said gain decomposer generates a first gain value and a second gain value comprises: the gain decomposer judges whether an integer gain value output by the first loop filter is within an effective gain range of the programmable gain amplifier, if so, the first gain value is 0dB, and the second gain value is the gain value output by the first loop filter; if the first gain value is not in the effective gain range, the first gain value is a value of a part of the gain value output by the first loop filter, which exceeds the effective gain range, and the second gain value is a value of a part of the gain value output by the first loop filter, which does not exceed the effective gain range.
4. The automatic gain control apparatus for OFDM power line communication according to claim 1, further comprising a digital gain compensator, an input of the digital gain compensator being connected to an output of the digital filter, the digital gain compensator compensating for a signal power loss caused by the digital filter.
5. The automatic gain control apparatus for OFDM power line communication according to claim 4, wherein the digital gain compensator comprises:
the input end of the second digital gain amplifier is connected with the output end of the digital filter and is used for amplifying the power line carrier digital signal received by the second digital gain amplifier according to the amplification factor of the second digital gain amplifier and then outputting the power line carrier digital signal;
a second power estimator having an input coupled to the second digital gain amplifierThe output end of the device is connected with the output end of the automatic gain control device and used for subtracting the signal power of each sampling point of the power line carrier digital signal received by the second power estimator to obtain the power error P 'of each sampling point'err(n)；
A second loop filter having an input connected to the output of the second power estimator for power error P 'for each of the sampling points'err(n) performing weighted averaging and integration operations, namely adopting the following relational expression: p'avg(n)＝P′avg(n-1)*(1-Ka)+P′err(n)*KaAnd P'acc(n)＝P′acc(n-1)+P′avg(n)*KI'wherein, P'avg(0)＝0，P′acc(0)＝1；KaRepresenting a custom weighted average coefficient, KI'is a custom integral coefficient, the P'avg(n) represents a weighted average of the power of the nth sample point of the power line carrier digital signal received by the second power estimator, P'acc(n) represents a weighted average integrated value of the power of the nth sampling point of the power line carrier digital signal received by the second power estimator, and the weighted average integrated value is finally output to the second digital gain amplifier as the amplification factor of the second digital gain amplifier.
6. The automatic gain control apparatus for OFDM power line communication according to claim 5, wherein said automatic gain control apparatus further comprises:
a timing synchronization module, an input end of which is connected to the digital gain compensator, and an output end of which is connected to both the input end of the gain controller and the input end of the digital gain compensator, wherein the timing synchronization module is configured to determine a starting position of a frame received by the receiver, perform coarse synchronization first, and then perform fine synchronization, and when the initial starting position of the frame is detected during the coarse synchronization, the gain controller and the digital gain compensator stop gain updating, that is, the first power estimator and the first loop filter stop working, and the second power estimator and the second loop filter stop working.
7. The automatic gain control apparatus for OFDM power line communication according to claim 1, wherein the glitch detection and suppressor is further configured to set a pulse detection flag after the glitch is detected, and otherwise to reset the pulse detection flag, and when the pulse detection flag is set, the first power estimator and the first loop filter of the gain controller stop operating.
8. The automatic gain control apparatus for OFDM power line communication according to claim 5, wherein the glitch detection and suppressor is further configured to set a pulse detection flag after the detection of the glitch, otherwise reset the pulse detection flag, when the pulse detection flag is set, the first power estimator and the first loop filter of the gain controller stop operating, and the second power estimator and the second loop filter of the digital gain compensator stop operating in a software configurable manner.
9. The automatic gain control apparatus for OFDM power line communication according to claim 6, wherein said automatic gain control apparatus further comprises:
and the input end of the demodulation and decoding module is connected with the output end of the timing synchronization module and is used for carrying out time-frequency transformation, frequency domain processing and bit level processing on the power line carrier digital signals received by the demodulation and decoding module.
10. The apparatus of claim 9, wherein the analog front end is implemented with analog circuitry, and the gain controller, the digital filter, the digital gain compensator, the timing synchronization module, and the demodulation and decoding module are implemented with digital circuitry, each of which can be integrated into an OFDM power communication baseband chip.
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| CN110677184B (en) * | 2019-11-04 | 2021-08-06 | 国网河南省电力公司襄城县供电公司 | Electric power information communication network signal reinforcing means |
| CN111245765A (en) * | 2020-01-19 | 2020-06-05 | 西安云维智联科技有限公司 | Wired carrier communication signal adaptive gain tracking and capturing method and device |
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