CN111107025B - Adaptive Equalizer in GFSK Receiver - Google Patents
Adaptive Equalizer in GFSK Receiver Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
- H04L25/03025—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception using a two-tap delay line
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
- H04L25/03057—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception with a recursive structure
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
- H04L25/03057—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception with a recursive structure
- H04L25/03063—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception with a recursive structure using fractionally spaced delay lines or combinations of fractionally and integrally spaced taps
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/01—Equalisers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
- H04L27/14—Demodulator circuits; Receiver circuits
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Abstract
The present disclosure relates to an adaptive equalizer in a GFSK receiver, comprising: the first equalization module performs filtering processing on an input signal to obtain a first filtered signal, and works at 4 times of symbol rate; the second equalization module performs filtering processing on the output signal to obtain a second filtered signal, and the second equalization module works at 1 time of symbol rate; an adder for adding the first and second filtered signals to output a summation signal; the judging module is used for judging the summation signals to obtain output signals; the error generation module outputs a first error signal and a second error signal; the first tap coefficient configuration module and the second tap coefficient configuration module are used for generating tap coefficients. The adaptive equalizer disclosed by the disclosure can eliminate intersymbol interference existing in a receiver, so that the demodulation performance of the receiver is improved.
Description
Technical Field
The present disclosure relates to the field of communications technologies, and in particular, to an adaptive equalizer in a GFSK receiver.
Background
In digital communication systems, intersymbol interference (ISI, intersymbol Interference), otherwise known as inter-symbol interference, etc., is an important factor affecting communication performance in the presence of multipath propagation in a channel. After introducing intersymbol interference in the receiver, the demodulation of the receiver will be erroneous due to the presence of intersymbol interference.
Therefore, there is an urgent need to propose a new scheme to eliminate intersymbol interference existing in a receiver, thereby improving demodulation performance of the receiver.
Disclosure of Invention
In view of this, the present disclosure proposes an adaptive equalizer in a GFSK receiver and a method of applying the same in order to eliminate intersymbol interference existing in the receiver and thereby improve demodulation performance of the receiver.
According to one aspect of the present disclosure, there is provided an adaptive equalizer in a GFSK receiver, the adaptive equalizer comprising:
The first equalization module is electrically connected with the first tap coefficient configuration module and is used for receiving an input signal and a first tap coefficient or a second tap coefficient transmitted by the first tap coefficient configuration module, and filtering the input signal according to the first tap coefficient or the second tap coefficient to obtain a first filtered signal, wherein the first equalization module works at 4 times of symbol rate;
the second equalization module is electrically connected with the judgment module and the second tap coefficient configuration module, and is used for receiving a third tap coefficient or a fourth tap coefficient transmitted by the second tap coefficient configuration module and an output signal transmitted by the judgment module, and carrying out filtering processing on the output signal according to the third tap coefficient or the fourth tap coefficient so as to obtain a second filtering signal, wherein the second equalization module works at 1 time of symbol rate;
The adder is electrically connected with the first equalization module and the second equalization module and is used for receiving the first filtering signal and the second filtering signal, adding the first filtering signal and the second filtering signal and outputting a summation signal;
the judging module is electrically connected with the adder and is used for judging the summation signals to obtain output signals;
The error generation module is electrically connected with the adder and the judging module and is used for receiving the summation signal transmitted by the adder and the output signal transmitted by the judging module and outputting a first error signal and a second error signal according to the summation signal and the output signal;
The first tap coefficient configuration module is electrically connected with the error generation module and is used for outputting the first tap coefficient according to the first error signal or outputting the second tap coefficient according to the second error signal;
And the second tap coefficient configuration module is electrically connected with the error generation module and is used for outputting the third tap coefficient according to the first error signal or outputting the fourth tap coefficient according to the second error signal.
In one possible implementation, the first equalization module obtains the first filtered signal according to the following formula:
Ffe_out (n) =x (n) = FFE _coeff (n), where X (n) includes a delay signal of an input signal at the current n time and delay signals of a plurality of input signals before the current n time, FFE _coeff (n) is a first tap coefficient or a second tap coefficient at the current n time, and ffe_out (n) is a first filtered signal at the current n time.
In one possible implementation, the first tap coefficient configuration module obtains the first tap coefficient or the second tap coefficient by the following formula:
ffe _coeff (n) = ffe _coeff (n-1) +delta×e_k (n) ×x (n), wherein ffe _coeff (n-1) is the first tap coefficient or the second tap coefficient at time n-1, delta is an error constant, e_k (n) is the first error signal or the second error signal, and x (n) is the input signal at the current time n.
In one possible implementation, the second equalization module obtains the second filtered signal according to the following formula:
FBE_out(n)＝D(n-1)*fbe_coef(n)，
Wherein D (n-1) is a delay signal of a plurality of output signals of the decision module before the current n moment, FBE _coef (n) is a third tap coefficient or a fourth tap coefficient of the current n moment, and fbe_out (n) is a second filtered signal of the current n moment.
In one possible implementation, the second tap coefficient configuration module obtains the third tap coefficient or the fourth tap coefficient according to the following formula:
fbe _coeff (n) = fbe _coeff (n-1) +delta×e_k (n) ×dec_out (n), wherein fbe _coeff (n-1) is a third tap coefficient or a fourth tap coefficient at time n-1, delta is an error constant, e_k (n) is the first error signal or the second error signal, and dec_out (n) is an output signal of the decision module at the current time n.
In one possible embodiment, the error generating module includes:
The enabling submodule is used for receiving the enabling signal and determining an error signal generation mode according to the enabling signal; and/or
And the calculating sub-module is electrically connected with the enabling sub-module and is used for starting counting after receiving the counting instruction and determining an error signal generating mode according to the relation between the counting value and the counting value threshold value.
In one possible implementation, when the enable signal is a first enable signal or the count value is less than the count value threshold, the error generation module obtains the first error signal according to the following formula:
e_k1 (n) =r× (dec_out (n) -eq_out (n)), where e_k1 (n) is the first error signal at the current n time, R is a constant, eq_out (n) is the sum signal at the current n time, dec_out (n) is the output signal at the current n time;
When the enabling signal is a second enabling signal or the count value is greater than or equal to the count value threshold, the error generating module obtains the second error signal according to the following formula:
e_k2 (n) =dec_out (n) -eq_out (n), where e_k2 (n) is the second error signal at the current n time instant.
In one possible implementation, the determiner obtains the output signal by the following formula:
dec_out (n) =sign (eq_out (n)), where dec_out (n) is the output signal at the current n time and eq_out (n) is the sum signal at the current n time.
In one possible implementation manner, the first equalization module and the second equalization module are respectively a FFE _n-order FFE equalizer and a FBE _n-order FBE equalizer, where FFE _n is an integer greater than 1 and FBE _n is an integer greater than 1.
In one possible implementation, the first equalization module and the second equalization module each include one of an FIR finite impulse response filter, a transversal filter, and a transposed form filter.
According to another aspect of the present disclosure, there is provided a method of applying an adaptive equalizer in a GFSK receiver, the method comprising:
Receiving an input signal and a first tap coefficient or a second tap coefficient at a 4-time symbol rate, and performing filtering processing on the input signal according to the first tap coefficient or the second tap coefficient to obtain a first filtering signal;
receiving a third tap coefficient or a fourth tap coefficient and an output signal at a 1-time symbol rate, and performing filtering processing on the output signal according to the third tap coefficient or the fourth tap coefficient to obtain a second filtering signal;
Adding the first filtering signal and the second filtering signal to output a summation signal;
Performing decision processing on the summation signals to obtain output signals;
Outputting a first error signal and a second error signal according to the summation signal and the output signal;
Outputting the first tap coefficient according to the first error signal or outputting the second tap coefficient according to the second error signal;
Outputting the third tap coefficient according to the first error signal or outputting the fourth tap coefficient according to the second error signal.
According to the adaptive equalizer of the GFSK receiver, intersymbol interference in a channel can be eliminated through the first equalization module and the second equalization module, multipath effect of the channel is overcome, demodulation performance of the GFSK receiver is improved, and timing error tolerance of the adaptive equalizer is greatly improved by setting the first equalization module to work at 4 times of symbol rate and the second equalization module to work at 1 time of symbol rate.
Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features and aspects of the present disclosure and together with the description, serve to explain the principles of the disclosure.
Fig. 1 shows a block diagram of an adaptive equalizer in a GFSK receiver in accordance with an embodiment of the present disclosure.
Fig. 2 shows a block diagram of an adaptive equalizer of a GFSK receiver in accordance with an embodiment of the present disclosure.
Fig. 3 shows a flowchart of a method of applying an adaptive equalizer in a GFSK receiver according to an embodiment of the disclosure.
Detailed Description
Various exemplary embodiments, features and aspects of the disclosure will be described in detail below with reference to the drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
In addition, numerous specific details are set forth in the following detailed description in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order not to obscure the present disclosure.
Communication systems employing GFSK (gaussian Frequency SHIFT KEYING) generally include a GFSK transmitter that can modulate a transmission signal as a modulation end and transmit the modulated signal, and a GFSK receiver that can be used to receive the signal transmitted by the GFSK transmitter and demodulate to obtain an original signal. The GFSK transmitter includes a gaussian shaping filter that introduces intersymbol interference, the presence of which causes errors in the demodulation of the received signal by the GFSK receiver, thereby affecting the demodulation performance of the GFSK receiver.
To address the problem of intersymbol interference in a GFSK receiver, the present disclosure proposes an adaptive equalizer in a GFSK receiver.
Referring to fig. 1, fig. 1 shows a block diagram of an adaptive equalizer in a GFSK receiver in accordance with an embodiment of the present disclosure.
As shown in fig. 1, the adaptive equalizer includes:
The first equalization module 10 is electrically connected to the first tap coefficient configuration module 11, and is configured to receive the input signal and the first tap coefficient or the second tap coefficient transmitted from the first tap coefficient configuration module 11, and perform filtering processing on the input signal according to the first tap coefficient or the second tap coefficient, so as to obtain a first filtered signal, where the first equalization module works at 4 times of symbol rate.
The second equalization module 12 is electrically connected to the decision module 14 and the second tap coefficient configuration module 12, and is configured to receive the third tap coefficient or the fourth tap coefficient transmitted from the second tap coefficient configuration module 12 and the output signal transmitted from the decision module 14, and perform filtering processing on the output signal according to the third tap coefficient or the fourth tap coefficient, so as to obtain a second filtered signal, where the second equalization module works at 1 time of symbol rate.
And an adder 16, electrically connected to the first equalization module 10 and the second equalization module 12, for receiving the first filtered signal and the second filtered signal, adding the first filtered signal and the second filtered signal, and outputting a summation signal.
The decision module 14 is electrically connected to the adder 16, and is configured to perform decision processing on the summed signal to obtain an output signal.
The error generating module 15 is electrically connected to the adder 16 and the decision module 14, and is configured to receive the sum signal transmitted from the adder 16 and the output signal transmitted from the decision module 14, and output a first error signal and a second error signal according to the sum signal and the output signal.
A first tap coefficient configuration module 11, electrically connected to the error generation module 15, for outputting the first tap coefficient according to the first error signal or outputting the second tap coefficient according to the second error signal.
A second tap coefficient configuration module 13, electrically connected to the error generation module 15, for outputting the third tap coefficient according to the first error signal or outputting the fourth tap coefficient according to the second error signal.
According to the adaptive equalizer of the GFSK receiver, intersymbol interference in a channel can be eliminated through the first equalization module and the second equalization module, multipath effect of the channel is overcome, demodulation performance of the GFSK receiver is improved, and timing error tolerance of the adaptive equalizer is greatly improved by setting the first equalization module to work at 4 times of symbol rate and the second equalization module to work at 1 time of symbol rate.
For the first equalization module 10:
In one possible implementation manner, the input signal may be a signal obtained by suppressing the out-of-band interference and noise of a baseband sampling signal received by the GFSK receiver through a low-pass filter, performing operation by a frequency discriminator, performing symbol synchronization through symbol synchronization, removing a direct current component, and then reducing the signal after removing the direct current component from an initial sampling rate to a symbol rate.
In one possible implementation, the first equalization module 10 may be a FFE _n-order FFE (Feed Forward Equalization, feed-forward equalization) equalizer, where FFE _n is an integer greater than 1.
In one possible implementation, the first equalization module 10 may include one of a FIR finite impulse response filter, a transversal filter, and a transposed form filter.
In one possible implementation, the first equalization module 10 obtains the first filtered signal according to the following formula:
Ffe_out (n) =x (n) × FFE _coeff (n), where X (n) includes a delay signal of an input signal at the current n time and delay signals of a plurality of input signals before the current n time, FFE _coeff (n) is a first tap coefficient or a second tap coefficient at the current n time, and ffe_out (n) is a first filtered signal at the current n time, where a symbol "×" is a convolution symbol.
In this embodiment, X (n) may be stored in the register of the first equalization module 10, and the input signals are sequentially shifted into the register for storage, for example, when the input signal X (n-1) at time n-1 arrives, the input signal X (n-1) is shifted into the register for storage, when the input signal X (n) at time n arrives, the input signal X (n) is shifted into the register for storage, and when the input signal X (n+1) at time n+1 arrives, the input signal X (n+1) is shifted into the register for storage.
When the first equalization module 10 operates at 4 times the symbol rate, the data in the input signal enters the first equalization module 10 at 4 times the symbol rate, e.g., 4 data enters the first equalization module 10 in one symbol period, and by setting the first equalization module 10 to operate at 4 times the symbol rate, the tolerance of the adaptive equalizer described in the present disclosure to timing errors will be greatly improved.
The first equalization module 10 may remove the forward intersymbol interference caused by multipath propagation in the channel, and may also remove other interference signals.
For the second equalization module 12:
In one possible implementation, the second equalization module 12 may be a FBE _n-order feedback equalizer (Feed Backward Eguaizer, FBE), where FBE _n is an integer greater than 1.
In one possible implementation, the second equalization module 12 may include one of a FIR finite impulse response filter, a transversal filter, a transposed form filter.
In one possible implementation, the second equalization module 12 obtains the second filtered signal according to the following formula:
Fbe_out (n) =d (n-1) = FBE _coef (n), where D (n-1) is a delay signal of a plurality of output signals of the decision module before the current n time, FBE _coef (n) is a third tap coefficient or a fourth tap coefficient of the current n time, and fbe_out (n) is a second filtered signal of the current n time.
D (n-1) may be stored in the decision module 14, where D (n-1) includes output signals D (n-1), D (n-2), D (n-3), etc. at a plurality of times, such as at n-1, n-2, n-3, etc.
When the second equalization module 12 is operating at 1 symbol rate, the tolerance of the adaptive equalizer described in this disclosure to timing errors will be greatly improved.
The first equalization module 12 may remove the backward intersymbol interference caused by multipath propagation in the channel, and may also remove other interference signals.
In a possible implementation manner, in the first equalization module 10 and the second equalization module 12, the first tap coefficient may correspond to the third tap coefficient, and when the first equalization module 10 performs filtering processing on the input signal according to the first tap coefficient to generate the first filtered signal, the second equalization module 12 may perform filtering processing on the output signal of the decision module 14 according to the third tap coefficient to generate the second filtered signal.
In a possible implementation manner, in the first equalization module 10 and the second equalization module 12, the second tap coefficient may correspond to the fourth tap coefficient, and when the first equalization module 10 performs filtering processing on the input signal according to the second tap coefficient to generate the first filtered signal, the second equalization module 12 may perform filtering processing on the output signal of the decision module 14 according to the fourth tap coefficient to generate the second filtered signal.
For adder 16:
In one possible implementation, the adder 16 outputs the sum signal eq_out (n) =ffe_out (n) +fbe_out (n), where eq_out (n) is the sum signal at the current time n.
In one possible implementation, the first equalization module 10 operates at 4 times the symbol rate, the second equalization module 12 operates at 1 time the symbol rate, for example, in the same time n (for example, one symbol period), the first equalization module 10 outputs 1 filtered signal at each of the times n/4,2n/4,3n/4 and n, and the filtered signal output at the time n can be used as the first filtered signal; at time n, the second equalization module 12 outputs a second filtered signal, and the adder 16 adds the first filtered signal and the second filtered signal to obtain a summed signal.
For decision block 14:
In a possible embodiment, the decision module 14 may comprise components or means for buffering the delay signal, such as a delay line (not shown).
In one possible implementation, the arbiter 14 obtains the output signal by the following formula:
dec_out (n) =sign (eq_out (n)), where dec_out (n) is the output signal at the current n-time.
For the error generation module 15:
Referring to fig. 2, fig. 2 shows a block diagram of an adaptive equalizer of a GFSK receiver in accordance with an embodiment of the present disclosure.
As shown in fig. 2, in one possible embodiment, the error generation module 15 may include:
An enabling submodule 151 for receiving the enabling signal and determining an error signal generation mode according to the enabling signal; and/or
The calculating sub-module 153 is electrically connected to the enabling sub-module 151, and is configured to start counting after receiving the counting command, and determine an error signal generating manner according to a relationship between the count value and the count value threshold.
In a possible implementation manner, when the enable signal received by the enable sub-module 151 is the first enable signal or the count value counted by the calculation sub-module 153 is smaller than the count value threshold, the error generation module obtains the first error signal according to the following formula:
e_k1 (n) =r× (dec_out (n) -eq_out (n)), where e_k1 (n) is the first error signal at the current n time, R is a constant, eq_out (n) is the sum signal at the current n time, and dec_out (n) is the output signal at the current n time.
In one possible implementation, when the enable signal is a second enable signal or the count value is greater than or equal to the count value threshold, the error generation module obtains the second error signal according to the following formula:
e_k2 (n) =dec_out (n) -eq_out (n), where e_k2 (n) is the second error signal at the current n time instant.
In one possible embodiment, the constant R can be obtained by the following formula:
r=e { x (n)/(2) }/E { |x (n) | } where E is the average sign.
In some specific embodiments, when the input signal is in 2-GFSK mode, R may be 1; when the input signal is in 4-GFSK mode, R may be 2.5.
In one possible implementation, the first enable signal may be a low level signal, the second enable signal may be a high level signal, the count value of the calculation submodule 153 may be the number of occurrences of the symbol period, and the count value threshold may be a symbol period number threshold.
In a possible implementation manner, the calculating submodule 153 may obtain the enable signal obtained by the enable submodule 151, take the enable signal as a counting instruction, calculate the number of symbol periods according to the state of the enable signal and take the enable signal as the count value, for example, when the enable signal is a high level signal, the enable signal may be considered to be a valid signal, at this time, the calculating submodule 153 may start counting the symbol periods, obtain the first error signal when the count value is smaller than the count value threshold, and obtain the second error signal in other cases (for example, the enable signal is invalid or the count value is larger than the count value threshold, etc.). The calculation submodule 153 may start to calculate the number of symbol periods after the adaptive equalizer receives the input signal and use the number as the count value, and may, of course, also receive other externally input command signals and start to calculate the number of symbol periods according to the received command signals and use the number as the count value.
After the enabling sub-module 53 obtains the second enabling signal, the error generating module 15 may obtain the second error signal according to the above formula.
As described above, the enabling submodule 151 and the calculating submodule 153 may determine the error signal separately, or may determine the error signal simultaneously, for example, when the enabling signal is valid (for example, the enabling signal is the second enabling signal), and when the count value is smaller than the count value threshold, the error generating module 15 generates the first error signal, and in other cases, the error generating module 15 generates the second error signal.
The adaptive equalizer of the GFSK receiver described in the present disclosure operates in a blind equalization mode of a local normal mode algorithm (Constant Modulus Algorithm, CMA) when the error generating module 15 generates a first error signal, and in a decision-oriented mode based on a least Squares algorithm ((LEAST MEAN Squares, LMS)) when the error generating module 15 generates a second error signal.
For the first tap coefficient configuration module 11:
in one possible implementation, the first tap coefficient configuration module 11 may obtain the first tap coefficient or the second tap coefficient by the following formula:
ffe _coeff (n) = ffe _coeff (n-1) +delta×e_k (n) ×x (n), wherein ffe _coeff (n-1) is the first tap coefficient or the second tap coefficient at time n-1, delta is an error constant, e_k (n) is the first error signal or the second error signal, and x (n) is the input signal at the current time n.
In the present embodiment, the first tap coefficient configuration module 11 may obtain the first tap coefficient through the first error signal and obtain the second tap coefficient through the second error signal.
In one possible embodiment, delta may be a fraction between 0 and 1, for example, delta may be 0.01.
In one possible implementation, the first tap coefficient configuration module 11 may override the first tap coefficient after generating the second tap coefficient.
For the second tap coefficient configuration module 13:
In one possible implementation, the second tap coefficient configuration module 13 may obtain the third tap coefficient or the fourth tap coefficient according to the following formula:
fbe _coeff (n) = fbe _coeff (n-1) +delta×e_k (n) ×dec_out (n), wherein fbe _coeff (n-1) is a third tap coefficient or a fourth tap coefficient at time n-1, delta is an error constant, e_k (n) is the first error signal or the second error signal, and dec_out (n) is an output signal of the decision module at the current time n.
In the present embodiment, the second tap coefficient configuration module 13 obtains the third tap coefficient by the first error signal and the fourth tap coefficient by the second error signal.
In a possible implementation, the first tap coefficient configuration module 11 and the second tap coefficient configuration module 13 may be initialized in advance, so that the initialized tap coefficients are stored in the first tap coefficient configuration module 11 and the second tap coefficient configuration module 13, and when the adaptive equalizer starts to operate, the operation may be performed by the initialized tap coefficients stored in the first tap coefficient configuration module 11 and the second tap coefficient configuration module 13, and thereafter, the first tap coefficient configuration module 11 and the second tap coefficient configuration module 13 update the respective tap coefficients in the foregoing manner.
In one possible implementation, the second tap coefficient configuration module 13 may override the third tap coefficient after generating the fourth tap coefficient.
It should be noted that the above descriptions of "first," "second," etc. are for clarity of presentation of the disclosure and are not intended to limit the disclosure.
Referring to fig. 3, fig. 3 shows a flowchart of a method of applying an adaptive equalizer in a GFSK receiver according to an embodiment of the disclosure.
As shown in fig. 3, the method includes:
Step S110, receiving an input signal and a first tap coefficient or a second tap coefficient at a 4-time symbol rate, and performing filtering processing on the input signal according to the first tap coefficient or the second tap coefficient to obtain a first filtered signal;
Step S120, receiving a third tap coefficient or a fourth tap coefficient and an output signal at a symbol rate of 1 time, and performing filtering processing on the output signal according to the third tap coefficient or the fourth tap coefficient to obtain a second filtered signal;
Step S130, adding the first filtering signal and the second filtering signal to output a summation signal;
Step S140, judging the summation signals to obtain output signals;
Step S150, outputting a first error signal and a second error signal according to the summation signal and the output signal;
step S160 of outputting the first tap coefficient according to the first error signal or outputting the second tap coefficient according to the second error signal;
step S170, outputting the third tap coefficient according to the first error signal or outputting the fourth tap coefficient according to the second error signal.
The foregoing description of the embodiments of the present disclosure has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the technical improvement of the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (8)
1. An adaptive equalizer in a GFSK receiver, the adaptive equalizer comprising:
The first equalization module is electrically connected to the first tap coefficient configuration module and is used for receiving an input signal and a first tap coefficient or a second tap coefficient transmitted by the first tap coefficient configuration module, and performing filtering processing on the input signal according to the first tap coefficient or the second tap coefficient to obtain a first filtered signal, wherein the first equalization module works at 4 times of symbol rate, and the first equalization module obtains the first filtered signal according to the following formula: ffe_out (n) =x (n) × FFE _coeff (n), where X (n) includes a delay signal of an input signal at the current n time and delay signals of a plurality of input signals before the current n time, FFE _coeff (n) is a first tap coefficient or a second tap coefficient at the current n time, ffe_out (n) is a first filtered signal at the current n time, and sign "×" is a convolution sign;
The second equalization module is electrically connected with the judgment module and the second tap coefficient configuration module, and is used for receiving a third tap coefficient or a fourth tap coefficient transmitted by the second tap coefficient configuration module and an output signal transmitted by the judgment module, and filtering the output signal according to the third tap coefficient or the fourth tap coefficient to obtain a second filtered signal, wherein the second equalization module works at 1 time of symbol rate, and the second equalization module obtains the second filtered signal according to the following formula: fbe_out (n) =d (n-1) = FBE _coef (n), wherein D (n-1) is a delay signal of a plurality of output signals of the decision module before the current n time, FBE _coef (n) is a third tap coefficient or a fourth tap coefficient of the current n time, and fbe_out (n) is a second filtered signal of the current n time;
The adder is electrically connected with the first equalization module and the second equalization module and is used for receiving the first filtering signal and the second filtering signal, adding the first filtering signal and the second filtering signal and outputting a summation signal;
the judging module is electrically connected with the adder and is used for judging the summation signals to obtain output signals;
The error generation module is electrically connected with the adder and the judging module and is used for receiving the summation signal transmitted by the adder and the output signal transmitted by the judging module and outputting a first error signal and a second error signal according to the summation signal and the output signal;
The first tap coefficient configuration module is electrically connected with the error generation module and is used for outputting the first tap coefficient according to the first error signal or outputting the second tap coefficient according to the second error signal;
And the second tap coefficient configuration module is electrically connected with the error generation module and is used for outputting the third tap coefficient according to the first error signal or outputting the fourth tap coefficient according to the second error signal.
2. The adaptive equalizer of claim 1, wherein the first tap coefficient configuration module obtains the first tap coefficient or the second tap coefficient by:
ffe _coeff (n) = ffe _coeff (n-1) +delta×e_k (n) ×x (n), wherein ffe _coeff (n-1) is the first tap coefficient or the second tap coefficient at time n-1, delta is an error constant, e_k (n) is the first error signal or the second error signal, and x (n) is the input signal at the current time n.
3. The adaptive equalizer of claim 1, wherein the second tap coefficient configuration module obtains the third tap coefficient or the fourth tap coefficient according to the following formula:
fbe _coeff (n) = fbe _coeff (n-1) +delta×e_k (n) ×dec_out (n), wherein fbe _coeff (n-1) is a third tap coefficient or a fourth tap coefficient at time n-1, delta is an error constant, e_k (n) is the first error signal or the second error signal, and dec_out (n) is an output signal of the decision module at the current time n.
4. The adaptive equalizer of claim 1, wherein the error generation module comprises:
The enabling submodule is used for receiving the enabling signal and determining an error signal generation mode according to the enabling signal; and/or
And the calculating sub-module is electrically connected with the enabling sub-module and is used for starting counting after receiving the counting instruction and determining an error signal generating mode according to the relation between the counting value and the counting value threshold value.
5. The adaptive equalizer of claim 4, wherein,
When the enabling signal is a first enabling signal or the count value is smaller than the count value threshold value, the error generating module obtains the first error signal according to the following formula:
e_k1 (n) =r× (dec_out (n) -eq_out (n)), where e_k1 (n) is the first error signal at the current n time, R is a constant, eq_out (n) is the sum signal at the current n time, dec_out (n) is the output signal at the current n time;
When the enabling signal is a second enabling signal or the count value is greater than or equal to the count value threshold, the error generating module obtains the second error signal according to the following formula:
e_k2 (n) =dec_out (n) -eq_out (n), where e_k2 (n) is the second error signal at the current n time instant.
6. The adaptive equalizer of claim 1, wherein the decision device obtains the output signal by:
dec_out (n) =sign (eq_out (n)), where dec_out (n) is the output signal at the current n time and eq_out (n) is the sum signal at the current n time.
7. The adaptive equalizer of claim 1, wherein the first and second equalization modules are a FFE _n-order FFE equalizer and a FBE _n-order FBE equalizer, respectively, wherein FFE _n is an integer greater than 1 and FBE _n is an integer greater than 1.
8. The adaptive equalizer of claim 1, wherein the first equalization module and the second equalization module each comprise one of a FIR finite impulse response filter, a transversal filter, and a transposed form filter.
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| CN102882817A (en) * | 2012-09-26 | 2013-01-16 | 华为技术有限公司 | Equalizer circuit, data transmission system and equalization method |
| CN209488618U (en) * | 2018-10-26 | 2019-10-11 | 上海晟矽微电子股份有限公司 | Adaptive equalizer in GFSK receiver |
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| EP1914884B8 (en) * | 2005-07-29 | 2016-09-21 | Fujitsu Ltd. | Delay regulating device |
| CN108259067A (en) * | 2016-12-29 | 2018-07-06 | 深圳市中兴微电子技术有限公司 | A kind of method and apparatus of adaptive decision-feedback equalization |
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| CN209488618U (en) * | 2018-10-26 | 2019-10-11 | 上海晟矽微电子股份有限公司 | Adaptive equalizer in GFSK receiver |
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