CN111107025A - Adaptive equalizer in GFSK receiver - Google Patents
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- 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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- 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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Abstract
The present disclosure relates to an adaptive equalizer in a GFSK receiver, comprising: the first equalization module is used for filtering an input signal to obtain a first filtered signal, and the first equalization module works at 4 times of symbol rate; the second equalization module is used for filtering the output signal to obtain a second filtered signal, and the second equalization module works at 1 time of symbol rate; an adder that adds the first filtered signal and the second filtered signal and outputs a sum signal; the decision module is used for carrying out decision processing on the summation signal to obtain an output signal; the error generating module outputs a first error signal and a second error signal; the device comprises a first tap coefficient configuration module and a second tap coefficient configuration module, wherein 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, thereby improving the demodulation performance of the receiver.
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 a digital communication system, Intersymbol Interference (ISI), also called Intersymbol Interference, etc., is an important factor affecting communication performance when multipath propagation exists in a channel. When intersymbol interference is introduced in the receiver, the demodulation of the receiver will be erroneous due to the presence of the intersymbol interference.
Therefore, it is urgently needed to provide a new scheme for eliminating the intersymbol interference existing in the receiver, so as to improve the demodulation performance of the receiver.
Disclosure of Invention
In view of the above, in order to eliminate inter-symbol interference existing in the receiver and thereby improve demodulation performance of the receiver, the present disclosure provides an adaptive equalizer in a GFSK receiver and an application method thereof.
According to one aspect of the present disclosure, an adaptive equalizer in a GFSK receiver is presented, the adaptive equalizer comprising:
the first equalization module is electrically connected to the first tap coefficient configuration module and 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 to the decision 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 decision 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;
the adder is electrically connected to the first equalization module and the second equalization module and used for receiving the first filtering signal and the second filtering signal, performing addition operation on the first filtering signal and the second filtering signal and outputting a summation signal;
the decision module is electrically connected to the adder and is used for performing decision processing on the summation signal to obtain an output signal;
the error generating module is electrically connected with the adder and the judging module and 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;
a first tap coefficient configuration module, electrically connected to the error generation module, 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 to 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 embodiment, 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 the delayed signal of the input signal at the current time n and the delayed signals of the plurality of input signals before the current time n, FFE _ coeff (n) is the first tap coefficient or the second tap coefficient at the current time n, and FFE _ out (n) is the first filtered signal at the current time n.
In one possible implementation, 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), where 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 current time n.
In a 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 time n, FBE _ coef (n) is a third tap coefficient or a fourth tap coefficient at the current time n, FBE _ out (n) is a second filtered signal at the current time n.
In a 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), where fbe _ coeff (n-1) is the third tap coefficient or the fourth tap coefficient at time n-1, delta is the error constant, e _ k (n) is the first error signal or the second error signal, and dec _ out (n) is the output signal of the decision module at current time n.
In one possible implementation, the error generating module includes:
the enabling submodule is used for receiving an enabling signal and determining an error signal generating mode according to the enabling signal; and/or
And the calculation submodule is electrically connected with the enabling submodule and used for starting counting after receiving the counting instruction and determining an error signal generation mode according to the relation between the counting value and the counting value threshold.
In one possible implementation, when the enable signal is a first enable signal or the count value is smaller than the count value threshold, the error generation module obtains the first error signal according to the following formula:
e _ k1(n) × (dec _ out (n) -EQ _ out (n)), where e _ k1(n) is the first error signal at the current time n, R is a constant, EQ _ out (n) is the sum signal at the current time n, and dec _ out (n) is the output signal at the current time n;
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 time n.
In one possible embodiment, the decision device obtains the output signal by the following formula:
dec _ out (n) is an output signal at the current time n, and EQ _ out (n) is a sum signal at the current time n.
In one possible implementation, the first equalization module and the second equalization module are FFE _ N order FFE equalizer and FBE _ N order FBE equalizer, respectively, where FFE _ N is an integer greater than 1 and FBE _ N is an integer greater than 1.
In a possible implementation, the first equalization module and the second equalization module each include one of a FIR finite impulse response filter, a transversal filter, and a transposed form filter.
According to another aspect of the present disclosure, a method for applying an adaptive equalizer in a GFSK receiver is provided, the method comprising:
receiving an input signal and a first tap coefficient or a second tap coefficient at a 4-time symbol rate, and carrying out filtering processing on the input signal according to the first tap coefficient or the second tap coefficient to obtain a first filtered signal;
receiving a third tap coefficient or a fourth tap coefficient and an output signal at 1 time of 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 filtered signal;
adding the first filtering signal and the second filtering signal to output a summation signal;
judging the summation signal to obtain an output signal;
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 self-adaptive equalizer of the GFSK receiver, the first equalizing module and the second equalizing module can eliminate intersymbol interference in a channel, the multipath effect of the channel is overcome, the demodulation performance of the GFSK receiver is improved, and the timing error tolerance of the self-adaptive equalizer provided by the disclosure is greatly improved by setting the first equalizing module to work at 4 times of symbol rate and setting the second equalizing 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 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 according to an embodiment of the disclosure.
Fig. 2 shows a block diagram of an adaptive equalizer of a GFSK receiver according to an embodiment of the disclosure.
Fig. 3 shows a flow chart of an application method of an adaptive equalizer in a GFSK receiver according to an embodiment of the disclosure.
Detailed Description
Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The word "exemplary" is used exclusively 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.
Furthermore, in the following detailed description, numerous specific details are set forth 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 that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.
A communication system using GFSK (gaussian Frequency Shift Keying) generally includes a GFSK transmitter and a GFSK receiver, where the GFSK transmitter may be used as a modulation terminal to modulate a transmission signal and transmit the modulated signal, and the GFSK receiver may be used to receive the signal transmitted by the GFSK transmitter and demodulate the signal to obtain an original signal. GFSK transmitters include gaussian shaping filters that introduce intersymbol interference, the presence of which can cause GFSK receivers to experience errors in demodulating the received signal, thereby affecting the demodulation performance of the GFSK receiver.
To solve the inter-symbol interference problem in a GFSK receiver, the present disclosure provides 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 according to an embodiment of the 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 configured to receive an input signal and a first tap coefficient or a second tap coefficient transmitted by 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 to obtain a first filtered signal, where the first equalization module operates at a symbol rate of 4 times.
And a second equalizing module 12, electrically connected to the decision module 14 and the second tap coefficient configuration module 12, configured to receive a third tap coefficient or a fourth tap coefficient transmitted by the second tap coefficient configuration module 12 and an output signal transmitted by the decision module 14, and perform filtering processing on the output signal according to the third tap coefficient or the fourth tap coefficient to obtain a second filtered signal, where the second equalizing module operates at 1-fold symbol rate.
And an adder 16, electrically connected to the first equalizing module 10 and the second equalizing 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 sum signal.
The decision module 14 is electrically connected to the adder 16, and is configured to perform decision processing on the summation signal to obtain an output signal.
The error generating module 15 is electrically connected to the adder 16 and the decision module 14, and configured to receive the summation 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 summation signal and the output signal.
A first tap coefficient configuration module 11, electrically connected to the error generating 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 generating 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 self-adaptive equalizer of the GFSK receiver, the first equalizing module and the second equalizing module can eliminate intersymbol interference in a channel, the multipath effect of the channel is overcome, the demodulation performance of the GFSK receiver is improved, and the timing error tolerance of the self-adaptive equalizer provided by the disclosure is greatly improved by setting the first equalizing module to work at 4 times of symbol rate and setting the second equalizing module to work at 1 time of symbol rate.
For the first equalization module 10:
in a possible implementation, the input signal may be a baseband sampling signal received by the GFSK receiver, after the baseband sampling signal is subjected to low pass filter to suppress out-of-band interference and noise, the baseband sampling signal is operated by a frequency discriminator, symbol synchronization is completed through symbol synchronization, a direct current component is removed, and then the signal after the direct current component is removed is decelerated from an initial sampling rate to a symbol rate to obtain a signal.
In one possible implementation, the first equalization module 10 may be an FFE (Feed forward equalization) equalizer of order FFE _ N, where FFE _ N is an integer greater than 1.
In a 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 a possible embodiment, 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 the delayed signal of the input signal at the current time n and the delayed signals of the input signals before the current time n, FFE _ coeff (n) is the first tap coefficient or the second tap coefficient at the current time n, FFE _ out (n) is the first filtered signal at the current time n, and where the sign "×" is a convolution sign.
In this embodiment, x (n) may be stored in the register of the first equalizing module 10, and the input signals may be sequentially shifted into the register for storage, for example, when the input signal x (n-1) at the time n-1 arrives, the input signal x (n-1) may be shifted into the register for storage, when the input signal x (n) at the time n arrives, the input signal x (n) may be shifted into the register for storage, and when the input signal x (n +1) at the time n +1 arrives, the input signal x (n +1) may be shifted into the register for storage.
When the first equalizing module 10 operates at 4 times the symbol rate, data in the input signal enters the first equalizing module 10 at 4 times the symbol rate, for example, 4 data enters the first equalizing module 10 in one symbol period, and by setting the first equalizing module 10 to operate at 4 times the symbol rate, the tolerance of the timing error of the adaptive equalizer according to the present disclosure is greatly improved.
The first equalization module 10 can remove the forward intersymbol interference caused by multipath propagation in the channel, and can also remove other interference signals.
For the second equalization module 12:
in one possible implementation, the second equalization module 12 may be a feedback equalizer (FBE) of FBE _ N order, 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, and a transposed form filter.
In a possible embodiment, the second equalization module 12 obtains the second filtered signal according to the following formula:
FBE _ out (n) (n-1) × FBE _ coef (n), where D (n-1) is a delay signal of the plurality of output signals of the decision module before the current time n, FBE _ coef (n) is a third tap coefficient or a fourth tap coefficient at the current time n, and FBE _ out (n) is a second filtered signal at the current time n.
D (n-1) may be stored in the decision block 14, D (n-1) comprising output signals D (n-1), D (n-2), D (n-3), etc. at a plurality of times, such as n-1, n-2, n-3, etc.
When the second equalization module 12 operates at 1 times the symbol rate, the tolerance of the timing error of the adaptive equalizer described in this disclosure will be greatly improved.
The first equalization module 12 can remove the backward intersymbol interference caused by multipath propagation in the channel, and can 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 a 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 a 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 a 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 a 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 a 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 a second filtered signal.
For adder 16:
in one possible embodiment, the adder 16 outputs the summation signal EQ _ out (n) ═ FFE _ out (n) + FBE _ out (n), where EQ _ out (n) is the summation signal at the current time n.
In one possible embodiment, the first equalization module 10 operates at 4 times the symbol rate, and the second equalization module 12 operates at 1 times the symbol rate, for example, in the same time n (e.g., one symbol period), the first equalization module 10 outputs 1 filtered signal at each of time n/4, 2n/4, 3n/4 and n time, and the filtered signal output at 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 the decision block 14:
in a possible embodiment, the decision module 14 may include a component or a device, such as a delay line (not shown), for temporarily storing the delayed signal.
In one possible embodiment, the decision device 14 obtains the output signal by the following formula:
dec _ out (n) denotes an output signal at the current time n.
For the error generating module 15:
referring to fig. 2, fig. 2 shows a block diagram of an adaptive equalizer of a GFSK receiver according to an embodiment of the disclosure.
As shown in fig. 2, in one possible implementation, the error generating module 15 may include:
an enable submodule 151 configured to receive an enable signal and determine an error signal generation manner according to the enable signal; and/or
The calculating submodule 153 is electrically connected to the enabling submodule 151, and is configured to start counting after receiving a counting instruction, and determine an error signal generation manner according to a relationship between a count value and a count value threshold.
In a possible implementation manner, when the enable signal received by the enable submodule 151 is a first enable signal or the count value counted by the calculation submodule 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) × (dec _ out (n) -EQ _ out (n)), where e _ k1(n) is the first error signal at the current time n, R is a constant, EQ _ out (n) is the sum signal at the current time n, and dec _ out (n) is the output signal at the current time n.
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 time n.
In one possible embodiment, the constant R may be obtained by the following formula:
r ═ E { x (n) ^2}/E { | x (n) | }, where E is the sign of the averaging.
In some embodiments, when the input signal is in a 2-GFSK mode, R may be 1; when the input signal is in 4-GFSK mode, R may be 2.5.
In one possible embodiment, 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 sub-module 153 may be the number of occurrences of the symbol period, and the count value threshold may be a symbol period number threshold.
In one possible implementation, the calculation sub-module 153 may obtain the enable signal obtained by the enable sub-module 151, use the enable signal as a count instruction, calculate the number of symbol periods according to the state of the enable signal and use the number as the count value, for example, when the enable signal is a high level signal, the enable signal may be considered as a valid signal, at this time, the calculation sub-module 153 may start counting the symbol periods, when the count value is less than a count value threshold, obtain a first error signal, and obtain a second error signal in other cases (for example, when the enable signal is invalid or the count value is greater than the count value threshold, etc.). The calculation sub-module 153 may start to calculate the number of symbol periods as the count value after the adaptive equalizer receives the input signal, or may receive another command signal input from the outside, start to calculate the number of symbol periods from the received command signal, 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 sub-module 151 and the calculating sub-module 153 may determine the error signals separately or simultaneously, for example, when the enabling signal is valid (for example, the enabling signal is the second enabling signal), and the count value is smaller than the count value threshold, the error generating module 15 generates the first error signal, otherwise, the error generating module 15 generates the second error signal.
The adaptive equalizer of the GFSK receiver of the present disclosure operates in a blind equalization mode of a Constant Modulus Algorithm (CMA) when the error generation module 15 generates the first error signal, and operates in a decision-oriented mode based on a Least mean square Algorithm (LMS) when the error generation module 15 generates the second error signal.
For the first tap coefficient configuration module 11:
in a 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), where 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 current time n.
In this embodiment, the first tap coefficient configuration module 11 may obtain the first tap coefficient by the first error signal and obtain the second tap coefficient by 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 overwrite the first tap coefficient after generating the second tap coefficient.
For the second tap coefficient configuration module 13:
in a 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), where fbe _ coeff (n-1) is the third tap coefficient or the fourth tap coefficient at time n-1, delta is the error constant, e _ k (n) is the first error signal or the second error signal, and dec _ out (n) is the output signal of the decision module at current time n.
In the present embodiment, the second tap coefficient arrangement block 13 obtains the third tap coefficient from the first error signal, and obtains the fourth tap coefficient from the second error signal.
In a possible embodiment, the first tap coefficient configuration module 11 and the second tap coefficient configuration module 13 may be initialized in advance, so as to store the initialized tap coefficients in the first tap coefficient configuration module 11 and the second tap coefficient configuration module 13, when the adaptive equalizer starts to operate, the adaptive equalizer may operate by using 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 tap coefficients thereof in the foregoing manner.
In one possible implementation, the second tap coefficient configuration module 13 may overwrite 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 description of the present disclosure, and are not intended to limit the present disclosure.
Referring to fig. 3, fig. 3 is a flow chart illustrating an application method of 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 4 times of symbol rate, and filtering 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 1 time of 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 filtered signal;
step S130, performing addition operation on the first filtered signal and the second filtered signal, and outputting a summation signal;
step S140, judging the summation signal to obtain an output signal;
step S150, outputting a first error signal and a second error signal according to the summation signal and the output signal;
step S160, 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.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein were chosen in order to best explain the principles of the embodiments, the practical application, or technical improvements to the techniques in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
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 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 to the decision 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 decision 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;
the adder is electrically connected to the first equalization module and the second equalization module and used for receiving the first filtering signal and the second filtering signal, performing addition operation on the first filtering signal and the second filtering signal and outputting a summation signal;
the decision module is electrically connected to the adder and is used for performing decision processing on the summation signal to obtain an output signal;
the error generating module is electrically connected with the adder and the judging module and 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;
a first tap coefficient configuration module, electrically connected to the error generation module, 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 to 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 equalization module obtains the first filtered signal according to the following equation:
FFE _ out (n) ═ x (n) × FFE _ coeff (n), where x (n) includes the delayed signal of the input signal at the current time n and the delayed signals of the plurality of input signals before the current time n, FFE _ coeff (n) is the first tap coefficient or the second tap coefficient at the current time n, and FFE _ out (n) is the first filtered signal at the current time n.
3. The adaptive equalizer of claim 2, 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), where 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 current time n.
4. The adaptive equalizer of claim 1, wherein the second equalization module obtains the second filtered signal according to the following equation:
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 time n, FBE _ coef (n) is a third tap coefficient or a fourth tap coefficient at the current time n, FBE _ out (n) is a second filtered signal at the current time n.
5. The adaptive equalizer of claim 4, wherein the second tap coefficient configuration module obtains the third tap coefficient or the fourth tap coefficient according to the following equation:
fbe _ coeff (n) ═ fbe _ coeff (n-1) + delta × e _ k (n) × dec _ out (n), where fbe _ coeff (n-1) is the third tap coefficient or the fourth tap coefficient at time n-1, delta is the error constant, e _ k (n) is the first error signal or the second error signal, and dec _ out (n) is the output signal of the decision module at current time n.
6. The adaptive equalizer of claim 1, wherein the error generation module comprises:
the enabling submodule is used for receiving an enabling signal and determining an error signal generating mode according to the enabling signal; and/or
And the calculation submodule is electrically connected with the enabling submodule and used for starting counting after receiving the counting instruction and determining an error signal generation mode according to the relation between the counting value and the counting value threshold.
7. The adaptive equalizer of claim 6,
when the enable signal is a first enable signal or the count value is smaller than the count value threshold, the error generation module obtains the first error signal according to the following formula:
e _ k1(n) × (dec _ out (n) -EQ _ out (n)), where e _ k1(n) is the first error signal at the current time n, R is a constant, EQ _ out (n) is the sum signal at the current time n, and dec _ out (n) is the output signal at the current time n;
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 time n.
8. The adaptive equalizer of claim 1, wherein the decision device obtains the output signal by:
dec _ out (n) is an output signal at the current time n, and EQ _ out (n) is a sum signal at the current time n.
9. The adaptive equalizer of claim 1, wherein the first equalizing module and the second equalizing module are an FFE equalizer of FFE N order and an FBE equalizer of FBE N order, respectively, wherein FFE N is an integer greater than 1 and FBE N is an integer greater than 1.
10. The adaptive equalizer of claim 1, wherein the first equalizing module and the second equalizing module each comprise one of a FIR finite impulse response filter, a transversal filter, and a transposed form filter.
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