CN106341101B - The calculation method of group delay filter coefficient and the simulation system of filter - Google Patents
The calculation method of group delay filter coefficient and the simulation system of filter Download PDFInfo
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- CN106341101B CN106341101B CN201610798270.0A CN201610798270A CN106341101B CN 106341101 B CN106341101 B CN 106341101B CN 201610798270 A CN201610798270 A CN 201610798270A CN 106341101 B CN106341101 B CN 106341101B
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- H03H17/02—Frequency selective networks
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- H—ELECTRICITY
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- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
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Abstract
The invention discloses a kind of calculation method of group delay filter coefficient and the simulation systems of filter, are related to technical field of satellite communication, easy to accomplish for improving the stability of system, and on FPGA.Wherein, the calculation method of group delay filter coefficient includes: to carry out inverse fast fourier transform to original group delay characteristic, obtains time-domain signal p (n)；Obtained time-domain signal p (n) is modified, time-domain value c is obtained, wherein time-domain value c includes amplitude-frequency characteristic and phase-frequency characteristic；Fast Fourier Transform (FFT) is carried out respectively to amplitude-frequency characteristic and phase-frequency characteristic；According to the value of the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT) and phase-frequency characteristic, initial group delay filter coefficient is calculated；Initial group delay filter coefficient is truncated according to the length of FPGA demand, obtains group delay filter coefficient.Transmission of the present invention for data in analog satellite channel.
Description
Technical field
The present invention relates to the calculation method of technical field of satellite communication more particularly to a kind of group delay filter coefficient and
The simulation system of filter.
Background technique
The high speed data transfer of wideband satellite communication system has reached several hundred Mbit/s, in the process of high speed data transfer
In, group delay (change rate of phase of the system at certain frequency for frequency) the channel of wideband satellite communication (hereinafter referred to as
Channel) in propagation will affect the transmission of wideband satellite communication, make the high-speed data distortion of transmission.
The distortion (hereinafter referred to as group delay distortion) of the high-speed data of the transmission for caused by group delay can pass through group at present
Group delay filter coefficient in Time-Delay Filter is adjusted.High-speed data is certain by allowing to have after group delay filter
Time domain delay, but it is not intended to generate the distortion that waveform is generated on frequency domain.
Group delay filter is typically all iir filter, and in the filter coefficient of the iir filter on molecule denominator all
There are data, can thus make the output of data system when through the iir filter not only related with current input, but also
Also related with output before, so that the filter stability of system is poor, resource consumption is also bigger, therefore more difficult in FPGA
It is realized in (Field-Programmable Gate Array, field programmable gate array).
Summary of the invention
The purpose of the present invention is to provide a kind of calculation method of group delay filter coefficient and the simulation systems of filter
System, it is easy to accomplish for improving the stability of system, and on FPGA.
In order to achieve the above objectives, the present invention adopts the following technical scheme:
The first aspect of the present invention provides a kind of calculation method of group delay filter coefficient, the group delay filter coefficient
Calculation method include:
Step 1: to original group delay characteristicInverse fast fourier transform is carried out,
Obtain time-domain signal p (n)；Wherein, group delay For phase shift, ω is angular frequency；The mean value of group delayK is Frequency point, and the value range of k is 0 to N-1, and N is in Fast Fourier Transform (FFT) or inverse quick Fu
The length of leaf transformation.
Step 2: being modified to obtained time-domain signal p (n), time-domain value c is obtained, wherein time-domain value c includes amplitude-frequency spy
Property and phase-frequency characteristic.
Step 3: carrying out Fast Fourier Transform (FFT) respectively to amplitude-frequency characteristic and phase-frequency characteristic.
Step 4: being calculated initial according to the value of the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT) and phase-frequency characteristic
Group delay filter coefficient.
Step 5: initial group delay filter coefficient is truncated according to the length of FPGA demand, group delay filter system is obtained
Number.
The calculation method of group delay filter coefficient further include: before step 1, frequency response is carried out to group delay filter
The setting of characteristic；Symmetrical treatment and DC processing are carried out to the frequency domain of group delay filter.
The calculation method of group delay filter coefficient further include: step signal is designed between step 2 and step 3, with
And between step 4 and step 5, Hilbert transform is carried out to initial group delay filter coefficient, initial group delay is filtered
Real part in wave device coefficient is as the frequency domain time delay under the different frequency point of group delay.
Carrying out Fast Fourier Transform (FFT) to amplitude-frequency characteristic in step 3 includes: using formula
Fast Fourier Transform (FFT) is carried out to amplitude-frequency characteristic, wherein | H (ω) | for the amplitude-frequency characteristic after Fast Fourier Transform (FFT)
Value, the positive integer that the value range of n is 1 to N, N is the length of Fast Fourier Transform (FFT), τSIt is group delay in each Frequency point
Time delay value.
Carrying out Fast Fourier Transform (FFT) to phase-frequency characteristic in step 3 includes: using formulaFast Fourier Transform (FFT) is carried out to phase-frequency characteristic, wherein θ (ω) is quick Fu
In phase-frequency characteristic after leaf transformation value, the positive integer that the value range of n is 1 to N, N is the length of Fast Fourier Transform (FFT), τS
For group delay each Frequency point time delay value.
Step 4 includes: to calculate group delay filter according to formula h h=IFFT (H (ω))=IFFT (H (ω) | exp (j θ))
Wave device coefficient, wherein hh is group delay filter coefficient, | H (ω) | for the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT), θ
For the phase information of group delay filter coefficient, ω is angular frequency, and j is that imaginary part indicates symbol.
According to the method for above-mentioned calculating group delay filter coefficient it is found that the present invention is special according to known original group delay
Property, group delay filter coefficient is finally obtained, and the calculated group delay filter coefficient of the present invention can be cut into according to demand
Corresponding length, therefore resource consumption is smaller, is easy to realize in FPGA.
The second aspect of the present invention provides a kind of simulation system of filter, and the simulation system of the filter is suitable for channel
Simulator in the simulation system of the filter, is applicable in through aforementioned present invention for the transmission of the data in analog channel
The group delay filter coefficient that the calculation method of group delay filter coefficient involved in first aspect is calculated.Filter
Simulation system includes:
Analog to digital conversion module, for being digital signal by the analog-signal transitions in channel simulator；With analog to digital conversion mould
The connected digital frequency conversion module of block extracts two point of one digital signal and carries out frequency after carrying out quadrature demodulation to digital signal
The transformation of rate；The filter module being connected with digital frequency conversion module, for using filter to the digital signal after frequency transformation into
Row filtering；The digital-to-analogue conversion module being connected with filter module, for filtered digital signal to be converted into analog signal
Output.
Digital frequency conversion module includes quadrature demodulation unit and frequency conversion unit, wherein quadrature demodulation unit is used for logarithm
Word signal carries out quadrature demodulation；Frequency conversion unit is used to extract two point of one progress frequency change of the digital signal after quadrature demodulation
It changes.
Filter module includes fixed point processing unit, for by the group delay filter coefficient in filter multiplied by 219.8,
Divided by 220Later, group delay filter coefficient is stored using 24BIT.
Filter module further includes the interception unit being connected with fixed point processing unit, for cutting out the filtered of 20BIT
Digital signal.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, embodiment will be described below
Needed in attached drawing be briefly described, it should be apparent that, the accompanying drawings in the following description is only of the invention some
Embodiment for those of ordinary skill in the art without creative efforts, can also be attached according to these
Figure obtains other attached drawings.
Fig. 1 is group delay-frequency curve chart in the prior art；
Fig. 2 is the flow chart one of the calculation method of group delay filter coefficient in the embodiment of the present invention one；
Fig. 3 is the flowchart 2 of the calculation method of group delay filter coefficient in the embodiment of the present invention one；
Fig. 4 is the numerical value contrast curve chart in the embodiment of the present invention one before and after group delay filter coefficient truncation；
Fig. 5 is group delay frequency domain characteristic contrast curve chart one in the embodiment of the present invention one；
Fig. 6 is group delay frequency domain characteristic contrast curve chart two in the embodiment of the present invention one；
Fig. 7 is the flow chart of the simulation system of filter in the embodiment of the present invention two.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are some of the embodiments of the present invention, instead of all the embodiments.Based on this hair
Embodiment in bright, every other implementation obtained by those of ordinary skill in the art without making creative efforts
Example, shall fall within the protection scope of the present invention.
It should be noted that filter involved in the present invention is FIR filter.
In order to which those skilled in the art better understand " group delay ", the definition of group delay is provided by way of example:
The charged particle in ionosphere slows down the propagation of radio signal in the channel in wideband satellite communication system, surpasses
The time delay for spending the free-space propagation time can be described as group delay, usually be indicated with t.When frequency difference, time delay is different, this
When one group frequency delay be exactly group delay.In MSS system, it is an important factor for must be taken into consideration.It can lead in the prior art
Cross the quantity that following formula calculates group delay: t=1.345NT/f2×10-7, wherein t indicate compared with true airborne spread when
Prolong, unit s；F indicates frequency, unit Hz；NTIt indicates total electron content (hereinafter referred to as TEC), unit e/m2, TEC can be by
Inclined propagation path determines.
Illustratively, when TEC is 1016~1019e/m2When section changes, in 1600MHz near band, the group delay of signal
Probably change in the section 0.5ns to 500ns.
Illustratively, as shown in Figure 1, when TEC is 1017e/m2, for frequency band in 1.6GHz~1.8GHz, group delay is with frequency
The increase of rate and reduce.
Embodiment one
The present embodiment provides a kind of calculation methods of group delay filter coefficient, as shown in Figures 2 and 3, group delay filter
The calculation method of wave device coefficient includes:
Step 1: to original group delay characteristicInverse fast fourier transform is carried out,
Obtain time-domain signal p (n)；Wherein, group delay For phase shift, ω is angular frequency；The mean value of group delayK is Frequency point, and the value range of k is 0 to N-1, and M is in Fast Fourier Transform (FFT) or inverse quick Fu
The length of leaf transformation.
Step 2: being modified to obtained time-domain signal p (n), time-domain value c is obtained, wherein time-domain value c includes amplitude-frequency spy
Property and phase-frequency characteristic.
Step 3: carrying out Fast Fourier Transform (FFT) respectively to amplitude-frequency characteristic and phase-frequency characteristic.
Step 4: being calculated initial according to the value of the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT) and phase-frequency characteristic
Group delay filter coefficient.
Step 5: initial group delay filter coefficient is truncated according to the length of FPGA demand, group delay filter system is obtained
Number.
Due to group delay signal energy all up front, truncation tail signal the characteristic of group delay will not be caused
Apparent to influence, the length of initial group delay filter coefficient, group can be truncated in those skilled in the art according to the demand of FPGA
The length of Time-Delay Filter coefficient can be 16,32,64,128 or 256 etc., as shown in figure 4, the length of group delay filter coefficient
It is 16.
It should be noted that as shown in figure 3, one to step 4 the step of the calculation method of above-mentioned group delay filter coefficient
Corresponding 3 to 6 with Fig. 3.The points of Fourier transformation can be set based on experience value in the present embodiment, value 512, certainly
It can be 1024 or 256, since the calculated group delay filter coefficient of the present embodiment is obtained based on Fourier transformation, because
The points of this Fourier transformation and the length of group delay filter coefficient are same numerical value.
The step one in calculation method in order to more clearly describe above-mentioned group delay filter coefficient is into step 5
The calculation method of group delay filter coefficient, below the present invention above-mentioned be related to " amplitude-frequency characteristic " and " phase-frequency characteristic " is done into one
Step ground explanation:
Amplitude-frequency characteristic refers to | H (ejω) |, wherein it can be by width during above-mentioned calculating group delay filter coefficient
The value of frequency characteristic is set as constant.
Phase-frequency characteristic refers toWherein, ndReferred to as phase delay, it represents curveOn a little and origin
The slope of line,Indicate that phase, value are negative, ω is angular frequency.
In addition, to above-mentioned steps one, into step 5, the calculation method of group delay filter coefficient is made with continued reference to Fig. 3
The formula used is described further:
Carrying out inverse fast fourier transform to original group delay characteristic τ (k) in above-mentioned steps one includes using formula p
(n)=IFFT (τ (k)) carries out inverse fast fourier transform to original group delay characteristic；
In above-mentioned steps two to obtained time-domain signal p (n) be modified including, using following formula to time-domain signal into
Row amendment:
C (1)=0；
N=2:N/2+1；
C (n)=p (n)/(n-1)；
N=N/2+2:N；
C (n)=- c (N+2-n).
Certainly, if when using system-computed group delay filter coefficient, obtained time-domain signal is carried out in step 2
Group delay signal must also be transformed in time domain before amendment, workable formula are as follows: p (n)=IFFT (Taus, N).
According to the method for above-mentioned calculating group delay filter coefficient it is found that the present invention is special according to known original group delay
Property, group delay filter coefficient is finally obtained, since the present invention is using FIR filter, the filter stability of system
Corresponding iir filter is preferable；And the calculated group delay filter coefficient of the present invention can be cut into corresponding length according to demand
Degree, therefore resource consumption is smaller, is easy to realize in FPGA.
In the following, the present embodiment difference with the prior art is described with reference to the drawings in the present invention:
It is calculated as shown in figure 5, " the group delay frequency domain characteristic of original setting " refers to according to above-mentioned formula in the prior art
Group delay filter coefficient curve out." the group delay frequency domain characteristic being calculated " refer to according to the step of the present embodiment one to
The group delay filter coefficient curve that step 5 obtains, can intuitively obtain from Fig. 5, and the group delay frequency domain being calculated is special
Property group delay error very little with the group delay frequency domain characteristic of original setting, error curve floats up and down in numerical value 0.It is exemplary
Ground is set if the length of the group delay filter coefficient obtained according to the step of this example one to step 5 is 32 with original
The group delay error for the group delay filter coefficient in group's time-frequency domain characteristic set only has 10%.In addition, as shown in fig. 6, working as root
When the length of the group delay filter coefficient obtained according to the step one in the present embodiment to step 5 is 128, group delay error is more
It is small, only 0.8%.
Further, in order to obtain group delay filter coefficient is more accurate, can carry out in advance to group delay filter
Some settings, as shown in figure 3, optionally, the calculation method of group delay filter coefficient further include: before step 1, to group
Time-Delay Filter carries out the setting of Frequency Response, carries out symmetrical treatment and DC processing to the frequency domain of group delay filter.
Wherein, the setting for carrying out Frequency Response to group delay filter may include the meter to amplitude-frequency characteristic and phase-frequency characteristic
Calculate, illustrate Frequency Response in order to clearer, below the present invention illustrate by taking the setting of satellite communication group delay as an example group delay frequency
Ring the design parameter of the setting of characteristic:
Start parameter are as follows: frf=1.6*109；1.6GHz.
Sweep bandwidth parameter are as follows: bw=200*106；200MHz.
Sweep interval parameter are as follows: detf=1*106；1MHz.
Bandwidth parameter are as follows: f=[frf+ (detf:detf:bw)]；160MHz, precision 1MHz, frequency sweep 200MHz.
Wherein, [10 Nt=17], indicate total electron content (TEC, m-2).The TEC of vertical pillar body is 1016To 1018el/m2
In the range of change；The unit of group delay is the second (s), and the present embodiment is used to be indicated with nanosecond (ns)；Tao_freq=1.345*Nt/
f2*10-7。
Wherein, carrying out symmetrical treatment to the frequency domain of group delay filter includes, using following formula to group delay filter
Frequency domain carry out symmetrical treatment:
N=1:N/2+1；
Taud (n)=tao_freq；
N=N/2+2:N；
Taud (n)=Taud (N+2-n).
Carrying out DC processing to the frequency domain of group delay filter includes, using following formula to the frequency of group delay filter
Domain carries out DC processing:
ETaud=sum (Taud)/N；
Taus=(Taud-eTaud)/2.
It should be noted that above-mentioned steps " carry out the setting of Frequency Response to group delay filter, to group delay filter
Frequency domain carry out symmetrical treatment and DC processing " in corresponding diagram 31 to 2.
Optionally, the calculation method of group delay filter coefficient may also include, and rank is designed between step 2 and step 3
Jump signal, and between step 4 and step 5, carries out Hilbert transform to initial group delay filter coefficient, will be initial
Real part in group delay filter coefficient is as the frequency domain time delay under the different frequency point of group delay.Certainly, step signal is designed
Including designing step signal using following formula:
Sgn (1)=0；
Sgn (N/2+1)=0；
N=2:N/2；
Sgn (n)=1；
N=N/2+2:N；
Sgn (n)=- 1；
Also, three kinds of above-mentioned steps carry out Fast Fourier Transform (FFT) to amplitude-frequency characteristic and phase-frequency characteristic and can be carried out by formula
Transformation, specific as follows:
Carrying out Fast Fourier Transform (FFT) to amplitude-frequency characteristic in step 3 includes: using formulaFast Fourier Transform (FFT) is carried out to amplitude-frequency characteristic, wherein | H (ω) |
For the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT), the positive integer that the value range of n is 1 to N, N is Fast Fourier Transform (FFT)
Length, τSFor group delay each Frequency point time delay value.
Carrying out Fast Fourier Transform (FFT) to phase-frequency characteristic in above-mentioned steps three includes: using formulaFast Fourier Transform (FFT) is carried out to phase-frequency characteristic, wherein θ (ω) is quick Fu
In phase-frequency characteristic after leaf transformation value, the positive integer that the value range of n is 1 to N, N is the length of Fast Fourier Transform (FFT), τS
For group delay each Frequency point time delay value.
Above-mentioned steps four include: to calculate group according to formula h h=IFFT (H (ω))=IFFT (| H (ω) | exp (j θ))
Time-Delay Filter coefficient, wherein hh is group delay filter coefficient, | H (ω) | for the amplitude-frequency characteristic after Fast Fourier Transform (FFT)
Value, θ is the phase information of group delay filter coefficient, and ω is angular frequency, and j is that imaginary part indicates symbol.
Embodiment two
The present embodiment provides a kind of simulation system of filter, the simulation system of filter is suitable for channel simulator, uses
The transmission of data in analog channel, in the simulation system of the filter, when the group being applicable in through the foregoing embodiment in one
Prolong the group delay filter coefficient that the calculation method of filter coefficient is calculated.As shown in fig. 7, the simulation system of the filter
Include:
Analog to digital conversion module 1, for being digital signal by the analog-signal transitions in channel simulator；With analog to digital conversion mould
The connected digital frequency conversion module 2 of block extracts two point of one digital signal and carries out frequency after carrying out quadrature demodulation to digital signal
The transformation of rate；The filter module 3 being connected with digital frequency conversion module 2, for utilizing filter to the digital signal after frequency transformation
It is filtered；The digital-to-analogue conversion module 4 being connected with filter module 3, for filtered digital signal to be converted into simulating
Signal output.
Digital frequency conversion module 2 includes quadrature demodulation unit 21 and frequency conversion unit 22, wherein quadrature demodulation unit 21 is used
In to digital signal progress quadrature demodulation；Frequency conversion unit 22 be used to extract two point one of the digital signal after quadrature demodulation into
Line frequency transformation.
Above-mentioned filter module 3 includes fixed point processing unit 31, for multiplying the group delay filter coefficient in filter
With 219.8, divided by 220Later, group delay filter coefficient is stored using 24BIT.
Above-mentioned filter module 3 may also include the interception unit 32 being connected with fixed point processing unit 31, for cutting out 20BIT
Filtered digital signal.
It should be pointed out that analog to digital conversion module 1 can (Analog-to-Digital Converter, modulus become for ADC
Parallel operation), digital frequency conversion module 2 can be DDC (Direct Digital Control, digital frequency converter), and filter module 3 can be group
Time-Delay Filter, digital-to-analogue conversion module 4 can be DAC (Digital to Analog Converter, digital-to-analogue conversion
Device).
By the group delay filter coefficient in the simulation system of filter in this present embodiment using by above-mentioned
The group delay filter coefficient that embodiment one is calculated, therefore the resource consumption of filter simulation system is small, stability is high.
Embodiment three
The present embodiment provides a kind of filter analogy methods, and the analogy method of the filter is suitable for above-described embodiment two
Filter simulation system.Wherein, the analogy method of the filter includes:
It is digital signal by analog-signal transitions；
Frequency transformation is carried out to digital signal；
The digital signal after frequency transformation is filtered using filter；
Filtered digital signal is converted into analog signal output.
Above-mentioned the step of carrying out frequency transformation to digital signal includes carrying out quadrature demodulation to digital signal；It extracts orthogonal
The transformation of two point of one progress frequency of the digital signal after demodulation.
Above-mentioned the step of being filtered using filter to the digital signal after frequency transformation, includes, to the filter in filter
Wave device coefficient carries out fixed point processing, and fixed point processing includes:
By the group delay filter coefficient in filter multiplied by 219.8, divided by 220；
Group delay filter coefficient is stored using 24BIT.
Above-mentioned the step of being filtered using filter to the digital signal after frequency transformation further includes in fixed point processing
The filtered digital signal of 20BIT is cut out later.
Beneficial effect in the present embodiment is identical as the beneficial effect in above-described embodiment two, and details are not described herein.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can easily think of the change or the replacement, and should all contain
Lid is within protection scope of the present invention.Therefore, protection scope of the present invention should be based on the protection scope of the described claims.
Claims (8)
1. a kind of calculation method of group delay filter coefficient characterized by comprising
Step 1: to the original group delay characteristic of radio signalCarry out inverse quick Fu
In leaf transformation, obtain time-domain signal p (n)；Wherein, group delay For phase shift, ω is angular frequency；Group
The mean value of time delayK is Frequency point, and the value range of k is 0 to N-1, N be Fast Fourier Transform (FFT) or
The length of inverse fast fourier transform；
Step 2: being modified to obtained time-domain signal p (n), obtain time-domain value c, wherein time-domain value c include amplitude-frequency characteristic and
Phase-frequency characteristic；
Step 3: carrying out Fast Fourier Transform (FFT) respectively to amplitude-frequency characteristic and phase-frequency characteristic；
Carrying out Fast Fourier Transform (FFT) to amplitude-frequency characteristic includes:
Use formulaFast Fourier Transform (FFT) is carried out to amplitude-frequency characteristic,
In, | H (ω) | for the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT), the positive integer that the value range of n is 1 to N, N is quick
The length of Fourier transformation, τSFor group delay each Frequency point time delay value；
Carrying out Fast Fourier Transform (FFT) to phase-frequency characteristic includes:
Use formulaFast Fourier Transform (FFT) is carried out to phase-frequency characteristic, wherein θ
(ω) is the value of the phase-frequency characteristic after Fast Fourier Transform (FFT), and the positive integer that the value range of n is 1 to N, N is fast Fourier
The length of transformation, τSFor group delay each Frequency point time delay value；Step 4: special according to the amplitude-frequency after Fast Fourier Transform (FFT)
The value of property and the value of phase-frequency characteristic, are calculated initial group delay filter coefficient；
Step 5: initial group delay filter coefficient is truncated according to the length 16,32,64,128 or 256 of FPGA demand, group is obtained
Time-Delay Filter coefficient.
2. the calculation method of group delay filter coefficient according to claim 1, which is characterized in that further include: in step
Before one,
The setting of Frequency Response is carried out to group delay filter；
Symmetrical treatment and DC processing are carried out to the frequency domain of group delay filter.
3. the calculation method of group delay filter coefficient according to claim 1, which is characterized in that further include: in step
Step signal is designed between two and step 3, and between step 4 and step 5, to initial group delay filter coefficient into
Row Hilbert transform, using the real part in initial group delay filter coefficient as when the frequency domain under the different frequency point of group delay
Prolong.
4. the calculation method of described in any item group delay filter coefficients according to claim 1~3, which is characterized in that step
Four include: to calculate group delay filter coefficient according to formula h h=IFFT (H (ω))=IFFT (| H (ω) | exp (j θ)),
In, hh is group delay filter coefficient, | H (ω) | for the value of the amplitude-frequency characteristic after Fast Fourier Transform (FFT), θ is group delay filtering
The phase information of device coefficient, ω are angular frequency, and j is that imaginary part indicates symbol.
5. the simulation system of a kind of simulation system of filter, filter is suitable for channel simulator, in analog channel
The transmission of data, which is characterized in that in the simulation system of the filter, be applicable in through any one of the claims 1~4 institute
The group delay filter coefficient that the calculation method for the group delay filter coefficient stated is calculated；
The simulation system of filter includes:
Analog to digital conversion module, for being digital signal by the analog-signal transitions in channel simulator；
The digital frequency conversion module being connected with analog to digital conversion module, for carrying out frequency transformation to digital signal；
The filter module being connected with digital frequency conversion module, for being filtered using filter to the digital signal after frequency transformation
Wave；
The digital-to-analogue conversion module being connected with filter module, it is defeated for filtered digital signal to be converted into analog signal
Out.
6. the simulation system of filter according to claim 5, which is characterized in that digital frequency conversion module includes quadrature demodulation
Unit and frequency conversion unit, wherein
Quadrature demodulation unit is used to carry out quadrature demodulation to digital signal；
Frequency conversion unit is used to extract two point of one progress frequency transformation of the digital signal after quadrature demodulation.
7. the simulation system of filter according to claim 5, which is characterized in that filter module includes that fixed point processing is single
Member, for by the group delay filter coefficient in filter multiplied by 219.8Again divided by 220, and filtered using 24BIT storage group delay
Device coefficient.
8. the simulation system of filter according to claim 7, which is characterized in that filter module further include at fixed point
The connected interception unit of unit is managed, for cutting out the filtered digital signal of 20BIT.
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| CN106911409B (en) * | 2017-02-27 | 2020-06-05 | 北京睿信丰科技有限公司 | Optimization method and device for group delay channel system |
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