CN113098436A - Design method of shaping filter for PSK modulation - Google Patents
Design method of shaping filter for PSK modulation Download PDFInfo
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- CN113098436A CN113098436A CN202110355488.XA CN202110355488A CN113098436A CN 113098436 A CN113098436 A CN 113098436A CN 202110355488 A CN202110355488 A CN 202110355488A CN 113098436 A CN113098436 A CN 113098436A
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- 238000013461 design Methods 0.000 title claims abstract description 29
- 238000007493 shaping process Methods 0.000 title claims abstract description 29
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000001228 spectrum Methods 0.000 claims abstract description 25
- 230000008030 elimination Effects 0.000 claims abstract description 13
- 238000003379 elimination reaction Methods 0.000 claims abstract description 13
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H2011/0488—Notch or bandstop filters
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Abstract
The invention discloses a design method of a shaping filter for PSK modulation, which comprises the following steps: s1: generating DPSK baseband signals of frequency points corresponding to L wave bands by using a digital processing module and a radio frequency power amplifier module, and carrying out differential coding on the DPSK baseband signals; s2: inputting the DPSK signal after differential coding into a spectrum analyzer to obtain a spectrum image; s3: analyzing the power attenuation of the first side lobe relative to the main peak according to the spectrum image; s4: utilizing matlab to carry out constraint design of a band elimination filter; s5: coe file of design parameters of the band elimination filter is derived; s6: and importing the coe file into the FPGA to complete the design of the shaping filter. The invention changes the traditional shaping filter into a band elimination filter, can solve the problem that the conventional filter influences signal receiving in order to improve the frequency spectrum bandwidth, so that side lobe signals are easy to reserve, and can filter the signal of a first side lobe in a signal frequency spectrum through the filter to reserve a main lobe signal frequency spectrum and other signals with little interference on receiving.
Description
Technical Field
The invention relates to the field of communication engineering, in particular to a design method of a shaping filter for PSK modulation.
Background
In the modulation system, whether ASK or PSK modulation, the original signal is a substantially square pulse signal, but since the baseband signal is not shaped and is equivalent to an impulse, the frequency domain is infinitely broadened. The rise and fall of the rectangular pulse are abrupt changes, which often causes that both low-frequency components and high-frequency components are large, the occupied frequency spectrum bandwidth is also wide, and if the rectangular pulse is transmitted into a limited channel for transmission, the following problems can occur: 1. the method occupies larger limited frequency spectrum resources, and more side lobe components can cause interference on the receiving and transmitting of other frequency points in the communication environment; 2. the subsequent circuit can cause more serious useless power loss when performing power amplification; 3. in the case of multi-frequency point applications, larger side lobes can have an impact on reception. This causes interference in practical engineering applications, and signals that are reflected as being off a certain frequency point may also be received and decoded.
The invention patent application document with the application number of CN201710156012.7 proposes a shaping filter and a shaping method thereof, and proposes a shaping filter for solving the problem of low operation speed of the existing shaping filter, but cannot solve the problem that the rise and fall time of the time domain waveform of the baseband signal caused by using a band-stop filter to relieve the shaping filtering in the PSK modulation process does not meet the engineering requirement. In practical engineering application, according to a conventional modulation design, the rising and falling of the PSK pulse signal in the time domain after shaping and filtering are not abrupt but rather are relatively smooth. However, in practical engineering, many items have strict time requirements on the rising edge and the falling edge of a pulse signal, and filtering is completed by using a conventional low-pass shaping filter, so that although the requirement of reducing the bandwidth can be well met and the advantages are provided, the requirement of the data edge is difficult to meet.
Disclosure of Invention
Based on this, the invention aims to provide a design method of a shaping filter for PSK modulation, which is used for solving the problem that the rise and fall time of a baseband signal time domain waveform caused by using a band elimination filter to relieve shaping filtering in the PSK modulation process does not meet the engineering requirement.
In order to achieve the above object, the present invention provides a shaping filter design method for PSK modulation, including the steps of:
s1: generating DPSK baseband signals of frequency points corresponding to L wave bands by using a digital processing module and a radio frequency power amplifier module, and carrying out differential coding on the DPSK baseband signals;
s2: inputting the DPSK signal after differential coding into a spectrum analyzer to obtain a spectrum image;
s3: analyzing the power attenuation of the first side lobe relative to the main peak according to the spectrum image;
s4: utilizing matlab to carry out constraint design of a band elimination filter;
s5: coe file of design parameters of the band elimination filter is derived;
s6: and importing the coe file into the FPGA to complete the design of the shaping filter.
Preferably, the S3 further includes:
s31: analyzing the power attenuation of the first side lobe relative to the main peak to obtain side lobe attenuation w 1;
s32: the frequency point difference f1 of the first side lobe relative to the main peak is obtained.
Preferably, the S4 further includes:
s41: setting a sampling rate Fs of the items;
s42: setting the left transition Fpass1 and Fstop1 of the band-stop filter so that Fpass1< Fstop1< f 1;
s43: setting a right transition band Fpass2 and Fstop2 of the band-stop filter, so that Fpass2> Fstop2> f 1;
s44: the magnitude of the rejection of the band stop portion is set at Astop.
Preferably, the S6 further includes:
s61: the filter design parameters of the coe file are imported inside the FPGA by using a filter module.
Preferably, the shaping filter is a band-stop filter.
The beneficial effect of this application: the traditional shaping filter is replaced by a band elimination filter, and the band elimination filter can inhibit signals in a certain frequency band and allows signals outside the frequency band to pass through; the filter can not only solve the problem that the frequency spectrum bandwidth is improved in order to meet engineering requirements by the conventional filter, so that the first side lobe signals except the main lobe are easy to remain and influence signal receiving, but also filter the signals of the first side lobe in the signal frequency spectrum by the filter, and remain the main lobe signal frequency spectrum and other signals with little interference on receiving, thereby solving the problem of the requirement on the rising and falling time of the signals in the engineering.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the structures of the drawings without creative efforts.
FIG. 1 is a schematic diagram of a DPSK signal modulation method according to the invention;
FIG. 2 is a block diagram of an embodiment of the present invention;
FIG. 3 is a waveform diagram of an original encoded modulated baseband signal;
FIG. 4 shows the modulated signal after filtering processing by the present method;
the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.
As shown in fig. 1, in this embodiment, the present invention provides a shaping filter design method for PSK modulation, where the shaping filter design method includes the following steps:
s1: generating DPSK baseband signals of frequency points corresponding to L wave bands by using a digital processing module and a radio frequency power amplifier module, and carrying out differential coding on the DPSK baseband signals;
s2: inputting the DPSK signal after differential coding into a spectrum analyzer to obtain a spectrum image;
s3: analyzing the power attenuation of the first side lobe relative to the main peak according to the spectrum image;
s4: utilizing matlab to carry out constraint design of a band elimination filter;
s5: coe file of design parameters of the band elimination filter is derived;
s6: and importing the coe file into the FPGA to complete the design of the shaping filter.
In this embodiment, the S3 further includes:
s31: analyzing the power attenuation of the first side lobe relative to the main peak to obtain side lobe attenuation w 1;
s32: the frequency point difference f1 of the first side lobe relative to the main peak is obtained.
In this embodiment, the S4 further includes:
s41: setting a sampling rate Fs of the items;
s42: setting the left transition Fpass1 and Fstop1 of the band-stop filter so that Fpass1< Fstop1< f 1;
s43: setting a right transition band Fpass2 and Fstop2 of the band-stop filter, so that Fpass2> Fstop2> f 1;
s44: the magnitude of the rejection of the band stop portion is set at Astop.
In this embodiment, the S6 further includes:
s61: the filter design parameters of the coe file are imported inside the FPGA by using a filter module.
In this embodiment, the shaping filter is a band-stop filter.
Specifically, the working principle and related steps of the scheme are as follows:
in the PSK modulation system, because the bandwidth of the original signal is infinite, but 90% of the energy is concentrated in the main lobe bandwidth, in order to improve the power utilization rate of the transmitting end and reduce the influence of noise, the original baseband signal is shaped and filtered before modulation, so as to filter out the signal and noise outside the main lobe.
Meanwhile, a strict time domain requirement is required for the rising edge and the falling edge of a baseband signal in engineering, so that a certain high-frequency component is required to be ensured to maintain the rising edge and the falling edge of the time domain when a filter is designed.
The traditional shaping filter is a single low-pass filter, and the time-domain rising edge and falling edge requirements of some engineering projects are often difficult to meet.
The scheme of the invention creatively changes the traditional shaping filter into a band-stop filter. The band-stop filter can suppress signals in a certain frequency band and allows signals outside the frequency band to pass through. The problem that the first side lobe signals except the main lobe are easy to remain to influence signal receiving due to the fact that the frequency spectrum bandwidth is improved by a traditional filter to meet engineering requirements can be solved. And the filter can filter the signal of the first side lobe in the signal spectrum, and the main lobe signal spectrum and other signals with little interference to reception are left. Therefore, the problem of the requirement on the rising and falling time of the signal in the engineering is solved.
Specifically, the product comprises a radio frequency power amplifier module, a digital processing module and the like.
Firstly, a digital processing module and a radio frequency power amplifier module are utilized to generate modulated DPSK signals of frequency points corresponding to L wave bands, and a spectrum analyzer is utilized to analyze spectrum images.
And analyzing the power intensity of the harmonic side lobe, and checking whether the power of the first side lobe is the maximum within the project requirement range, wherein the analysis is the key point.
Under the requirement of inhibiting the side lobe, the band elimination filter is reasonably designed, the power attenuation of the first side lobe is ensured, the communication influence of the side lobe frequency point on a receiving end is reduced, and then the double indexes of a time domain and a frequency domain are ensured.
The filter design method comprises the following steps:
1. and analyzing the power attenuation of the first side lobe relative to the main peak to obtain the current side lobe attenuation w1 and the frequency point difference f1 of the first side lobe relative to the main peak.
2. The constrained design of the band-stop filter is carried out by using a matlab tool, the sampling rate fs of an input item is used, and the left transition band Fpass1 and Fstop1 of the band-stop filter are set, so that Fpass1 is smaller than Fstop1 and smaller than f1, and the transition band is reduced as much as possible under the condition that the order of the filter is realized.
3. The right transition band Fpass2 and Fstop2 of the band-stop filter are arranged, so that Fpass2> Fstop2> f1, and the transition band is reduced as much as possible under the condition that the order of the filter is considered to be achievable.
4. The magnitude of the rejection of the band stop portion is set at Astop.
5. The design parameters of the derived digital filter are the coe file.
6. Filter design parameters of coe files are imported by a filter module inside fpga, and the design of the shaping filter is completed.
The specific flow and scheme of signal processing:
1. a communication transmission module with psk modulation is constructed as shown in fig. 2, where s (t) signal is original encoded modulated baseband signal, and its signal waveform is as shown in fig. 3 (encoded as 10101010 in the figure).
2. The baseband signal passes through the digital filter circuit (the digital filter circuit is implemented in the FPGA) designed in the present patent as shown in fig. 3, the attenuation of the harmonic signal is completed, and the time sequence requirement of the rising edge and the falling edge of the time domain is satisfied, and the waveform of the filtered baseband signal is as shown in fig. 4.
3. The up-conversion of the signal is completed inside the FPGA, and the method is as shown in fig. 3, i.e. a carrier trigonometric function signal is multiplied in time domain.
4. The up-converted signal is converted into analog quantity through the DAC signal, and then amplified in power by the rf power amplifier module shown in fig. 2 and transmitted through the antenna.
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (5)
1. A method for designing a shaping filter for PSK modulation, comprising the steps of:
s1: generating DPSK baseband signals of frequency points corresponding to L wave bands by using a digital processing module and a radio frequency power amplifier module, and carrying out differential coding on the DPSK baseband signals;
s2: inputting the DPSK signal after differential coding into a spectrum analyzer to obtain a spectrum image;
s3: analyzing the power attenuation of the first side lobe relative to the main peak according to the spectrum image;
s4: utilizing matlab to carry out constraint design of a band elimination filter;
s5: coe file of design parameters of the band elimination filter is derived;
s6: and importing the coe file into the FPGA to complete the design of the shaping filter.
2. The method of claim 1, wherein the S3 further includes:
s31: analyzing the power attenuation of the first side lobe relative to the main peak to obtain side lobe attenuation w 1;
s32: the frequency point difference f1 of the first side lobe relative to the main peak is obtained.
3. The method of claim 1, wherein the S4 further includes:
s41: setting a sampling rate Fs of the items;
s42: setting the left transition Fpass1 and Fstop1 of the band-stop filter so that Fpass1< Fstop1< f 1;
s43: setting a right transition band Fpass2 and Fstop2 of the band-stop filter, so that Fpass2> Fstop2> f 1;
s44: the magnitude of the rejection of the band stop portion is set at Astop.
4. The method of claim 1, wherein the S6 further includes:
s61: the filter design parameters of the coe file are imported inside the FPGA by using a filter module.
5. The method of claim 1, wherein the shaping filter is a band-stop filter.
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| CN106908768A (en) * | 2017-02-24 | 2017-06-30 | 四川九洲空管科技有限责任公司 | A kind of impulse compression method of ULTRA-LOW SIDE LOBES |
| CN111654260A (en) * | 2020-07-08 | 2020-09-11 | 中国电子科技集团公司第九研究所 | Band-stop filtering component with variable stop band depth |
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2021
- 2021-04-01 CN CN202110355488.XA patent/CN113098436A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5070337A (en) * | 1991-04-05 | 1991-12-03 | Chen Xiao H | Optimization method and an optimized filter for sidelobe suppression |
| CN1468465A (en) * | 2000-10-06 | 2004-01-14 | 新泻精密株式会社 | Filter circuit |
| CN101651463A (en) * | 2008-08-13 | 2010-02-17 | 大唐移动通信设备有限公司 | Method and device for suppressing narrowband interference of baseband signals |
| CN103344944A (en) * | 2013-07-02 | 2013-10-09 | 西安电子科技大学 | Radar pulse compression filter optimization design method applied to random signal waveforms |
| CN103823177A (en) * | 2014-02-20 | 2014-05-28 | 广东省电信规划设计院有限公司 | Performance detecting method and system for filter based on window function design |
| CN104618286A (en) * | 2014-12-30 | 2015-05-13 | 苏州东奇信息科技股份有限公司 | Strictly band-limited efficient modulating system based on impact filter forming |
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