CN105048990A - Multi-frequency filter - Google Patents
Multi-frequency filter Download PDFInfo
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- CN105048990A CN105048990A CN201510311375.4A CN201510311375A CN105048990A CN 105048990 A CN105048990 A CN 105048990A CN 201510311375 A CN201510311375 A CN 201510311375A CN 105048990 A CN105048990 A CN 105048990A
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Abstract
The invention relates to a multi-frequency filter, and belongs to the field of digital signal spread spectrum communication. A filter of each order is composed of two matched filters, the frequency of one matched filter is corresponding to the upper limit frequency of carrier wave signals, and the frequency of the other matched filter is corresponding to the lower limit frequency of the carrier wave signals; and the frequencies of the two matched filters in each order change according to the frequency of input carrier wave signals, at the same time, the filtering orders of the multi-frequency programmable matched filters are adjustable, a difference comparison is made between data output by the matched filters and a local carrier wave template, and if output signals are smaller than a difference of the local carrier wave template, the programmable matched filters input the output signals to matched filters of a next order for filtering until output carrier wave signals are greater than the value of the local carrier wave template. According to the invention, multi-order filtering is carried out on the carrier wave signals, useful components of the output carrier wave signals can be enhanced as much as possible, and the signal-to-noise ratio is higher.
Description
The present invention relates to a kind of multi-frequency filter, belong to the technical field of power carrier, specifically belong to digital signal processing technique field.
A basic conception in communication is modulated exactly, refer to the modulation signal carrying useful information go control high-frequency carrier signal.Frequency-shift keying is also known as frequency shift keying, and it transmits digital signal with different carrier waves.FM signal and 2FSK signal are a kind of communication modes that digital communication system uses comparatively early, and this communication mode easily realizes, and antinoise and anti-decay property are comparatively strong, are widely used in slow data transmission communication system.
In a power line communication system, carrier signal, when transmitting, due to interference such as the change of input impedance on power line and the Stochastic accessing of power line device cut out, can be mixed into the noise of various frequency in carrier signal, cause carrier signal transmission unreliable, real time communication rate is not high.Now, the positive develop rapidly of Digital Signal Processing, the digitlization of signal, intellectuality and networking are the main trend of modern information technology development, and digitlization is basis that is intelligent and networking.Filtering technique is the important branch of Digital Signal Analysis, treatment technology.No matter acquisition, the transmission of signal, or the process of signal and exchange and all be unable to do without filtering technique, it to signals security reliably and efficient, flexible to transmit be vital.In all electronic systems, the frequency of utilization of filter is the most extensive.In the design of optimum linear filter, have one to be make filter output signal-to-noise ratio reach maximum in a certain particular moment, the optimum linear filter of deriving therefrom is called matched filter.Matched filter is the maximum linear filter of the signal transient power of output and noise average power ratio, and the transfer function form of filter is the conjugation of signal spectrum.Matched filter has been local spreading code and the related operation of input data i.e. wherein h(i) be local spreading code, x(i) be input data.Y (n) is local spreading code and the related operation of input data.Matched filter does two kinds of process to signal: (1) removes any non-linear partial in signal phase frequency function, and all frequency components in signal thus at a time can be made all to form peak value at output in-phase stacking.(2) according to the amplitude-frequency characteristic of signal, input waveform is weighted, so as most effectively Received signal strength energy and suppress disturb power output.
The present invention proposes a kind of multi-frequency filter to solve the problem a little, its objective is that solution matched filter filter order is non-adjustable, the problem that filter frequencies can not change according to the change of incoming carrier frequency.
A kind of multi-frequency filter, every single order matched filter is made up of two matched filters, the upper limiting frequency of the corresponding carrier signal of frequency of a matched filter, the lower frequency limit of the corresponding carrier signal of another matched filter;
Often in group the frequency of two matched filters according to the frequency change of carrier signal of input, when the frequency of carrier signal of input being detected, control the value of the local generator 1 of adjustment and local generator 0, adjust the value of the upper limiting frequency of matched filter and the value of matched filter lower frequency limit by local generator 1 and local generator 0;
The filter order of matched filter carries out regulating according to the signal to noise ratio of output signal, concrete regulative mode is as follows: the signal that every single order matched filter exports can send relevant decision device to, the signal exported through matched filter and local template signal are made difference comparsion by relevant decision device, if the signal exported is greater than local template signal, then signal directly enters next stage process by relevant decision device; If output signal is less than local template signal, then signal can enter the input port of lower single order matched filter, carries out multistage filtering;
Carrier signal is after programmable matched filter, and the carrier signal of output has higher signal to noise ratio.
Carrier signal is after programmable matched filter, and the carrier signal of output has higher signal to noise ratio.
The present invention is when carrier signal and interference noise enter filter simultaneously, and it makes carrier signal useful component occur kurtosis in a flash at certain, and noise contribution is suppressed.Therefore select different filter order in different situations, smaller snr loss can be obtained, and this loss normally system acceptable, multi-frequency programmable matched filter can save the consumption to resource greatly simultaneously, has very large using value.
When considered in conjunction with the accompanying drawings, by referring to detailed description below, more completely can understand the present invention better and easily learn wherein many adjoint advantages, but accompanying drawing described herein is used to provide a further understanding of the present invention, form a part of the present invention, schematic description and description of the present invention, for explaining the present invention, does not form inappropriate limitation of the present invention, as schemed wherein:
Fig. 1 is the structure chart of matched filter.
Fig. 2 is the structure chart of multistage programmable filter.
Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples are for illustration of the present invention.
Embodiment 1:
As the structure chart that Fig. 1 is single order matched filter, comprise local generator 1, local generator 0, matched filter FL1, matched filter FL0.The wherein coupling of the corresponding carrier signal lower frequency limit of matched filter FL1, the coupling of the corresponding carrier signal upper limiting frequency of FL0.Carrier signal is input to the input of matched filter after analog-to-digital conversion, and wherein " 1 " is corresponding to carrier wave lower frequency limit f1, and symbol " 0 " is corresponding to carrier wave upper limiting frequency f0.The frequency of local generator 1 and local generator 0 can be adjusted dynamically in real time by software control.Therefore often the frequency of two matched filters also can real-time change in group, when the frequency of the carrier signal inputted changes, the frequency of matched filter impulse response signal also changes, therefore different frequency carrier signal is after matched filter, the signal of output can have higher signal to noise ratio.
As the structure chart that Fig. 2 is multistage programmable filter, carrier signal sends the digital signal FC1 of output to relevant decision device after single order matched filter, the difference of the digital signal FC1 of input and local carrier template is made comparisons by relevant decision device, if the signal exported is greater than local template signal, then signal directly enters next stage process by relevant decision device.If output signal is less than local template signal, then signal can enter the input port of lower single order matched filter, carries out multistage filtering.Carrier signal is after multi-stage filter, and the signal of output has higher signal to noise ratio.
Those skilled in the art will understand further, can be implemented as electronic hardware, computer software or both combination in conjunction with the system block diagram openly described, circuit and algorithm steps herein.For this interchangeability of hardware and software is clearly described, various Illustrative components, frame, circuit and step are do vague generalization with the form of its function collection to describe above.This type of function collection is implemented as hardware or software depends on embody rule and forces at the design constraint of total system.Technical staff can realize described function collection by different way for often kind of application-specific, but this type of realizes decision-making and should not be interpreted as causing disengaging the scope of the present disclosure.
Claims (2)
1. a multi-frequency filter, is characterized in that every single order matched filter is made up of two matched filters, the upper limiting frequency of the corresponding carrier signal of frequency of a matched filter, the lower frequency limit of the corresponding carrier signal of another matched filter.
2. often in group the frequency of two matched filters according to the frequency change of the carrier signal of input, when the frequency of carrier signal of input being detected, control the value of the local generator 1 of adjustment and local generator 0, adjust the value of the upper limiting frequency of matched filter and the value of matched filter lower frequency limit by local generator 1 and local generator 0.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510311375.4A CN105048990A (en) | 2015-07-21 | 2015-07-21 | Multi-frequency filter |
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| CN201510311375.4A CN105048990A (en) | 2015-07-21 | 2015-07-21 | Multi-frequency filter |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1433594A (en) * | 2000-06-05 | 2003-07-30 | 连宇通信有限公司 | Synchronization capture method of downline in CDMA system |
| CN102246437A (en) * | 2008-12-16 | 2011-11-16 | 阿尔卡特朗讯美国公司 | Communication system and method with signal constellation |
| CN103338058A (en) * | 2013-05-28 | 2013-10-02 | 北京中宸泓昌科技有限公司 | Multi-frequency programmable matching filter |
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2015
- 2015-07-21 CN CN201510311375.4A patent/CN105048990A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1433594A (en) * | 2000-06-05 | 2003-07-30 | 连宇通信有限公司 | Synchronization capture method of downline in CDMA system |
| CN102246437A (en) * | 2008-12-16 | 2011-11-16 | 阿尔卡特朗讯美国公司 | Communication system and method with signal constellation |
| CN103338058A (en) * | 2013-05-28 | 2013-10-02 | 北京中宸泓昌科技有限公司 | Multi-frequency programmable matching filter |
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