CN101616112A - Frequency offset estimation unit and method of estimation thereof - Google Patents
Frequency offset estimation unit and method of estimation thereof Download PDFInfo
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- CN101616112A CN101616112A CN200810126786A CN200810126786A CN101616112A CN 101616112 A CN101616112 A CN 101616112A CN 200810126786 A CN200810126786 A CN 200810126786A CN 200810126786 A CN200810126786 A CN 200810126786A CN 101616112 A CN101616112 A CN 101616112A
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Abstract
The invention discloses a kind of frequency offset estimation unit and evaluation method, it can fast and accurately estimate the frequency offset of input signal, because this frequency offset estimation unit and method of estimation are not subjected to the influence of channel characteristic, therefore applicable to various channel environment.It includes a n power computing module and a spectrum analysis module.Receive signal by butt joint and carry out the computing of n power drawing a n power signal, and the frequency spectrum of analyzing this n power signal.
Description
Technical field
The present invention relates to a kind of frequency offset estimation unit and method of estimation thereof, refer to a kind of estimation unit and method of estimation thereof of utilizing spectrum analysis (spectrum analysis) to draw frequency offset especially.
Background technology
General communication system is signal to be stated from the high frequency carrier transmit, and with a harmony device (tuner) signal is amplified and frequency reducing in receiving terminal, carry out demodulation to offer the subsequent demodulation device, but the harmony device can be because factors such as mechanical aging or performance errors, can't provide stable frequency-dropping function, so that produce time dependent frequency shift (FS) (frequency offset).The existing method that solves frequency shift (FS) mostly is in recurrence (iteration) mode and progressively estimates frequency offset, but when the situation of channel attenuation (channel fading) and frequency shift (FS) is serious, the method need expend the long time could restrain estimated value, is vulnerable to restriction on reality is used.
Summary of the invention
Technical problem to be solved by this invention provides a kind of frequency offset estimation unit and method of estimation thereof, it can fast and accurately estimate the frequency offset of input signal, because this frequency offset estimation unit and method of estimation are not subjected to the influence of channel characteristic, therefore applicable to various channel environment.The present invention simultaneously also provides a kind of frequency offset its method of estimation, and it also can fast and accurately estimate the frequency offset of input signal, also applicable to various channel environment.
In order to solve above technical problem, the invention provides following technical scheme:
The embodiment one of according to the present invention, it is for providing a kind of method of estimated frequency side-play amount.This method includes and receives signal to one and carry out the computing of n power drawing a n power signal, and this n power signal is carried out spectrum analysis to draw a frequency offset.
Another embodiment according to the present invention, it is for providing a kind of frequency offset estimation unit.This device includes a n power computing module and a spectrum analysis module, wherein n power computing module system is used for receiving signal to one and carries out the computing of n power drawing a n power signal, and spectrum analysis module system is used for this n power signal is carried out spectrum analysis and draws a frequency offset according to results of spectral.
The present invention adopts butt joint receipts signal to carry out the computing of n power and spectrum analysis draws the frequency offset that receives signal, compared to existing method with recursive fashion estimated frequency side-play amount, the present invention not only fast, accurately, more is not subjected to the influence of channel characteristic, therefore applicable to various channel environment.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.
Fig. 1 is the block schematic diagram of one of frequency offset estimation unit of the present invention embodiment.
Fig. 2 is the block schematic diagram of one of frequency offset estimation unit shown in Figure 1 embodiment.
Fig. 3 is the schematic diagram that frequency offset estimation unit shown in Figure 1 is arranged at an embodiment of a digital video broadcast system.
[primary clustering symbol description]
100,200 frequency offset estimation units, 110 Nth power computing modules
120 spectrum analysis module, 122 frequency spectrum computing units
124 comparing units, 126 processing units
202 selected cells, 204 converting units
The 206 unit 310 harmony devices that add up
320 frequency controllers, 330 time sequence reply devices
340 equalizers, 350 weakened phase restoring devices
360 back coupling equalizers
Embodiment
See also Fig. 1, it is the block schematic diagram of one of frequency offset estimation unit of the present invention embodiment.As shown in the figure, frequency offset estimation unit 100 includes a n power computing module 110 and a spectrum analysis module 120, and wherein spectrum analysis module 120 includes a frequency spectrum computing unit 122, a comparing unit 124 and a processing unit 126 again.Frequency offset estimation unit 100 is when estimating the frequency offset of a reception signal, system receives signal with 110 butt joints of n power computing module earlier and carries out the computing of n power to draw a n power signal, analyze the frequency spectrum of this n power signal again by spectrum analysis module 120, and draw a frequency offset according to results of spectral.In general, n system is designed to 2 m times of (n=2m, m is a positive integer), in the present embodiment, n is 4, butt joint is received signal and is carried out the computing of n power and can eliminate the transmission end and be added in modulation (modulation) on the signal, for example 4 kinds of phase places of quadriphase PSK (QPSK) modulation all equate after through 4 power computings, for orthogonal amplitude modulating and changing (QAM), the characteristic that equates through phase place above-mentioned after the 4 power computings still can occur, just can add a little noise, but not influence follow-up results of spectral.
N power signal then is admitted to frequency spectrum computing unit 122 in the spectrum analysis module 120 to calculate its frequency spectrum.Frequency spectrum computing unit 122 does not limit the algorithm of employing, and any algorithm that draws spectral characteristic all can be applicable to the present invention.In one embodiment, frequency spectrum computing unit 122 is to calculate frequency spectrum according to the Welch algorithm: as shown in Figure 2, frequency spectrum computing unit 122 includes a selected cell 202, one converting unit 204 and one unit 206 that adds up, selected cell 202 is in time domain, (each section is made of a continuous N sampling point by the section of N to take out K length from n power signal, but each section can not be to take from n power signal continuously), converting unit 204 then is converted to those sections respectively frequency domain and calculates its power, and the power of unit 206 each section of accumulative total that add up is to draw the frequency spectrum of this n power signal.The frequency spectrum computing unit 122 of present embodiment has (because can adopt fast fourier transform (FFT) and be no female number analysis) simply easy to implement, save advantages such as power consumption and saving hardware memory source, and the purpose of power of K section of accumulative total is to reduce The noise, thus present embodiment do not limit K must be greater than 1.
Behind the frequency spectrum that draws n power signal, comparing unit 124 is just found out a frequency values that has maximum power in the frequency spectrum, this frequency values system is proportional to the frequency offset that receives signal, therefore, processing unit 126 can be by adjusting this frequency values and draw frequency offset Δ f according to a zoom factor (scaling factor), and wherein zoom factor system decides according to the sampling rate (sampling rate) that receives signal.
The estimated frequency offset Δ f that goes out of frequency offset estimation unit 100 (200) can be used for but is not limited to the frequency shift (FS) that receives signal in the compensation communication system.(DVB) system is an example with digital video broadcasting, please refer to Fig. 3, and it is the schematic diagram that frequency offset estimation unit 100 is arranged at one of digital video broadcast system embodiment.Receive signal and after through harmony device (tuner) 310 down conversion process, have frequency shift (FS), frequency offset estimation unit 100 is to be used for estimating this frequency offset, and the frequency offset Δ f that estimates is offered frequency controller 320 is offset with compensating frequency.In the present embodiment, frequency offset estimation unit 100 is to be coupled to after time sequence reply device (timing recovery) 330 and the equalizer (equalizer) 340, receive the output signal that signal carries out change processing post analysis equalizers 340 such as time sequence reply and passage in time sequence reply device 330 and equalizer 340 butt joints, but please note, this only is one of the present invention embodiment, and frequency offset estimation unit 100 does not limit and must be coupled to after the equalizer 340.
In addition, more can a controller (not shown) when being in the frequency compensation pattern, the digital video broadcast system start frequency offset estimation unit 100 and close follow-up as weakened phase restoring device (phaserecovery) 350, feedback equalizer (feedback equalizer) 360 circuit such as grade, finish the estimation of frequency offset Δ f up to frequency offset estimation unit 100, after frequency offset Δ f offered frequency controller 320 compensating frequencies skews, restart the weakened phase restoring device 350 of before closing, feedback equalizer 360 circuit such as grade, and close frequency offset estimation unit 100, with the consumption of saving power, and this moment, the digital video broadcast system promptly was returned to normal operating mode.
Please note, above-mentioned n power computing module 110 and spectrum analysis module 120 can realize by software mode, for example with a processor executive program code, yet, the present invention is not as limit, under the situation of the present invention's spirit, n power computing module 110 and spectrum analysis module 120 also can adopt hardware mode or the software and hardware hybrid mode is done in fact.
In sum, frequency offset estimation unit 100 (200) is to receive signal to one to carry out the frequency offset that the computing of n power and spectrum analysis draw the reception signal, compared to known method with recursive fashion estimated frequency side-play amount, frequency offset estimation unit 100 (200) not only fast, accurately, more be not subjected to the influence of channel characteristic, therefore applicable to various channel environment.
The above only is the present invention's preferred embodiment, and all equalizations of being done according to the present patent application claim change and modify, and all should belong to the present invention's covering scope.
Claims (17)
1. the method for an estimated frequency side-play amount is characterized in that, it includes:
Receive signal to one and carry out the computing of n power to draw a n power signal; And
This n power signal is carried out spectrum analysis to draw a frequency offset.
2. the method for estimated frequency side-play amount as claimed in claim 1 is characterized in that, wherein n is 2 integral multiple.
3. the method for estimated frequency side-play amount as claimed in claim 1 is characterized in that, wherein the step that this n power signal is carried out spectrum analysis includes:
Calculate the frequency spectrum of this n power signal; And
Find out a frequency values with maximum power according to this frequency spectrum;
And include according to the step that this results of spectral draws this frequency offset:
Draw this frequency offset according to this frequency values.
4. the method for estimated frequency side-play amount as claimed in claim 3 is characterized in that, the step that wherein calculates the frequency spectrum of this n power signal includes:
In time domain, take out plurality of sections from this n power signal;
Those sections are converted to frequency domain and calculate its power; And
The power of those sections of accumulative total is to draw the frequency spectrum of this n power signal.
5. the method for estimated frequency side-play amount as claimed in claim 4 is characterized in that, wherein those sections are respectively to include continuous a plurality of sampling points in this n power signal.
6. the method for estimated frequency side-play amount as claimed in claim 4 is characterized in that, wherein the length of those sections is identical.
7. the method for estimated frequency side-play amount as claimed in claim 3 is characterized in that, wherein the step that draws this frequency offset according to this frequency values includes:
Adjust this frequency values to draw this frequency offset according to a zoom factor.
8. the method for estimated frequency side-play amount as claimed in claim 1 is characterized in that, it is applied to a digital video broadcast system this frequency offset with this reception signal of estimating this digital video broadcast system.
9. frequency offset estimation unit is characterized in that it includes:
One n power computing module is used for receiving signal to one and carries out the computing of n power to draw a n power signal; And
One spectrum analysis module is coupled to this n power computing module, is used for this n power signal is carried out spectrum analysis and draws a frequency offset according to results of spectral.
10. frequency offset estimation unit as claimed in claim 9 is characterized in that, wherein n is 2 integral multiple.
11. frequency offset estimation unit as claimed in claim 9 is characterized in that, wherein this spectrum analysis module includes:
One frequency spectrum computing unit is coupled to this n power computing module, is used for calculating the frequency spectrum of this n power signal;
One comparing unit is coupled to this frequency spectrum computing unit, is used for finding out the frequency values with maximum power according to this frequency spectrum; And
One processing unit is coupled to this comparing unit, is used for drawing this frequency offset according to this frequency values.
12. frequency offset estimation unit as claimed in claim 11 is characterized in that, wherein said frequency spectrum calculates unit pack and contains:
One selected cell is coupled to this n power computing module, is used in time domain, takes out plurality of sections from this n power signal;
One converting unit is coupled to this selected cell, is used for those sections are converted to frequency domain and calculate its power; And
One unit that adds up is coupled to this converting unit, is used for the power of those sections of accumulative total to draw the frequency spectrum of this n power signal.
13. frequency offset estimation unit as claimed in claim 12 is characterized in that, wherein said selected cell takes out a plurality of sampling points continuous in this n power signal with as a section.
14. frequency offset estimation unit as claimed in claim 12 is characterized in that wherein the length of those sections is identical.
15. frequency offset estimation unit as claimed in claim 11 is characterized in that wherein said processing unit includes an adjustment unit, is used for adjusting this frequency values to draw this frequency offset according to a zoom factor.
16. frequency offset estimation unit as claimed in claim 9 is characterized in that it also includes:
One controller, be coupled to this n power computing module and this spectrum analysis module, it starts this n power computing module and this spectrum analysis module when a frequency compensation pattern, and closes this n power computing module and this spectrum analysis module when a normal manipulation mode.
17. frequency offset estimation unit as claimed in claim 9 is characterized in that, it is arranged at a digital video broadcast system this frequency offset with this reception signal of estimating this digital video broadcast system.
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| CN200810126786A CN101616112A (en) | 2008-06-23 | 2008-06-23 | Frequency offset estimation unit and method of estimation thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103916203A (en) * | 2013-01-07 | 2014-07-09 | 晨星软件研发(深圳)有限公司 | Timing sequence recovery device and method |
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2008
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103916203A (en) * | 2013-01-07 | 2014-07-09 | 晨星软件研发(深圳)有限公司 | Timing sequence recovery device and method |
| CN103916203B (en) * | 2013-01-07 | 2016-08-17 | 晨星软件研发(深圳)有限公司 | Time sequence reply device and method |
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