CN111416918B - Method and device for estimating frequency offset of analog television - Google Patents
Method and device for estimating frequency offset of analog television Download PDFInfo
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- CN111416918B CN111416918B CN202010246370.9A CN202010246370A CN111416918B CN 111416918 B CN111416918 B CN 111416918B CN 202010246370 A CN202010246370 A CN 202010246370A CN 111416918 B CN111416918 B CN 111416918B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/14—Picture signal circuitry for video frequency region
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
Abstract
The invention discloses a method and a device for estimating frequency offset of an analog television. The method comprises the following steps: receiving an analog television signal; carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal; performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal; calculating the signal power of each filtered signal; and performing frequency offset estimation through a frequency offset estimation circuit according to the calculated signal power of the filtering signal. The invention achieves the effect of improving the frequency offset estimation speed and accuracy of the analog television signal.
Description
Technical Field
The invention relates to the technical field of analog television signal transmission, in particular to an analog television frequency offset estimation method and device.
Background
The analog television systems are divided into three types: NTSC, PAL and SECAM. The television signals of the three systems are all composed of a brightness signal, a chrominance signal, a synchronous signal and a blanking signal.
The in-band spectrum of an analog television signal is not flat, but includes two lobes, a luminance carrier (Luma) and a chrominance subcarrier (Chroma), as compared to a digital television signal. During demodulation, the receiver needs to firstly recognize the accurate frequency of Luma and Chroma to complete the subsequent system recognition, and then correctly recover the brightness signal, the chrominance signal, the synchronous signal and the blanking signal.
For an analog television receiver, the frequency offset estimation module of the analog television signal will directly determine the overall performance of the receiver, since the frequency offset estimation module is the basis for implementing the subsequent signal processing functional link of the receiver.
The existing frequency offset estimation technology of the analog television is generally finished by a phase-locked loop (PLL), and has more complex calculation and low convergence speed.
Aiming at the problems of complex frequency offset estimation algorithm and inaccurate result of a receiver to analog television signals in the related art, no effective solution is provided at present.
Disclosure of Invention
The invention mainly aims to provide a method and a device for estimating frequency offset of an analog television, which are used for solving the problems of complex frequency offset estimation algorithm and inaccurate result of a receiver for an analog television signal.
In order to achieve the above object, according to an aspect of the present invention, there is provided an analog television frequency offset estimation method, including: receiving an analog television signal; carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal; performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal; calculating the signal power of each filtered signal; and performing frequency offset estimation through a frequency offset estimation circuit according to the calculated signal power of the filtering signal.
Further, performing a gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal includes: determining the frequency of each step of frequency spectrum shifting according to the step length and the range of the frequency spectrum shifting; and taking the frequency shifted by each step of spectrum as a set step length to carry out gradual frequency shift on the analog television signal to obtain the signal after frequency shift.
Further, performing, by the frequency offset estimation circuit, frequency offset estimation according to the calculated signal power of the filtered signal includes: determining a plurality of peak values and a plurality of valley values of the received analog television signal; determining a maximum point in the plurality of wave peak values; determining a first power difference between each peak value and a maximum value according to the plurality of wave peak values and the plurality of wave valley values; calculating a second power difference between each adjacent crest value and trough value; and filtering the plurality of wave peak values according to the first power difference and the second power difference to obtain filtered wave peak values.
Further, after filtering a plurality of wave crest values according to the first power difference and the second power difference, the method further comprises: judging whether a wave peak value exists after filtering; if yes, screening out a peak value corresponding to the brightness carrier; and if not, outputting prompt information, wherein the prompt information is used for prompting that the frequency offset estimation is invalid.
Further, the analog television signal format includes NTSC, PAL or SECAM.
In order to achieve the above object, according to another aspect of the present invention, there is also provided an analog television frequency offset estimation apparatus, including: a receiving unit for receiving an analog television signal; the frequency shifting unit is used for carrying out gradual frequency shifting on the analog television signal according to a set step length to obtain a frequency-shifted signal; the filtering unit is used for carrying out narrow-band filtering on each frequency-shifted signal to obtain a filtering signal; a calculation unit for calculating a signal power of each of the filtered signals; and the estimation unit is used for carrying out frequency offset estimation through the frequency offset estimation circuit according to the calculated signal power.
Further, the frequency shift unit includes: the first determining module is used for determining the frequency of each step of frequency spectrum shifting according to the step length and the range of the frequency spectrum shifting; and the frequency shifting module is used for performing gradual frequency shifting on the analog television signal by taking the frequency shifted by each step of the frequency spectrum as a set step length to obtain a frequency-shifted signal.
Further, the estimation unit includes: a second determining module for determining a plurality of peak values and a plurality of valley values of the received analog television signal; a third determining module, configured to determine a maximum point in the plurality of peak values; a fourth determining module, configured to determine a first power difference between each peak and a maximum according to the plurality of peak values and the plurality of valley values; the calculating module is used for calculating a second power difference between each adjacent wave peak value and each adjacent wave trough value; and the filtering module is used for filtering the plurality of wave peak values according to the first power difference and the second power difference to obtain the filtered wave peak values.
In order to achieve the above object, according to another aspect of the present invention, there is also provided a storage medium including a stored program, wherein when the program runs, a device in which the storage medium is located is controlled to execute the analog television frequency offset estimation method according to the present invention.
In order to achieve the above object, according to another aspect of the present invention, there is also provided an apparatus, which includes at least one processor, and at least one memory and a bus connected to the processor, wherein the processor and the memory complete communication with each other through the bus, and the processor is configured to call program instructions in the memory to execute the analog television frequency offset estimation method according to the present invention.
The invention receives analog television signals; carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal; performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal; calculating the signal power of each filtered signal; the frequency offset estimation is carried out through the frequency offset estimation circuit according to the signal power of the filter signal obtained through calculation, the problem that the frequency offset estimation of the analog television signal by the receiver is inaccurate is solved, and the effect of improving the frequency offset estimation accuracy of the analog television signal is achieved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a flow chart of an analog television frequency offset estimation method according to a first embodiment of the present invention;
fig. 2 is a flow chart of an analog television frequency offset estimation method according to a second embodiment of the present invention;
FIG. 3 is a schematic diagram of an alternative analog television signal spectrum according to an embodiment of the present application;
FIG. 4 is a block diagram of an alternative circuit for estimating frequency offset of an analog television signal according to an embodiment of the present application; and
FIG. 5 is a schematic diagram of a data processing process according to an embodiment of the present application;
fig. 6 is a schematic diagram of an analog television frequency offset estimation apparatus according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The embodiment of the invention provides a frequency offset estimation method for an analog television.
Fig. 1 is a flowchart of an analog television frequency offset estimation method according to a first embodiment of the present invention, as shown in fig. 1, the method includes the following steps:
step S1: receiving an analog television signal;
step S2: carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal;
step S3: performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal;
step S4: calculating the signal power of each filtered signal;
step S5: and performing frequency offset estimation through a frequency offset estimation circuit according to the calculated signal power of the filtering signal.
This embodiment employs receiving an analog television signal; carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal; performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal; calculating the signal power of each filtered signal; the frequency offset estimation is carried out through the frequency offset estimation circuit according to the signal power of the filter signal obtained through calculation, the problem that the frequency offset estimation of the analog television signal by the receiver is inaccurate is solved, and the effect of improving the frequency offset estimation accuracy of the analog television signal is achieved.
Optionally, performing a gradual frequency shift on the analog television signal according to a set step size, and obtaining a frequency-shifted signal includes: determining the frequency of each step of frequency spectrum shifting according to the step length and the range of the frequency spectrum shifting; and taking the frequency shifted by each step of spectrum as a set step length to carry out gradual frequency shift on the analog television signal to obtain a signal after frequency shift.
Optionally, performing, by the frequency offset estimation circuit, frequency offset estimation according to the calculated signal power of the filtered signal includes: determining a plurality of peak values and a plurality of valley values of the received analog television signal; determining a maximum point in the plurality of wave peak values; determining a first power difference between each peak value and a maximum value according to the plurality of wave peak values and the plurality of wave valley values; calculating a second power difference between each adjacent crest value and trough value; and filtering the plurality of wave peak values according to the first power difference and the second power difference to obtain filtered wave peak values.
Optionally, after filtering the plurality of peak values according to the first power difference and the second power difference, determining whether there are any peak values after filtering; if yes, screening out a peak value corresponding to the brightness carrier; and if not, outputting prompt information, wherein the prompt information is used for prompting that the frequency offset estimation is invalid.
Alternatively, the format of the analog television signal may be NTSC or PAL or SECAM.
Fig. 2 is a flowchart of an analog tv frequency offset estimation method according to a second embodiment of the present invention, as shown in fig. 2, the method includes the following steps:
step S102, receiving an analog television signal with a certain deviation between the actual center frequency and the ideal center frequency.
In an alternative, the bandwidth of the input signal may be 6MHz, 7MHz or 8MHz and is known in advance, and the format may be NTSC, PAL or SECAM and is unknown in advance.
Fig. 3 is a schematic diagram of an alternative spectrum of an analog television signal according to an embodiment of the present application, in which the spectrum has three distinct peaks, Luma, Chroma and Audio. The embodiment of the application utilizes the characteristic that the power of the Luma is obviously higher than that of the signal nearby to carry out frequency offset estimation. The key of this embodiment is to find the location of the Luma (which is not called the actual location of the Luma), and make a difference between the location of the Luma and the ideal location of the Luma, so as to obtain the frequency offset.
Step S104, frequency-shifts the signal step by step.
Fig. 4 is a block diagram of an alternative circuit for estimating frequency offset of an analog television signal according to an embodiment of the present application, where an expression of a frequency-shifted signal according to a frequency-shift step and a frequency-shift range is:
exp(j2πn·step/fs) (1)
wherein f issStep is the frequency shift step length, and the value range of N is-N1≤n≤N2，N1And N2Ranges of frequency shifts are defined, which may or may not be equal.
It should be noted that step should not be too large, which may cause the Luma peak to shift out of the narrow-band filter, and step should not be too small, which may cause the frequency offset estimation speed to be too slow. In addition, N1And N2Nor should it be too large to move Chroma and Audio into our observation range, making location determination of Luma difficult.
Step S106, narrow-band filtering is carried out on the signals after frequency shift;
in an alternative, the narrow band filter may be implemented using a digital resonator, expressed as
The bandwidth and stop band attenuation of the resonator can be varied by adjusting the magnitude of r.
Step S108, calculating the power of the filtered signal;
in one alternative, a simple algorithm for calculating the modulus of a complex signal may be used to calculate the signal power. Assuming that the complex signal is V ═ I + jQ, its modulus is
Max is the larger of the absolute values of I and Q, and Min is the smaller of the absolute values of I and Q. An alternative value scheme for alpha and beta is
The signal power is
Step S110, sending the signal powers to a frequency offset estimation circuit for frequency offset estimation.
In one alternative, the maximum point of the power vector is searched; searching a peak point of the power vector; indicating the magnitude relation of the front power value and the rear power value. If the posterior value is greater than the anterior value, it is represented by "1"; if the latter value is smaller than the former value, it is represented by "-1"; if the two are equal, the value is represented by "0"; searching left and right valleys corresponding to each peak, comparing the left and right valleys, and taking the smaller one as the valley corresponding to the peak; calculating the power difference between each peak value and the maximum value, and recording as a first power difference; calculating the power difference between each peak value and each valley value, and recording as a second power difference; filtering some peak points which do not meet the conditions according to the first power difference and the second power difference; if the peak value does not exist after the peak value is filtered, outputting a frequency offset estimation invalid signal; if a plurality of peak values remain after the peak value filtering, selecting the peak value corresponding to the brightness carrier according to the designed selection logic, and further calculating the frequency offset.
Fig. 5 is a schematic diagram of a data processing procedure according to an embodiment of the present application. Based on the scheme provided by the above embodiment of the present application, an analog television signal with a certain frequency difference between the actual center frequency and the ideal center frequency is received, the signal is subjected to frequency shift step by step and narrowband filtering, the signal power after each step of frequency shift and filtering is calculated, and the signal powers are sent to a frequency offset estimation circuit for frequency offset estimation. Compared with the prior art, the method and the device achieve the purpose of estimating the frequency offset of the analog television signal by utilizing the frequency spectrum characteristic of the analog television signal and adopting a simple frequency shift and filtering mode, and further solve the technical problems that the frequency offset of the analog television cannot be quickly, simply and accurately estimated in the prior art, so that the analog television is slow in channel searching and difficult in system identification.
It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than presented herein.
The embodiment of the invention provides an analog television frequency offset estimation device, which can be used for executing the analog television frequency offset estimation method of the embodiment of the invention.
Fig. 6 is a schematic diagram of an analog television frequency offset estimation apparatus according to an embodiment of the present invention, as shown in fig. 6, the apparatus includes:
a receiving unit 10 for receiving an analog television signal;
the frequency shift unit 20 is configured to perform gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal;
a filtering unit 30, configured to perform narrow-band filtering on each frequency-shifted signal to obtain a filtered signal;
a calculation unit 40 for calculating a signal power of each filtered signal;
and an estimating unit 50, configured to perform frequency offset estimation according to the calculated signal power of the filtered signal through a frequency offset estimating circuit.
Optionally, the frequency shift unit 20 includes: the first determining module is used for determining the frequency of each step of frequency spectrum shifting according to the step length and the range of the frequency spectrum shifting; and the frequency shifting module is used for performing gradual frequency shifting on the analog television signal by taking the frequency shifted by each step of the frequency spectrum as a set step length to obtain a frequency-shifted signal.
Optionally, the estimation unit comprises: a second determining module for determining a plurality of peak values and a plurality of valley values of the received analog television signal; a third determining module, configured to determine a maximum point in the plurality of peak values; a fourth determining module, configured to determine a first power difference between each peak and a maximum according to the plurality of peak values and the plurality of valley values; the calculating module is used for calculating a second power difference between each adjacent wave peak value and each adjacent wave trough value; and the filtering module is used for filtering the plurality of wave peak values according to the first power difference and the second power difference to obtain the filtered wave peak values.
This embodiment employs a receiving unit 10 for receiving an analog television signal; the frequency shift unit 20 is configured to perform gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal; a filtering unit 30, configured to perform narrow-band filtering on each frequency-shifted signal to obtain a filtered signal; a calculation unit 40 for calculating a signal power of each filtered signal; and an estimating unit 50, configured to perform frequency offset estimation according to the calculated signal power of the filtered signal through a frequency offset estimating circuit. The problem that the frequency offset estimation of the analog television signal by the receiver is inaccurate is solved, and the effect of improving the frequency offset estimation accuracy of the analog television signal is achieved.
The frequency deviation estimation device of the analog television comprises a processor and a memory, wherein the receiving unit, the frequency shifting unit and the like are stored in the memory as program units, and the processor executes the program units stored in the memory to realize corresponding functions.
The processor comprises a kernel, and the kernel calls the corresponding program unit from the memory. The kernel can be set to be one or more, and the frequency offset estimation accuracy of the analog television signal is improved by adjusting the kernel parameters.
The memory may include volatile memory in a computer readable medium, Random Access Memory (RAM) and/or nonvolatile memory such as Read Only Memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip.
An embodiment of the present invention provides a storage medium, on which a program is stored, and when the program is executed by a processor, the program implements the analog television frequency offset estimation method.
The embodiment of the invention provides a processor, which is used for running a program, wherein the program runs to execute the frequency offset estimation method of an analog television.
The embodiment of the invention provides equipment, which comprises at least one processor, at least one memory and a bus, wherein the memory and the bus are connected with the processor; the processor and the memory complete mutual communication through a bus; the processor is used for calling the program instructions in the memory to execute the analog television frequency offset estimation method. The device herein may be a server, a PC, a PAD, a mobile phone, etc.
The present application further provides a computer program product adapted to perform a program for initializing the following method steps when executed on a data processing device: receiving an analog television signal; carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal; performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal; calculating the signal power of each filtered signal; and performing frequency offset estimation through a frequency offset estimation circuit according to the calculated signal power of the filtering signal.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
The memory may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.
Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (8)
1. A frequency offset estimation method for an analog television is characterized by comprising the following steps:
receiving an analog television signal;
carrying out gradual frequency shift on the analog television signal according to a set step length to obtain a frequency-shifted signal;
performing narrow-band filtering on each frequency-shifted signal to obtain a filtered signal;
calculating the signal power of each filtered signal;
performing frequency offset estimation through a frequency offset estimation circuit according to the signal power of the filter signal obtained by calculation;
the frequency offset estimation carried out by the frequency offset estimation circuit according to the signal power of the filter signal obtained by calculation comprises the following steps:
determining a plurality of peak values and a plurality of valley values of the received analog television signal;
determining a maximum point in the plurality of wave peak values;
determining a first power difference between each peak value and a maximum value according to the plurality of wave peak values and the plurality of wave valley values;
calculating a second power difference between each adjacent crest value and trough value;
and filtering the plurality of wave peak values according to the first power difference and the second power difference to obtain filtered wave peak values.
2. The method of claim 1, wherein gradually frequency shifting the analog television signal by a set step size to obtain a frequency shifted signal comprises:
determining the frequency of each step of frequency spectrum shifting according to the step length and the range of the frequency spectrum shifting;
and taking the frequency shifted by each step of spectrum as a set step length to carry out gradual frequency shift on the analog television signal to obtain the signal after frequency shift.
3. The method of claim 1, wherein after filtering a plurality of peak values based on the first power difference and the second power difference, the method further comprises:
judging whether a wave peak value exists after filtering;
if yes, screening out a peak value corresponding to the brightness carrier;
and if not, outputting prompt information, wherein the prompt information is used for prompting that the frequency offset estimation is invalid.
4. The method of claim 1, wherein the format of the analog television signal comprises NTSC, PAL, or SECAM.
5. An analog television frequency offset estimation apparatus, comprising:
a receiving unit for receiving an analog television signal;
the frequency shifting unit is used for carrying out gradual frequency shifting on the analog television signal according to a set step length to obtain a frequency-shifted signal;
the filtering unit is used for carrying out narrow-band filtering on each frequency-shifted signal to obtain a filtering signal;
a calculation unit for calculating a signal power of each of the filtered signals;
the estimation unit is used for carrying out frequency offset estimation through a frequency offset estimation circuit according to the filtering signal power obtained by calculation;
the estimation unit includes:
a second determining module for determining a plurality of peak values and a plurality of valley values of the received analog television signal;
a third determining module, configured to determine a maximum point in the plurality of peak values;
a fourth determining module, configured to determine a first power difference between each peak and a maximum according to the plurality of peak values and the plurality of valley values;
the calculating module is used for calculating a second power difference between each adjacent wave peak value and each adjacent wave trough value;
and the filtering module is used for filtering the plurality of wave peak values according to the first power difference and the second power difference to obtain the filtered wave peak values.
6. The apparatus of claim 5, wherein the frequency shift unit comprises:
the first determining module is used for determining the frequency of each step of frequency spectrum shifting according to the step length and the range of the frequency spectrum shifting;
and the frequency shifting module is used for performing gradual frequency shifting on the analog television signal by taking the frequency shifted by each step of the frequency spectrum as a set step length to obtain a frequency-shifted signal.
7. A storage medium, comprising a stored program, wherein the program is executed to control an apparatus in which the storage medium is located to perform the method for estimating frequency offset of analog tv according to any one of claims 1 to 4.
8. An apparatus, characterized in that the apparatus comprises at least one processor, and at least one memory and a bus connected to the processor, wherein the processor and the memory are configured to perform mutual communication via the bus, and the processor is configured to call program instructions in the memory to perform the analog television frequency offset estimation method according to any one of claims 1 to 4.
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| US8902365B2 (en) * | 2007-03-14 | 2014-12-02 | Lance Greggain | Interference avoidance in a television receiver |
| CN102263981B (en) * | 2010-05-25 | 2013-07-10 | 北京创毅视讯科技有限公司 | Method and device for automatically detecting analog television PAL (Phase Alternating Line) system |
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| CN104469236B (en) * | 2013-09-25 | 2017-11-07 | 扬智科技股份有限公司 | The correcting device and correcting method of sampling frequency offset |
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