CN111416917B - Analog television signal processing method and device - Google Patents
Analog television signal processing method and device Download PDFInfo
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- CN111416917B CN111416917B CN202010239578.8A CN202010239578A CN111416917B CN 111416917 B CN111416917 B CN 111416917B CN 202010239578 A CN202010239578 A CN 202010239578A CN 111416917 B CN111416917 B CN 111416917B
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- H—ELECTRICITY
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Abstract
The invention discloses an analog television signal processing method and device. The method comprises the following steps: converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal; judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition; if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal; IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result; carrying out digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking; and performing IQ compensation on the signal subjected to digital phase locking to obtain a compensation signal. The invention achieves the effect of improving the quality of the analog television signal.
Description
Technical Field
The invention relates to the technical field of digital information transmission, in particular to a method and a device for processing an analog television signal.
Background
Analog television signals are typically composed of an image signal and an audio signal. The image signal is subjected to vestigial sideband amplitude modulation (VSB), and the audio signal is transmitted in a frequency modulation manner. In China, no matter cable television or wireless open circuit transmission, the frequency band of one radio frequency television signal occupies the bandwidth of 8 MHz. The residual carrier frequency of the image is called luma frequency, and is 1.25MHz away from the left boundary of the frequency band in terms of 8MHz bandwidth, and is equivalent to 2.75MHz away from the central frequency point under the 8MHz bandwidth; the audio carrier frequency is 6.5MHz (at 8MHz bandwidth) higher than the image carrier frequency.
The IQ imbalance means that when a receiver with a quadrature structure is adopted, carrier phases of an I path and a Q path of a mixer do not strictly differ by 90 °, so that the final I path and the final Q path interfere with each other, which is reflected in a frequency domain that mirror frequencies interfere with each other. If IQ imbalance is estimated and compensated for, interference at the image frequency can be suppressed.
Since analog television signals have strong luma frequencies, the signal quality is severely affected if the image frequency of the luma frequencies falls within the band of the desired signal when there are adjacent channels of the signal.
Aiming at the problem of poor signal quality caused by IQ imbalance of analog television signals in the related art, no effective solution is provided at present.
Disclosure of Invention
The invention mainly aims to provide an analog television signal processing method and device to solve the problem of poor signal quality caused by IQ imbalance of an analog television signal.
In order to achieve the above object, according to one aspect of the present invention, there is provided an analog television signal processing method including: converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal; judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition; if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal; IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result; performing digital phase-locked loop processing on the estimation result to obtain a signal subjected to digital phase locking; and performing IQ compensation on the signal subjected to the digital phase locking to obtain a compensation signal.
Further, the determining whether the intermediate frequency analog signal has an adjacent frequency satisfying a preset condition includes: and judging whether the intermediate frequency analog signal has an adjacent frequency exceeding a preset threshold value.
Further, before pre-filtering the intermediate frequency analog signal, the method further comprises: and judging whether the intermediate frequency analog signal has a luma component, wherein when the judgment result is yes, the intermediate frequency analog signal is pre-filtered.
Further, before pre-filtering the intermediate frequency analog signal, the method further comprises: when the intermediate frequency analog signal has a luma component, calculating the power of the luma frequency position; and judging whether the power difference value between the power of the luma frequency position and the adjacent frequency exceeds a preset difference value, wherein when the judgment result is yes, pre-filtering the intermediate frequency analog signal.
Further, before calculating the power of the luma frequency location, the method further comprises: filtering the intermediate frequency analog signal through a narrow-band filter to obtain a filtered signal; judging whether the difference value of the output power corresponding to the main frequency in the pre-filtered signal and the output power of the adjacent frequency exceeds the preset difference value or not; and if so, recording the position of the main frequency in the current pre-filtered signal as the position of the luma frequency.
Further, pre-filtering the intermediate frequency analog signal comprises: and carrying out narrow-band filtering on the intermediate frequency analog signal to obtain a signal only containing a luma component.
In order to achieve the above object, according to another aspect of the present invention, there is also provided an analog television signal processing apparatus comprising: the conversion unit is used for converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal; the judging unit is used for judging whether the intermediate frequency analog signal has adjacent frequency meeting preset conditions; the pre-filtering unit is used for pre-filtering the intermediate-frequency analog signal under the condition that the intermediate-frequency analog signal exists to obtain a pre-filtered signal; the estimation unit is used for carrying out IQ imbalance estimation on the pre-filtered signal to obtain an estimation result; the processing unit is used for carrying out digital phase-locked loop processing on the estimation result to obtain a signal subjected to digital phase locking; and the compensation unit is used for carrying out IQ compensation on the signal subjected to the digital phase locking to obtain a compensation signal.
Further, the judging unit is configured to: and judging whether the intermediate frequency analog signal has an adjacent frequency exceeding a preset threshold value.
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, an apparatus in which the storage medium is located is controlled to execute the analog television signal processing 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 at least includes a 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 signal processing method according to the present invention.
The invention obtains the intermediate frequency analog signal by converting the frequency of the received analog television signal to the intermediate frequency; judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition; if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal; IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result; carrying out digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking; IQ compensation is carried out on the signal after digital phase locking to obtain a compensation signal, the problem of poor signal quality caused by IQ imbalance of the analog television signal is solved, and the effect of improving the quality of the analog television signal is further 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 signal processing method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a frequency spectrum of an alternative analog television signal according to an embodiment of the present application;
fig. 3 is a flow chart of the intermediate frequency conversion of the present application;
FIG. 4 is a block diagram of the elements of the present application;
fig. 5 is a flowchart of the present embodiment for determining whether or not there is a luma frequency;
FIG. 6 is a schematic diagram of a circuit structure for estimating IQ imbalance according to IQ two-path input data;
FIG. 7 is a diagram illustrating a digital phase-locked loop architecture according to the present embodiment;
FIG. 8 is a diagram illustrating an IQ imbalance compensation scheme according to the present embodiment;
FIG. 9 is a schematic diagram of an analog television signal processing apparatus according to an embodiment of the present invention;
fig. 10 is a schematic diagram of an alternative circuit configuration of the present embodiment.
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 method for processing an analog television signal.
Fig. 1 is a flow chart of an analog television signal processing method according to an embodiment of the present invention, as shown in fig. 1, the method comprising the steps of:
step S101: converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal;
step S102: judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition;
step S103: if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal;
step S104: IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result;
step S105: carrying out digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking;
step S106: and performing IQ compensation on the signal subjected to digital phase locking to obtain a compensation signal.
In the embodiment, the frequency of the received analog television signal is converted to the intermediate frequency to obtain an intermediate frequency analog signal; judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition; if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal; IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result; carrying out digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking; IQ compensation is carried out on the signal after digital phase locking to obtain a compensation signal, the problem of poor signal quality caused by IQ imbalance of the analog television signal is solved, and the effect of improving the quality of the analog television signal is further achieved.
In this embodiment, the analog television signal is received and converted to an intermediate frequency, for example, the analog television signal may be an 8MHz bandwidth mode signal, the intermediate frequency may be selected to be 5MHz, that is, the frequency of the local oscillator is 5MHz lower than the radio frequency of the television signal, and the adjacent frequency that meets the preset condition may be an adjacent frequency analog signal that is 8MHz lower than the center frequency of the analog television signal.
Since analog television signals have strong luma frequencies, the signal quality is severely affected if the image frequency of the luma frequencies falls within the band of the desired signal when there are adjacent channels of the signal. In the foregoing situation, if the narrow-band filtering is performed in advance at the luma frequency position and then the IQ estimation is performed, the compensation result will greatly reduce the image component of the adjacent-channel luma frequency, thereby solving the problem that the image component of the luma frequency generates strong interference on the useful signal due to the inaccurate estimation and compensation of the IQ imbalance of the analog television receiver.
Optionally, the determining whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition includes: and judging whether the intermediate frequency analog signal has an adjacent frequency exceeding a preset threshold value.
In practical cases, the preset condition may be changed and set according to the needs of different application scenarios, for example, the preset condition may further include a plurality of specific conditions.
Optionally, before pre-filtering the intermediate-frequency analog signal, determining whether the intermediate-frequency analog signal has a luma component, wherein when the determination result is yes, the intermediate-frequency analog signal is pre-filtered, and the pre-filtering may be implemented by using a resonator.
Optionally, before pre-filtering the intermediate frequency analog signal, calculating a power of a luma frequency position when the intermediate frequency analog signal has a luma component; and judging whether the power difference value between the luma frequency position and the adjacent frequency exceeds a preset difference value, wherein if the judgment result is yes, pre-filtering the intermediate frequency analog signal.
Optionally, before calculating the power of the luma frequency position, filtering the intermediate frequency analog signal through a narrow band filter to obtain a filtered signal; judging whether the difference value of the output power corresponding to the main frequency in the pre-filtered signal and the output power of the adjacent frequency exceeds a preset difference value or not; and if so, recording the position of the main frequency in the current pre-filtered signal as the position of the luma frequency.
Optionally, pre-filtering the intermediate frequency analog signal comprises: and carrying out narrow-band filtering on the intermediate-frequency analog signal to obtain a signal only containing a luma component.
The present embodiment also provides a preferred embodiment.
In step S1, an analog television signal is received and converted to an intermediate frequency.
In one alternative, the analog television signal may be an 8MHz bandwidth mode signal and there is an adjacent channel analog signal that is 8MHz below the center frequency of the analog television signal.
Fig. 2 is a schematic diagram of a frequency spectrum of an alternative analog television signal according to an embodiment of the present application. The input signal is formed by superposing two analog television signals with the same frequency spectrum shape, and the central frequencies of the two analog television signals are different by 8 MHz.
In an alternative the intermediate frequency may be chosen to be 5MHz, i.e. the frequency of the local oscillator is 5MHz lower than the radio frequency of the television signal. The radio frequency is 200MHz and the frequency of the local oscillator is 195 MHz. After the above processing, the analog television signal of 8MHz bandwidth is converted into 8MHz bandwidth with 5MHz as the center frequency, i.e., the frequency range of the intermediate frequency signal is 1MHz to 9 MHz. Fig. 3 is a flow chart of the intermediate frequency conversion of the present application. After converting the signal to the intermediate frequency, the embodiment of the present application may be decomposed into several units according to the function, and fig. 4 is a structural diagram of the units of the present application, and mainly consists of a narrow band filter and a control unit thereof, an IQ imbalance estimation unit, a digital phase-locked loop unit, and an IQ imbalance compensation unit.
In step S2, it is determined whether a large adjacent channel exists in the intermediate frequency signal and whether a luma component exists.
The sequence of the sampled intermediate frequency analog signals (including adjacent frequencies) is set as x (n), the intermediate frequency signals are up-converted to 8MHz and filtered by a real low-pass filter with single-side bandwidth of 4MHz and impulse response of h (n), the obtained signal sequence is marked as y (n), namely,
y(n)＝[x(n)exp(j2π·8·106nTs)]*h(n)
wherein T issIs the inverse of the sampling frequency, one possible scheme is to sample at 50MHz, then T s1/50 mus, the power of the signal is calculated, the power of the in-band adjacent frequency can be obtained, as follows:
then, the signal is shifted by a set of frequencies and passed through a narrow-band filter with sharp frequency response, and the shifted frequency is recorded as fn，fnIs the range of the image frequency in the signal band of 1MHz to 9MHz, so that fnIs in the range of-9 MHz to-1 MHz. For a narrow band filter, in one alternative, a resonator may be used, the transfer function of which is:
the intermediate frequency signal is shifted according to the series of frequencies, then the output power is calculated through the resonator, when the output power corresponding to a group of frequencies is higher than the frequency power on two sides of the group of frequencies, and the difference value of the power and the whole adjacent frequency power is less than a threshold value, namely
Pn＞Pn-1And P isn＞Pn+1And P isn-Pinband_aci＜thr
When, it is considered that there is a luma frequency here; in an alternative, the state of each luma frequency may be recorded in order to stabilize the samples of the luma frequencies, and the luma frequencies are updated only if the distance between consecutive 8 luma frequencies and the current luma frequency exceeds a threshold, which prevents jitter in the luma frequencies and thereby stabilizes the filter coefficients.
It should be noted that fig. 5 is a flowchart of determining whether there is luma frequency in this embodiment, and in step S1, the adjacent channel power is calculated and the power difference is calculated by the narrow-band filter, and the generated use _ filter signal is used to control the switch of the pre-filter.
And step S2, when the power of the in-band adjacent frequency is judged to be larger and the mirror image of the luma frequency of the in-band adjacent frequency exists, starting a narrow-band filter to perform pre-filtering before IQ imbalance estimation. In one alternative, the pre-filter may be implemented using a resonator having a transfer function of:
wherein, ω is0The luma frequency given by the aforementioned luma decision block.
Step S3, IQ imbalance estimation is carried out on the pre-filtered signals, and the signals of the path I and the path Q are respectively set as xI(n) and xQ(n) then
It should be noted that fig. 6 is a schematic diagram of a circuit structure for estimating IQ imbalance according to two paths of input data of IQ, in this feasible scheme, two paths of signals pass through a narrow-band filter, then pass through a square circuit, and respectively perform difference and summation, and a ratio of the two results is obtained, so as to obtain an imbalance coefficient of amplitude; the unbalance coefficient of the phase is obtained by multiplying I, Q two paths of data after passing through a narrow-band filter, and then calculating the ratio of the product and the sum of squares of the product.
In step S4, fig. 7 is a schematic diagram of the digital phase-locked loop architecture of the present embodiment, and the IQ imbalance estimation result is passed through a digital phase-locked loop to make its value more stable.
And compensating the intermediate frequency signal by the IQ imbalance estimation result through a feedback link. Fig. 8 is a schematic diagram of an IQ mismatch compensation structure according to the present embodiment, in which an if signal can be IQ compensated by an estimated IQ mismatch according to the following equation.
xI_comp(n)＝(1-delta/2)*xI(n)+theta/2*xQ(n)
xQ_comp(n)＝theta/2*xI(n)+(1+delta/2)*xQ(n)
By the scheme, more effective IQ compensation can be carried out on the analog television signal with the mirror image analog adjacent frequency, the part of the adjacent frequency with luma falling in a useful signal band is fully inhibited, and the receiving quality of the analog television signal is improved. According to the method, the pre-filtering link before IQ estimation and compensation is adaptively opened or closed according to the power of adjacent frequency and the position of luma frequency, when larger analog adjacent frequency exists and the mirror image with luma frequency enters the band, the mirror image component is fully inhibited, and the technical problems that IQ imbalance estimation and compensation of analog television signals are not accurate enough and the quality of received signals is reduced in the prior art are solved.
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 signal processing device which can be used for executing the analog television signal processing method of the embodiment of the invention.
Fig. 9 is a schematic diagram of an analog television signal processing apparatus according to an embodiment of the present invention, as shown in fig. 9, the apparatus including:
a conversion unit 10, configured to convert a frequency of a received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal;
a judging unit 20, configured to judge whether an intermediate frequency analog signal has an adjacent frequency that meets a preset condition;
a pre-filtering unit 30, configured to pre-filter the intermediate-frequency analog signal if the intermediate-frequency analog signal exists, so as to obtain a pre-filtered signal;
an estimating unit 40, configured to perform IQ imbalance estimation on the pre-filtered signal to obtain an estimation result;
the processing unit 50 is configured to perform digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking;
and a compensation unit 60, configured to perform IQ compensation on the digital phase-locked signal to obtain a compensation signal.
The embodiment adopts a conversion unit for converting the frequency of a received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal; the judging unit is used for judging whether the intermediate frequency analog signal has adjacent frequency meeting the preset condition; the pre-filtering unit is used for pre-filtering the intermediate-frequency analog signal under the condition that the intermediate-frequency analog signal exists to obtain a pre-filtered signal; the estimation unit is used for carrying out IQ imbalance estimation on the pre-filtered signal to obtain an estimation result; the processing unit is used for carrying out digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking; and the compensation unit is used for performing IQ compensation on the signal subjected to digital phase locking to obtain a compensation signal, so that the problem of poor signal quality caused by IQ imbalance of the analog television signal is solved, and the effect of improving the quality of the analog television signal is achieved.
Optionally, the determining unit 20 is configured to: and judging whether the intermediate frequency analog signal has an adjacent frequency exceeding a preset threshold value.
The analog television signal processing apparatus of the present embodiment includes a narrow band filter and its control unit, an IQ imbalance estimation unit, a digital phase-locked loop unit, and an IQ imbalance compensation unit.
In an alternative, the narrow-band filter may be implemented by using a resonator, fig. 10 is an alternative circuit structure diagram of this embodiment, and a hardware resource may be saved by using an IIR filter with feedback.
In one possible solution, the control unit of the narrow-band filter may adopt the circuit structure shown in fig. 5, the frequency conversion operation may be implemented by using a complex multiplier, and both the low-pass filter and the narrow-band filter are implemented by using an IIR filter; the calculated power needs to be compared with a threshold value, and a comparator is adopted on a circuit to realize the function; and finally, logically AND-ing the indicating signal with larger adjacent frequency power and the indicating signal with the existence of the luma component and larger power to obtain a signal for starting pre-filtering.
Optionally, the IQ imbalance estimation unit requires several real multipliers and adders for calculating intermediate results of the IQ imbalance estimation; the storage units are used for storing the accumulated result of IQ imbalance estimation; for the operation of reciprocal, in an alternative, it can be implemented in a look-up table to avoid the use of a divider.
Optionally, the digital phase-locked loop needs several constant coefficient multipliers and adders, wherein the constant coefficient multiplication can be realized by adopting a shift addition mode; and a memory for storing intermediate variables for feedback; and the delay unit is used for feeding back the output result of the phase-locked loop to stabilize the estimated IQ imbalance coefficient.
Optionally, the IQ mismatch compensation unit may also adopt the structure shown in fig. 8, and in a possible scheme, a plurality of constant coefficient multipliers, variable coefficient multipliers and adders are required to calculate intermediate results of IQ mismatch compensation; and the storage unit is used for storing the temporary storage value of IQ imbalance compensation.
The analog television signal processing device comprises a processor and a memory, wherein the converting unit, the judging 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 one or more than one, and the quality 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 having a program stored thereon, which when executed by a processor implements the analog television signal processing method.
The embodiment of the invention provides a processor, which is used for running a program, wherein the program executes the analog television signal processing method during running.
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 so as to execute the analog television signal processing 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: converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal; judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition; if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal; IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result; carrying out digital phase-locked loop processing on the estimation result to obtain a signal after digital phase locking; and performing IQ compensation on the signal subjected to digital phase locking to obtain a compensation 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 (6)
1. A method for processing analog television signals, comprising:
converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal;
judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition;
if the intermediate frequency analog signal exists, pre-filtering the intermediate frequency analog signal to obtain a pre-filtered signal;
IQ imbalance estimation is carried out on the pre-filtered signal to obtain an estimation result;
performing digital phase-locked loop processing on the estimation result to obtain a signal subjected to digital phase locking;
performing IQ compensation on the signal subjected to digital phase locking to obtain a compensation signal;
judging whether the intermediate frequency analog signal has an adjacent frequency meeting a preset condition comprises the following steps:
judging whether the intermediate frequency analog signal has an adjacent frequency exceeding a preset threshold value;
prior to pre-filtering the intermediate frequency analog signal, the method further comprises:
determining whether the intermediate frequency analog signal has a luma component,
when the intermediate frequency analog signal has a luma component, calculating the power of the luma frequency position;
judging whether the difference value between the power of the luma frequency position and the power of the adjacent frequency exceeds a preset difference value,
when the judgment result is yes, pre-filtering the intermediate-frequency analog signal;
judging whether the intermediate frequency analog signal has a luma component, comprising: the intermediate frequency analog signal is converted into a digital signalSetting the sequence after sampling as x (n), up-converting the intermediate frequency analog signal by 8MHz, and filtering the intermediate frequency analog signal by a real low-pass filter with a unilateral bandwidth of 4MHz and an impulse response of h (n), wherein the obtained signal sequence is marked as y (n): y (n) ═ x (n) exp (j2 pi · 8 · 106nTs)]*h(n)，
Wherein T issCalculating the power of the signal sequence y (n) to obtain the power of the in-band adjacent frequency:
and (c) performing frequency shift on the sequence x (n) according to a group of frequencies and filtering the sequence by a narrow-band filter with a sharp frequency response to obtain output power, wherein when the output power corresponding to the group of frequencies is higher than the frequency power on two sides of the group of frequencies, and the difference value between the output power and the power of the whole adjacent frequency is smaller than a threshold value: pn＞Pn-1And P isn＞Pn+1And P isn-Pinband_aci< thr, it is determined that the luma component is present in the intermediate frequency analog signal.
2. The method of claim 1, wherein prior to calculating the power for the luma frequency location, the method further comprises:
filtering the intermediate frequency analog signal through a narrow-band filter to obtain a filtered signal;
judging whether the difference value of the output power corresponding to the main frequency in the pre-filtered signal and the output power of the adjacent frequency exceeds the preset difference value or not;
and if so, recording the position of the main frequency in the current pre-filtered signal as the position of the luma frequency.
3. The method of claim 1, wherein pre-filtering the intermediate frequency analog signal comprises:
and carrying out narrow-band filtering on the intermediate frequency analog signal to obtain a signal only containing a luma component.
4. An analog television signal processing apparatus, comprising:
the conversion unit is used for converting the frequency of the received analog television signal to an intermediate frequency to obtain an intermediate frequency analog signal;
the judging unit is used for judging whether the intermediate frequency analog signal has adjacent frequency meeting preset conditions;
the pre-filtering unit is used for pre-filtering the intermediate-frequency analog signal under the condition that the intermediate-frequency analog signal exists to obtain a pre-filtered signal;
the estimation unit is used for carrying out IQ imbalance estimation on the pre-filtered signal to obtain an estimation result;
the processing unit is used for carrying out digital phase-locked loop processing on the estimation result to obtain a signal subjected to digital phase locking;
the compensation unit is used for carrying out IQ compensation on the signal subjected to the digital phase locking to obtain a compensation signal;
the judgment unit is used for:
judging whether the intermediate frequency analog signal has an adjacent frequency exceeding a preset threshold value;
the processing device is further configured to perform the steps of:
before pre-filtering the intermediate frequency analog signal, judging whether the intermediate frequency analog signal has a luma component or not,
when the intermediate frequency analog signal has a luma component, calculating the power of the luma frequency position;
judging whether the difference value between the power of the luma frequency position and the power of the adjacent frequency exceeds a preset difference value,
when the judgment result is yes, pre-filtering the intermediate-frequency analog signal;
the processing device is further configured to perform the steps of:
judging whether the intermediate frequency analog signal has a luma component, comprising: setting the sequence of the intermediate frequency analog signal after sampling as x (n), up-converting the intermediate frequency analog signal by 8MHz, and using a single-side signal with the bandwidth of 4MHz and the impulse response of h (n)The real low-pass filter filters the intermediate frequency analog signal, and the resulting signal sequence is denoted as y (n): y (n) ═ x (n) exp (j2 pi · 8 · 106nTs)]*h(n)，
Wherein T issCalculating the power of the signal sequence y (n) to obtain the power of the in-band adjacent frequency:
and (c) performing frequency shift on the sequence x (n) according to a group of frequencies and filtering the sequence by a narrow-band filter with a sharp frequency response to obtain output power, wherein when the output power corresponding to the group of frequencies is higher than the frequency power on two sides of the group of frequencies, and the difference value between the output power and the power of the whole adjacent frequency is smaller than a threshold value: pn＞Pn-1And P isn＞Pn+1And P isn-Pinband_aci< thr, it is determined that the luma component is present in the intermediate frequency analog signal.
5. A storage medium comprising a stored program, wherein the program, when executed, controls an apparatus in which the storage medium is located to perform the analog television signal processing method of any one of claims 1 to 3.
6. An analog television signal processing apparatus, comprising at least a processor, and at least a memory and a bus connected to the processor, wherein the processor and the memory communicate with each other via the bus, and the processor is configured to call the program instructions in the memory to execute the analog television signal processing method according to any one of claims 1 to 3.
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