KR20170030730A - Apparatus and method for removing spurious in an intermediate frequency band of broadband system - Google Patents

Abstract

Suggested are an apparatus and method for removing spurious in the intermediate frequency band of a broadband system with software by using a 1 stage mixer structure. The device includes a mixer for converting an input frequency to a lower frequency band; a signal adjusting part for adjusting the output frequency of the mixer and outputting a final frequency signal; and a PLL control part for applying a first PLL sweep signal and a second PLL sweep signal which are different from each other, to the mixer, analyzing a sweep result by the first PLL sweep signal and the second PLL sweep signal, and removing spurious.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for removing an intermediate frequency band in a broadband system,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an apparatus and method for removing harmonics in an intermediate frequency band of a wideband system, and more particularly, to an apparatus and a method for removing harmful waves in an intermediate frequency band of a wideband system.

Usually, a broadband system uses a method of modulating and transmitting a data signal to an AC signal such as frequency modulation.

This conventional broadband system uses three stages of mixers 10, 20 and 30 as shown in FIG. 1 to change to the final intermediate frequency. FIG. 1 shows a conventional three-stage mixer structure, and FIG. 2 shows a conventional three-stage mixer structure. That is, the mixer 10 of the first stage outputs an IF signal corresponding to approximately twice the input frequency. The mixer 20 of the second stage outputs IF signals of several hundred MHz, and the mixer 30 of the third stage outputs IF signals of several tens of KHz.

In order to prevent generation of unwanted waves in the final IF signal of several tens of kHz band, the conventional method is as follows. The input frequency passes through the first stage mixer 10 and is converted to a first IF signal that is higher than the input frequency. Then, the first IF signal having a frequency higher than the input frequency is removed from the input frequency component, which is one of the spurious components that can be applied to the final IF band via the filters (BPF) 12 and 16. Thereafter, the first IF signal passes through the mixer 20 of the second stage and is converted into a second IF signal, and then passes through the filters 22 and 26 again to remove unnecessary components. The second IF signal passes through the mixer 30 of the third stage to convert it to the final third IF signal, and then passes through the filters 32 and 36 to remove the unnecessary wave components.

In other words, in Fig. 1, a low pass filter (LPF) 9 passes a low frequency and suppresses a high frequency. The mixer 10 in the first stage is a device for converting a frequency to a frequency band higher than a spectrum frequency band. The mixer 20 in the second stage is a device for converting the frequency raised by the mixer 10 in the first stage to a lower frequency. The mixer 30 in the third stage is a device for converting a lower frequency to a lower frequency in the mixer 20 in the second stage. The band pass filters (BPF) 7, 8, 12, 12, 16, 22, 26, 32 and 36 pass only each frequency band and suppress low or high frequencies. AMP (Power Amplifier) 4, 5, 6, 14, 24, 34 is a device for amplifying the signal level. 1, reference numerals 1, 2, and 3 denote voltage controlled oscillators (VCO).

In FIG. 1, the PLL (Phase Locked Loop) is a local oscillator signal of the mixer. The PLL1 sweep is a high frequency signal required to increase the spectrum input frequency band by the output frequency of the first stage mixer 10, Is a Local Oscillator required to convert the frequency according to the output of the mixer 20 of the second stage and PLL3 FIX is a Local Oscillator necessary to convert the frequency to match the output of the mixer 30 of the third stage.

In the conventional method using the three mixers, spurious can be removed by hardware, and the first IF is introduced into the IF stage at a very high frequency, and the introduced signal can be removed by the filter.

Thus, the conventional method using the three mixers requires high frequency components at least twice the input frequency, which is expensive. Also, the use of three mixers creates additional filters and amplifiers and increases the physical space required. In addition, power consumption is high due to the additional components, and battery consumption is also fast when applied to small devices.

Accordingly, Applicants have studied to remove spurious waves using only one mixer as in FIG. 3, reference numeral 40 denotes a voltage-controlled oscillator, reference numerals 42 and 48 denote amplifiers, reference numeral 44 denotes a mixer, and reference numerals 46 and 50 denote BPFs.

In the structure as shown in FIG. 3, the spurious waves can not be removed by hardware. As shown in the frequency table of FIG. 4, the IF frequency is located within the input frequency band, and the isolation characteristic has influenced the measurement.

In other words, in the case of the one-stage mixer structure, as shown in FIG. 5, the input signal is not converted by the mixer 44 but the signal is input to the IF stage directly as an isolation characteristic. There is no real signal, but a signal is generated on the screen due to the isolation characteristics. 6 is a table illustrating an actual input signal A MHz and the input signal IS is converted into a conversion signal CS of FIG. 7 to convert the center B MHz to a center A signal is generated at a position symmetrical with respect to the center axis. In Fig. 7, the dotted line US is a spurious signal that appears at the output due to the isolation characteristic. This signal is removed by hardware in 3 - stage mixer, but it is not removed by hardware in 1 - stage mixer structure.

Prior Art 1: Korean Patent No. 10-0429565 (Digital down converter) Prior Art 2: Korean Patent No. 10-0460498 (Local oscillation frequency removing device of transceiver)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and a method which employ a single stage mixer structure and can remove unwanted waves in an intermediate frequency band of a broadband system by software .

According to another aspect of the present invention, there is provided an apparatus for canceling an intermediate frequency band spurious component in a broadband system, including: a mixer for converting an input frequency into a low frequency band; A signal adjuster for adjusting the output frequency of the mixer and outputting the final signal; And a PLL controller for applying a first PLL sweep signal and a second PLL sweep signal that are different from each other to the mixer and analyzing a sweep result by the first PLL sweep signal and the second PLL sweep signal to remove unwanted waves .

The PLL control unit sets the first PLL sweep signal and the second PLL sweep signal, compares the data for each signal with a reference signal to determine a noise component and a normal signal, PLL data and second PLL data, respectively, and the first PLL data and the second PLL data stored in the second PLL data are processed in a forward direction to remove unnecessary waves caused by the isolation.

As a result of the forward processing, if the first PLL data and the second PLL data are seen at the same position, the PLL controller can determine that the PLL data is unnecessary due to isolation and remove the unnecessary waves.

The PLL control unit may perform reverse processing if it is not compatible with the case of the forward processing.

The reverse processing can be performed by determining the signal as a 2 * IF signal when the signal is generated in the same place in conversion in the reverse order of the memory address of the first PLL data and the memory address of the second PLL data.

Preferably, the mixer is one.

A method for removing harmonics of an intermediate frequency band in a broadband system according to a preferred embodiment of the present invention includes a mixer for converting an input frequency into a lower frequency band and a signal adjusting unit for adjusting an output frequency of the mixer to output a final signal In a broadband system comprising:

The PLL controller applying different first PLL sweep signals and second PLL sweep signals to the mixer; And the PLL controller analyzes sweep results of the first PLL sweep signal and the second PLL sweep signal to remove unwanted waves.

Wherein the removing the spurious wave comprises: setting the first PLL sweep signal and the second PLL sweep signal, respectively; Comparing the data for each signal with a reference signal to determine a noise component and a normal signal; Storing the determined result as a first PLL data and a second PLL data, respectively; And processing the stored first PLL data and the stored second PLL data in a forward direction to remove spurious waves caused by the isolation.

The step of performing the forward processing and removing the unnecessary waves by isolation may be performed by determining that the first PLL data and the second PLL data are located at the same position,

And performing reverse processing after the step of removing the unnecessary waves due to isolation by the forward processing.

The step of performing the backward processing may be performed by determining a 2 * IF signal if the signal is generated at the same place in conversion in the reverse order of the memory address of the first PLL data and the memory address of the second PLL data.

According to the present invention having such a configuration, unnecessary waves can be removed by software, and it is applicable not only to a single stage mixer but also to a multi-stage mixer structure. In other words, it is possible to eliminate the isolation unnecessary wave which flows in the IF band signal input, to remove the unnecessary wave which occurs when the signal of twice the IF is input, and to remove the IF band signal in the other system can do.

Especially, it is easy to apply to small-sized broadband products and low-power products.

FIG. 1 and FIG. 2 illustrate a three-stage mixer structure applied to a conventional wideband system.
FIGS. 3 to 7 are diagrams for explaining problems of the single stage mixer structure.
FIG. 8 is a diagram illustrating an apparatus for removing harmonics of an intermediate frequency band in a wideband system according to the present invention, and is a view for explaining removal of unwanted waves by isolation.
9 is a diagram illustrating an apparatus for removing an intermediate frequency band spurious wave in a wideband system according to the present invention.
FIG. 10 is a flowchart illustrating a method for removing an intermediate frequency band spurious component in a wideband system according to the present invention.
11 to 15 are views used in the description of Fig.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

An apparatus for removing an intermediate frequency band spurious component in a wideband system according to the present invention is shown in Figs. FIG. 8 is a view for explaining removal of unwanted waves by isolation, and FIG. 9 is a view for explaining removal of spurious waves at the input of an input frequency 2 * IF band.

8 adds a second PLL sweep in order to remove spurious waves by isolation, and the apparatus of FIG. 9 is placed on the same frequency line when a double IF signal is applied after applying the spurious wave removal algorithm by isolation In order to solve the problem that it is impossible to remove it, the algorithm for double IF input is reinforced.

The apparatus for removing harmonics of an intermediate frequency band of a broadband system according to the present invention shown in FIGS. 8 and 9 includes an amplifier 42 for amplifying a signal level of a voltage-controlled oscillator 40, an input frequency A MHz, A band pass filter (BPF) 46 for passing only a desired frequency band at an output frequency of the mixer 44, a band pass filter (BPF) 46 for passing only a desired frequency band at an output frequency of the mixer 44, A band pass filter (BPF) 50 for passing only a desired frequency band at an output frequency of the amplifier 48; and a PLL control unit 60. The PLL control unit 60 includes:

The bandpass filter 46, the amplifier 48, and the bandpass filter 50 adjust the output frequency of the mixer 44 and output it as a final signal.

On the other hand, the input frequency (A MHz) in FIG. 8 is set to satisfy "(B-? / 2) MHz? A MHz? (B +? / 2) MHz". On the other hand, the input frequency (A MHz) in FIG. 9 is set to satisfy "(2B-β / 2) MHz ≦ A MHz ≦ (2B + β / 2) MHz".

Then, the PLL controller 60 sets the first PLL sweep signal (A + B) MHz and the second PLL sweep signal (A + 3B) MHz to the voltage controlled oscillator 40 Output. That is, the PLL controller 60 performs the PLL control for converting to the IF frequency once more and analyzes the result of the two sweeps to remove the unnecessary waves.

More specifically, the PLL control unit 60 first proceeds to the first PLL control for converting to a desired IF. That is, after setting the first PLL sweep signal, the data is extracted by reading the raw data and compared with the reference signal Noise / Signal. As a result of the comparison, if it is "0", it is judged as noise. If it is "1", it is judged as a signal. And stores the determined result in a memory (not shown). After such analysis and storage are completed, the second PLL control proceeds. After the second PLL sweep signal is set, the raw data is read to extract the data and compared with the reference signal Noise / Signal. As a result of the comparison, if it is "0", it is judged as noise. If it is "1", it is judged as a signal. And stores the determined result in a memory (not shown). Thereafter, the PLL controller 60 processes the first PLL data and the second PLL data stored in the two processes (i.e., the first PLL process and the second PLL process) in a forward process. As a result of forward processing, if the first PLL data and the second PLL data are seen at the same position, it is determined to be spurious due to isolation and converted into noise data. If reverse processing is not performed in the case of forward processing, reverse processing is performed. In the case of the reverse processing, if a signal is generated at the same place in conversion in the reverse order of the memory address of the first PLL data and the memory address of the second PLL data, it is determined as a 2 * IF signal and converted into noise data after removal .

On the other hand, if the PLL controller 60 does not comply with the forward processing and the reverse processing described above, the PLL controller 60 determines that the signal is a normal signal and outputs the first PLL data.

In this way, the PLL controller 60 can divide a signal in the final IF band into a normal signal and a spurious signal by a forward process and a reverse process. As a result, the PLL control unit 60 can process only normal signals by applying an algorithm.

8 and 9, the voltage-controlled oscillator 40 and the PLL controller 60 are configured separately from each other. However, the voltage-controlled oscillator 40 may be regarded as being included in the PLL controller 60. FIG.

FIG. 10 is a flowchart for explaining a method for removing harmonics of an intermediate frequency band in a wideband system according to the present invention, and FIGS. 11 to 15 are views employed in the description of FIG.

First, the PLL control unit 60 proceeds to the first PLL control for converting to a desired IF. That is, after setting the first PLL sweep signal, the PLL control unit 60 reads the raw data to extract data (S10, S12). Then, it is compared with the reference signal Noise / Signal (S14). As a result of the comparison, if it is "0", it is judged as a noise component. If it is "1", it is judged as a normal signal and then the judgment result is stored in a memory (not shown) (S16). Here, the set first PLL sweep signal may be "(A + B) MHz ".

After such analysis and storage are completed (i.e., completion of the first PLL process), the second PLL control proceeds. That is, after setting the second PLL sweep signal, the PLL controller 60 reads the raw data and extracts the data (S18, S20). Then, it is compared with the reference signal Noise / Signal (S22). As a result of the comparison, if it is "0", it is judged as a noise component. If it is "1", it is judged as a normal signal and then the judgment result is stored in a memory (not shown) (S24). Here, S18 to S24 may be referred to as a second PLL process. Here, the set second PLL sweep signal may be "(A + 3B) MHz ".

Thereafter, the PLL controller 60 performs a forward process on the first PLL data and the second PLL data stored in the two processes (i.e., the first PLL process and the second PLL process) (S26). As a result of the forward processing, if the first PLL data and the second PLL data are found at the same position, the PLL controller 60 determines that the spurious is caused by isolation and converts the spurious data into noise data (S28, S30). In other words, forward processing is a method for eliminating unwanted waves due to isolation. As shown in FIG. 11, a signal judged to be at the same frequency (based on a memory address) is determined as an unnecessary wave by isolation and is changed to a noise signal do.

If the forward processing is not performed, the PLL controller 60 performs a reverse process (S32). In the case of the reverse processing, if a signal is generated at the same place in conversion in the reverse order of the memory address of the first PLL data and the memory address of the second PLL data, it is determined as a 2 * IF signal and converted into noise data after removal (S34, S36). In other words, the reverse processing is a method for eliminating the spurious generated when the double IF signal is applied. The twice-IF signal is symmetric with respect to the center of the first PLL data and the second PLL data. In the case of reverse processing, as shown in FIG. 12, if the first PLL data is read backward and the second PLL data is normally read and read at the same position, it is judged as twice IF input and then removed.

On the basis of the frequency table of Fig. 13, the removal of unwanted waves by isolation will be described again. It should be understood that the frequency table of Fig. 13 is generated by the structure of Fig.

First, the first PLL sweep is set to be apart from the IF frequency by the conventional method.

Next, as a result of the first PLL sweep, a normal signal CS and an isolation signal US to be removed simultaneously occur as shown in the frequency table of FIG.

Accordingly, in order to remove the spurious signal due to the isolation, the second PLL sweep is performed while being separated from the IF frequency by three times the IF frequency.

As a result of the second PLL sweep, the spurious signal due to the isolation is generated at the same frequency as the dotted line (US).

As a result, the first PLL sweep result is compared with the dotted line US of the second PLL sweep result, and a signal appearing at the same frequency is determined as a spurious due to isolation and removed. This description corresponds to the forward processing scheme described above.

Now, based on the frequency table of Fig. 14, the description will be made again on the removal of unwanted waves when twofold IF signals are applied after removal of unnecessary waves by isolation. It should be understood that the frequency table of Fig. 14 is generated by the structure of Fig.

First, an input signal (2 * IF signal) is converted to a "1st PLL sweep (RF-LO) generated" signal by a first PLL sweep as shown in the frequency table of Fig. The "1st PLL Sweep (RF-LO)" signal is a signal that should not be shown on the spectrum analyzer screen.

Thereafter, it is converted into the "2nd PLL Sweep (LO-RF) generated" signal by the second PLL sweep.

As described above, the noise removal algorithm by isolation eliminates the spurious signal at the same frequency, but the signal (dotted line) occurs at another frequency when the double IF signal is applied, as shown in FIG.

The two signals shown in Fig. 14 (i.e., the dotted lines) have the characteristics shown in Fig. That is, the signal by the first PLL sweep and the signal by the second PLL sweep are converted symmetrically at a distance of? From the IF center (B MHz) as shown in FIG. Thus, the sum of the frequencies of the two signals always maintains a value of twice the IF. It can be determined that a double IF signal is applied based on a signal different from the IF signal of two times, and noise is displayed after the corresponding signal is erased. This description corresponds to the above-described reverse processing method.

As described above, an optimal embodiment has been disclosed in the drawings and specification. While specific terms have been employed herein, they are used for the purpose of describing the invention only and are not used to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

40: Voltage controlled oscillator 42, 48: Amplifier
44: mixer 46, 50: band pass filter (BPF)
60: PLL controller

Claims (12)

A mixer for converting an input frequency to a lower frequency band;
A signal adjuster for adjusting the output frequency of the mixer and outputting the final signal; And
And a PLL controller for applying a first PLL sweep signal and a second PLL sweep signal, which are different from each other, to the mixer and analyzing sweep results by the first PLL sweep signal and the second PLL sweep signal to remove unwanted waves Frequency band unwanted wave canceller of the broadband system. The method according to claim 1,
The PLL control unit includes:
The first PLL sweep signal and the second PLL sweep signal, respectively, and compares the data for each signal with a reference signal to determine a noise component and a normal signal, and outputs the determined result as the first PLL data and the second PLL sweep signal. PLL data, and processes the stored first PLL data and second PLL data in a forward direction to remove spurious waves caused by the isolation. The method of claim 2,
The PLL control unit includes:
Wherein when the first PLL data and the second PLL data are found at the same position as the result of the forward processing, it is determined to be unnecessary due to isolation and removed. The method of claim 2,
The PLL control unit includes:
And reverse processing is performed if the forward processing is not performed in the case of the forward processing. The method of claim 4,
Wherein the reverse processing is based on a 2 * IF signal and is removed when a signal is generated in the same place in conversion in the reverse order of the memory address of the first PLL data and the memory address of the second PLL data. Frequency band unwinding device. The method according to claim 1,
Wherein the mixer is a single mixer. A broadband system comprising a mixer for converting an input frequency into a low frequency band, and a signal adjuster for adjusting an output frequency of the mixer to output the final frequency signal,
The PLL controller applying different first PLL sweep signals and second PLL sweep signals to the mixer; And
And the PLL controller analyzes the sweep result by the first PLL sweep signal and the second PLL sweep signal to remove unwanted waves. The method of claim 7,
Wherein the step of removing the spurious component includes:
Setting the first PLL sweep signal and the second PLL sweep signal, respectively;
Comparing the data for each signal with a reference signal to determine a noise component and a normal signal;
Storing the determined result as a first PLL data and a second PLL data, respectively; And
And processing the stored first PLL data and the stored second PLL data in a forward direction to remove spurious waves due to isolation. The method of claim 8,
Wherein the step of removing the unnecessary waves by the isolation process comprises:
If the first PLL data and the second PLL data are seen at the same position, it is determined that the first PLL data and the second PLL data are unnecessary due to isolation and removed. The method of claim 8,
After the step of removing the unnecessary waves due to the isolation by the forward processing,
Further comprising the step of performing an inverse process on the intermediate frequency band of the wideband system. The method of claim 10,
The step of performing the reverse processing includes:
IF signal is generated when a signal is generated at the same place in conversion in the reverse order of the memory address of the first PLL data and the memory address of the second PLL data. Removal method. The method of claim 7,
Wherein the mixer is a single mixer.

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