KR20190107348A - Digital Phase Shifting Method using Software Defined Radio for Element level Digital Phased Arrays Architecture and Digital Phase Shifter - Google Patents

Abstract

Disclosed are a digital phase shifting method and digital phase shifter using software defined radio (SDR) for element level digital phase array architecture. According to one embodiment of the present invention, the digital phase shifting method comprises the steps of: converting an input signal into a first digital signal using SDR; mixing the first digital signal with an up converting digital signal having a first frequency and first phase to generate a second digital signal in which a frequency and phase of the first digital signal are changed; and mixing the second digital signal and a down converting digital signal having a second frequency to generate a third digital signal in which only phase of the first digital signal is shifted by the first phase.

Description

Digital Phase Shifting Method using Software Defined Radio for Element level Digital Phased Arrays Architecture and Digital Phase Shifter}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital phase shifter, and more particularly, to digitally implement the phase of each array in order to implement an element level digital phase array architecture, which is one of phased array architectures. And a digital phase shifter.

The beamforming technique is a method of changing a radiation pattern of an antenna using a phased array architecture. This beamforming technique is based on a phased array. The phased array architecture has been focused on passive phased array architecture and active phased array architecture. The research of Digital Phased Array Architecture is focused on.

Prior to 2010, the company had focused on active phase array architectures, but with recent advances in radio frequency integrated circuits (RFICs), data converters, and digital processing circuits, digital phased array architectures have many advantages over active phased arrays. Research is beginning.

In the case of an active phase array, there is an analog phase shifter stage in each element level to change the phase in the analog domain, and combine it with a combiner, and the digital phase array is an analog digital converter (ADC) at each element level. ) To convert an analog signal to a digital signal and then change the phase in the digital domain.

However, it is still used as a digital phased array area to cover the analog phase shifter digitally rather than to study the phase in the digital domain. The digital phased array method of digitally processing the existing analog phase shifter has three disadvantages in constructing the phase shifter stage. The first is that the complexity of constructing the phase shifter stage is high, and the second is that it is difficult to adjust delicately due to poor resolution when changing the phase, and the third is to change the amplitude after manufacturing. This is hard.

Thus, there is a need for a digital phase shifter that can ameliorate the aforementioned disadvantages in an element level digital phased array architecture.

Embodiments of the present invention provide a method for digitally changing the phase of each array to implement an Element Level Digital Phase Arrays Architecture, one of Phased Array Architectures. Provides a digital phase shifter.

Embodiments of the present invention provide a digital phase shifting method and a digital phase shifter that can change phase in a complete digital domain.

A digital phase shifting method according to an embodiment of the present invention includes converting an input signal into a first digital signal using software defined radio (SDR); Mixing the first digital signal with an up-converting digital signal having a first frequency and a first phase to generate a second digital signal having a changed frequency and phase of the first digital signal; And mixing the second digital signal with a down-converting digital signal having a second frequency to generate a third digital signal shifted only by the first phase of the first digital signal.

Furthermore, the digital phase shifting method according to an embodiment of the present invention receives the phase value for the first phase and generates the up-converting digital signal through digital processing using the received phase value and the first frequency. Doing; And generating the down-converting digital signal through digital processing using the second frequency.

The generating of the third digital signal may include mixing the second digital signal and the down-converting digital signal and canceling the first digital signal by the first frequency so that only the phase of the first digital signal is shifted by the first phase. Digital signals can be generated.

The generating of the second digital signal and the generating of the third digital signal may be performed by signal processing of software.

A digital phase shifter in accordance with one embodiment of the present invention comprises a software defined radio (SDR) for converting an input signal into a first digital signal; A first digital mixer for mixing the first digital signal with an up-converting digital signal having a first frequency and a first phase to generate a second digital signal having a changed frequency and phase of the first digital signal; And a second digital mixer that mixes the second digital signal with a down-converting digital signal having a second frequency to generate a third digital signal shifted by only the phase of the first digital signal.

Furthermore, the digital phase shifter according to an embodiment of the present invention receives a phase value for the first phase and generates the up-converting digital signal through digital processing using the received phase value and the first frequency. An up-converting signal generator; And a down converting signal generator configured to generate the down converting digital signal through digital processing using the second frequency.

The second digital mixer mixes the second digital signal and the down-converting digital signal to cancel by the first frequency to generate the third digital signal in which only the phase of the first digital signal is shifted by the first phase. can do.

According to embodiments of the present invention, the phase of each array may be varied in the fully digital domain to implement an element level digital phased array architecture.

According to embodiments of the present invention, by digitally configuring the phase shifter stage to change the phase in the digital domain, it is more accurate than changing the phase in the existing analog stage, and can reduce the cost of constructing the phase shifter. Because of the improved phase shift resolution in digital beamforming, the radiation pattern can be finely adjusted.

Since the present invention is applicable to the beamforming technique, the present invention can be applied to many fields such as SAR of a satellite tower system, a vehicle radar, a drone detecting RADAR, and 5G mobile communication.

1 is a flowchart illustrating an operation of a digital phase shifting method according to an embodiment of the present invention.
2 shows an exemplary diagram for explaining the principle of digital phase shifting.
3 illustrates a mathematical process of changing frequency and phase by the digital phase shifting of FIG. 2.
4 is a flowchart illustrating an embodiment of a process of generating an up-converting digital signal and a down-converting digital signal.
FIG. 5 illustrates an example of GNUradio of an up-converting source and a down-converting source for explaining the process of FIG. 4.
6 shows an exemplary view of the final output signal output by the digital phase shifting method.
7 illustrates a configuration of a digital phase shifter according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the embodiments. Also, like reference numerals in the drawings denote like elements.

Embodiments of the present invention utilize a software defined radio (SDR) and a digital mixer to change the phase of each array in an element-level digital phased array architecture in the fully digital domain, thereby changing the phase in existing analog stages. The key point is to provide a digital phase shifting technique that can precisely control the radiation pattern because it is more accurate than that, can reduce the cost of constructing the phase shifter, and improves the phase shift resolution in digital beamforming.

That is, the present invention first changes the input signal from the analog signal to the digital signal to change the phase in the digital domain, and uses SDR for this.

Software Defined Radio (SDR) is composed of VGA, Analog to Digital Converter (ADC), Mixer, Filter, and Phase Locked Loop (PLL) circuits. Change the input signal input to SDR into digital signal by reducing the frequency to a band that can be converted into a digital signal at.

In addition, the present invention may use a signal processing program, for example GNUradio, to change the phase of the digital signal converted by SDR. GNUradio is a free software development toolkit that provides basic signal processing blocks (or functions), allowing users to create blocks in C and Python. Signals can be processed using these blocks in the form of a flow graph.

As described above, the phase shifter is implemented in the digital stage using SDR and a signal processing program, for example, GNUradio, so that the phase of the digital signal for the input signal can be digitally changed.

This invention will be described with reference to FIGS. 1 to 7.

1 is a flowchart illustrating an operation of a digital phase shifting method according to an embodiment of the present invention.

Referring to FIG. 1, the digital phase shifting method according to an embodiment of the present invention converts an input signal into a digital signal (eg, a first digital signal) using SDR (S110).

That is, step S110 converts the analog input signal into a digital signal using SDR and then provides the converted digital signal.

Steps S120 and S130 are steps that are processed in software by a signal processing program, for example, GNUradio, and phase shift the digital signal converted by SDR through signal processing.

As described above, when the digital signal converted from the input signal is received in step S110, an up-converting digital signal having a first frequency and a first phase generated in advance and a digital signal converted by SDR, that is, the first digital signal By mixing, a second digital signal having a changed frequency and phase is generated (S120).

Here, step S120 is a step for changing the phase of the digital signal with respect to the input signal, and the frequency of the first digital signal may be changed by the first frequency and the phase may be changed by the first phase. The first phase of the up-converting digital signal in step S120 is a phase value to be shifted of the digital signal finally output from the digital phase shifter, which may be set by a user's input, or to which the digital phase shift is applied. It can also be set automatically in.

When a second digital signal whose frequency and phase are converted by the first frequency and the first phase is generated in step S120, the down-converting digital signal having the second frequency and the second digital signal are mixed to correspond to the input signal. In other words, a third digital signal having a first phase difference from the first digital signal is generated (S130).

That is, step S130 finally generates a digital signal shifted in phase by the first phase.

Here, step S130 is a step of converting only the frequency of the second digital signal into the frequency of the first digital signal, which is a digital signal corresponding to the input signal, and converts the frequency converted by the first frequency while maintaining the phase changed by the first phase as it is. Returning to the frequency of the first digital signal. Accordingly, the first frequency and the second frequency may have values having the same absolute value and different signs.

The digital phase shifting method according to the present invention will be described below with reference to FIGS. 2 and 3.

2 shows an exemplary diagram for explaining the principle of digital phase shifting.

Referring to FIG. 2, two digital mixers and two digital sources are provided. The signal before passing through the first digital mixer is a digitized signal from the SDR to the ADC. Digitized signals come in at certain frequencies and with specific phases. You must keep the specific frequency and change only the phase as desired. The digitized signal is mixed with the Upconvert Source as it passes through the first digital mixer, which generates a signal with a certain preset frequency and the phase to change. The up-convert source is likewise a digital signal. The signal mixed by the first digital mixer is converted from the original received signal to the signal plus the frequency and phase of the up-converted source. The signal mixed by the first digital mixer is mixed with the downconvert source in the second digital mixer, which is a digital signal with zero phase and only frequency. The frequency of the down-convert source is set to a frequency that can reduce the frequency raised by the up-convert source. The signal that passes through the second digital mixer is finally a digital signal that changes in phase only as desired without changing its frequency. Unlike the method of changing in the existing analog domain, the signal output through this process is digitally changed so that no distortion occurs.

가 수신되면, 수신된 제1 디지털 신호

와 미리 생성된 업 컨버팅 디지털 신호

가 디지털 믹서에 의해 혼합되어 업 컨버팅 디지털 신호의 주파수

와 위상

만큼 변화된 제2 디지털 신호

가 생성된다.Specifically, the first digital signal which is a digital signal for the input signal converted by SDR

Is received, the received first digital signal

And pre-generated up-converting digital signals

The frequency of the upconverting digital signal that is mixed by the digital mixer

And phase

The second digital signal changed by

Is generated.

와 미리 생성된 다운 컨버팅 디지털 신호

가 디지털 믹서에 의해 혼합되어 다운 컨버팅 디지털 신호의 주파수 -

만큼 변화된 제3 디지털 신호

가 생성됨으로써, 제1 위상

만큼 쉬프트된 디지털 신호가 최종 디지털 신호로 출력된다.The second digital signal generated when the second digital signal is generated

And pre-generated down-converting digital signals

The frequency of the down-converting digital signal is mixed by the digital mixer

The third digital signal changed by

Is generated, so that the first phase

The shifted digital signal is output as the final digital signal.

와 위상

는 첫 번째 디지털 믹서를 이용한 업 컨버팅 디지털 신호의 주파수

와 위상

에 의해 주파수가

+

로 변환되고 위상이

+

로 변환된다. 또한, 제2 디지털 신호의 주파수

+

와 위상

+

는 두 번째 디지털 믹서를 이용한 다운 컨버팅 디지털 신호의 주파수 -에 의해 주파수가

로 변화되고 위상은

+

로 그대로 유지됨으로써, 입력 신호에 대한 제1 디지털 신호의 위상이

만큼 쉬프트된 디지털 신호가 최종 디지털 신호로 생성 또는 출력된다.Referring to only the frequency and phase change using FIG. 3, the frequency of the first digital signal with respect to the input signal

And phase

Is the frequency of the up-converting digital signal using the first digital mixer.

And phase

By frequency

+

Is converted to

+

Is converted to. In addition, the frequency of the second digital signal

+

And phase

+

Is the frequency of the down-converting digital signal using a second digital mixer. By frequency

The phase changes to

+

The phase of the first digital signal relative to the input signal is

The shifted digital signal is generated or output as the final digital signal.

4 is a flowchart illustrating an embodiment of a process of generating an up-converting digital signal and a down-converting digital signal, and FIG. 5 is a diagram of GNUradio of an up-converting source and a down-converting source for explaining the process of FIG. 4. An illustration is shown.

4 and 5, when a phase value to be shifted, for example, a phase value of 180 is received, an upconverting source with phase shifter and a downconverting digital signal based on the received phase value downconverter source) is generated (S410 and S420).

Here, step S420 may generate an up-converting digital signal and a down-converting digital signal by using Constant Source, Sp ff, Vector to Stream, and Float to Complex blocks.

Constant source is a block that puts the phase value that you want to change, for example, 180 degrees and 0 degrees, and Sp ff block is a source block that generates a frequency and a desired phase, and a block that generates a digital signal having a frequency and a desired phase.

Here, the Sp ff block may be a block coded using a specific language, for example, C language, and an imaginary signal and a real signal may be output, respectively. May be output.

 The Vector to Stream block converts the signal output bit by bit from the Sp ff block into a Float to Complex block.The vector to stream block is a digital signal, The converting digital signal and the down converting digital signal are finally output.

When the up-converting digital signal and the down-converting digital signal are generated by the process as shown in FIG. 5, the up-converting digital signal is provided to the first digital mixer (the first digital mixer) and the down-converting digital signal is the second digital mixer (the second digital mixer). Digital mixer), the digital phase shifted digital signal can be finally output (S430).

As described above, the digital phase shifting method according to the present invention is a signal generated from an up-converted source having a desired phase to be changed when a signal input to the SDR from the signal source is converted into a digital signal after being passed through the ADC. And are mixed in the first mixer and in the second mixer with the signal output from the down-convert source, which cancels the frequency generated by the up-convert source. That is, the signal mixed by the first digital mixer and the second digital mixer is the digital phase shifted signal as the final output signal. Here, the phase value to be changed may be input to a predetermined block, and when the phase value is input, the digital signal shifted in phase by the input phase value is output as the final output signal.

6 illustrates an example of the final output signal output by the digital phase shifting method, and compares the final output signal of the digital phase shifter and the input signal of the digital phase shifter.

As shown in FIG. 6, the first result is when the phase value to be shifted to 0 is 0. When the phase value is 0, it can be seen that the phases of the input signal and the output signal do not differ.

The second result is when the phase value to be shifted is set to 90. When the phase value is set to 90, it can be seen that the input signal passes through the digital phase shifter and the phase of the input signal and the output signal is shifted by 90 degrees. .

The second result is when the phase value to be shifted is set to 180. When the phase value is set to 180, it can be seen that the input signal passes through the digital phase shifter and the phase of the input signal and the output signal differs by 180 degrees. .

In addition, the present invention can obtain a resolution (resolution) that is the minimum angle of the phase control, the resolution can be expressed as shown in Equation 1 below.

[Equation 1]

As can be seen from Equation 1, it can be seen that the resolution is related to the sampling rate and the frequency of the up-converted source. Dividing the sampling rate by the up-converted source yields the number of samples within one wavelength of the up-converted source. Dividing 360 by this number of samples yields the minimum adjustable phase. For example, the minimum adjustable phase may be 0.5 degrees. Thus, by properly adjusting the sampling rate and the frequency of the up-converted source, phase shift can be achieved to very small values.

As such, the method according to the present invention utilizes a digital mixer to vary the phase of each array of the element level digital phased array architecture in the fully digital domain, thereby providing a more accurate phase shifter than changing the phase in existing analog stages. The cost of construction can be reduced and the radiation pattern can be finely adjusted because of the better phase shift resolution in digital beamforming.

7 illustrates a configuration of a digital phase shifter according to an embodiment of the present invention and illustrates a configuration of a functional digital phase shifter for performing the digital phase shifting method described with reference to FIGS. 1 to 6.

Referring to FIG. 7, the digital phase shifter according to the present invention includes an SDR 710, a first digital mixer 720, a second digital mixer 730, an up-converting signal generator 740, and a down-converting signal generator ( 750).

The SDR 710 converts the input signal into a digital signal by lowering the frequency into a band that can be converted into a digital signal in the ADC using a mixer and a PLL circuit configuring the SDR.

The up-converting signal generator 740 is a means for generating an up-converting digital signal having a first phase which is a phase value to be shifted with the first frequency. The up-converting signal generator 740 uses constant source, sp ff, vector to stream, and float to complex blocks. To generate an up-converting digital signal.

Here, the up-converting signal generator 740 may generate an up-converting digital signal and provide it to the first digital mixer.

The down-converting signal generator 750 is a means for generating a down-converting digital signal having a second frequency for canceling a first frequency of the up-converting digital signal. The down-converting signal generator 750 is a constant source, a sp ff, a vector to stream, and a float to complex block. To generate the down-converting digital signal.

Here, the down converting signal generator 750 may generate a down converting digital signal and provide it to the second digital mixer.

The first digital mixer 720 mixes the digital signal with respect to the input signal converted by the SDR and the up-converting digital signal generated by the up-converting signal generator to output a digital signal having a changed frequency and phase to the second digital mixer. do.

Here, the first digital mixer 720 may output a digital signal whose frequency of the digital signal with respect to the input signal is changed by the first frequency and whose phase is changed by the first phase to the second digital mixer.

The second digital mixer 730 mixes the digital signal output from the first digital mixer 720 and the down-converting digital signal generated by the down-converting signal generator to cancel the change by the first frequency and the first phase. Only the shifted digital signal is output as the final output signal.

Although the description thereof is omitted in the digital phase shifter illustrated in FIG. 7, it is apparent to those skilled in the art that the digital phase shifter according to the present invention may include all the contents described in FIGS. 1 to 6. .

The system or apparatus described above may be implemented with hardware components, software components, and / or combinations of hardware components and software components. For example, the systems, devices, and components described in the embodiments may include, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable arrays (FPAs). ), A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions, may be implemented using one or more general purpose or special purpose computers. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

The method according to the embodiments may be embodied in the form of program instructions that may be executed by various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims (7)

Converting an input signal into a first digital signal using software defined radio (SDR);
Mixing the first digital signal with an up-converting digital signal having a first frequency and a first phase to generate a second digital signal having a changed frequency and phase of the first digital signal; And
Mixing the second digital signal with a down-converting digital signal having a second frequency to generate a third digital signal shifted by only the phase of the first digital signal by the first phase;
Digital phase shifting method comprising a.
The method of claim 1,
Receiving a phase value for the first phase and generating the up-converting digital signal through digital processing using the received phase value and the first frequency; And
Generating the down-converting digital signal through digital processing using the second frequency
Digital phase shifting method further comprising.
The method of claim 1,
Generating the third digital signal
The second digital signal and the down-converting digital signal are mixed to cancel by the first frequency to generate the third digital signal shifted by only the phase of the first digital signal by the first phase. Phase shifting method.
The method of claim 1,
Generating the second digital signal and generating the third digital signal
Digital phase shifting method characterized in that performed by signal processing of software.
Software defined radio (SDR) for converting an input signal into a first digital signal;
A first digital mixer for mixing the first digital signal with an up-converting digital signal having a first frequency and a first phase to generate a second digital signal having a changed frequency and phase of the first digital signal; And
A second digital mixer that mixes the second digital signal with a down-converting digital signal having a second frequency to generate a third digital signal shifted only by the first phase in phase of the first digital signal;
Digital phase shifter comprising a.
The method of claim 5,
An up-converting signal generator configured to receive a phase value for the first phase and to generate the up-converting digital signal through digital processing using the received phase value and the first frequency; And
A down-converting signal generator for generating the down-converting digital signal through digital processing using the second frequency.
Digital phase shifter further comprises.
The method of claim 5,
The second digital mixer
The second digital signal and the down-converting digital signal are mixed to cancel by the first frequency to generate the third digital signal shifted by only the phase of the first digital signal by the first phase. Phase shifter.

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