JP6657499B2 - Frame synchronization apparatus, measurement apparatus including the same, frame synchronization method and measurement method - Google Patents

Description

  The present invention relates to a frame synchronization device for detecting, for example, a head position of a frame, a measurement device including the same, a frame synchronization method and a measurement method.

  Conventionally, this type of apparatus prepares a reference frame having the same format as a frame to be received in advance, and performs a correlation process by sequentially shifting the symbols of the reference frame with respect to the symbols of the received signal, so-called sliding correlation process. By executing the process, a correlation peak is obtained, and a head position of a frame is detected based on the correlation peak (for example, see Patent Document 1).

JP 2001-211137 A

  However, in the conventional sliding correlation processing, each time a capture signal is captured from a received signal, the sliding correlation processing is performed to determine the head position of a frame included in the capture signal. There was a problem that it would take a long time.

  SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and provides a frame synchronization apparatus capable of shortening the processing time of the frame synchronization processing, a measurement apparatus including the same, a frame synchronization method and a measurement method. The purpose is to provide.

A measuring apparatus according to claim 1 of the present invention includes at least down-converting means (21) for down-converting an input signal input from a device under test (1) into a baseband signal, and a plurality of frames having a known frame length. receiver for outputting a single quadrature demodulated signal (b) containing (20) and a frame synchronization detecting the head position of the frame captured from a single of the quadrature demodulated signal received from the receiving unit (b) A demodulation signal output means (13) for demodulating the baseband signal based on the detection signal (c) output from the frame synchronization device and outputting a demodulated signal (d); and measuring means (14) for measuring the demodulated signal, a measuring device wherein the frame synchronizer includes first and second frame preparative time interval of the frame length Frame trigger generating means (31) for generating a frame trigger (70) including a first frame trigger; and a first capture signal for capturing a first capture signal including a first frame from the input signal based on the first frame trigger. Capture means (41), and a first frame head for detecting a head position of the first frame included in the captured first capture signal and outputting the detection signal (c) to the demodulated signal output means. A position detecting means (42); and a time from the first frame trigger referenced by the first capturing means to a head position of the first frame detected by the first frame head position detecting means. Reference time detecting means (43) for detecting the reference time as a reference time, and after the reference time is detected by the reference time detecting means, A second capture means (51) for capturing a second capture signal including a second frame from the input signal with reference to the second frame trigger, and the second capture means (51) included in the captured second capture signal. a second frame head position detecting means (53) for outputting the detection signal detected on the basis of the head position of the second frame to the reference time (c) on the demodulated signal output means comprises a further said A detection window setting unit (52) for setting a detection window (W) for detecting a head position of the second frame based on a reference time, wherein the second frame head position detection unit includes the detection window setting unit In the detection window set by the above, the head position of the second frame is detected .

  With this configuration, the frame synchronizer according to claim 1 of the present invention detects the reference time from the first frame trigger to the head position of the first frame, and then detects the reference time of the second frame based on the reference time. The head position can be detected.

  Therefore, the frame synchronization apparatus according to claim 1 of the present invention performs processing such as sliding correlation processing every time a capture signal is captured from an input signal to determine the head position of a frame. Shortening can be achieved.

This configuration measuring apparatus according to claim 1 of the present invention, and detects the head position of the second frame in the detection window, it is possible to shorten the processing time of the frame synchronization processing.

This configuration measuring apparatus according to claim 1 of the present invention, since comprises a frame synchronization device which can shorten the processing time of the frame synchronization processing, it is possible to shorten the measurement time.

A measuring method according to claim 2 of the present invention includes at least a down-converting step (S11) for down-converting an input signal input from the device under test (1) into a baseband signal, and a plurality of frames having a known frame length. Receiving a single quadrature demodulated signal (b) including: a frame synchronization method for detecting a head position of a frame captured from the single quadrature demodulated signal (b) received from the receiving step ; Demodulating the baseband signal based on the detection signal (c) output from the frame synchronization method and outputting a demodulated signal (d) (S24); and measuring the output demodulated signal. measurements and step (S25), a measuring method including the frame synchronization method, the frame length in the time interval the first and second A frame trigger generating step (S13) for generating a frame trigger (70) including a frame trigger; and a first capturing a first capture signal including a first frame from the input signal based on the first frame trigger. A step of detecting a head position of the first frame included in the captured first capture signal and outputting the detection signal (c) to the demodulated signal output step (S24) . One frame head position detecting step (S16), and the head of the first frame detected in the first frame head position detecting step from the first frame trigger referenced by the first capturing step A reference time detecting step (S17) of detecting a time to the position as a reference time; A second capture step of capturing a second capture signal including a second frame from the input signal based on the second frame trigger after the reference time is detected in the reference time detection step (S19). And detecting a head position of the second frame included in the captured second capture signal based on the reference time and outputting the detection signal (c) to the demodulated signal output step (S24) . And a detection window setting step (S21) for setting a detection window (W) for detecting a head position of the second frame based on the reference time. The second frame head position detecting step includes the step of detecting the second frame head position in the detection window set by the detection window setting step. It has a configuration for detecting the head position of the second frame .

With this configuration, the measurement method according to claim 2 of the present invention detects the reference time from the first frame trigger to the start position of the first frame, and then detects the start time of the second frame based on the reference time. The position can be detected.

Therefore, the measuring method according to the second aspect of the present invention can reduce the processing time of the frame synchronization processing compared with the conventional technique of performing a sliding correlation process or the like every time a capture signal is captured from an input signal to determine a head position of a frame. Can be achieved.

This configuration measuring method according to claim 2 of the present invention, and detects the head position of the second frame in the detection window, it is possible to shorten the processing time of the frame synchronization processing.

With this configuration, the measurement method according to claim 2 of the present invention includes a measurement method capable of shortening the processing time of the frame synchronization processing, and thus can reduce the measurement time.

  The present invention can provide a frame synchronization device having an effect of shortening the processing time of the frame synchronization process, a measurement device including the same, a frame synchronization method and a measurement method.

FIG. 1 is a block configuration diagram in an embodiment of a measuring device according to the present invention. FIG. 3 is an explanatory diagram of functions of a frame synchronization device according to the present invention. FIG. 4 is a conceptual explanatory diagram comparing a frame head position detection method according to an embodiment of the frame synchronization apparatus according to the present invention with a frame head position detection method according to the related art. It is a flowchart in one Embodiment of the measuring device which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A description will be given of an example in which the frame synchronizer of the present invention is applied to a measuring device that measures a device under test (DUT) that outputs an Orthogonal Frequency Division Multiplexing (OFDM) signal.

  First, the configuration of an embodiment of the measuring device according to the present invention will be described.

  As shown in FIG. 1, the measuring apparatus 10 according to the present embodiment includes a receiving unit 20, a frame synchronizer 30, an OFDM demodulating unit 13, a measuring unit 14, and a display unit 15, and measures the DUT 1. An input signal a input from the DUT 1 includes an input frame having a known format, and has a signal component of a data symbol and a reference signal component. That is, the measuring apparatus 10 knows in advance the format of the frame included in the OFDM signal (input signal a) input from the DUT 1, and the position of the reference signal component in the input frame is known.

  The receiving unit 20 includes a down converter 21, an ADC (analog-to-digital converter) 22, and a quadrature demodulation unit 23.

  The downconverter 21 converts the frequency of the input signal a input from the DUT 1 into a baseband signal and outputs the baseband signal to the ADC 22. The down converter 21 is an example of a down converter.

  The ADC 22 converts a signal whose frequency has been converted by the down converter 21 from an analog value to a digital value, and outputs the digital value to the quadrature demodulation unit 23.

  The quadrature demodulation unit 23 performs quadrature demodulation on the output signal of the ADC 22 into an I (in-phase) signal component and a Q (quadrature) signal component, and outputs the quadrature demodulated signal b to the frame synchronization device 30 and the OFDM demodulation unit 13. It has become.

  The frame synchronization device 30 performs a frame synchronization process by detecting a head position of a frame included in an input signal. Specifically, the frame synchronization device 30 detects the head position of the frame included in the quadrature demodulation signal b output from the quadrature demodulation unit 23, and outputs the head position detection signal c indicating the head position of the detected frame to the outside of the device. To the OFDM demodulation unit 13. The detailed configuration of the frame synchronization device 30 will be described later. Note that the quadrature demodulated signal b is an input signal of the frame synchronizer 30.

  The OFDM demodulation unit 13 receives the quadrature demodulation signal b from the quadrature demodulation unit 23 and the head position detection signal c from the frame synchronization device 30. Then, the OFDM demodulation section 13 demodulates the orthogonal demodulation signal b from the orthogonal demodulation section 23 based on the head position detection signal c input from the frame synchronizer 30 to generate a demodulation signal d, and outputs the demodulation signal d to the measurement section 14. It is supposed to. The OFDM demodulation unit 13 is an example of a demodulated signal output unit.

  The measurement unit 14 is configured to be able to measure, for example, transmission power, EVM (Error Vector Magnitude), constellation, and the like for the demodulated signal d demodulated by the OFDM demodulation unit 13. The measuring unit 14 is an example of a measuring unit.

  The display unit 15 displays data, graphs, and the like of the measurement results obtained by the measurement unit 14.

  Next, the configuration of the frame synchronization device 30 will be described. The frame synchronization device 30 includes a first synchronization processing unit 40, a second synchronization processing unit 50, a frame trigger generation unit 31, a reference time storage unit 32, and a synchronization state detection unit 33.

  The first synchronization processing section 40 includes a first capture section 41, a first head position detection section 42, and a reference time detection section 43. The second synchronization processing unit 50 includes a second capture unit 51, a detection window setting unit 52, and a second head position detection unit 53.

  Hereinafter, the detailed configuration of the frame synchronization device 30 will be described with reference to FIG. FIG. 2 is a diagram for explaining the function of the frame synchronization device 30.

  FIG. 2 shows an input signal 60, a frame trigger 70, a capture signal 80, and a reference frame 90 of the frame synchronizer 30.

  The input signal 60 includes a plurality of frames such as frames 1 and 2 whose frame lengths are known. Although the start position 61 of frame 1 and the start position 62 of frame 2 are shown, these start positions are unknown when the frame synchronizer 30 inputs the input signal 60.

  The frame trigger generation unit 31 generates a frame trigger 70 and outputs the frame trigger 70 to the first synchronization processing unit 40 and the second synchronization processing unit 50. The frame trigger 70 includes frame triggers 71 to 76. The time interval of each frame trigger is equal to the frame length of each frame included in the input signal 60. Note that the frame trigger generation unit 31 is an example of a frame trigger generation unit.

  The first capture unit 41 captures a capture signal 81 having a length including at least one frame based on a frame trigger 71 (first frame trigger) as a first capture process for the input signal 60. It has become. In the illustrated example, the capture signal 81 has a length of two frames and includes a frame 2 (hatched portion). The frame 2 corresponds to the first frame, and the data included in the frame 2 is to be measured by the measuring unit 14. The first capture unit 41 is an example of a first capture unit.

  The first start position detection unit 42 uses the reference frame 90 prepared in advance having the same format as the input frame and performs, for example, a sliding correlation process on the frame included in the capture signal 81, that is, the start position 62 of the frame 2. Is to be detected. In the illustrated example, the reference frame 90 is slid by the time Ta during the sliding correlation processing. As a result of the sliding correlation processing, the first head position detection unit 42 can detect the head position 62 of the frame 2. The start position 62 of the frame 2 corresponds to the start position of the first frame. The first head position detection unit 42 is an example of a first frame head position detection unit.

  The reference time detection unit 43 detects a time from the frame trigger 71 set as a reference by the first capture unit 41 to the start position 62 of the frame 2 detected by the first start position detection unit 42 as a reference time Ts. It has become. Note that the reference time detection unit 43 is an example of a reference time detection unit.

  The reference time storage unit 32 stores data of the reference time Ts detected by the reference time detection unit 43.

  The synchronization state detection unit 33 determines whether the head position synchronization state indicating the state where the data of the reference time Ts is stored in the reference time storage unit 32 (the state where the reference time Ts is detected) or the data of the reference time Ts is One of the head position asynchronous states indicating a state not stored in the reference time storage unit 32 (a state in which the reference time Ts is not detected) is detected. Then, the synchronization state detection unit 33 outputs the input signal 60 to the first synchronization processing unit 40 when the head position synchronization state is detected, and outputs the second synchronization processing when the head position synchronization state is detected. The data is output to the unit 50.

  The second capture unit 51 uses the frame trigger 74 (second frame trigger) as a reference after the reference time Ts is detected by the reference time detection unit 43, that is, as the second or subsequent capture processing for the input signal 60. , A capture signal 82 having a length that includes at least one frame. In the illustrated example, the capture signal 82 has a length of two frames and includes the frame 12 (hatched portion). The frame 12 corresponds to the second frame, and data included in the frame 12 is a measurement target of the measurement unit 14. The second capture unit 51 is an example of a second capture unit.

  The detection window setting section 52 reads the data of the reference time Ts stored in the reference time storage section 32 and sets a detection window (window) W having a relatively narrow time width based on the frame trigger 74. I have. Note that the detection window setting unit 52 is an example of a detection window setting unit.

  The second head position detection unit 53 uses the reference frame 90 prepared in advance in the detection window W set by the detection window setting unit 52, for example, by performing a sliding correlation process, the frame included in the capture signal 82, The head position 64 of the frame 12 is detected. The start position 64 of the frame 12 corresponds to the start position of the second frame. The second head position detection unit 53 is an example of a second frame head position detection unit.

  In the example shown in FIG. 2, the capture signal 81 starts capturing at the same time as the frame trigger 71 and the capture signal 82 starts capturing at the same time as the frame trigger 74. However, the present invention is not limited to this. Instead, a configuration may be adopted in which capture is started at a time separated from the frame trigger by a certain time.

  Next, the effect of the frame synchronization device 30 in the present embodiment will be described with reference to FIG. FIG. 3A conceptually shows a method of detecting the head position of a frame according to the related art. FIG. 3B conceptually illustrates a method of detecting the head position of a frame by the frame synchronizer 30 according to the present embodiment.

  As shown in FIG. 3A, in the related art, for each capture signal 100 captured from the input signal 60, the detection time of the head position of the frame by the sliding correlation processing differs for each capture processing. Specifically, in the illustrated example, the detection time is Ta for the first capture signal 101, the detection time Tb for the second capture signal 102, and the detection time Tc for the third capture signal 103.

  On the other hand, as shown in FIG. 3B, in the frame synchronizer 30 of the present embodiment, the detection time Ta of the first capture signal 81 is the same as in the related art, but the capture signal 82 of the second and subsequent capture signals is used. , 83 differ from the prior art. In FIG. 3B, the capture start time of the capture signal 81 matches the capture start time of the capture signal 101 in order to simplify the description.

  Specifically, the frame synchronizer 30 is configured to detect the head position of the frame by the sliding correlation process in the detection window W set based on the reference time Ts in the second and subsequent times. Becomes the detection time Tw, and the time can be significantly reduced as compared with the related art.

  Note that the frame 22 (hatched portion) included in the third capture signal 83 corresponds to the second frame, and the data included in the frame 22 is to be measured by the measurement unit 14. Further, the head position 66 of the frame 22 corresponds to the head position of the second frame. The frame trigger 77 corresponds to a second frame trigger.

  Next, the operation of the measuring device 10 in the present embodiment will be described based on FIG. 4 and with reference to FIG. FIG. 4 is a flowchart illustrating a frame synchronization method and a measurement method according to the present embodiment.

  The downconverter 21 downconverts the input signal a input from the DUT 1 to a baseband signal (step S11). The down-converted signal is converted from an analog value to a digital value by the ADC 22 and output to the quadrature demodulation unit 23.

  The orthogonal demodulation unit 23 orthogonally demodulates the output signal of the ADC 22 into an I signal component and a Q signal component, and outputs the orthogonal demodulated signal b to the frame synchronization device 30 and the OFDM demodulation unit 13 (step S12).

  The frame trigger generation unit 31 generates a frame trigger 70 at a time interval of the frame length of each frame included in the input signal 60, and outputs the frame trigger 70 to the first synchronization processing unit 40 and the second synchronization processing unit 50 (step S13). ).

  The synchronization state detection unit 33 detects that the data of the reference time Ts is not stored in the reference time storage unit 32 when the data is not stored in the reference time storage unit 32. A synchronization state is detected (step S14). Then, when detecting that the head position is out of synchronization, the synchronization state detection unit 33 outputs the input signal b (the input signal 60 in FIG. 2) input from the reception unit 20 to the first synchronization processing unit 40. On the other hand, when the synchronization state detection unit 33 detects the start position synchronization state, it outputs the input signal b to the second synchronization processing unit 50.

  If it is determined in step S14 that the head position is out of synchronization, the first synchronization processing unit 40 operates as follows.

  The first capture unit 41 captures the capture signal 81 (first capture signal) based on the frame trigger 71 (first frame trigger) (step S15).

  The first start position detection unit 42 detects the start position 62 (the start position of the first frame) of the frame 2 included in the capture signal 81 by, for example, a sliding correlation process using the reference frame 90 prepared in advance. (Step S16).

  The reference time detection unit 43 detects a time from the frame trigger 71 set as a reference by the first capture unit 41 to the start position 62 of the frame 2 detected by the first start position detection unit 42 as a reference time Ts. (Step S17).

  The reference time storage unit 32 stores the data of the reference time Ts detected by the reference time detection unit 43 (Step S18).

  On the other hand, if it is detected in step S14 that the head position is synchronized, the second synchronization processing unit 50 operates as follows.

  The second capture unit 51 captures the capture signal 82 (second capture signal) based on the frame trigger 74 (Step S19).

  The detection window setting unit 52 reads the data of the reference time Ts stored in the reference time storage unit 32 (Step S20), and sets the detection window W based on the frame trigger 74 (second frame trigger) (Step S21). ). For example, the detection window setting unit 52 sets the detection window W so that the time from the frame trigger 74 to the center of the detection window W becomes the reference time Ts.

  The second head position detection unit 53 uses the reference frame 90 prepared in advance in the detection window W set by the detection window setting unit 52 to perform, for example, a sliding correlation process on the frame 12 included in the capture signal 81. The start position 64 (the start position of the second frame) is detected (step S22).

  The first head position detection unit 42 and the second head position detection unit 53 output the head position detection signal c to the OFDM demodulation unit 13 (Step S23).

  The OFDM demodulation unit 13 demodulates the quadrature demodulation signal b from the quadrature demodulation unit 23 based on the head position detection signal c, generates a demodulation signal d, and outputs the demodulation signal d to the measurement unit 14 (Step S24).

  The measurement unit 14 performs a predetermined measurement on the demodulated signal d from the OFDM demodulation unit 13 (Step S25).

  When the measurement is continuously performed after step S25, the measurement apparatus 10 executes the processing after step S14, captures a new capture signal, and measures the capture signal.

  When it is necessary to newly detect the reference time Ts after the detection of the reference time Ts, for example, when the signal from the DUT 1 is interrupted after the detection of the reference time Ts, the measuring device 10 , The first synchronization processing unit 40 performs a process of newly detecting the reference time Ts.

  As described above, after detecting the reference time Ts from the first frame trigger 71 to the start position 62 of the frame 2, the frame synchronizer 30 according to the present embodiment, based on the reference time Ts, sets the frames 12, 22, etc. , And so on, so that each time a capture signal is captured from an input signal, a sliding correlation process or the like is performed to determine the start position of a frame. Shortening can be achieved.

  In addition, since the measurement device 10 in the present embodiment includes the frame synchronization device 30 that can reduce the processing time of the frame synchronization process, the measurement time can be reduced.

  As described above, the frame synchronization apparatus according to the present invention, the measurement apparatus including the same, the frame synchronization method and the measurement method have an effect that the processing time of the frame synchronization processing can be reduced, and the frame synchronization The present invention is useful as a frame synchronization device for detecting a head position, a measurement device including the same, a frame synchronization method and a measurement method.

1 DUT (device under test)
2 frames (first frame)
10 measuring device 13 OFDM demodulation unit (demodulation signal output means)
12, 22 frames (second frame)
14 Measuring unit (measuring means)
21 Down converter (down conversion means)
30 frame synchronizer 31 frame trigger generator (frame trigger generator)
40 first synchronization processing unit 41 first capture unit (first capture unit)
42 First Head Position Detector (First Frame Head Position Detecting Means)
43 Reference time detection unit (reference time detection means)
50 second synchronization processing section 51 second capture section (second capture means)
52 detection window setting unit (detection window setting means)
53 Second Head Position Detection Unit (Second Frame Head Position Detection Means)
Reference Signs List 60 input signal 62 first frame start position 64, 66 second frame start position 70 frame trigger 71 first frame trigger 74, 77 second frame trigger 80 capture signal 81 first capture signal 82, 83 Second capture signal 90 Reference frame Tb Detection time W Detection window

Claims (2)

A down-conversion unit (21) for down-converting an input signal input from the device under test (1) into a baseband signal is provided, and a single quadrature demodulated signal (b) including a plurality of frames whose frame lengths are known is provided. A receiving unit (20) for outputting,
A frame synchronizer (30) for detecting a head position of a frame captured from the single quadrature demodulated signal (b) received from the receiving unit ;
Demodulated signal output means (13) for demodulating the baseband signal based on the detection signal (c) output from the frame synchronizer and outputting a demodulated signal (d);
Measuring means (14) for measuring the output demodulated signal;
A measuring device comprising :
The frame synchronization device,
Frame trigger generating means (31) for generating a frame trigger (70) including first and second frame triggers at the time interval of the frame length;
First capture means (41) for capturing a first capture signal including a first frame from the input signal on the basis of the first frame trigger;
First frame start position detection means (42) for detecting the start position of the first frame included in the captured first capture signal and outputting the detection signal (c) to the demodulation signal output means ; ,
A reference time for detecting a time from the first frame trigger set as a reference by the first capture means to the start position of the first frame detected by the first frame start position detection means as a reference time Detecting means (43);
Second capture means (51) for capturing, from the input signal, a second capture signal including a second frame based on the second frame trigger after the reference time is detected by the reference time detection means When,
A second frame head position for detecting a head position of the second frame included in the captured second capture signal based on the reference time and outputting the detection signal (c) to the demodulation signal output means. Detecting means (53);
Equipped with a,
A detection window setting means (52) for setting a detection window (W) for detecting a head position of the second frame based on the reference time;
The second frame head position detection means, the measuring device, characterized in that in the detection window set by the detection window setting means is for detecting the head position of the second frame. A single quadrature demodulated signal (b) including at least a down-converting step (S11) for down-converting an input signal input from the device under test (1) into a baseband signal and including a plurality of frames having known frame lengths. A receiving step to output;
A frame synchronization method for detecting a head position of a frame captured from the single quadrature demodulated signal (b) received from the receiving step ;
A demodulation signal output step of demodulating the baseband signal based on the detection signal (c) output from the frame synchronization method and outputting a demodulation signal (d) (S24);
A measuring step (S25) for measuring the output demodulated signal;
A measurement method comprising :
The frame synchronization method includes:
A frame trigger generating step (S13) of generating a frame trigger (70) including first and second frame triggers at the time interval of the frame length;
A first capture step (S15) of capturing, from the input signal, a first capture signal including a first frame based on the first frame trigger;
A first frame start position detecting step (S24) for detecting a start position of the first frame included in the captured first capture signal and outputting the detection signal (c) to the demodulated signal output step (S24); S16),
A reference time for detecting a time from the first frame trigger used as a reference in the first capture step to a start position of the first frame detected in the first frame start position detection step as a reference time A detecting step (S17);
A second capture step of capturing a second capture signal including a second frame from the input signal based on the second frame trigger after the reference time is detected in the reference time detection step (S19). When,
A second step of detecting a head position of the second frame included in the captured second capture signal based on the reference time and outputting the detection signal (c) to the demodulated signal output step (S24) . A frame head position detecting step (S22);
It includes,
The method further includes a detection window setting step (S21) of setting a detection window (W) for detecting a start position of the second frame based on the reference time,
The second frame leading position detecting step, measuring method, wherein in the detection window set by the detection window setting step is for detecting the head position of the second frame.

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