CN106645855B - A method of eliminating four-way digital three-dimensional waveform randomized jitter - Google Patents

Abstract

The invention discloses a method for eliminating the random beating of a four-channel digital three-dimensional oscilloscope waveform. Taking the synchronization signal Sync_sig1 of the waveform data of channels 1 and 2 as a reference, the random beating of the waveforms of channels 3 and 4 is eliminated; The signals Sync_sig1 and Sync_sig2 generate the time interval signal Sync_interval under the synchronization of the clock signal Sync_clk_R, and then use the clock signal Sync_clk_R to count the time interval signal Sync_interval to obtain the time when the waveform data Wave_dat1 is ahead of the Wave_dat2, and then use this time to delay the waveform data Wave_dat1 Adjust and set the synchronization signal Sync_sig2 of the waveform data Wave_dat2 as the final received clock signal Sync_sig_R to realize the reception of two channels of waveform data, thereby eliminating the random beating of the waveforms of channels 3 and 4.

Description

A Method for Eliminating Random Beating of Four-channel Digital 3D Oscilloscope Waveform

technical field

The invention belongs to the technical field of digital oscilloscopes, and more particularly relates to a method for eliminating random beating of a four-channel digital three-dimensional oscilloscope waveform.

Background technique

The digital three-dimensional oscilloscope realizes the multiple superposition of the waveforms collected multiple times through its fast and efficient parallel processing architecture, records the number of times the signal appears at different amplitudes and time positions in real time, and converts this information into a liquid crystal screen according to a certain proportional relationship when displaying. Intensity information for the upper waveform color. Therefore, when operating the digital three-dimensional oscilloscope, the user can judge the probability of the input signal appearing at a certain amplitude or time position by the depth of the waveform color displayed on the screen.

In the digital three-dimensional oscilloscope shown in Figure 1, after the analog signal passes through the signal conditioning channel, it is sampled by the ADC, and the sampled output is stored in the acquisition memory. When the memory storage is completed, that is, after one acquisition is completed, the data stored in the memory is read out in turn, and the sampled data is mapped into the waveform database corresponding to the LCD screen dot matrix in the parallel coprocessor. After the mapping is completed, a new one starts again. Collection and mapping of wheels. After multiple acquisitions and mappings, the waveform database records the number of times the input signal appears at different amplitudes and time positions (or on different storage units of the waveform database) in real time; at the same time, the microprocessor performs waveform operations, menu management and Human-computer interaction, etc. When the LCD screen timed refresh time is reached, the display refresh control logic is activated, the waveform database is automatically transferred to the waveform area of the display memory, and then combined with the menu data in the menu area of the display memory and sent to the LCD screen for display.

The part in the dotted box in Figure 1 is the core of the digital three-dimensional oscilloscope, and its implementation process is shown in Figure 2. All the processes in Figure 2 are implemented in an FPGA, where the timing signals are sent by the microprocessor. In a complete software cycle, when the microprocessor completes a series of operations such as waveform calculation, menu management and human-computer interaction and has updated the contents of the menu area in the video memory, it will send a timing signal to the FPGA. When the FPGA receives the timing signal, it will transfer all the information in the waveform database to the waveform area of the video memory in the way of increasing the address after the current acquisition waveform mapping is completed.

In the two-channel oscilloscope, since it is implemented in the same FPGA, the acquisition and mapping of the two channels are completed synchronously regardless of whether it is currently a point mapping or a vector mapping. After the timing signal arrives, the data transmission of their respective waveform databases starts at the same time, and the two channels of data are synthesized into one channel of data at the video memory end according to certain rules, and stored in the video memory waveform area.

However, in a four-channel digital oscilloscope, more FPGA chips are needed to complete the acquisition and display of the four channels due to the multiplication of IO resources and logic resources, and the acquisition and mapping of the four channels cannot be completed synchronously.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a method for eliminating the random beating of a four-channel digital three-dimensional oscilloscope waveform. By setting a clock synchronization signal, the synchronization of the acquisition and mapping of the four channels is controlled, thereby effectively eliminating the display on the display screen. Random beating of the waveform.

In order to realize the above-mentioned purpose of the invention, the method for eliminating the random beating of the waveform of the four-channel digital three-dimensional oscilloscope according to the present invention is characterized in that, comprising the following steps:

(1) Start the four-channel digital three-dimensional oscilloscope, turn on the display of all four channels, and use the synchronization signal Sync_sig1 of the waveform data of channels 1 and 2 as a reference on the display screen to observe whether the waveforms of channels 3 and 4 appear random beats. , if the waveforms of channels 3 and 4 jump, go to step (2), otherwise keep unchanged;

(2), eliminate the random beating of the waveform on the display

(2.1), use the clock signal Sync_clk_R of the same frequency to synchronously receive the waveform data Wave_dat1 of channels 1 and 2 and the waveform data Wave_dat2 of channels 3 and 4, as well as the synchronization signals Sync_sig1 and Sync_sig2 of the two;

(2.2), use the synchronization signals Sync_sig1 and Sync_sig2 to generate the time interval signal Sync_interval between the rising edges of the two under the synchronization of the clock signal Sync_clk_R;

(2.3), use the clock signal Sync_clk_R to count the time interval signal Sync_interval, and obtain a count value of M, that is, the time when the waveform data Wave_dat1 is ahead of Wave_dat2 is MT, where T represents the period of the clock signal Sync_clk_R;

(2.4) According to the M value obtained by counting, delay adjustment is performed on the waveform data Wave_dat1, that is, Wave_dat1 is delayed by M clock signal Sync_clk_R cycles to ensure that the waveform data Wave_dat1 and the waveform data Wave_dat2 are completely aligned;

(2.5) Set the synchronization signal Sync_sig2 of the waveform data Wave_dat2 as the final received clock signal Sync_sig_R, and then realize the reception of two channels of waveform data and send them to the display screen for display.

The purpose of the invention of the present invention is achieved in this way:

The present invention is a method for eliminating the random beating of a four-channel digital three-dimensional oscilloscope waveform. Taking the synchronization signal Sync_sig1 of the waveform data of channels 1 and 2 as a reference, the random beating of the waveform of channels 3 and 4 is eliminated. Specifically, the synchronization signal Sync_sig1 is used first. and Sync_sig2 generate the time interval signal Sync_interval under the synchronization of the clock signal Sync_clk_R, and then use the clock signal Sync_clk_R to count the time interval signal Sync_interval to obtain the time when the waveform data Wave_dat1 is ahead of the Wave_dat2, and then use the time to adjust the delay of the waveform data Wave_dat1, The synchronization signal Sync_sig2 of the waveform data Wave_dat2 is set as the finally received clock signal Sync_sig_R, so as to realize the reception of two channels of waveform data, thereby eliminating the random beating of the waveforms of channels 3 and 4.

At the same time, the method for eliminating the random beating of the waveform of the four-channel digital three-dimensional oscilloscope of the present invention also has the following beneficial effects:

(1) The present invention has a simple implementation structure, does not need to add additional hardware chips, and can be implemented by simple hardware code programming on the basis of an existing hardware platform.

(2) The present invention can significantly eliminate the random jitter of the four-channel digital three-dimensional oscilloscope waveform. It accurately detects the delay time between two channels of waveform data from two different sources in real time, and dynamically adjusts the time alignment relationship between the two channels of waveform data on this basis. After adjustment, the waveform data of the two channels are always aligned, thus eliminating random jitter of the waveform.

Description of drawings

Figure 1 is a block diagram of a two-channel digital oscilloscope;

Fig. 2 is the working flow chart of the two-channel digital oscilloscope;

Figure 3 is a four-channel digital oscilloscope FPGA structure diagram;

Figure 4 is a structural block diagram of a four-channel digital oscilloscope;

Figure 5 is a four-channel waveform data transmission timing diagram;

Fig. 6 is the timing chart of the time interval measurement of the rising edge of the synchronization signal;

FIG. 7 is a schematic diagram of dynamic adjustment of four-channel waveform data.

Detailed ways

The specific embodiments of the present invention are described below with reference to the accompanying drawings, so that those skilled in the art can better understand the present invention. It should be noted that, in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

Example

FIG. 3 is a structural block diagram of a four-channel digital three-dimensional oscilloscope of the present invention.

In this embodiment, the four-channel digital three-dimensional oscilloscope adopts the structure of three FPGAs as shown in FIG. 3 . Among them, FPGA1 and FPGA2 are of the same model, and are respectively responsible for the acquisition and mapping of channels 1 and 2 and channels 3 and 4, and FPGA3 is responsible for receiving The waveform data from the four channels are written into the video memory after synthesis, and the display function of the LCD screen is controlled.

The total trigger signal of the system is generated by FPGA1 and sent to FPGA2 to synchronize the signal acquisition of four channels. The microprocessor sends a timing signal, and FPGA1 and FPGA2 start to transmit the waveform data in the waveform database of each channel to the video memory at the same synchronous clock frequency after completing the mapping of the current acquisition waveform. Since the input waveform of each channel may be different, the current acquisition and mapping of FPGA1 and FPGA2 are not completed at the same time. In order to display the waveform normally, the waveform data transmission must be completed only after the current acquisition and mapping in FPGA1 and FPGA2 are completed. As shown in Figure 3, set F1 and F2 to represent the mapping completion signals of the current acquisition waveforms of FPGA1 and FPGA2 respectively after the timing is up. The total completion signal F=F1&F2 is generated in FPGA1 and sent to FPGA2. Therefore, the two FPGAs will not start their respective waveform data transmission until F is valid. Considering the influence of signal transmission delay between FPGAs, FPGA1 may judge that F is valid before FPGA2, and thus start waveform data transmission first. Therefore, when the two channels of data are received in FPGA3, due to the time difference, whether the synchronization signal from FPGA1 or FPGA2 is used to receive the two channels of data synchronously, the two channels of waveform data will not be aligned.

Below in conjunction with Fig. 4, a kind of method of eliminating the random beat of the waveform of a four-channel digital three-dimensional oscilloscope of the present invention is described in detail, and specifically comprises the following steps:

(1) Start the four-channel digital three-dimensional oscilloscope, turn on the display of all four channels, and use the synchronization signal Sync_sig1 of the waveform data of channels 1 and 2 as a reference on the display screen to observe whether the waveforms of channels 3 and 4 appear random beats. , if the waveforms of channels 3 and 4 jump, go to step (2), otherwise keep unchanged;

In this embodiment, according to the waveform data transmission shown in FIG. 5, the waveforms of channels 1 and 2 will be observed to be displayed stably on the display screen, while the waveforms of channels 3 and 4 will appear random beating; the reason is that During the design process, the waveform data of channels 1 and 2 are ahead of the waveform data of channels 3 and 4 in time, and the delay between the two channels of waveform data is random.

(2), eliminate the random beating of the waveform on the display

(2.1), use the clock signal Sync_clk_R of the same frequency to synchronously receive the waveform data Wave_dat1 of channels 1 and 2 and the waveform data Wave_dat2 of channels 3 and 4, as well as the synchronization signals Sync_sig1 and Sync_sig2 of the two;

(2.2) As shown in Figure 6, the time interval signal Sync_interval between the rising edges of the two is generated under the synchronization of the clock signal Sync_clk_R by using the synchronization signals Sync_sig1 and Sync_sig2, that is, when the signal Sync_sig1 is high and Sync_sig2 is low. , Sync_interval is valid as high, otherwise invalid as low;

(2.3), use the clock signal Sync_clk_R to count the time interval signal Sync_interval, and obtain a count value of M, that is, the time when the waveform data Wave_dat1 is ahead of Wave_dat2 is MT, where T represents the period of the clock signal Sync_clk_R;

In this embodiment, as shown in FIG. 6 , after the last waveform data reception is completed, the system clears the count value. During the current waveform data reception process and Sync_interval is at a high level, the system counts the rising edge of the clock signal Sync_clk_R, Every time a rising edge comes, the count value is incremented by 1, and the count is stopped when Sync_interval is low, and the count value is M. M is the number of cycles of the clock signal Sync_clk_R of the waveform data Wave_dat1 ahead of Wave_dat2.

(2.4) According to the M value obtained by counting, delay adjustment is performed on the waveform data Wave_dat1, that is, Wave_dat1 is delayed by M clock signal Sync_clk_R cycles to ensure that the waveform data Wave_dat1 and the waveform data Wave_dat2 are completely aligned;

In this embodiment, as shown in FIG. 7 , the time when the waveform data Wave_dat1 leads Wave_dat2 is M cycles of the clock signal Sync_clk_R. In order to synchronize the display of the two, eliminate the random jitter of the waveform display of channels 3 and 4 relative to channels 1 and 2, according to the delay count value M between the two waveform data measured in (2.3), under the control of the receiving clock Sync_clk_R , delay the waveform data Wave_dat1 by M clock Sync_clk_R cycles to achieve complete alignment of the two channels of waveform data.

(2.5) Set the synchronization signal Sync_sig2 of the waveform data Wave_dat2 as the final received clock signal Sync_sig_R, and then realize the reception of two channels of waveform data and send them to the display screen for display.

Although the illustrative specific embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, As long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the inventive concept are included in the protection list.

Claims (3)

1. a method for eliminating random beating of four-channel digital three-dimensional oscilloscope waveform, is characterized in that, comprises the following steps: (1) Start the four-channel digital three-dimensional oscilloscope, turn on the display of all four channels, and use the synchronization signal Sync_sig1 of the waveform data of channels 1 and 2 as a reference on the display screen to observe whether the waveforms of channels 3 and 4 appear random beats. , if the waveforms of channels 3 and 4 jump, go to step (2), otherwise keep unchanged; (2), eliminate the random beating of the waveform on the display (2.1), use the clock signal Sync_clk_R of the same frequency to synchronously receive the waveform data Wave_dat1 of channels 1 and 2 and the waveform data Wave_dat2 of channels 3 and 4, as well as the synchronization signals Sync_sig1 and Sync_sig2 of Wave_dat1 and Wave_dat2; (2.2), use the synchronization signals Sync_sig1 and Sync_sig2 to generate the time interval signal Sync_interval between the rising edges of the two under the synchronization of the clock signal Sync_clk_R; (2.3), use the clock signal Sync_clk_R to count the time interval signal Sync_interval, and obtain a count value of M, that is, the time when the waveform data Wave_dat1 is ahead of Wave_dat2 is MT, where T represents the period of the clock signal Sync_clk_R; (2.4) According to the M value obtained by counting, delay adjustment is performed on the waveform data Wave_dat1, that is, Wave_dat1 is delayed by M clock signal Sync_clk_R cycles to ensure that the waveform data Wave_dat1 and the waveform data Wave_dat2 are completely aligned; (2.5) Set the synchronization signal Sync_sig2 of the waveform data Wave_dat2 as the final received clock signal Sync_sig_R, and then realize the reception of two channels of waveform data and send them to the display screen for display. 2. a kind of method that eliminates four-channel digital three-dimensional oscilloscope waveform random beat according to claim 1, is characterized in that, the generation method of described time interval signal Sync_interval is: When the clock Sync_clk_R arrives, if the signal Sync_sig1 is high and Sync_sig2 is low, then Sync_interval is active high, otherwise it is active low. 3. a kind of method that eliminates four-channel digital three-dimensional oscilloscope waveform random beat according to claim 1, is characterized in that, in described step (2.3), utilize clock signal Sync_clk_R to the method that time interval signal Sync_interval is counted as: 1) After the last waveform data reception is completed, the system clears the count value; 2) During the current waveform data reception process and Sync_interval is high, the rising edge of the clock signal Sync_clk_R is counted. The count value is incremented by 1, and the count is stopped when Sync_interval is low.