Eye pattern generation method based on pseudo sequence code modification

Abstract

The invention discloses an eye pattern generation method based on pseudo sequence code modification, which comprises the following steps of: firstly, generating a pseudo sequence code as an original signal through a random sequence generator; in the equalization part, the original signal is subjected to emphasis processing at the transmitting end to enhance the high-frequency component of the signal, the signal with jitter and noise added is subjected to filtering processing at the receiving end, and finally an equalized eye pattern is generated according to the eye pattern superposition generation principle. And in the modulation part, the range of the intercepted signal is doubled, the intercepted signal is translated into a new level according to a calculation principle, an adjusted excitation signal is generated, the excitation signal is processed by a system to obtain an output response, and finally a modulated eye pattern is generated according to an eye pattern superposition generation principle. By performing targeted calculation of equalization and modulation on the pseudo sequence code used for eye pattern generation, the invention realizes the compensation of noise and jitter, and can effectively improve the signal quality and the data transmission rate.

Description

Technical Field

[0001] The present invention relates to the field of electronic design automation, and particularly to an eye diagram generation method based on pseudo-sequence code modification for signal integrity verification. Background Art

[0002] In modern high-speed communication systems, the quality of signal transmission is of crucial importance. As an intuitive and effective tool, the eye diagram is widely used to evaluate the performance of digital signal transmission. The eye diagram is a graph formed by superimposing and displaying multiple cycles of a digital signal on an oscilloscope, and it gets its name because of its shape similar to an eye. It can clearly show many key characteristics of the signal, such as the distortion degree of the signal, the noise level, the timing jitter, and the inter-symbol interference situation, etc. By observing parameters such as the opening degree of the eye diagram, the slope of the eye diagram, and the position of the zero-crossing point, engineers can quickly judge the health status of the communication link and then accurately evaluate the signal transmission quality.

[0003] With the development of communication technology towards high speed and large capacity, signals face increasingly serious problems such as attenuation and dispersion during transmission. These problems cause serious inter-symbol interference in the signal, resulting in the closure of the eye diagram and seriously affecting the communication quality. Especially in high-speed data transmission systems, the basic eye diagram generation method gradually exposes its limitations and is difficult to effectively cope with signal distortion problems in high-speed and high-complexity scenarios, with poor applicability, mainly reflected in the following aspects: 1. Sensitivity to noise and jitter The basic eye diagram generation method lacks a compensation mechanism for noise and jitter. In high-speed data transmission systems, the influence of noise (such as random noise, crosstalk) and jitter (such as deterministic jitter, random jitter) will be significantly aggravated, resulting in the inability to effectively solve the signal distortion problem. It is impossible to distinguish the sources of noise and jitter, and it is also difficult to provide a targeted compensation scheme, thus reducing the reliability and stability of the system.

[0004] 2. Limited data transmission rate In the basic eye diagram generation method, the analysis method is based on the traditional non-return-to-zero (NRZ) modulation technology, which is applicable to lower data transmission rates. However, in higher-rate scenarios, problems such as high-frequency attenuation of the signal, inter-symbol interference (ISI), and non-linear distortion are more prominent. It is difficult to accurately reflect the integrity of the signal and cannot meet the requirements of high-speed data transmission systems. Modern high-speed data transmission systems generally adopt multi-level modulation technologies, such as four-level pulse amplitude modulation (PAM4), to achieve higher spectral efficiency.

[0005] In summary, it is of great practical significance and application value to develop an eye diagram generation method that combines equalization and modulation techniques, can more efficiently and accurately improve the quality of the eye diagram, and at the same time has a low computational complexity and good adaptability. Summary of the Invention

[0006] The object of the present invention is to provide an eye diagram generation method based on the modification of pseudo-sequence codes. By performing targeted calculations of equalization and modulation on the pseudo-sequence codes used for eye diagram generation, noise and jitter compensation are achieved, and the data transmission rate is increased.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows. In a first aspect, the present invention provides an eye diagram generation method based on the modification of pseudo-sequence codes, including the following steps: Step S1: Build a simulation circuit, which includes a pseudo-random sequence generator. Step S2: Initialize the pseudo-random sequence generator, and then generate a pseudo-sequence code as the original signal input at the transmitting end. Step S3: Perform equalization and / or modulation according to the pseudo-sequence code to obtain an equalized and / or modulated signal. Step S4: Transmit the equalized and / or modulated signal to the receiving end, and then generate an eye diagram according to the eye diagram superposition generation principle.

[0008] Further, the pseudo-random sequence generator uses a Linear Feedback Shift Register (LFSR).

[0009] Further, the equalization includes: performing emphasis processing on the original signal at the transmitting end to enhance the high-frequency components of the signal, and then performing filtering processing on the emphasized signal at the receiving end.

[0010] Further, the modulation includes: segmenting the pseudo-sequence code by time, sampling each segment of the signal, then performing level mapping on the sampled signal, and reconstructing the mapped level signals into a continuous waveform in chronological order to generate an excitation signal (i.e., the modulated signal).

[0011] In a second aspect, the present invention provides an eye diagram generation device, including the following modules: A pseudo-sequence code generation module, which is used to generate a pseudo-sequence code through a linear feedback shift register. An equalization module, which is used to emphasize the pseudo-sequence code to obtain an equalized signal. A modulation module, which is used to segment the pseudo-sequence code, perform level mapping, and reconstruct the signal to obtain a modulated signal. A filtering module for performing signal filtering processing on the equalized signal and / or the modulated signal; An eye diagram generation module for generating an eye diagram based on the filtered signal according to the eye diagram superposition generation principle.

[0012] In a third aspect, the present invention provides a computing device, including a memory and a processor. An executable code is stored in the memory. When the processor executes the executable code, the above method is implemented.

[0013] In a fourth aspect, the present invention provides a machine-readable storage medium. The machine-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions cause the processor to implement the above method.

[0014] Compared with the prior art, the beneficial effects of the present invention are: The present invention performs equalization calculation, pre-emphasis and filtering on the pseudo-sequence code used for eye diagram generation to offset the distortion and interference introduced by the channel, modulates the pseudo-sequence code used for eye diagram generation, doubles the intercepted signal range and translates the level, increases the amount of data included in each amplitude, improves the data transmission rate, reduces the real-time processing pressure, reduces the influence of noise, and facilitates system adjustment and optimization. Compared with the signal processed and transmitted in the simulation process, the present invention directly processes the pseudo-sequence code, that is, performs equivalent functional processing on the source signal at the transmitting end, so that the output signal at the transmitting end is the input signal required at the receiving end, which can reduce the calculation in the transmission process and make the transmission process more concise. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : The algorithm flowchart of the implementation method of the present invention.

[0016] Figure 2 : Schematic diagram of the equalization principle of the implementation method of the present invention.

[0017] Figure 3 : Schematic diagram of level translation in the modulation principle of the implementation method of the present invention.

[0018] Figure 4 : Simulation result of eye diagram equalization in Embodiment 1 of the implementation method of the present invention.

[0019] Figure 5 : Simulation result of eye diagram modulation in Embodiment 2 of the implementation method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions of the present invention will be further specifically described below through embodiments in conjunction with the drawings.

[0021] The present invention is applicable to simulation scenarios, such as the channel simulation function of signal integrity simulation software. The specific implementation is described in detail by taking the eye diagram simulation problem as an example.

[0022] As Figure 1 shown, the present invention provides an eye diagram equalization modulation method based on the modification of pseudo-sequence codes. The specific steps of this method are as follows: S1. Build a simulation circuit diagram Design the following circuit modules: Pseudo-random sequence generator: used to generate pseudo-sequence codes. In this embodiment, a linear feedback shift register (LFSR) is adopted; Modulation module: used to modulate the pseudo-sequence codes; Equalization module: used to perform equalization processing on the signals; Channel model: used to simulate the noise and jitter in signal transmission; Receiving module: used to receive and process the signals.

[0023] Connect the circuit modules: Connect each module in the order of signal transmission to ensure the correct signal flow.

[0024] S2. Set the simulation information Pseudo-sequence code generation parameters: Select the order of the linear feedback shift register, such as 7th order; Select the primitive polynomial. Taking the 7th order as an example, the primitive polynomial of the LFSR is: (1) Among them, in the primitive polynomial, x the power represents the position of the register in the LFSR. For example, x 7 represents the 7th register bit, x 6 represents the 6th register bit, and so on. f(x) is the primitive polynomial itself, representing the feedback structure of the LFSR. As shown in (1), it means that the feedback structure is the exclusive OR result of the 7th bit and the 6th bit fed back to the 1st bit.

[0025] Set the initial state, such as [1, 0, 0, 0, 0, 0, 0]; Specify the length of the sequence, such as 1000 bits.

[0026] Modulation parameters: Select a modulation method, such as PAM4 (4-Level Pulse Amplitude Modulation) or NRZ (Non-Return-to-Zero). Set the symbol period T and the sampling rate (such as 8 times or 16 times the symbol rate).

[0027] Equalization parameters: Set the number of taps and the weighting coefficients of the Feed-Forward Equalizer (FFE). Set the number of taps and the weighting coefficients of the Finite Impulse Response (FIR) filter.

[0028] Channel parameters: Set the noise type and intensity, such as Gaussian noise. Set the jitter type and intensity, such as random jitter.

[0029] S3. Initialize the LFSR: Initialize the LFSR according to the set primitive polynomial and initial state. Generate a sequence: Generate a pseudo-random sequence through shift and feedback operations, such as generating a 1000-bit Maximum Length Sequence (M sequence).

[0030] S4. Equalization 4-1 Transmitter pre-emphasis processing, that is, use FFE to pre-emphasize the original signal at the transmitter.

[0031] The pre-emphasis processing formula is: (2) Where, y(n) is the output signal of the FFE, x(n−k) is the original signal after delay, w k is the weighting coefficient of the k-th tap, N is the number of taps of the FFE.

[0032] 4-2 Receiver filtering processing, that is, use the FIR filter to filter the signal with added jitter and noise at the receiver.

[0033] The filtering processing formula is: (3) Where, v(m) is the output signal of the FIR, u(m-j) is the signal with added jitter and noise after delay, c jis the j weighting coefficient of the M th tap, where

[0034] S5. Modulation 5-1 Signal segmentation: Segment the pseudo-random sequence code by time, with each segment having a length of the symbol period T; sample each segment of the signal at a sampling rate of 8 times or 16 times the symbol rate.

[0035] 5-2 Level mapping: Define the level mapping rule according to the modulation method: For PAM4, map 2-bit binary codes to 4 levels: 00 → −3, 01 → −1, 10 → 1, 11 → 3; for NRZ, map 1-bit binary codes to 2 levels: 0 → 0, 1 → 1.

[0036] Convert the intercepted signal to new levels. For example, map [0, 1, 0, 1] to [−1, 1, −1, 1].

[0037] 5-3 Signal reconstruction: Reconstruct the level signal after mapping into a continuous waveform in chronological order, ensuring that the time axis of the signal is consistent with the original signal.

[0038] 5-4 Generate the excitation signal: Use the reconstructed waveform as the adjusted excitation signal for subsequent processing or transmission.

[0039] S6. Signal transmission: Pass the modulated excitation signal through the channel model to simulate the noise and jitter in signal transmission.

[0040] S7. Signal reception: Sample and process the signal at the receiving end to obtain the output response signal.

[0041] S8. Generate the eye diagram: Sample the output response signal at a sampling rate of 8 times or 16 times the symbol rate.

[0042] Segment the sampled signal waveform by the symbol period and superimpose and display it within one period to form an eye diagram.

[0043] Embodiment 1 As Figure 2 shown, the present invention provides an eye diagram generation method with an equalization function: Step S1: Generate the original signal Use an LFSR to generate an M sequence as the original signal; Select a primitive polynomial; Initialize the LFSR register to a non-all-zero state, such as [1, 0, 0, 0, 0, 0, 0]; Generate the M sequence through shift and feedback operations, for example, generate a 1000-bit pseudo-random sequence.

[0044] Step S2: Transmitter equalization processing At the transmitter, perform pre-equalization processing on the original signal using FFE; Step S3: Receiver filtering processing At the receiver, filter the signal with added jitter and noise using an FIR filter; Step S4: Generate the equalized eye diagram Sample the filtered signal at a sampling rate of 8 times or 16 times the symbol rate; Segment the sampled signal waveform by symbol period and superimpose and display it within one period to form the equalized eye diagram.

[0045] Result analysis: As Figure 4 shown, after the equalization post-processing, the eye diagram in the result is clear, with good vertical and horizontal openings and a good opening degree, which conforms to the equalization principle.

[0046] Embodiment 2 As Figure 3 shown, the present invention provides an eye diagram generation method with modulation function: Step S1: Generate the original signal Use LFSR to generate the M sequence as the original signal, and the method is the same as that in Embodiment 1.

[0047] Step S2: Modulation processing Segment the original signal by time, and the length of each segment is the symbol period T; Sample each segment of the signal at a sampling rate of 8 times or 16 times the symbol rate; Double the number of sampling points for each segment of the signal, for example, double the N sampling points to 2N sampling points through interpolation; Define the level mapping rule according to the modulation method (such as PAM4, NRZ, etc.): Table 1 PAM4 level mapping rule in Embodiment 2 of the present invention Table 2 NRZ level mapping rule in Embodiment 2 of the present invention Convert the intercepted signal to a new level, for example, [0, 1, 1, 0], which will be mapped to [−1, 1] in PAM4 and [0, 1, 1, 0] in NRZ; Reconstruct the translated level signal into a continuous waveform in chronological order as the adjusted excitation signal.

[0048] Step S3: Obtain the output response through the system Pass the adjusted excitation signal through a communication channel, filter, amplifier, or other signal processing module.

[0049] Step S4: Generate the modulated eye diagram Sample the output response signal, with the sampling rate being 8 times or 16 times the symbol rate; Segment the sampled signal waveforms by symbol period and superimpose and display them within one period to form the modulated eye diagram.

[0050] Result analysis: As Figure 5 shown, after the PAM4 modulation post-processing, the eye diagram in the result is clear, all 3 eye diagrams are visible, the 3-level distributions are uniform, and there are no offset or asymmetry phenomena, which conforms to the modulation principle of PAM4.

[0051] In summary, the present invention patent provides a method for generating an eye diagram based on the modification of pseudo-sequence codes, including the equalization and modulation methods of the eye diagram. The equalization method provides a method for compensating for jitter and noise for the basic eye diagram, and the eye diagram in the result is clear and has a good opening; the modulation method improves the data transmission rate for the basic eye diagram, and the eye diagram in the result is clear, all 3 eye diagrams are visible, the 3-level distributions are uniform, and there are no offset or asymmetry phenomena, which conforms to the modulation principle of PAM4.

[0052] The above embodiments are not limitations on the present invention. The present invention is not limited to the above embodiments. As long as it meets the requirements of the present invention, it falls within the protection scope of the present invention.

Claims

1. A method for generating an eye diagram based on pseudo sequence code modification, characterized in that: The following steps are involved: Step S1, building a simulation circuit, wherein the simulation circuit includes a pseudo-random sequence generator; Step S2, initializing a pseudo-random sequence generator, and then generating a pseudo-sequence code as the original signal input of the transmitting end; Step S3, performing equalization and / or modulation according to the pseudo sequence code to obtain an equalized and / or modulated signal; Step S4: transmitting the equalized and / or modulated signal to a receiving end, and then generating an eye diagram according to an eye diagram superposition generation principle.

2. The eye diagram generation method based on pseudo sequence code modification according to claim 1, characterized in that: The pseudo-random sequence generator adopts a linear feedback shift register.

3. The eye diagram generation method based on pseudo sequence code modification according to claim 1, characterized in that: The equalization includes: performing emphasis processing on the original signal at the transmitting end to enhance the high frequency component of the signal, and then performing filtering processing on the emphasized signal at the receiving end.

4. The eye diagram generation method based on pseudo sequence code modification according to claim 3 is characterized in that: The emphasis processing adopts a forward equalizer, and its formula is: in, y(n) is the output signal of the forward equalizer, x(n−k) is the original signal after delay, w k It is k The weighting coefficients of the taps, N is the number of taps of FFE; The filtering process uses a FIR filter, and its formula is: in, v(m) is the output signal of the FIR, u(mj) It is the delayed signal with jitter and noise added. c j It is j The weighting coefficients of the taps, M is the number of taps of the FIR.

5. The eye diagram generation method based on pseudo sequence code modification according to claim 1, characterized in that: The modulation includes: dividing the pseudo sequence code into time segments, sampling each segment signal, then level mapping the sampled signal, reconstructing the mapped level signal into a continuous waveform in time sequence, and generating an excitation signal.

6. An eye diagram generating device for implementing the method according to any one of claims 1 to 5, characterized in that: Includes the following modules: A pseudo-sequence code generating module, used for generating a pseudo-sequence code through a linear feedback shift register; An equalization module, used for emphasizing the pseudo sequence code to obtain an equalized signal; A modulation module is used to perform signal segmentation, level mapping, and signal reconstruction on the pseudo-sequence code to obtain a modulated signal; A filtering module, used for performing signal filtering processing on the equalized signal and / or the modulated signal; The eye diagram generation module generates an eye diagram for the signal after filtering according to the eye diagram superposition generation principle.

7. A computing device comprising a memory and a processor, characterized in that: The memory stores executable code, and when the processor executes the executable code, the method described in any one of claims 1 to 5 is implemented.

8. A machine-readable storage medium, characterized in that: The machine-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the method described in any one of claims 1 to 5.

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