Device and method for measuring system delay by using oscilloscope

Abstract

The invention relates to a device and method for measuring system delay by using an oscilloscope, and belongs to the technical field of system delay measurement, and the method comprises the following steps: obtaining a to-be-measured system, connecting the output end of a signal generator with the input end of the to-be-measured system, and connecting the output end of the to-be-measured system with a first channel of the oscilloscope; the output end of the signal generator is connected to the second channel of the oscilloscope at the same time; a signal generator is used for generating a test signal, the test signal is processed by a to-be-tested system and then input to a first channel of an oscilloscope, and meanwhile the test signal is directly input to a second channel of the oscilloscope; setting a test signal input by a trigger source as the second channel on the oscilloscope, and setting a trigger condition; the waveforms of the test signals received by the first channel and the second channel are respectively obtained on the oscilloscope, and the time delay of the to-be-tested system is calculated according to the time difference of the waveforms of the two channels; the method has the beneficial effects that the measurement error is minimized by selecting consistent feature points and reasonably setting time base gears.

Description

Technical Field

[0001] The present invention belongs to the technical field of system delay measurement, and in particular relates to a device and method for measuring system delay using an oscilloscope. Background Art

[0002] In modern electronic systems, system latency is a critical parameter, and its accurate measurement is crucial for evaluating system performance and optimizing system design. For example, in communication or data processing systems, the length of system latency directly affects the accuracy of signal transmission.

[0003] However, common system delay measurements currently have limitations. Traditional oscilloscope delay measurement relies on the operator manually selecting waveform feature points and measuring the delay using cursors. This method is significantly affected by human interaction, and when different operators measure the delay of the same system, the delay results can vary by up to ±5ns. Furthermore, when the signal is subject to jitter or distortion, feature points are difficult to accurately identify, reducing the reliability of delay measurements. Summary of the Invention

[0004] The present invention provides a device and method for measuring system delay using an oscilloscope, which is used to solve the technical problem of measurement deviation in existing oscilloscope measurement system delay. The device and method minimize the measurement error by selecting consistent feature points and reasonably setting the time base gear.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0006] A method for measuring system delay using an oscilloscope comprises the following steps:

[0007] Obtain a system to be tested, connect the output end of a signal generator to the input end of the system to be tested, and connect the output end of the system to be tested to the first channel of an oscilloscope;

[0008] Connect the output of the signal generator to the second channel of the oscilloscope at the same time;

[0009] A test signal is generated by a signal generator. The test signal is processed by the system under test and then input into the first channel of the oscilloscope. At the same time, the test signal is directly input into the second channel of the oscilloscope.

[0010] On the oscilloscope, set the trigger source to the test signal input from the second channel and set the trigger conditions;

[0011] The waveforms of the test signals received by the first channel and the second channel are respectively obtained on the oscilloscope, and the delay of the system to be tested is calculated based on the time difference between the waveforms of the two channels.

[0012] Optionally, the system under test can be obtained as follows:

[0013] During the equipment preparation phase, equipment parameter matching is performed: based on the operating frequency range and input signal amplitude requirements of the system under test, a signal generator with an output frequency range that includes the operating frequency band of the system under test and an output amplitude that can cover the input amplitude requirements of the system under test is selected;

[0014] Connection cable selection for the first channel: Select a suitable coaxial cable based on the signal frequency and transmission distance;

[0015] Check before connection: device interface check and signal generator mode setting;

[0016] Connection operation: connect the signal generator to the system under test and connect the system under test to the oscilloscope;

[0017] After connection, confirm: turn on the device power, check the indicator light, detect the signal, and troubleshoot.

[0018] Optionally, the output end of the signal generator is simultaneously connected to the second channel of the oscilloscope, which includes the following steps: selecting a connection line, checking and preparing before connection, performing specific connection operations, and confirming and debugging after connection.

[0019] Optionally, the test signal generated by the signal generator is: output frequency is f, amplitude is V in Sine wave: V in (t) = A in sin(2πft);

[0020] The output signal of the signal generator is V in (t), the output signal of the system under test is V out (t), the first channel signal collected by the oscilloscope and the second channel signal collected by the oscilloscope are CH1(t) and CH2(t) respectively; then: CH1(t)=V out (t), CH2(t)=V in (t).

[0021] Optionally, the voltage gain of the first channel signal and the second channel signal is calculated, the phase difference between the first channel signal and the second channel signal is measured, and the transfer function of the first channel and the second channel signal is calculated, so as to systematically analyze the linear and nonlinear characteristics of the system to be tested and provide data support for circuit design, debugging and troubleshooting.

[0022] Optionally, for the trigger type, select pulse width trigger, the steps are: set the pulse width condition; enter the target pulse width value;

[0023] In multi-channel trigger mode, use the second channel signal as the trigger source, observe the waveforms of the first channel signal and the second channel signal at the same time, and intuitively compare the time difference and phase difference between the two signals.

[0024] Optionally, the steps for calculating the delay of the system under test are:

[0025] Synchronous triggering: Set the oscilloscope trigger source to one of the channels to ensure that the waveforms of the two channels are stably aligned;

[0026] Select characteristic points: select similar points that are easy to identify in the waveforms of the two channels;

[0027] Measurement interval: Get the time difference between two points through the scale number or the oscilloscope's built-in measurement function;

[0028] The digital oscilloscope directly reads the time difference between the two channel waveforms. If the oscilloscope displays the time difference between the two channel signals as Δt, then: delay = |Δt|.

[0029] Optionally, the time difference Δt is calculated as:

[0030] Δt=|X2-X1|×T div ;

[0031] Where X1 and X2 are the horizontal positions of cursor 1 and cursor 2 respectively, T div It is the time base gear.

[0032] Optionally, if the signal of the first channel lags behind that of the second channel, Δt is a negative value, and the absolute value is the delay. The delay of Δt is calculated as:

[0033] |Δt|=|t CH2 -t CH1 |;

[0034] Among them, t CH1 is the time coordinate of the first channel signal feature point; t CH2 is the time coordinate of the characteristic point corresponding to the second channel signal, and |·| ensures that the delay is non-negative, without considering the direction of signal advance or lag.

[0035] A device for measuring system delay using an oscilloscope, comprising:

[0036] Signal generator, capable of transmitting test signals;

[0037] The system under test is used to obtain and process the test signal transmitted by the signal generator, and transmit the processed test signal to the oscilloscope;

[0038] Oscilloscope, used to obtain the test signals emitted by the signal generator and the system under test;

[0039] The signal generator is connected to the system under test and the oscilloscope, and the system under test is connected to the oscilloscope. The test signals of the signal generator and the system under test are respectively obtained on the oscilloscope. The delay of the system under test is calculated and obtained based on the time difference between the waveforms of the two signals.

[0040] Beneficial effects of the present invention:

[0041] The present invention is that cursor measurement is one of the core functions of the oscilloscope. Through the process of "locating feature points → calculating grid difference → combining with time base conversion", the time difference of the signal can be accurately obtained. The key lies in selecting consistent feature points and reasonably setting the time base gear to minimize measurement errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 Schematic diagram of the device system structure of the present invention;

[0044] Figure 2 It is the workflow diagram of the present invention. DETAILED DESCRIPTION

[0045] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0046] Example 1

[0047] like Figure 1 As shown, this embodiment provides a device for measuring system delay using an oscilloscope, including:

[0048] Signal generator, capable of transmitting test signals;

[0049] The system under test is used to obtain and process the test signal transmitted by the signal generator, and transmit the processed test signal to the oscilloscope;

[0050] Oscilloscope, used to obtain the test signals emitted by the signal generator and the system under test;

[0051] The signal generator is connected to the system under test and the oscilloscope, and the system under test is connected to the oscilloscope. The test signals of the signal generator and the system under test are respectively obtained on the oscilloscope. The delay of the system under test is calculated and obtained based on the time difference between the waveforms of the two signals.

[0052] The signal generator transmits a test signal to the system under test and the oscilloscope. The system under test processes the transmitted test signal. The oscilloscope simultaneously measures the test signal transmitted by the signal generator and the test signal processed by the system under test. The oscilloscope calculates and obtains the delay of the system under test based on the time difference between the waveforms of the two signals.

[0053] Example 2

[0054] Based on Example 1, Figure 2 As shown, this embodiment provides a method for measuring system delay using an oscilloscope, comprising the following steps:

[0055] Obtain a system to be tested, connect the output end of a signal generator to the input end of the system to be tested, and connect the output end of the system to be tested to the first channel of an oscilloscope;

[0056] Specifically:

[0057] 1. Equipment preparation stage

[0058] Equipment parameter matching: Based on the operating frequency range and input signal amplitude requirements of the system under test, select a signal generator with an output frequency range that includes the operating frequency band of the system under test and an output amplitude that can meet the input amplitude requirements of the system under test. For example, if the operating frequency of the system under test is between 10MHz and 100MHz, you should select a signal generator with an output frequency of at least 100MHz. If the input voltage range of the system under test is 0-5V, the output amplitude of the signal generator should be set to 3-5V to ensure that the signal effectively excites the system under test. At the same time, referring to the output signal characteristics and measurement accuracy requirements of the system under test, select an oscilloscope with a bandwidth at least 5 times the highest operating frequency of the system under test and a sufficiently high sampling rate (e.g., at least 10 times the highest signal frequency) to ensure that the signal waveform of the system under test can be accurately acquired.

[0059] Select the appropriate coaxial cable for the first channel based on the signal frequency and transmission distance. For example, for high-frequency signals (over 100MHz), prioritize low-loss, highly shielded coaxial cables, such as RG-58 or RG-174. For low-frequency signals, use standard coaxial cables. Also, check the cable length and choose a shorter cable to minimize signal transmission loss. Ensure the connectors on both ends of the cable match the device's connector, such as BNC or SMA.

[0060] 2. Check before connection

[0061] Device interface inspection: Use a magnifying glass to carefully observe the signal generator output interface, the input interface of the system to be tested, the output interface, and the oscilloscope channel interface to check whether there is any physical damage such as bent, broken, or oxidized black pins. For devices with threaded interfaces, check whether the threads are complete and free of slippage. If any problems are found with the interfaces, repair or replace the equipment in a timely manner.

[0062] Signal Generator Mode Settings: Enter the signal generator's menu settings interface and set the output mode according to the requirements of the system under test. If the system under test requires a sine wave input, set the signal generator to sine wave output mode and set the appropriate frequency, amplitude, and offset parameters. If the system under test requires a pulse signal, set it to pulse output mode and adjust the pulse width, rise time, and fall time parameters to ensure that the output signal meets the operating conditions of the system under test.

[0063] 3. Connection operation

[0064] Connect the signal generator to the system under test: Take the prepared coaxial cable, align the BNC interface (or corresponding interface type) at one end with the output interface of the signal generator, gently insert the interface, and rotate the interface nut clockwise until the nut is completely tightened to ensure a tight connection. Then connect the other end of the cable to the input of the system under test in the same way. After the connection is completed, gently shake the cable to check whether the connection is stable.

[0065] Connect the system to be tested to the oscilloscope: Take another coaxial cable and connect one end of it to the output interface of the system to be tested. Pay attention to the direction and matching of the interfaces when connecting, ensure that the interfaces are completely consistent with each other, and then tighten the nut; insert the other end of the cable into the first channel interface of the oscilloscope, ensure that it is completely inserted into the interface, and then tighten the nut to secure it. Ensure that the cable is tightly connected to the oscilloscope channel to prevent poor signal contact.

[0066] 4. Confirm after connection

[0067] Turn on the power of each device and check the indicator lights: Turn on the power of each device in the order of signal generator, then the system under test, and finally the oscilloscope. Observe whether the power indicator and working status indicator of each device are lit normally. If any indicator light is off or flashes abnormally, check whether the power connection of the device is normal and whether there is any device fault.

[0068] Signal detection and troubleshooting: On the oscilloscope interface, select the first channel through the menu, adjust the vertical scale and horizontal timebase parameters of the channel, and observe whether a signal waveform is displayed. If no signal waveform is displayed on the oscilloscope screen, first check whether the signal generator is outputting the signal normally. Check the output parameters on the signal generator's display to see if they are set correctly. Then, check the connecting wires for looseness or poor contact, and reconnect them. If there is still no signal, use a multimeter to measure the continuity of the connecting wires to determine whether there is any damage, and replace any damaged wires promptly.

[0069] Connect the output of the signal generator to the second channel of the oscilloscope at the same time;

[0070] (1) Cable selection: Select an appropriate coaxial cable according to the interface type of the signal generator and oscilloscope, such as a coaxial cable with a BNC-BNC interface. Ensure that the cable is not damaged, the outer sheath is not aged, and the internal shielding layer and wires are not broken. If high-frequency signals (above 100MHz) are involved, low-loss coaxial cables, such as RG-58 and RG-142, are preferred to reduce signal transmission loss.

[0071] Auxiliary tools: prepare an anti-static wrist strap (to prevent static electricity from damaging the device) and interface cleaning tools (such as dust-free cotton swabs and anhydrous alcohol for cleaning the interface oxide layer).

[0072] (2) Inspection and preparation before connection

[0073] Device status confirmation: Ensure that the signal generator and oscilloscope are powered off to avoid interface damage or device failure caused by live operation.

[0074] Interface inspection: Carefully inspect the signal generator output interface and the oscilloscope's second channel interface for bent pins, loose connectors, and oxidation and blackening. If slight oxidation is present, wipe the interface surface with a dust-free cotton swab dipped in a small amount of anhydrous alcohol and allow to dry before reconnecting.

[0075] Parameter presetting: Set the output signal type (sine wave or square wave), frequency, and amplitude parameters on the signal generator to ensure that the output signal meets the measurement requirements. Also, pre-set the vertical sensitivity and coupling mode (AC / DC) of the second channel on the oscilloscope to facilitate subsequent rapid signal observation.

[0076] (3) Specific connection operations

[0077] Connect the signal generator: Align the BNC connector on one end of the coaxial cable with the output connector on the signal generator. Gently insert the coaxial cable and then rotate the plug nut clockwise until it is fully tightened to ensure a tight connection.

[0078] Connecting to the oscilloscope: Plug the other end of the coaxial cable into the oscilloscope's second channel connector in the same manner. After insertion, tighten the nut appropriately to ensure the plug fits snugly into the connector. Avoid excessive bending of the cable during insertion, maintaining a bend radius of at least five times its outer diameter to prevent breakage of the internal conductors or damage to the shield.

[0079] (4) Confirmation and debugging after connection

[0080] Device power-on inspection: Turn on the signal generator and oscilloscope in sequence and check whether the device indicators light up normally. If the signal generator and oscilloscope self-test process displays abnormal prompts (such as error codes or flashing warning lights), disconnect them and troubleshoot the device.

[0081] Signal Observation and Adjustment: Select the second channel on the oscilloscope interface and adjust parameters such as the vertical scale and horizontal time base through the menus to observe whether a stable signal waveform is displayed. If the waveform amplitude is too small or too large, adjust the output amplitude of the signal generator or the vertical sensitivity of the oscilloscope's second channel to ensure that the waveform occupies an appropriate proportion on the screen (60%-80% of the screen height is recommended).

[0082] Trigger test: Set the trigger source to the second channel on the oscilloscope and adjust the trigger threshold (Trigger Level) and trigger edge (rising / falling edge) to ensure a stable waveform display. If the trigger is unstable (e.g., the waveform jitters or cannot be locked), check the stability of the signal generator output or fine-tune the trigger parameters until the waveform stabilizes.

[0083] A signal generator is used to generate a test signal. The test signal is processed by the system under test (filtering and denoising) and then input into the first channel of the oscilloscope. At the same time, the test signal is directly input into the second channel of the oscilloscope.

[0084] The test signal generated by the signal generator is: output frequency is f, amplitude is V in A sine wave:

[0085] V in (t) = A in sin(2πft).

[0086] The output signal of the signal generator is V in (t), the output signal of the system under test is V out (t), the first channel signal collected by the oscilloscope and the second channel signal collected by the oscilloscope are CH1(t) and CH2(t) respectively; then: CH1(t)=V out (t), CH2(t)=V in (t);

[0087] The voltage gain (amplitude-frequency characteristic) of the first channel signal and the second channel signal, that is, the ratio of the amplitude of the first channel test signal of the oscilloscope to the amplitude of the second channel test signal of the oscilloscope (usually expressed in decibels) is:

[0088] Gain

[0089] Among them, A in is the amplitude of the second channel signal (such as the peak value or effective value of the sine wave); A out is the amplitude of the first channel signal.

[0090] Specifically, voltage gain calculation (taking a sine wave as an example);

[0091] The specific steps are:

[0092] Step 1: Measure the amplitude;

[0093] CH2(t) is the peak value of the sine wave V in-peak Or effective value V in-rms Peak A in =V in-peak , effective value CH1(t) is the peak value A out Or effective value V out-rms .

[0094] Step 2: Calculate the gain (dB value);

[0095] Formula selection:

[0096] If calculated using peak value: Gain

[0097] If calculated using effective value: Gain

[0098] Example: Input Peak A in =2V, output peak value A out =10V, then:

[0099]

[0100] Amplitude-frequency characteristic test of amplifier circuit: measure the gain of the amplifier circuit at different frequencies.

[0101] Procedure: Use a signal generator to output a sine wave, gradually increasing the frequency from 10 Hz to 100 kHz while maintaining a constant amplitude (e.g., 100 mVrms). After each frequency change, record the amplitudes of CH1(t) and CH2(t), calculate the gain, and plot the amplitude-frequency characteristic curve. If the gain decreases at high frequencies, this may be due to circuit bandwidth limitations.

[0102] The phase difference (phase-frequency characteristic) Δφ between the first channel test signal of the oscilloscope and the second channel test signal of the oscilloscope is: or (radian);

[0103] Among them, t delay is the time delay between the two signals (which can be measured by the oscilloscope cursor); T is the signal period (T = 1 / f, obtained from the signal generator frequency f).

[0104] Phase difference measurement (dual-trace oscilloscope method);

[0105] Step 1: Align the waveform starting point;

[0106] Adjust the vertical positions of CH1(t) and CH2(t) on the oscilloscope so that the baselines of the two signals coincide, making it easier to observe the phase difference.

[0107] Step 2: Measure the time delay t delay ;

[0108] Use the oscilloscope cursor function to measure the time difference t between the same phase points (such as the rising edge zero crossing point) of the CH1(t) and CH2(t) waveforms. delay .

[0109] Step 3: Calculate the phase difference Δφ;

[0110] Wherein, T=1 / f is the signal period.

[0111] Example: signal frequency f = 1kHz (period T = 1ms), time delay t delay =0.25ms, then:

[0112]

[0113] Filter phase delay test: Measures the phase delay of the low-pass filter to the input signal.

[0114] Operation steps: Input a sine wave with a frequency of f, observe the phase difference between the waveforms of CH1(t) and CH2(t), change the frequency (for example, from 100 Hz to 10 kHz), record the phase difference Δφ at different frequencies, and analyze the phase-frequency characteristics. The phase delay of an ideal low-pass filter should be proportional to the frequency (linear phase).

[0115] The distortion (THD, total harmonic distortion) of the oscilloscope's first channel test signal and the oscilloscope's second channel test signal, that is, the ratio of the harmonic component to the fundamental component, reflects the degree of signal distortion:

[0116]

[0117] Among them, V1 is the amplitude of the fundamental component (which can be obtained through oscilloscope FFT analysis); V2, V3, ..., V n is the amplitude of each harmonic component.

[0118] The distortion (THD) calculation (FFT analysis method) is:

[0119] Step 1: Enable the FFT function of the oscilloscope;

[0120] Switch the CH1(t) signal to frequency domain display (FFT mode) and set an appropriate frequency range (e.g., 0 to 10f, covering the fundamental wave and higher harmonics).

[0121] Step 2: Read the amplitude of each frequency component;

[0122] The fundamental frequency is f, the amplitude is V1; the second harmonic frequency is 2f, the amplitude is V2; the third harmonic frequency is 3f, the amplitude is V3, and so on;

[0123] Step 3: Calculate THD;

[0124]

[0125] Example: Fundamental amplitude V1 = 10V, second harmonic V2 = 0.5V, third harmonic V3 = 0.3V, then:

[0126]

[0127] Power amplifier distortion test: measure the harmonic distortion of the power amplifier output signal;

[0128] Procedure: Input a large signal (close to the amplifier's rated power) and enable the oscilloscope's FFT function to analyze the CH1(t) signal. Read the amplitudes of the fundamental wave and each harmonic, and calculate the THD. If THD > 1%, distortion is high and circuit parameters need to be adjusted.

[0129] The transfer function (frequency domain analysis) between the oscilloscope's first channel test signal and the oscilloscope's second channel test signal, that is, the ratio of the Fourier transform of the oscilloscope's first channel test signal to the oscilloscope's second channel test signal, characterizes the system's frequency domain characteristics:

[0130]

[0131] Where, |H(f)| is the amplitude-frequency characteristic (corresponding to the gain formula), |H(f)|=10 增益(dB) / 20 ; φ(f) is the phase-frequency characteristic (corresponding to the phase difference formula), φ(f) = Δφ.

[0132] The transfer function H(f) is tested by frequency sweep (changing the signal frequency) and combined with the gain and phase difference formulas to draw the system's Bode diagram (amplitude-frequency characteristic and phase-frequency characteristic curves).

[0133] If supported by the oscilloscope, you can use the Bode Plot function to automatically plot |H(f)| and φ(f) curves, eliminating the need for manual calculations.

[0134] Observe the waveforms of the first channel signal and the second channel signal collected by the oscilloscope:

[0135] By using the above specific operations and formula applications, the linear characteristics (such as gain and phase) and nonlinear characteristics (such as distortion) of the system under test can be systematically analyzed, providing data support for circuit design, debugging, and troubleshooting.

[0136] On the oscilloscope, set the trigger source to the test signal input from the second channel and set the trigger conditions;

[0137] Specific steps:

[0138] Enter the trigger setting menu: Press the Trigger button on the oscilloscope panel;

[0139] Select the trigger source (Source): Find the Source option in the trigger menu and select CH2(t) (the second channel) using the knob or touch screen. Make sure that the CH2(t) channel is correctly connected to the test signal and is in the Enable state (not disabled).

[0140] Trigger condition settings (taking common trigger types as an example): Trigger conditions are used to define when a signal meets certain characteristics to start sampling, specifically pulse width trigger (Pulse Width Trigger) or edge trigger (Edge Trigger).

[0141] Trigger condition: Trigger when the pulse width of the CH2(t) signal exceeds or is less than the set value.

[0142] Applicable scenarios: Capturing abnormally narrow or wide pulses (such as interference signals).

[0143] Steps:

[0144] Select Pulse Width Trigger as the trigger type.

[0145] Set the pulse width condition (for example, "greater than 500ns" or "less than 1μs").

[0146] Enter the target pulse width value (unit: time, such as ns, μs, ms).

[0147] In addition, there is edge trigger (Edge Trigger);

[0148] Trigger condition: Trigger when the rising or falling edge of the CH2(t) signal exceeds the set level.

[0149] Steps:

[0150] Set the trigger type (Type);

[0151] Select Edge Trigger in the trigger menu, which is the most commonly used basic trigger type.

[0152] Set the trigger level (Level);

[0153] Find the Level knob or menu option and adjust it to the target level (for example, midway between the peak-to-peak values ​​of the signal).

[0154] You can also enter a value directly (if the oscilloscope supports it) in voltage units (e.g. 1V).

[0155] Select the trigger edge direction (Slope);

[0156] Rising edge (Rise): Triggered when the signal jumps from low level to high level.

[0157] Falling edge (Fall): Triggered when the signal jumps from high level to low level.

[0158] Select the desired edge direction (usually rising edge by default) through the menu or panel button.

[0159] Example: If the CH2(t) input signal is a sine wave with an amplitude of 2V and the trigger level is set to 1V and rising edge trigger, the oscilloscope triggers when the signal rises from 0V to 1V.

[0160] For verification and adjustment:

[0161] Observe the trigger status:

[0162] The oscilloscope panel usually has a Triggered indicator light. If it is continuously lit, it means the trigger is successful; if it flashes or goes out, it means that the trigger conditions are not met and need to be adjusted.

[0163] To adjust the trigger level or edge:

[0164] If the signal cannot be triggered stably, you can fine-tune the trigger level knob or switch the edge direction (for example, from rising edge to falling edge).

[0165] Check signal connection and attenuation:

[0166] Ensure that the CH2(t) probe attenuation ratio (e.g., 1× or 10×) is consistent with the oscilloscope settings (adjustable in the channel menu).

[0167] Try using the oscilloscope's built-in calibration signal (e.g., 1kHz square wave) to test whether the trigger function is normal.

[0168] Setting a trigger condition involves synchronizing the signal period. For periodic signals (such as sine waves and square waves), trigger conditions (such as edge triggering and level triggering) align the oscilloscope's sweep start point with a specific phase of the signal, resulting in a stable waveform display on the screen and preventing waveform oscillation or overlap. The trigger condition acts as a "synchronous clock" for the oscilloscope, ensuring that each sweep begins at the same position in the signal.

[0169] Advanced trigger conditions (such as pulse width trigger) can accurately capture occasional abnormal signals (such as narrow pulse interference and voltage drop).

[0170] Trigger Coupling: If the signal contains a DC offset, try setting the trigger coupling to AC (DC isolation) to prevent the DC level from interfering with the trigger.

[0171] Trigger holdoff: If the signal is densely repeated, the holdoff time can be increased to avoid false triggering (advanced function, need to enter the trigger advanced menu setting).

[0172] By following these steps, you can use the CH2(t) signal as the trigger source and stably capture the target waveform. In actual operation, it is recommended to refer to the oscilloscope manual or online tutorial to make detailed adjustments based on the specific model.

[0173] In multi-channel trigger mode (for example, using CH2(t) as the trigger source and observing the waveforms of CH1(t) and CH2(t) simultaneously), you can intuitively compare the time difference, phase difference, or causal relationship between the two signals (for example, the synchronization of clock and data signals).

[0174] The waveforms of the test signals received by the first channel and the second channel are respectively obtained on the oscilloscope, and the delay of the system to be tested is calculated based on the time difference between the waveforms of the two channels.

[0175] Specific steps:

[0176] Synchronous triggering: Set the oscilloscope trigger source to one of the channels (for example, the second channel) to ensure that the waveforms of the two channels are stably aligned.

[0177] Select feature points: Select easily identifiable points of the same nature in the waveforms of the two channels (such as the 50% threshold point of the rising edge).

[0178] Measurement interval: Get the time difference between two points through the scale number or the oscilloscope's built-in measurement function.

[0179] Digital oscilloscopes can usually directly read the time difference between two channel waveforms (some require the cursor measurement function to be enabled). If the oscilloscope displays the time difference between the two channel signals as Δt, then: Delay = |Δt|;

[0180] If the signal of the first channel lags behind that of the second channel, Δt is a negative value, and the absolute value is the delay.

[0181] Furthermore, the delay of Δt is calculated as:

[0182] |Δt|=|t CH2 -t CH1 |;

[0183] Among them, t CH1is the time coordinate of the first channel signal feature point (unit: seconds, microseconds); t CH2 is the time coordinate of the feature point corresponding to the second channel signal (the unit should be the same as t CH1 To ensure that the delay is non-negative, the direction of the signal advance or lag is not considered (only the time difference is considered).

[0184] Among them, the input signal of the first channel is V1(t), and the output signal of the second channel is V2(t). After the signal passes through the system to be measured, a delay τ is generated, that is, V2(t) = V1(t-τ). The time coordinates of the characteristic points of the two channels (such as the rising edge trigger point) are t1 and t2 respectively. Then: τ = t2-t1. After taking the absolute value, the actual delay |Δt| = |t CH2 -t CH1 |.

[0185] The oscilloscope uses cursor measurement to directly read the time difference. Specifically, it uses the horizontal cursor (HorizontalCursor) to measure the time difference:

[0186] Move cursor 1: align with the key point of the first channel signal A(t) and record its horizontal position as X1 (unit: grid, div).

[0187] Move cursor 2: align with the corresponding key point of the second channel signal B(t), and record its horizontal position as X2 (unit: grid, div).

[0188] Calculate the difference in the number of cells N: N = |X2-X1|;

[0189] Substitute the time base gear to calculate the delay: Δt=N×T div .

[0190] Such as: time base position T div =10μs / div (each division represents 10 microseconds).

[0191] The horizontal interval between two key points on the screen is N=3.5 div (3.5 grids).

[0192] Calculation: Δt = 3.5 div × 10 μs / div = 35 μs.

[0193] X1 and X2 are the horizontal positions of the key points of the two channel signals (divisions, div), T div It is the time base scale of the oscilloscope (seconds / division, s / div).

[0194] Horizontal cursor time difference measurement accurately measures system delay and adjusts measurement accuracy as needed (for example, reducing the number of grids or increasing timebase resolution). By displaying movable "cursors" (similar to lines on coordinate axes) on the screen, the instrument helps users intuitively obtain waveform details.

[0195] The horizontal cursor moves along the horizontal axis (time axis). By measuring the horizontal interval between the two cursors and combining it with the oscilloscope's time base, the time difference Δt is calculated.

[0196] Time base position T div It refers to the length of time represented by each division on the oscilloscope screen. The units are usually s / div, ms / div and μs / div.

[0197] The grid difference N is the horizontal interval between the two cursors, which can be positive or negative (the sign indicates the order), and the absolute value represents the size of the time difference.

[0198] Time difference Δt = |X2-X1| × T div ;

[0199] X1 and X2 are the horizontal positions of cursor 1 and cursor 2, respectively (unit: division, div). For example, if the time base is 5μs / div and the interval between the two cursors is 4.2 div, the time difference is: Δt = 4.2 × 5μs = 21μs.

[0200] Operation steps (taking manual horizontal cursor as an example):

[0201] Turn on the cursor function: Select "Cursor" → "Horizontal Cursor" in the oscilloscope menu, and two horizontal lines (Cursor 1 and Cursor 2) will be displayed on the screen.

[0202] Select reference channel: Determine which signal (such as the second channel) is used as the reference signal and which signal (such as the first channel) is used as the signal to be measured.

[0203] Position the cursor to the key point (i.e., feature point): Move cursor 1: align with the feature point of the reference signal (i.e., the second channel) (e.g., the 50% threshold point on the rising edge), and record its horizontal position X1; Move cursor 2: align with the corresponding feature point of the signal to be measured (i.e., the first channel), and record its horizontal position X2.

[0204] Read time difference: The oscilloscope will automatically calculate |X2-X1|×T div If X2>X1, it means the signal of the second channel lags behind the first channel (delay is positive); otherwise, it leads.

[0205] For the time coordinate (t CH1 and t CH2 ): If the time base gear is 5ns / Div, one screen grid corresponds to 5 nanoseconds, then the time resolution of each pixel is:

[0206] (For example, when the pixel density is 1000 pixels / grid, the resolution is 5ns / 1000=5ps).

[0207] Some oscilloscopes support setting a horizontal offset (Horizontal Offset), which sets the center of the screen to time zero (t=0) to facilitate observation of positive and negative time differences.

[0208] The physical meaning of time difference:

[0209] If t CH2 >t CH1 : Indicates that the CH2(t) signal (output) lags behind the CH1(t) signal (input). The delay is positive, which conforms to the conventional physical meaning (it takes time for a signal to pass through the system).

[0210] If t CH2 <t CH1 : The trigger source may be incorrectly selected (for example, CH1(t) trigger is mistakenly selected), or the signal has lead distortion (it is necessary to check whether the system introduces phase lead, such as a differential circuit).

[0211] Base accuracy: Ensure that the oscilloscope's time base is accurately calibrated to avoid selecting too coarse a range (e.g., using 1s / Div to measure μs-level delays).

[0212] Signal integrity: If the signal is noisy or distorted, adjust the oscilloscope bandwidth or use edge triggering to optimize the waveform display.

[0213] Sign determination: The direction of the delay (which channel signal is ahead) needs to be determined in combination with the system signal flow direction. The absolute value in the formula is the actual delay.

[0214] Application scenarios: Measuring signal delays in electronic components such as amplifiers and filters, calibrating synchronization errors in multi-channel data acquisition systems, and analyzing time delays in signal transmission in communication systems.

[0215] Cursor measurement is one of the core functions of an oscilloscope. By following the process of "locating characteristic points → calculating grid differences → combining them with time base conversion," you can accurately obtain signal time differences. The key lies in selecting consistent characteristic points and properly setting the time base to minimize measurement errors.

[0216] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for measuring system delay using an oscilloscope, characterized in that: The steps include: Obtain a system to be tested, connect the output end of a signal generator to the input end of the system to be tested, and connect the output end of the system to be tested to the first channel of an oscilloscope; Connect the output of the signal generator to the second channel of the oscilloscope at the same time; A test signal is generated by a signal generator. The test signal is processed by the system under test and then input into the first channel of the oscilloscope. At the same time, the test signal is directly input into the second channel of the oscilloscope. On the oscilloscope, set the trigger source to the test signal input from the second channel and set the trigger conditions; The waveforms of the test signals received by the first channel and the second channel are respectively obtained on the oscilloscope, and the delay of the system to be tested is calculated based on the time difference between the waveforms of the two channels.

2. The method for measuring system delay using an oscilloscope according to claim 1, wherein: The system to be tested is obtained as follows: During the equipment preparation phase, equipment parameter matching is performed: based on the operating frequency range and input signal amplitude requirements of the system under test, a signal generator with an output frequency range that includes the operating frequency band of the system under test and an output amplitude that can cover the input amplitude requirements of the system under test is selected; Connection cable selection for the first channel: Select a suitable coaxial cable based on the signal frequency and transmission distance; Check before connection: device interface check and signal generator mode setting; Connection operation: connect the signal generator to the system under test and connect the system under test to the oscilloscope; After connection, confirm: turn on the device power, check the indicator light, detect the signal, and troubleshoot.

3. The method for measuring system delay using an oscilloscope according to claim 1, wherein: The output end of the signal generator is simultaneously connected to the second channel of the oscilloscope, which includes the following steps: connection line selection, pre-connection inspection and preparation, specific connection operation, and post-connection confirmation and debugging.

4. The method for measuring system delay using an oscilloscope according to claim 1, wherein: The test signal generated by the signal generator is: the output frequency is f and the amplitude is V in Sine wave: V in (t) = A in sin(2πft); The output signal of the signal generator is V in (t), the output signal of the system under test is V out (t), the first channel signal collected by the oscilloscope and the second channel signal collected by the oscilloscope are CH1(t) and CH2(t) respectively; then: CH1(t)=V out (t), CH2(t)=V in (t).

5. The method for measuring system delay using an oscilloscope according to claim 4, wherein: Calculate the voltage gain of the first channel signal and the second channel signal, measure the phase difference between the first channel signal and the second channel signal, and calculate the transfer function of the first channel and the second channel signal, so as to facilitate the systematic analysis of the linear and nonlinear characteristics of the system under test and provide data support for circuit design, debugging and troubleshooting.

6. The method for measuring system delay using an oscilloscope according to claim 1, wherein: For the trigger type, select pulse width trigger. The steps are: set the pulse width condition; enter the target pulse width value; In the multi-channel trigger mode, the second channel signal is used as the trigger source, and the waveforms of the first channel signal and the second channel signal are observed simultaneously to visually compare the time difference and phase difference between the two signals.

7. The method for measuring system delay using an oscilloscope according to claim 1, wherein: The steps for calculating the delay of the system under test are: Synchronous triggering: Set the trigger source of the oscilloscope to one of the channels to ensure that the waveforms of the two channels are stably aligned; Select characteristic points: select similar points that are easy to identify in the waveforms of the two channels; Measurement interval: Get the time difference between two points through the scale number or the oscilloscope's built-in measurement function; The digital oscilloscope directly reads the time difference between the two channel waveforms. If the oscilloscope displays the time difference between the two channel signals as Δt, then: delay = |Δt|.

8. The method for measuring system delay using an oscilloscope according to claim 7, wherein: The time difference Δt is calculated as: Δt=|X2-X1|×T div ; Where X1 and X2 are the horizontal positions of cursor 1 and cursor 2 respectively, T div It is the time base gear.

9. The method for measuring system delay using an oscilloscope according to claim 7, wherein: If the signal of the first channel lags behind that of the second channel, Δt is a negative value, and the absolute value is the delay. The delay of Δt is calculated as: |Δt|=|t CH2 -t CH1 |; Among them, t CH1 is the time coordinate of the first channel signal feature point; t CH2 is the time coordinate of the characteristic point corresponding to the second channel signal, and |·| ensures that the delay is non-negative, without considering the direction of signal advance or lag.

10. A device for measuring system delay using an oscilloscope, used to execute the method for measuring system delay using an oscilloscope according to any one of claims 1 to 9, characterized in that: include: Signal generator, capable of transmitting test signals; The system under test is used to obtain and process the test signal transmitted by the signal generator, and transmit the processed test signal to the oscilloscope; Oscilloscope, used to obtain the test signals emitted by the signal generator and the system under test; The signal generator is connected to the system under test and the oscilloscope, and the system under test is connected to the oscilloscope. The test signals of the signal generator and the system under test are respectively obtained on the oscilloscope. The delay of the system under test is calculated and obtained according to the time difference between the waveforms of the two signals.

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