A multimeter is a high-accuracy precision measuring instrument. For example, the DC voltage measurement accuracy of a six and a half-digit multimeter can reach 35ppm (parts per million).

On the other hand, an oscilloscope is a measuring instrument that can display the waveform of electrical signals. There are no strict industry requirements for measurement accuracy. Most oscilloscopes have voltage amplitude accuracy around 3% to 5%. This can meet the quantitative analysis requirements for most cases. However, for certain calibration needs, it is still necessary to use a multimeter with higher measurement accuracy for measurement purposes.

In the valid frequency range, the measured value of the true RMS multimeter corresponds to the root mean square (RMS) value measured by the oscilloscope. The oscilloscope has a measurement error of 3%, while the general multimeter has a higher measurement accuracy.

Please follow these steps:
1. The power supply should be loaded and output fully.
2. Set the oscilloscope channel as follows: AC coupling, 20MHz bandwidth limit, attenuation ratio × 1. Use a probe setting of 1 ×.
3. Adjust the oscilloscope's vertical deflection coefficient and time base setting to appropriate values.
4. To minimize interference, connect a short spring to the grounding terminal, as close as possible to the power supply's output terminal.
5. It is recommended to measure the ripple's peak-to-peak value using the cursor function on the oscilloscope.

Due to the influence of environmental factors, the measurement error is too large,

you can try using the "self-correction" function of the oscilloscope.

(1) General Maintenance

Do not store or put the instrument under direct sunlight for a long time, especially the LCD display panel. Caution: Sprays, liquids or solvents are not allowed for the instrument or probe to avoid damage to the instrument or the probe.

(2) Cleaning

Check the instrument and probe frequently according to the operating conditions. Fellow the steps to clean the surfaces of the instrument.

Please use a soft cloth to wipe dust on the surface of the instrument and probe. When cleaning the LCD panel, be careful not to scratch the transparent protective film.

Power off the instrument first and wipe the instrument with a soft cloth.Use a mild detergent or water to clean if necessary.

Do not use any abrasive chemical cleaners as they may damage the instrument or the probe.

Warning: Make sure the instrument is completely dry before rebooting. Moisture may cause electrical short-circuit or even personal injury!

Correct settings but no waveform output

1) Check whether the BNC cable is properly connected to the channel output.

2) Check whether the key CH1 or CH2 is turned on.

3) Save the current settings of the instrument to a USB flash drive and "restore factory settings", then restart the instrument.

4) If the instrument still can't work normally, please contact your UNI-T dealer or local offices for support.

If the generator still remains blank screen when power on.

1) Check whether the power supply is connected properly.

2) Check whether the power switch on the rear panel is set to "I".

3) Check whether the power switch on the front panel is connected .

4) Restart the instrument.

5) If the instrument still can't work normally, please contact your UNI-T dealer or local offices for support.

Real-time sampling: It refers to the collection of all waveform data in one acquisition. Real-time sampling is particularly useful for observing single signals.
Real-time sampling is especially suitable for signals with frequencies below half of the maximum sampling rate of an oscilloscope. (Sampling signal ≥ 2 times the signal being tested)

Equivalent sampling: Equivalent time sampling captures a small amount of information from each repetition to construct an image of the repetitive signal.
Using a sampling frequency that is lower than twice the frequency of the original signal allows distortion-free sampling and restoration of the original signal. This method is suitable for sampling and analyzing high-frequency periodic signals.

1. Waveform distortion
2. Confusion of the measured waveform
3. Impact on the amplitude and edge testing of high-frequency signals

Taking the sine wave as an example: Vpp = 2 * Vp, Vpp = (2 * square root of 2) * Vrms. Vrms = Vpp/ (2 * square root of 2).

For example:
The RMS value of a 220V AC is approximately 220 * 2.82 ≈ 620Vpp.
The peak-to-peak value of a 60V waveform is approximately 60 / 2.828 ≈ 21Vrms.
The peak value of a 28.28V waveform is 28.28 / 1.414 = 20Vrms.

When observing signals, the channel coupling mode can be set through the menu below "CH1/CH2". The functions of selecting DC, AC, and ground are as follows: DC coupling allows all signals to pass through, AC coupling isolates the DC component, and ground coupling provides grounding effects.

On the other hand, coupling in trigger settings refers to the settings for the trigger system. Trigger coupling determines which components of the signal are transmitted to the trigger circuit and does not process the test signal itself.

The RMS values will be different for different lengths of time on the waveform screen.

For two measured waveforms, if the waveform is shifted to the left or right, the measured result will change and the RMS value will also change accordingly.

The expression ±(3% x reading + 0.05div) represents the allowable error range of the measured voltage value, which is ±3% multiplied by the current reading, plus an error range of +0.05div with respect to the nominal value range.

One sampling interval refers to the reciprocal of the maximum sampling rate of an oscilloscope. For example, for a sampling rate of 1GS/s, the sampling interval is 1ns, which is equivalent to 1 divided by 10 to the power of 9.

The bandwidth in actual oscilloscope measurements generally refers to the comprehensive bandwidth of the oscilloscope and probe system. However, the bandwidth of the probe is limited to 6MHz when in 1X mode, and signals higher than 6MHz will experience significant attenuation. Only when the probe is switched to 10X mode (where the bandwidth reaches the full bandwidth) will the measurement results be accurate. For high-frequency signals, the system bandwidth of the oscilloscope and probe combined should be smaller than the individual bandwidths. Therefore, selecting a suitable probe is of great importance in oscilloscope testing.

In order to capture the occasional pulse signal, use single trigger mode for single capture. In order to prevent the interference signal from being captured, be sure to increase the trigger level appropriately, which can filter out the interference and facilitate the capture of the desired signal.

In order to display a stable waveform on the oscilloscope screen, a condition needs to be set to make the oscilloscope start scanning, and this condition is the trigger.

Waveform capture rate refers to how fast the oscilloscope acquires waveforms.An oscilloscope with a high waveform capture rate can significantly increase the probability of capturing occasional signals such as jitter, burr, etc.

Auto Trigger: Scanning is triggered regardless of whether there is an input, in sync with the signal.
Normal Trigger: It will stay on the last triggered interface until the next trigger, and then perform the scan.
Single Trigger: Once a waveform is captured with a single trigger, it will enter the STOP state.

UTD2000CEX can record up to 500 frames, UTD2000CL/CL+, UTD2000CEX+ can record up to 1000 frames, MSO/UPO2000E can record up to 80,000 frames, MSO/UPO3000E can record up to 100,000 frames.

The waveform recording storage space of the Oscilloscope is fixed. The more points per frame, the less frames can be recorded, and the number of points per frame depends on the current memory depth and the current horizontal time base. Therefore, when the memory depth is set small, the number of frames that can be recorded will be large. For example, if the current horizontal time base is 1ms, then the maximum recording time is 1ms*1000 frames=1000ms. If the time base is greater than 50ms/div, the recording function is invalid in ROLL mode.

For example,let's consider the MSO/UPO2000E oscilloscope,when the memory depth is automatic and the time base is ≤50ns/div, the maximum of 80000 frames can be recorded ,the storage depth is 56Mpts, the number of points per frame is 56M, and a maximum of one frame can be recorded.

To set the maximum recording frame number on the UPO2000E, follow these steps:
1: Press Acquire-Storage depth and select AUTO
2: Press Utility - Record waveform - Settings (set the end frame number, interval time, and playback time).
3: Adjust the time base/horizontal scale to ≤50ns
As shown in the figure on the right.

1. The closer the measured signal is to the upper limit of the oscilloscope bandwidth, the greater the distortion. Generally, using an oscilloscope with a bandwidth ≥ 5 times the signal bandwidth can obtain a signal with minimal distortion.

2. Improper selection of the oscilloscope probe can result in distorted waveforms. Firstly, the probe bandwidth should be greater than the signal bandwidth, preferably ≥ 5 times the signal bandwidth. Secondly, if the probe has two gears, the bandwidth of the two gears is different. The bandwidth for the 1X gear is usually 6MHz-10MHz, while the 10X gear is the maximum bandwidth specified by the probe specification.

1. Check if the trigger source channel of the control panel matches the actual signal channel being used.
2. Manually adjust the LEVEL trigger knob and observe if the waveform is stable.
3. Use the AUTO function to automatically adjust the waveform and observe if it is stable.
4. Adjust the time base to eliminate false wave interferences.

In order to display a stable waveform on the oscilloscope screen, a condition needs to be set to make the oscilloscope start scanning, and this condition is the trigger.

The oscilloscope completes a trigger and it takes a period of time to resume work. This period of time is called trigger hold off.

Make sure the instrument pre-heat for at least 30min and the temperature at 20-30℃. These are the requirements for instrument to remain stable and within specifications.

The Fourier transform operation function(FFT) can be used to analyze the frequency components of the measured signal. According to the frequency range, so as to determine the type of interference. Digital oscilloscope can only do qualitative measurements. If user want to do a comprehensive quantitative measurement of radiation interference, then it should select the spectrum analyzer.

Like detect small signal of audio frequency amplifier, noise wave of power supply.

① The grounding issue of an oscilloscope is crucial for measuring interference, as both the chassis of the oscilloscope and the reference ground line of the probe are connected to the ground line. Therefore, a good grounding connection is essential.

② Interference caused by the reference ground line of an oscilloscope can be significant, as the grounding line of a typical probe, when connected to the measurement point, forms an interference path similar to a loop antenna. To minimize this interference, a possible method is to remove the probe cap and directly connect the measurement point using the tip of the probe and the ground point inside the probe, without using the ground line provided on the probe.

③ The use of differential measurement method helps to eliminate common-mode noise.

The best method is to use a differential probe, which provides the most accurate and reliable signal measurement. If a differential probe is not available, you can use two probes connected to the two channels of a digital oscilloscope (e.g. Ch1, Ch2). Then, with mathematical operations, you can obtain the waveform of Ch1 minus Ch2 and analyze it. In this case, it is important to ensure that the two probes are identical and that the vertical range settings of the two oscilloscope channels are the same. Otherwise, there may be significant errors.

Rise time refers to the time it takes for the test voltage to increase gradually from 0V to the rated test voltage. In oscilloscope, it generally refers to the time when the voltage increase from 10% to 90%.

Analog oscilloscopes mainly utilize analog circuit techniques such as electrode plates and electron guns, while digital oscilloscopes primarily employ digital circuit techniques such as A/D converters.

There are differences in bandwidth: due to the limitation of electron beam speed, the bandwidth of analog oscilloscopes can only reach a few hundred megahertz, while digital oscilloscopes have already exceeded 100 GHz.

There are differences in functionality: in addition to stable observation of continuous periodic signals, digital oscilloscopes, by digitizing waveforms, can achieve various functions such as automatic waveform measurements, waveform storage, waveform analysis, multiple waveform triggering, and remote control.

There are differences in stability: analog oscilloscopes, being fully analog devices, are more susceptible to variations in specifications and temperature drift.

Other differences include the relatively larger size of analog oscilloscopes. Analog oscilloscopes can achieve real-time waveform capture, while digital oscilloscopes may have some waveform loss due to processing. However, with the improvement of ADC speed and processing algorithms, the waveform capture rate of digital oscilloscopes can meet the requirements of most applications.

Because multiple signals that meet the triggering conditions occur within one cycle, the waveform overlaps when the oscilloscope triggers at different positions. By adjusting the trigger holdoff to a slightly smaller value, this can be improved.

The function of trigger holdoff in an oscilloscope is to delay the triggering based on the user-set holdoff time. It is mainly used when there are multiple signals that meet the triggering conditions within one cycle. After setting the trigger holdoff time, the first point that meets the condition will not be triggered, and only the points that meet the triggering conditions after the holdoff time will be triggered. This allows for triggering the waveform at a specific point according to the user's needs.

1. If the instrument is connected to a computer, it will enter remote control mode. Click the "Local" button to exit the remote mode.
2. If the instrument is not connected to a computer, inserting an incompatible USB drive may cause the instrument system to crash and the screen to freeze. Restarting the instrument can resolve this issue.
3. If the instrument is neither connected to a computer nor has a USB drive inserted, and the buttons are unresponsive frequently, please check if the keyboard lock is enabled. If the issue persists, please contact the after-sales service for further assistance and consider sending the instrument back to the factory for inspection and repair.

If you want to measure the phase difference between two signals, you must set the trigger mode to "Single Trigger". This way, you will be able to accurately measure the phase difference between the two channel signals.

When measuring low-frequency signals (below 100Hz), the input channel coupling must be set to "DC". If set to "AC", signal distortion may occur, and a square wave could potentially become a triangle wave.

Users who are viewing square waves on an oscilloscope may choose to view a sine wave of the same frequency as a substitute for the square wave. This does not necessarily indicate a malfunction of the oscilloscope, but rather the influence of high-frequency harmonic components in the composition of the square wave.

To better understand this aspect, it is necessary to have a better understanding of the impact of harmonics.

For example, a 25MHz square wave will be seen as a 25MHz sine wave on the UTD2052CL (50 MHz oscilloscope), even though the actual square wave itself is lower than the oscilloscope's frequency bandwidth limit. However, its harmonic components have already exceeded the oscilloscope's -3dB high-frequency cutoff point. Due to this natural cutoff, the primary harmonic components of the square wave are filtered out beyond the second harmonic component (2 * 25 = 50 MHz). However, the third and fifth harmonic components have center frequencies of 75MHz and 125MHz, respectively. These components are naturally much larger than the 25MHz component of the square wave and far exceed the bandwidth limit of the oscilloscope.

In order to view the square wave signal on the oscilloscope, the third and fourth harmonic components of the square wave must not exceed the bandwidth limit of the oscilloscope.

1. If the measured signal is not a periodic signal, you need to set the corresponding parameters based on the basic characteristics of the signal and manually adjust to obtain the signal.
2. The parameters such as signal frequency or amplitude are too low.

This sentence is correct in a certain sense: the higher the bandwidth, the more accurately the bandwidth of the measured signal can be determined, which increases its value and cost. However, from a user's perspective, higher bandwidth is not necessarily better.

You can follow the steps below to set up:
1. Set the storage depth to the highest.
2. Adjust the time base to the appropriate range based on the time you want to observe. For example, if you want to observe 1 second, set the time base to 100ms/Div, which means the entire screen represents 100ms * 14 divisions = 1.4s.
3. Select the triggering mode as single trigger. When the waveform meets the triggering condition, the waveform will be captured and stably displayed on the screen.