GW Instek MSO-2102EA 100 MHz, 2-Ch. Digital Storage Oscilloscope
100 MHz bandwidth
Equipped with a 16-Channel Logic Analyzer and a dual channel 25 MHz arbitrary waveform generator
Real time sample rate for each channel is 1GSa/s
Free Frequency Response Analyzer Software (Download from manufacture website only)
Maximum 10M memory depth and VPO waveform display technology
Waveform update rate up to 120,000 wfms/s
8" WVGA TFT LCD screen display
Maximum 1M FFT provides higher frequency domain resolution measurements
High Pass, Low Pass and Band Pass Filter Functions
29,000 segmented memory sections and waveform search function
I2C/SPI/UART/CAN/LIN serial bus trigger and decoding functions
Data log function is able to track signal changes up to 100 hours
Network storage function
Basic principle and measuring method of analytical oscilloscope
Oscilloscope is a widely used electronic measuring instrument.It can transform the invisible electric signal to the naked eye into the visible image, which is convenient for people to study the change process of various electric phenomena. A oscilloscope USES a narrow beam of high-speed electrons, struck on a surface coated with fluorescent material, to produce tiny points of light (this is how a traditional analog oscilloscope works). Under the action of the measured signal, the electron beam ACTS like the tip of a pen and can plot the instantaneous value of the measured signal on the screen. Use oscilloscope to be able to observe all sorts of different signal amplitude the waveform curve that changes with time, still can use it to test all sorts of different electric quantity, be like voltage, current, frequency, phase difference, amplitude modulation.
(1) Presetting: rotate the brightness knob counterclockwise to the bottom, move the vertical and horizontal position to the middle, and the attenuation is placed in the highest level, and the scanning is placed in the "outer X gear";
(2) Turn on the power again, and wait for one or two minutes after the light is on for preheating before carrying out relevant operations;
(3) First adjust the grayscale, then focus, and then adjust the horizontal and vertical displacement to make the highlights in the center of the appropriate area;
(4) Adjust scanning, scanning fine tuning and X gain, observe scanning;
(5) Unplug the outer X gear to the appropriate position in the scanning range file, and observe the voltage waveform in the vertical direction changing according to the law of sines and cosines provided by the machine;
(6) To study the external voltage from Y input and indirectly into the oscilloscope, adjust each gear to the appropriate position, you can observe the voltage waveform (and time changes of the image)(synchronous polarity switch can make the starting point of the image from the positive half cycle or negative half cycle start;
(7) If you want to observe the vertical offset of bright spot (such as when applied with a constant current voltage), you can adjust the scan to "outer X gear". (different oscilloscopes may operate in different ways), etc.
(1) Insert the oscilloscope probe into the socket of channel 1, and put the attenuation on the probe into "1" gear;
(2) Put channel selection in CH1 and coupling mode in DC file;
(3) Insert the probe into the pinhole of the calibration signal source, and the light trace appears on the oscilloscope screen;
(4) Adjust the vertical knob and horizontal knob to stabilize the waveform displayed on the screen, and put the vertical fine-tuning and horizontal fine-tuning in the calibration position;
(5) The number of cells occupied by the waveform in the vertical direction is multiplied by the indicating value of the vertical attenuation knob to obtain the amplitude of the calibration signal.
(6) The number of bars occupied by each period of the waveform in the horizontal direction is multiplied by the indicating value of the horizontal scanning knob to obtain the period of the calibration signal (the inverse of the period is the frequency).
(7) In general, the frequency of the calibration signal is 1kHz and the amplitude is 0.5v, which is used to calibrate the internal scanning oscillator frequency of the oscilloscope. If it is abnormal, the corresponding potentiometer of the oscilloscope (internal) should be adjusted until it is consistent.
Main classification and and characteristics of oscilloscopes’ probes
The passive probe is made of wires and connectors and includes resistors and capacitors when compensation or attenuation is required. There are no active devices (transistors or amplifiers) in the probe, so no power supply is required for the probe. Passive probes are generally the strongest and most economical probes, and they are not only easy to use, but also widely used.
1.2 High resistance passive voltage probe
Actually, voltage probes are widely used among which high resistance passive probes are the most. Passive voltage probes provide attenuation 1x, 10x and 100x for different voltages. During these passive probes, 10x passive probes are most widely used probes. For applications where the signal amplitude is 1 v peak-to-peak or lower, a 1 x probe may be appropriate or even necessary. In application where low - and medium-amplitude signals are mixed (tens of millivolts to tens of volts), the switchable 1 x /10 x probe is much more convenient. However, the switchable 1 /10 probe is essentially two different probes in the same product, with not only different attenuation coefficients, but also different bandwidth, rise time and impedance (R and C) characteristics. Therefore, these probes do not exactly match the input of the oscilloscope and do not provide the optimal performance achieved by the standard 10 x probe.
1.3 Low resistance passive voltage probes
Bandwidth of most high resistance passive probes range from less than 100MHZ to 500 MHZ or more than. However, frequency characteristics of low resistance passive probes(also called 50 Ohm probe, Zo probe, voltage divider probe) are very good, adopting probe matching coaxial cable, bandwidth could reach 10GHZ and 100 psec or faster rise time. The probe is designed for use in 50 ohm environments such as high-speed equipment verification, microwave communications and time domain reflectometers (TDR).
1.4 Passive high voltage probes
High voltage is one relative concept. We can define a high voltage as any voltage that exceeds the voltage that a typical generic 10 x passive probe can safely handle. High voltage probes require great dielectric strength to ensure safety of user and probes.
2. Active voltage probe
2.1 Active probes
Active probes include or depends on active circuits, such as crystal valve. Most commonly, an active device is a field effect transistor (FET) that provides very low input capacitance, which leads to high input impedance over a wider frequency band.
2.2 Passive FET probe
Bandwidth of passive FET probes are usually during 500MHZ to 4GHZ. The high input impedance of an active FET probe allows measurements to be made at test points with unknown impedance, and the risk of a load effect is much lower. In addition, because low capacitance reduces the effect of ground wires, longer ground wires can be used.
Active FET probes have no passive probe voltage range. The linear dynamic range of active probe is generally between ±0.6v and ±10V
2.3 Active differential probe
Differential signals are signals that refer to one another rather than to ground. The differential probe can measure the signal of the floating device, which is essentially composed of two symmetrical voltage probes with good insulation and high impedance to the location, respectively. The differential probe provides a high common mode rejection ratio (CMRR) over a wider frequency range.
3. Current probe
In principle, the current value can be easily obtained by dividing the voltage measured by the impedance measured by a voltage probe. However, in practice this measurement introduces a large error, so generally do not use voltage conversion current method. The current probe can accurately measure the current waveform. The method is to use the current transformer input, the signal current magnetic flux is transformed into voltage by the mutual inductance transformer, and then amplified by the amplifier inside the probe and sent to the oscilloscope.
3.1 Ac current probe
The alternating current in the transformer will generate electric field and induce voltage with the change of current direction. The ac current probe is a passive device that requires no external power supply.
3.2 DC current probe
Conventional current probes can only measure ac and ac signals, because a stable dc current cannot induce current in a transformer. However, using the hall effect, a semiconductor device with a bias current will generate a voltage corresponding to the direct current field. Therefore, the dc current probe is an active device that needs external power supply.
So current probes are basically divided into two kinds: AC current probes and AC/DC current probes. AC current probes are usually passive probes and AC/DC active probes.
4. Logic probe
When observing and analyzing the analog characteristics of digital waveform with oscilloscope, logic probe is needed. In order to isolate the exact cause, digital designers usually need to check the specific data pulse that occurs under specific logic conditions, which requires logic trigger function.
5. Other probes
Because the application scope of oscilloscope is very wide, so in addition to the above types of probes there are a variety of special probes, these professional probes according to the different front-end sensors and have different functions, we introduce two of them below, only for readers to understand.
Photoelectric probe is a combination of common voltage probe and photoelectric conversion device in principle, which can directly measure optical device and optical signal transmitted by optical fiber.
Temperature probe is a combination of common voltage probe and temperature sensor, which can directly measure the temperature of an object.Temperature probe is a kind of sensor probe. Various sensor probes and oscilloscopes can be combined to measure a variety of physical quantities.