2CH Digital Oscilloscope 20M Virtual oscilloscope Spectrum Analyzer Data Recorder DDS Sweep
Introduction:
Dualchannel digital oscilloscope, with "lowcost, highperformance" as the design goals. welldesigned bandwidth of 20M, 48M sampling rate, 2 channels, alternating support X, Y and XY alternating pattern of twochannel virtual oscilloscope, spectrum analyzer, data recorder. Meanwhile, it support DDS and Sweep function. DDS support 5 kinds of waveform output, Sine wave can output up to 20M. The device communicate with the PC via high speed USB2.0.
Specifications:
Digital oscilloscope 

Channels 
2 
Impedance 
1MΩ 25pF 
Coupling 
AC/DC 
Vertical resolution 
8Bit 
Gain range 
6V ~ 6Vï¼ˆprobe X1ï¼‰ 
Vertical accuracy 
±3% 
Timebase range 
1ns20s 
Input Protection 
Diodeï¼Œ50Vpk 
Autoset 
Yes(10Hz to 20MHz) 
Trigger Mode 
Autoã€?Normal and Signal 
Trigger Type 
Noã€?Rising edgeã€?Falling edgeã€? 
Trigger level 
Yes 
Trigger Source 
CH1, CH2 
Buffer Size 
1MB/CH 
Bandwidth 
20MHz 
Max sample 
48MS/s 
Vertical mode 
CH1, CH2, ADD, SUB, MUL 
Display Mode 
Xã€?YTå’ŒXY 
measurements 
Yes 
Wave save 
Osc(Private)ã€?Excel and Bmp 
Spectrum analyzers 

Channels 
2 
Bandwidth 
20MHz 
Algorithm 
FFT(18 windows)ã€?correlationã€?power spectrum 
FFT points 
81048576/CHN 
FFT measure 
Harmonic(17)ã€?SNRã€?SINADã€?ENOBã€?THDã€?SFDR 
Filter processing 
FIR filter supports arbitrary range of frequency sampling method , and Rectangle, bartlett, triangular, cosine, hanning, bartlett_hanning, hamming, blackman, blackman_Harris, tukey, Nuttall, FlatTop, Bohman, Parzen, Lanczos, kaiser, gaussand dolph_chebyshev, window method design. 
Data recorder 

Channel 
2 
Impedance 
1MΩ 25pF 
Coupling 
AC/DC 
Vertical resolution 
8Bit 
Gain range 
6V ~ 6Vï¼ˆprobe X1ï¼‰ 
Sample 
1 channel : 1K~24M Hz 
Save File 
The maximum 4G, recording time associated with the sampling rate 
DDS 

Wave 
Sine, Square(Duty circle variable),Triangle,Up Sawtooth,Down Sawtooth 
Amplitude 
≥9Vpp(no load) 
Impedance 
200Ω±10% 
Offset 
±2.5V 
Frequency range 
1Hz ~ 20MHz(Sine), 1Hz ~ 2MHz(Others) 
Frequency resolution 
1Hz 
Frequency steadiness 
±1×103 
Frequency precision 
±5×103 
Triangular wave linearity 
≥98% (1Hz~10kHz) 
Sine wave distortion 
≤0.8% (1kHz) 
Square wave rising/falling time 
≤100ns 
Square wave duty circle 
1%~99% 
SWEEP 

Sweep range 
Fsåˆ° Fe 
Sweep time range 
0.1 ~10 s 
Amplitude 
0.5Vpp ~ 10Vpp 
Sweep 

Sweep Style 
Linear Sweepã€?Log Sweep 
Linear Sweep Range 
1Hz20MHz, Min 1Hz step 
Log Sweep Range 
1Hz10MHz, 1,10,100....Logarithmic step 
What does an oscilloscope do?
Oscilloscope is a kind of instrument which is widely used to display the trace change of instantaneous value measured. It can transform the electric signal invisible to the naked eye into visible image, which is convenient for people to study the change process of various electric phenomena. An oscilloscope USES a narrow beam of highspeed electrons to produce tiny points of light by hitting a surface coated with fluorescent material. 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, if voltage, current, frequency, phase difference, adjust amplitude to wait a moment.
The response characteristic of digital oscilloscope and its choose and buy skill
Another reason why high speed digital oscilloscope chooses brick wall reaction type is to avoid or minimize Aliasing phenomenon. When using digital oscilloscopes to measure high speed signals, graphics confusion can occur, mainly because some signals are mixed with unnecessary waveforms when reproducing the sampled high speed signals. These mixed signal frequency components can distort the original signal waveform and, in severe cases, cause measurement errors.
Most of the pattern confusion occurs in the analog to digital converter (adc) continuous signals, which contain components that exceed the Nyquist frequency, or half the sampling frequency.This component retraces in the Nyquist frequency domain and appears in the oscilloscope measurement bandwidth. It can be clearly seen from the frequency characteristic diagram that the figure confusion effect of the brick wall reactive oscilloscope is negligible.
Under the same conditions, it can be clearly seen that in the field beyond the Nyquist frequency of 2GHz, there is almost no signal, which can inhibit the occurrence of confusion.
In addition, if 20GHz, 10GHz and 5GHz sampling frequencies are used to measure waveforms with a period of 2.2ns and a rise time of about 90ps, different results will be obtained.The lower the sampling frequency is, the longer the actual measurement value of rising time is, and the waveform cannot be faithfully presented.
At present, the highspeed serial interface measurement USES the realtime sampling broadband digital oscilloscope, and the sampling frequency of the high performance machine equipped with the analog to digital converter is up to about 20GHz. Generally, in order to reduce the occurrence of graphics confusion, the sampling frequency of a gaussian reactive oscilloscope should be 46 times of the input signal, while that of a brick wall reactive oscilloscope only needs 2.5 times.
Generally, the frequency band is lower than 1GHz, so gaussian reaction system is mostly adopted, while the instruments higher than 1GHz are mostly brick wall reaction system.Table 2 shows the advantages and disadvantages of the two types of reactive oscilloscopes.
Choose oscilloscope according to performance requirement
So, how to choose the most suitable oscilloscope? There are four simple steps:
Calculate the highest frequency component fmax of the measured signal.The upper limit of the signal frequency component can be calculated by measuring the rising time of the signal.Assuming that the rise time is migrated from 20% to 80%, the approximate value can be estimated using the mathematical formula (0.4/ signal rise time) rather than directly from the data transmission rate.Take the popular thirdgeneration bus PCIExpress, which in most cases has a rise time of about 100ps.
Select the response characteristics of the oscilloscope. That is to choose a suitable one between the gaussian reaction system and the brick wall reaction system.
The necessary input bandwidth must be secured. It is related to the measurement error of rise time. An instrument company has done simulation experiments: if the brick wall reactive system allows 3% error, the bandwidth can be calculated with (1.4 fmax); If the error is limited to 10%, use (1.2 fmax) to calculate. When the tolerance error is 20%, it is calculated by (1.0 fmax).
Estimate the lowest sampling frequency. This value takes advantage of the above bandwidth value, which is a minimum (2.5 bandwidth) for a brick wall reactive oscilloscope.
The above four points can be used to illustrate a case: the rise time of 100ps digital signal, its fmax is 4GHz, select the brick wall reaction oscilloscope, assuming that the error of the rise time is limited to 3%, then the bandwidth of the input signal is 5.6ghz, therefore, the minimum sampling frequency also needs 14GHz.
If the sampling frequency of 14GHz is applied to the gaussian reaction system, the input bandwidth becomes 3.5ghz, and the rising time of the measured signal is 220ps, which is half of the difference with the brick wall reaction system.Some wideband realtime oscilloscopes rely on the active application of digital signal processing to realize the characteristics of brick wall reactive system.After all, circuit technology alone is unlikely to achieve desirable characteristics.
In a word, whether the bandwidth and sampling frequency are suitable or not is an important pointer when choosing expensive oscilloscope.In addition, understanding the characteristics of the test instrument is also the key to mastering the correct measurement.