Application of SIGLENT SDS2000 series Sequence and History Function

March 3, 2014 - PRLog -- For measurement of bursts with low duty cycle or long idle time, like laser pulse or radar pulse with low duty cycle, even occasional narrow pulse signal in embedded circuit, through oscilloscope with high sampling rate and bandwidth, it is essential to increase the sampling time.

According to the following formular:

Sampling rate ×Sampling time = Memory depth

To increase the sampling time, the sampling rate must be lowered while the memory depth is definite. In addition, you can also upgrade the memory depth, which needs a higher cost yet.

Through SIGLENT new SDS2000 series oscilloscope is featured with 28Mpts memory depth and 2GSa/s sampling rate, it could capture signal only long to 14ms, which is far from enough for acquiring and observing continuous signal with long idle time. Therefore, upgrading the memory depth is not an economic and efficient way.

As a result, SIGLENT offer an effective solution: Sequence function. Sequence function is to divide the oscilloscope memory into a number of sequences, the current triggered waveforms will be put into each sequence, for each trigger, there comes a saving.

For Siglent SDS2000 series oscilloscope, the capture rate can also get up to 110,000wfms/s while the Sequence function is enabled. Meanwhile, if you continue to open the History function, you will get a easy observation of time when a waveform is triggered and time interval between two triggered waveforms on the screen.

Figure1 Work functional diagram

(http://www.siglent.com/Sequence/F1.gif)

1. Long-time acquisition of burst signal

Burst signal is frequently used in radar or sonar signal. Using traditional acquisition methods for long-time acquisition isnow a big challenge, which needs to strike a balance between long-time acquisition and high sampling rate. In many cases, through lowering the sampling rate, you also will not get along-time acquisition.

As shown in figure 2, the cycle and pulse width is respectively 1ms and 5us. The oscilloscope is set to 28Mpts memory depth and 2GSa/s sampling rate, thus get the current acquisition time: 14ms, namely 14 Burst signals that display in the upper half main scan window. However, it is obviously not enough for characteristic analysis of burst signal. And if we set the memory depth to 2.8Mpts, we will get a shorter time: 1.4ms, which is definitely far from enough.

Figure2 Burst signal zoom view for SDS2000 series oscilloscpe

(http://www.siglent.com/Sequence/F2.jpg)

For similar burst signal, if we open the Sequence function of Siglent SDS2000, more burst signals can be acquired as shown in figure 3.

Figure3 Sequence waveforms view under overlap display mode.

(http://www.siglent.com/Sequence/F3.jpg)

Siglent SDS2000 series oscilloscope can support up to 8000frame sequences. For instance, as shown in figure 3 and 4, set the frame to 4067 under Sequence, then you will get a long-time burst signal acquisition of 4067 frames.

Figure4 Sequence waveforms view under interval display mode

(http://www.siglent.com/Sequence/F4.jpg)

2. Enable History function

History function includes navigation and playback of waveform sequences. Based on that, we can use the fast forward or return function to quickly find the wanted period of time, and then current sequence No. and time information, which can help us to know the time that each event happens and time interval between two continuous event.

Figure5 Waveform playback view under History function

(http://www.siglent.com/Sequence/F5.jpg)

3. Long-time acquisition of occasional narrow pulse

For capture of continuous occasional narrow pulse, we usually trigger it using pulse trigger mode. Through we set the memory depth to the maximum 28Mpts, as discussed before, we could only get14ms acquisition time.

Figure6 Occasional narrow pulse view in zoom window ofSDS2000

(http://www.siglent.com/Sequence/F6.jpg)

However, if we open the Sequence function of Siglent SDS2000series oscilloscope, we will get a easier acquisition of more occasional narrow pulses. Meanwhile, we could also enable History function for playback and analysis of narrow signals that you care.

Figure7 Narrow signal view under sequence waveforms

 (http://www.siglent.com/Sequence/F7.jpg)

Figure8 History waveforms playback view of narrow signal
 (http://www.siglent.com/Sequence/F8.jpg)

Summary

With the Sequence function and History function, SiglentSDS2000 series oscilloscope improves greatly the problem that under limited memory depth , while at high sampling rate, you can also get a probably long-time acquisition.