Binary data formatting often provides the smallest payload size and therefore transfers via USB/LAN more quickly. Unfortunately, binary is very difficult to interpret by humans. So, binary data is often reformatted to other types (ASCII, etc..)/

Here is a link to the binary data format for many popular SIGLENT oscilloscopes:

Extract Binary Data from an SDS oscilloscope

The post How to Extract Data from the Binary File of Siglent Oscilloscope appeared first on Siglent.

Generate a stereo-FM multiplex waveform with Python and AWG

The post Baltic Labs: Generate a stereo-FM multiplex waveform with Python and AWG appeared first on Siglent.

The basic idea is simple enough – measure the clock edges and see if they are all exactly evenly spaced or if they change (jitter) over time. A non-uniform clock fed to an ADC or DAC will produce FM and/or AM effects, as well as raise the noise floor. The effects of the clock jitter depend on the nature of the jitter. Random jitter can have less objectionable audible effects than jitter dominated by a specific frequency. There are many ways for interfering signals to couple into clock lines to cause problems.

The link below takes you to the note that looks at using a garden variety DSO (200 MHz BW, 1 Gsample/sec) to see if it can take the place of a $50,000 setup that would normally be wheeled out to investigate a jitter problem.

https://clk.works/2020/05/jitter-spectrum-measurement-with-a-dso/

The post Jitter spectrum measurements with a digital oscilloscope appeared first on Siglent.

One method of quickly determining stability is to use a load step response.

In this test, a DC electronic load is used to provide a current load that steps from a low current draw to a higher value in a short period of time. By directly measuring the voltage and current output of the supply with the stepped load, we can visually observe the recovery of the power supply feedback loop and make changes to the design to optimize the response.

For this note, we are going to perform identical tests on two supplies and compare the output voltage and current waveforms: One has been tuned so that the output quickly recovers with minimal overshoot and ringing. The other supply is not tuned and subsequently oscillates. We will also discuss some measurement techniques to help get the right data as quickly as possible.

We also have a video to accompany this note:

Power Supply Design: Load Step Response with a SIGLENT DC Electronic Load

The Equipment:

• A DC Electronic Load: The SIGLENT SDL1020X-E is a 200 W load with dynamic testing capabilities to perform the load step. It also features remote sense capabilities to compensate for the voltage drop across the load leads. High currents can provide a substantial voltage drop across the leads and will add unwanted error.
• An oscilloscope: The SIGLENT SDS2354X Plus scope has a large display, easy-to-use interface, and features that make capturing these waveforms very easy.
• A power supply: The SIGLENT SPD1168X single output supply delivers power to our power supply board
• A current probe: The SIGLENT CP4070 features a 150 kHz bandwidth that will minimize most switching noise from the measurement
• Power supplies to test: The Analog Devices LTM4646 series of uModule Regulators. This module features two 10A DC-DC converters. One has been “detuned” to show some common problems associated with power supply design. The other supply has been left in it’s tuned state as a comparison to the detuned supply.

The Setup:

• Connect the SPD bench power supply to the power supply to test and configure the output values to match your supply needs. Here, we set the SPD for 12 V @ 3 A.

• Connect the SDL electronic DC load to the output of the power supply to test. Configure the load for Constant Current (CC), set the voltage and current ranges to the lowest ranges that still accommodate the requirements of the test, set the current load to a value near the maximum for your design. You may also wish to wire up and enable the SDL remote sense which enables remote voltage measurement to minimize the voltage drop caused by the high current flow through the electronic load leads. Here, we set the current to 5 A.

• Connect a passive probe to the oscilloscope CH1. This probe should be connected to the power supply feedback loop to monitor the voltage as the supply adjusts to the load.
• On the oscilloscope, configure CH1 for AC coupling to provide the most resolution to view the feedback voltage which can have high DC offsets. Enabling the Bandwidth Limit (BW limit) can also decrease noise. Here, the SDS2X Plus also has on-screen labels for traces, which can be a convenient way of keeping information organized. Here, I labeled CH1 Vout.

• Connect the current probe to the oscilloscope CH2.
• On the oscilloscope, set the trigger for Rising Edge, CH2 and AUTO. This will allow you to adjust the current probe zero position without dealing with the trigger setting.
• Configure CH2 as a current probe (Units = A), set the Probe attenuation to the proper value (50 mV/A in this case). DC coupling here because we want to see the total signal amplitude. I also applied a label to the output current (Iout).

• Zero the current probe. The CPs have a knob that you can use to move the DC offset. Set the scope to a low current range and adjust the probe to get 0 A on the display.

• Clip the current probe around the positive current lead going from the power supply under test to the DC load. Make sure to have the clamp connected such that positive current flow (into the load) produces a positive signal on the scope.

Now, everything is connected and ready to test:

Be on the lookout for interlopers and/or pesky critters wondering where the magic smoke came from:

DC Load Verification

Now, you can power on the SPD power supply and SDL load.

Make sure that the scope is set to AUTO trigger for now. You can also add an RMS measurement on CH2 so that you can verify the current draw matches the setting on the DC Load.

Here, we have a setting of 5 A on the DC load.. and we show 5 A RMS on the scope:

Things are looking good. The current output matches our load setting.

DC Load Step Response

Now, set the DC load to Dynamic Current mode by pressing Utility > CC.. and configure the appropriate ranges, low and high current values and duration, and slew rate for your application.

Here are the settings used for this test:

This will continuously cycle from 1 A for 5 ms to 5 A for 5 ms with 500 mA/us slew rate.

Now, switch the scope trigger mode to Normal and adjust the vertical, horizontal scales and positions.. as well as the trigger level to get a stable trigger and a few periods of transition on the display:

Verify that the supply high and low current values match the setpoints. For this example, we have 1 A for 5 ms and 5 A for 5 ms.. which is what we observe.

Observe and Optimize

Now, let’s compare a tuned setup to one that is not tuned for our load as well as some techniques to gather more information about the response.

First, you likely see quite a bit of noise on your signal. The majority of this is due to switching noise in the supply being tested. Here is a zoomed image of the feedback voltage where you can see the switching noise quite clearly.

Enabling waveform averaging can help:

Now, we see the output voltage from CH1 (yellow), output current from CH2 (pink/purple), and the average voltage math function (orange):

This is the tuned setup.

Now, let’s look at a detuned supply:

The scaling on these two images is exactly the same. You can see a large amount of ringing associated with the detuned supply. This design is very close to becoming an oscillator with this load. If our step duration was any shorter, the supply voltage wouldn’t be settled and our output would be very poorly regulated.

Here are some closer images of the rising and falling edges on shorter time scales:

Tuned, Rising:

Tuned, Falling:

Detuned, Rising:

Detuned, Falling:

Conclusions

A DC load step test can quickly show you the performance and stability of a power supply design. Using a few common pieces of test gear, you can ensure that your design is ready to undertake the most challenging application requirements.

The post Power Supply Design: Load Step Response with a SIGLENT DC Electronic Load appeared first on Siglent.

NOTE: This program saves the picture/display image file to the E: drive, which may or may not exist on the specific computer being used to run the application.

Download Python 3.4, connect a SIGLENT SDS Oscilloscope using a USB cable, get the scope USB VISA address, and run the attached .PY program to save an image of the oscilloscope display. The type of file saved is determined by the instruments setting when the program is run.

You can download the .PY file here: PyVISA SDS Screen Capture

Tested with:

Python 3.4

SDS1102CML+

#Example that returns a copy of the displayed image on SIGLENT SDS
#Oscilloscopes via USB and saves to a drive location
#
#Dependencies:
#Python 3.4 32 bit
#PyVisa 1.7
#
#Rev 1: 02262020 JC

import visa
import time # for sleep

def main():
 _rm = visa.ResourceManager()
 sds = _rm.open_resource("USB0::0xF4EC::0xEE3A::SDS1MFCQ3R5086::INSTR") #Replace with specific USB information from scope
 file_name = "E:\\SCDP.bmp" #Make suere that the drive specified is available on your computer
 sds.write("SCDP")
 result_str = sds.read_raw()
 f = open(file_name,'wb')
 f.write(result_str)
 f.flush()
 f.close()
if __name__=='__main__':
 main()

The post Programming Example: SDS Oscilloscope save a copy of a screen image via Python/PyVISA appeared first on Siglent.

You can download the VI here: VISA_IDN.ZIP

In this example, the user can:

• Select the connected instruments from the VISA Resource List drop down menu:

NOTE: USB devices will automatically appear. For LAN connections, you will need to add the device. This is commonly done using NI Measurement and Automation Explorer (NI-MAX)

• Request the identification string once-per-press of the RUN button.

This sends the “*IDN?” identification query string to the instrument. The instrument then responds to the query with its identification string information. The identification string data will appear in the text box.

This code also uses the event structure connected to the value change of the RUN button to run once-and-only-once per keypress. This is a useful method of controlling code execution.

• Stop and exit upon pressing the STOP button

To run:

1. Connect instruments using a USB or LAN connection (see users manual for specific instrument details)
2. Power on instrument
3. Open LabVIEW and select the IDN.VI. This will open the VI front panel:

4. Select the instrument of interest from the VISA Resource drop down menu:

5. Press RUN on the LabVIEW VI menu strip to run the program:

6. Now, the “graph paper” background goes clear, indicating that the code is running. Now, you can press RUN in the VI Front Panel to execute the code:

The identification string should appear in the textbox:

7. Press STOP on the VI Front Panel to exit the code

The post Programming Example: Identification String (*IDN?) return with LabVIEW 2018 appeared first on Siglent.

The post Comparison / Differences between the SDS1000X and SDS1000X-E oscilloscope families appeared first on Siglent.

The VXI bus and subsequent software drivers form a convenient software API that can make remote control of instrumentation over LAN quite simple. In fact, it forms the basis of the TCPIP communications used in LXI format that is being implemented across the industry.

For more info on VXI, you can check out the VXI Consortium

VXI has a small installation size and is quite flexible.. especially when compared to VISA based applications. VISA is convenient and does allow for easy bus changes (from GPIB to USB with just a few lines of code), but it is also a large installation that isn’t always easy to use on machines that are not running Windows.

VXI has many flavors.. and can be used with many OS’ and can be used on many instruments that do not have “open sockets” on their LAN connection.

Here is a list of SIGLENT products that have LAN but do not have open sockets:

SDS2000

SDS2000X

SDS1000X/X+

SPD3000X/XE

In this note, we are going to show how to use VXI-11 with Python to control an instrument. This can be used with traditional OS’ like Windows but offer even more when coupled with Linux variants like those running on Rasberry Pis and other single board computers (SBCs).

Configuration

First, you will need to download a few programs..

• Python: https://www.python.org/downloads/release/python-2714/

NOTE: This technique works with version 2.x and 3.x.. in this example, we will use Python 2.7.14 for Windows 64 bit OS’

• Python VXI-11: https://github.com/alexforencich/python-vxi11

Once downloaded, you can add VXI-11 to your Python instance..

1. Open the command line program in Windows. You can find it by searching for “CMD” or by going to the Start Menu >  Windows System > Command Prompt as shown here:

2. In another window, find the location of the Python VXI-11 folder that was downloaded previously and find the path for setup.py. In this case, the path on my PC is shown as:

Now, you can click on the “address” to open the exact path:

Here, I suggest opening Notepad and “copy-paste” the path. It will make the transfer easier:

3. Change the directory in the Command line program to match the path from step 2:

Type “cd <PATH>” as shown:

4. Now, the directory has changed to match the path. You can run the setup.py file by typing “python setup.py install” as shown:

5. Close the Command Prompt

Test the installation

Now that everything has been installed, let’s test the communications link.

1. Connect the instrument to the LAN of the controlling computer and power it on

2. Check the IP address for the product (see the User’s Guide of the specific product for more info), In this case, I am using an SDS2000X oscilloscope. Here is the IP address information:

3. Now, start the Python shell. There are a few ways to start this application. In this case, you can find the Python folder in the Windows start folder.

Open IDLE (A Python GUI):

Now, click Run > Python Shell to open the shell:

4. Now, import the VXI11 library by typing “import vxi11”

5. Now, we can assign the variable “instr” to the instrument as shown:

6. Now, we can use the VXI Ask command to send the identification string (*IDN?), request the response, and print it to the screen:

The VXI11 library features a number of functions to handle writing and reading strings and other formats. You can use this technique to establish communications and control the instrument efficiently.

Click here to download a Python file of this example: PythonVXI11_IDN

The post Programming Example: Using VXI11 (LXI) and Python for LAN control without sockets appeared first on Siglent.

This example scans and lists the available resources.

It requires PyVISA to be installed (see the PyVISA documentation for more information)

***

#Example that scans a computer for connected instruments that
#are compatible with the VISA communication protocol.
#
#The instrument VISA resource ID for each compatible instrument
#is then listed.
#
#
#Dependencies:
#Python 3.4 32 bit
#PyVisa 1.7
#
#Rev 1: 08302018 JC

import visa

def main():
    rm = visa.ResourceManager()
    print (rm.list_resources())

if __name__=='__main__':
    main()

*****

Here is the code:

And here is the result of a scan:

Each connected instrument returns a specific formatted string of characters called the VISA Resource ID.

The resource ID format is as follows:

‘Communication/Board Type (USB, GPIB, etc.)::Resource Information (Vendor ID, Product ID, Serial Number, IP address, etc..)::Resource Type’

In the response, each resource is separated by a comma. So, we have three resources listed in this example:

‘USB0::0x0483::0x7540::SPD3XGB4150080::INSTR’ – This is a power supply (SPD3X) connected via USB (USB0)

‘USB0::0xF4EC::0x1301::SVA1XEAX2R0073::INSTR’ – This is a vector network analyzer (SVA1X) connected via USB (USB0)

‘TCPIP0::192.168.55.122::inst0::INSTR’ – This is an instrument connected via LAN using a TCPIP connection at IP address 192.168.55.122

The post Programming Example: List connected VISA compatible resources using PyVISA appeared first on Siglent.

FFTs are commonly used on high frequencies, but they can also be used on signals with fairly low frequencies.

In this note, I am going to show the FFT performance of two series of our scopes by sourcing a 10 mHz (100 s period), 10 Vpp sine wave using a SIGLENT SDG805 Function Generator into Channel 1.

For those interested, here are the specs for the SDG805

SDS1000X/SDS2000X Series:

The SDS1000X and 2000X series feature an FFT function that uses up to 16 kpts of timebase data to calculate the frequency data and a timebase maximum of 50 s/div.

Here are the FFT results with the available window settings for a 10 mHz sinewave –

The scope can show a split timebase and FFT view:

For the rest, I will use the exclusive FFT view.

Rectangle

Blackman

Hanning

Hamming

Flat Top

SDS1000X-E Series:

The SDS1000X-E series feature a new math co-processor that increases the maximum data depth of the FFT function to 1 Mpts. They also feature a timebase maximum of 100 s/div. These increases allow the X-E to have much finer timebase detail and to acquire useful data for even lower frequencies than many scopes on the market.

Here are the FFT results with the available window settings for a 10 mHz sinewave –

The scope can show a split timebase and FFT view:

For the rest, I will use the exclusive FFT view.

Rectangle

Blackman

Hanning

Hamming

Flat Top

The post SDS FFT performance on low frequency signals appeared first on Siglent.