Instek DSO/MDO/MSO  FFT spectrum analysis - Page 1
Forum section: electronics / testgear

author: rhb
author_rank: Super Contributor
timestamp: November 21, 2017, 06:29:31 pm
content: I've been evaluating an MSO-2204EA. The UI is fairly maddening, but the hardware seems quite good and the company is responsive.I just upgraded from FW 1.28 to 1.32. Under the App section there is a Demo button. If you select it you get a series of static demos, one of the options is spectrum analysis which has a pair of demos of AM & FM modulation. The demos are static and don't allow changing the parameters, *but* if you press the  in the lower right corner you get the menu for a very usable SA window which is much better than the FFT window under  though it won't let you change the record length which is fixed at 10k.I think this is the SA function from the MDO line. I cannot for the life of me understand why this is not a feature of both the MDO & MSO lines. Or why they don't allow setting a longer record length.Here are some screenshots.

author: nctnico
author_rank: Super Contributor
timestamp: November 21, 2017, 06:39:29 pm
content: I agree. GW Instek should get rid of the MDO series altogether and implement the SA like FFT into the GDS2000E and MSO2000E series. I have asked GW Instek whether the SA controls would become available for the GDS2000E / MSO2000E series but the answer was no. IMHO not a wise choice.

author: MrW0lf
author_rank: Frequent Contributor
timestamp: November 21, 2017, 08:53:34 pm
content: Quote from: rhb on November 21, 2017, 06:29:31 pmBTW there is existing thread would be good to collect stuff there:https://www.eevblog.com/forum/testgear/gw-instek-gds-2000e-released/As for SA/FFT record length - what if you set small span in VHF range while at max 10k points - what RBW you get? For example 1MHz span, 100MHz CF.

author: rhb
author_rank: Super Contributor
timestamp: November 21, 2017, 10:09:23 pm
content: Quote from: MrW0lf on November 21, 2017, 08:53:34 pmIt's hard to say. I don't have a 100 MHz source. It claims a RBW of 1 KHz. The update rate is really poor. From the appearance of the display I think the actual RBW is 10 KHz. In the normal FFT mode with 1 Mpts (no zoom), the RBW is nominally 1 KHz. With zoom it drops back to 10 KHz.I've got a Feeltech FY6660 on the way. When it arrives I'll try 50-60 MHz. The Instek sine is limited to 25 MHz. To go higher I'll need to get my HP 8601A or ADF43XX going.I don't understand how they are doing the restricted span. All my work with FFTs has been in recorded time on seismic data and well logs. But it appears that the SA mode is just a better interface for a zoom of the regular FFT with some additional averaging of the FFT spectrum.I've been in touch with Instek about being able to choose the X & Y channels. I want to characterize some magnetic core material. To do a hystersis loop I need to plot the current against the integral of the voltage across the coil. Damn nuisance to have to dump a CSV file to a PC to do it. But easier than building a 200 MHz integrator.With a 10 Mpt record sampling at 1 GSa/S one has an RBW of 150-200 Hz (100 Hz nominal).Most hams are active in HF through 2 meters though 70 cm has become popular with the advent of dual band VHF/UHF handsets.So with good software the 2000E series could be a huge hit with DIY hams.I'll take a look at the other thread.

author: nctnico
author_rank: Super Contributor
timestamp: November 22, 2017, 11:05:35 am
content: I tried to get the SA demo to run on my GDS2000E but that didn't work. Probably because my scope (obviously) doesn't have the generator hardware.Maybe I should take time to do some hacking. During an earlier firmware update my scope wrote the contents of the filesystem onto the USB stick. This should allow me to get some insight in how the firmware images are constructed. I already noticed that a lot of functionality is driven by Lua (a programming language). Maybe getting the SA function to work is a matter of writing a APP module in Lua and upload it into the scope. After all it seems the DSO/MDO/MSO share the same firmware.

author: rhb
author_rank: Super Contributor
timestamp: November 22, 2017, 02:46:50 pm
content: If the apps are written with Lua that would be great. And something Instek should document. It would really differentiate their products if users could program apps themselves. I'll take a look at the firmware update file. I wish I had some older updates.