FeelTech FY3224S 24MHz 2-Channel DDS AW Function Signal Generator

[Aldo22]

I know I'm a little late to the party, but the FY3224S is still being sold and is still the cheapest 2 channel AWG available as far as I know.
I got it yesterday.

Board version: 3.2
PSU version: 1.32
Firmware version: 4.1

So far everything works.
But I have some jitter at the square wave.
Strangely not at 6MHz, but for example at 5MHz and around.
I see two vertical traces (See fy3200s_5MHz_sqr.jpg).

Is this a known problem or is my device faulty?
There is also a possibility that it is partly due to the cheap Zeeweii DSO2512G, but normally it is still stable in these frequency ranges.

Does anyone know this phenomenon?

Thank you!

[Aldo22]

I'll answer my own question:
here you can see that it is not due to the oscilloscope. This jitter seems to be typical for the FY3200S.
The images there look partly worse than on my device.
Especially 5V/5MHz looks more like a square wave on my version. There was apparently a small improvement.

[Pygmalion]

So far everything works.
But I have some jitter at the square wave.
Strangely not at 6MHz, but for example at 5MHz and around.
I see two vertical traces (See fy3200s_5MHz_sqr.jpg).

Does anyone know this phenomenon?

This reminds me irresistibly of the Fourier series of a square signal. The frequency of the oscillator is fixed at 24 MHz, and the final signal is probably the sum of a series of sine waves with frequencies, multiples of which is 24 kHz. It will therefore be much more difficult to fit a 5MHz square wave than a 6MHz square wave into series of 6MHz, 12MHz, 18MHz and 24MHz.

See https://en.wikipedia.org/wiki/Fourier_series

[Aldo22]

This reminds me irresistibly of the Fourier series of a square signal. The frequency of the oscillator is fixed at 24 MHz, and the final signal is probably the sum of a series of sine waves with frequencies, multiples of which is 24 kHz. It will therefore be much more difficult to fit a 5MHz square wave than a 6MHz square wave into series of 6MHz, 12MHz, 18MHz and 24MHz.

Yes.
The good thing is that there are "sweet spots" at certain frequencies (multiples).
With an appropriate waveform, the device can also generate stable 36MHz or 48 MHz, which is twice the specified bandwidth.
Not particularly nice (forget the amplitude), but stable.

[Aldo22]

I know the FY3200s isn't the latest and greatest anymore, but it's still the cheapest AWG and it's not that bad.

However, the user interface is a bit annoying.
Fortunately, you can control the device remotely with a PC.
Since I couldn't find a GUI application that also runs on Linux and Raspberry Pi 4, I wrote one myself.
I have added function to function and now I'm almost finished. ;-)

Features are (besides the obvious).

- 50Ohm load resistor mode
- Attenuator mode (dB)
- Amplitude limitation for sensitive devices (e.g. TinySA).
- Amplitude correction table (for adjusting e.g. oscilloscopes).
- Display of Vrms for standard waveforms and dBm at 50 ohms.
- Software sweep with amplitude sweep.
- Unlimited named presets.
. Waveform upload (15 seconds)
- Waveform conversion from bitmaps (PNG etc.) with single and double scan for fun shapes.

I still have some tweaking to do.
When it's done I can share the source code if anyone is interested.