Inquiry on Generating a Programmable Harmonic 50Hz Signal Using Eclypse Z7 with Zmod AWG

[Mavitaka]

Hi,

Wishing you a prosperous New Year.

I'm intrigued by the capabilities of the Eclypse Z7 with Zmod AWG and have a technical query regarding its potential in generating a 50Hz signal with adjustable harmonics (3, 5, 7, 9, 11).

I'm curious to explore whether this is feasible and, if so, would greatly appreciate guidance on the steps to achieve this functionality.

Thank you for your anticipated assistance.

Warm regards,

[zygot]

I'll bite..
First can you provide a more specific description of what you mean by "adjustable harmonics" ?

[Mavitaka]

Hi @zygot,

This means that I can modify the amplitude of each harmonic.

Thank you in advance for your reply.

Best regards.

[artvvb]

Hi @Mavitaka

Modifiable in what way? By a human tweaking amplitudes in real-time, setting amplitudes from software on a computer, or selection based on some FPGA input? The first two could potentially be accomplished via a custom waveform in the WaveForms app (see below, where the third harmonic of a wave is set to 0.3x of the original wave's amplitude) or WaveForms SDK. The last would require a custom design in Vivado potentially adapting one of the demos, which would not be trivial.

If you haven't bought hardware, you can try out the WaveForms app without it. Edit to add: Note that any WaveForms-compatible device with analog output (like AD3, which is cheaper) is capable of this, ignoring any other specifications that might be necessary for your application.

Thanks,

Arthur

 

[zygot]

Generally speaking, harmonics are features of a synthesized signal that the designer gets for free.. and doesn't particularly want.

I guess that the answer depends on how you intend to go about constructing your 50 Hz signal, as well as what the specifications for the signal ( other than harmonics ) are.

There are a number of ways to synthesize signals. There are a number of ways to implement them in logic. Usually the prominent implementations are using a look-up table that contains pre-calculated samples, using a DDS type structure, or direct calculation using some algorithm. All of these will produce harmonics in the logic output samples. Then, once they are fed into a DAC and go through the analog circuitry that follows the DAC additional artifacts will be added to the signal. Then there's the transmission to whatever is receiving the signal... etc., etc...

I suppose that you want some control over the prominent frequency components that aren't a 50 Hz pure tone.

The way that one does any project like this is to simulate a prototype of their algorithm and implementation. This would be done first in MATLAB or OCTAVE using all of the high level features that these tools provide. Then, once you have a promising candidate, if using a algorithmic approach, redo the OCTAVE, but only using structures and simple keywords that can be implemented using an HDL such as VHDL or Verilog. Then you write your HDL implementation and simulate that using the Vivado simulator or your favorite alternative. Ideally, all of your simulation more or less agree ( accounting for differences in numerical dynamic range ). If you are using a look-up table implementation then your pre-calculated samples are what your output will be ( except of course for hardware dependent effects ) and the OCTAVE simulation is a lot easier.

Only after you are happy with all of these simulations would you even attempt to create a bitstream and try it out on hardware. That's the basic idea.

As for how one might synthesize a signal that meets some set of requirements.. this is a whole field of study. It really depends on on the specifications and what you are tryng to accomplish. If 50 Hz is just a reference to the signal cycle period, then there are a lot of possibilities that have been used. Instead of trying to manipulate a 50 Hz tone, you might combine multiple tones... similar to DTMF.

Oh, and do you intend to construct a fixed signal or want to manipulate it on the fly in hardware?

BTW. This is the kind of project that the Eclyspe-Z7 isn't bad for. You might find this project interesting: https://forum.digilent.com/topic/20299-fun-with-phasors/
You can read through the source code and documentation to get the idea of what's going on. There's even OCTAVE code. I wouldn't recommend buying an Eclypse-Z7 based on just one application, but you can see that for some applications, it's an acceptable platform. Edited January 4 by zygot