What function generator, that does a bit more than just a simple signal

[eTobey]

Hi,

i have the following things, that i think i would need to test my uC and my BLDC controller:

- introduce spikes of defined characteristics (from 1Hz to 34kHz)
- introducing single pulse deviations in PWM  of defined characteristics
- Frequency sweep

Would this be already a 300$ device, or are there some good cheap ones? I dont mind them to not have a perfect sine, or not beeing more accurate than 3% in amplitude or frequency. But those should be fairly stable then.

I read about the FY6900, that there are a few issues (hardware/software) and it seems a bit pricey to me. Is it really that much worth?

[johansen]

Seems to me you can do a lot of this with a second pulse generator and some additional circuitry.

Most signal generators are 50 ohm output and it is ok to short them out and over ride them with a lower impedance on a short term basis. For example if you want to trigger a glitch by holding the pwm high for just one cycle. Use a second triggerable pulse gen to pull the signal high with a mosfet, with some additional circuitry to enable amd disable it as a one (or n) shot timer.

For adding noise, use a resistor divider to mix in the spikes.

[Doctorandus_P]

I read about the FY6900, that there are a few issues (hardware/software) and it seems a bit pricey to me. Is it really that much worth?

So what do you think it costs or is worth?

I bought the JDS6600 myself, which is quite similar to the FY6900, but I bought the "low frequency" variant ("Only" up to 15MHz). It's plenty for my needs and paid around EUR80 for it.

And these things use DDS, and can do much more then sine waves. In the end the limitations are with memory depth and the software to generate a waveform. But I agree with johansen. It may be better to combine the outputs from multiple devices. From your description, it looks like you want to do some signal modification mostly based on logic levels, and that is probably best done with a microcontroller.

[eTobey]

I would pay about 80€ like you had. But they are all around 140€... There is not much in it, its 95% air.

But i think one device would be good, as they have 2 channels which i could combine, to have them running synchronously.

My primary use at the moment would not be logic levels.

[shapirus]

I would pay about 80€ like you had. But they are all around 140€... There is not much in it, its 95% air.

But i think one device would be good, as they have 2 channels which i could combine, to have them running synchronously.

My primary use at the moment would not be logic levels.

One of these https://www.aliexpress.com/item/1005005364938931.html ? Not sure what it displays for you in terms of price, for me it's US$85 for the 60 MHz version.

Not the best ergonomics-wise, but it works. Two channels, so you can combine them using some RF power combiner. I've not tried that though.

It also supports arbitrary waveforms uploaded from a computer. Never tried that, either, so I'm not sure what software is available and if it's any good.

[radiolistener]

It also supports arbitrary waveforms uploaded from a computer. Never tried that, either, so I'm not sure what software is available and if it's any good.

It is possible that it is compatible with PSG9080. If so, then can be used my tool: https://github.com/qrp73/PSG9080_ARB

[Doctorandus_P]

The box is indeed mostly empty, but it's size is still manageable. Unlike benchtop DMM's. These still have the same form factor as 40 years ago, but are mostly empty too these days, and I just do not have room for a 35cm deep empty box on my desk.

The power adapter that came with my JDS6600 was utter garbage, and I threw it in the bin. On the plus side, there is plenty of room in the box to add decent a power supply in it.   

[eTobey]

It is possible that it is compatible with PSG9080. If so, then can be used my tool: https://github.com/qrp73/PSG9080_ARB

This looks like a good instrument! Alltough its not so cheap, i consider getting it.

Have you used the programming feature? The manual is not so good to explain things here. Also i wonder if there are limitations when using some more complex function on one channel, for example using sweep or FM/AM/... : The other channel can be used what ever you want to do with it? Is it possible to use AM/FM/... on one channel, and sweep (with fm) on the other?

[radiolistener]

Have you used the programming feature? The manual is not so good to explain things here. Also i wonder if there are limitations when using some more complex function on one channel, for example using sweep or FM/AM/... : The other channel can be used what ever you want to do with it? Is it possible to use AM/FM/... on one channel, and sweep (with fm) on the other?

If you're talking about JDS2800, I don't have it so I can't say. I have PSG9080.

Both are manufactured by the same manufacturer and has similar display interface.
So I think my tool designed for PSG9080 can be compatible with JDS2800 either. Needs to test it.

Regarding to PSG9080, it has nice front panel with large contrast display. The performance is comparable with the same class generators like FY6800, may be a little bit less noise but harmonics may be a little bit higher. I would not expect something special, this is just a signal generator. It has sweep and modulation, but these functions are limited and has not a good quality. If you want some more functions or better quality sweep and modulation, it's better to look for something more higher class. Like Siglent SDG2048X.

[shapirus]

JDS2800 can't do AM/FM btw, so look elsewhere if you need that.

PWM single pulse deviations, not via its standard means, either.

Introducing spikes, probably yes, by creating a respective wave on second channel and then combining them externally.

Or maybe it's possible using arbitrary waveform, but I've never tried that.

[radiolistener]

Or maybe it's possible using arbitrary waveform, but I've never tried that.

Can you please check if my tool to read/write arb waveform for PSG9080 works with JDS2800?

just connect it to PC and try to execute:

Code: [Select]

PSG9080_ARB.exe COM3 -read 1 wave01.txt

where COM3 is a port which appears when you connect signal generator to PC.

It should read arb wavform 1 from generator to "wave01.txt" file

[shapirus]

Can you please check if my tool to read/write arb waveform for PSG9080 works with JDS2800?

just connect it to PC and try to execute:

Code: [Select]

PSG9080_ARB.exe COM3 -read 1 wave01.txt

where COM3 is a port which appears when you connect signal generator to PC.

hmm... COM3, sounds like something from the ancient past. I think I had my 2400 baud modem on COM2 and mouse on COM1 in mid-90's.

Jokes aside, I'll try some time later. Of course I'm using Linux. Will see if it works with mono.

[radiolistener]

hmm... COM3, sounds like something from the ancient past. I think I had my 2400 baud modem on COM2 and mouse on COM1 in mid-90's.

USB serial interface is very popular these days, it also use COMx name on Windows.

Jokes aside, I'll try some time later. Of course I'm using Linux. Will see if it works with mono.

it should works with mono with no issue. Just add "mono" before command and provide proper name of serial port.

[shapirus]

(moved to PM)

[eTobey]

Please delete your offtopic when you have noted down those details.

You can also use PM instead.