Oscilloscope and function generator for robotics research

[Snoopy]

Hello, I am in the process of setting up a lab at home to do high end robotics research.

I have a Fluke ScopeMeter 123 and a Kenwood FG273A function generator. The probes of both are missing. I am considering whether to buy a new set of probes or get a better digital oscilloscope and function generator. I guess it may be better to have a 2-4 channel oscilloscope. (Not sure if buying two is better than one in terms of cost and practical use), perhaps a color one if additional cost is not too much. Having a way to store the data may be good. Any opinion? Could you please recommend function generator and oscilloscope?

http://en-us.fluke.com/products/port...illoscope.html
http://www.recontest.com/index.php?m...oducts_id=1593

[KurtEck]

It will be interesting to see what others suggest here. I don't personally have a decent Scope. All I have is an old Parallax digital experimenters kit... Which was very primitive. At different times I have thought about picking up something else, but so far have not. But it probably depends on what it is you wish to use the devices for. For me I am mainly interested in the digital logic and timings. So:

What I use most of the time (99%) is one of my logic Analyzers. I have had 3 of their Analyzers. Their original one, which worked great and I gave that one away, then purchased their next one, the logic 16, which I still use, and when they came out with their new versions, I picked up a new Logic 8. One of the nice things about their new ones is they also can capture the analog data, so you can see things like if the voltage on the AX-BUS changes...

But if you are wanting to check out high speed analog data and the like, you may want something else...

[Snoopy]

It seems that the logic analyzers require a computer. Do they slow down the computer? What do you guys think of the Fluke 123? I haven't used it for many years. As far as I recall, the display was slow.

[jwatte]

The logic analyzers may use some CPU and USB bandwidth while you're capturing. They do not slow down the computer while not capturing data.
Fluke? Anything that shows you what you need to see is good! Exactly what it is is less important. Go for it!

[Snoopy]

I already have the Fluke 123 but the probes are missing. Considering to buy the probes or get another scope.

[KurtEck]

As I mentioned, I don't have anything decent... If it were me and it worked for you before, I would maybe start of buying new probes. I think I saw them on ebay for about $100.

I have seen a few threads about suggestions for scopes over the last couple of years in a few different forums, like:

https://forum.pjrc.com/threads/25730...loscope-advice
or
https://forum.pjrc.com/threads/32196...hat-to-use-buy

[Snoopy]

Thanks. For robotics research, what features of the scope would be good to have? For example, sampling rate?

[tician]

If I already had the Fluke, I would just buy some cheap BNC or banana plug probe (plus BNC coupler and a BNC to banana plug adapter if needed). Being handheld and battery operated is very advantageous, even if its other specs may not be quite as nice as a benchtop model. Can watch the signal while the bot is moving around in its natural habitat without extension cables or carrying around a big battery pack powering an inverter to get 110/220V with noise on the input power line. Also some isolation from mains 50/60Hz noise and a completely isolated/floating ground while on battery power.

[jwatte]

Robotics research may mean many things.

The two obvious use cases are:

- "what's the voltage and signal quality of this line?"
- "what data is going on this digital bus?"
- "how much overshoot is there on this motor driver PWM bridget?"

For analog audio frequencies, and various PWM controlled power electronics (DC converters, motor drivers, etc,) and busses like SPI, I2C, UART and the like, a 50 MHz sampling rate is usually sufficient, and 100 MHz would be plenty. 20 MHz of your Fluke will work for most cases, unless you need to debug something like an SPI serial display.
An affordable bench scope with an easy-to-read display would be sufficient (and maybe not much more expensive than factory Fluke probes ...)
I have a $279 Owon. Rigols are fine too. Stay away from the SainSmart ones. Here's a good one: http://amzn.to/1Sqm5zs
Portability of the Fluke is cool though.

However, for the "what data goes across this line," a logic analyzer is going to give you better data. And the Saleae family is my favorite for this.
When developing hardware, an oscilloscope is your friend. When developing low-level software, a logic analyzer is your friend. When developing high-level software, some logging-and-display solution in your computer is your friend.

There are other more specialized use case:
- How well is this radio module tracking its RF frequency?
- Where do these video glitches come from?
- What's ailing my gigabit Ethernet signal quality?
- Is there a memory bus bug in my host CPU?

Those need ... very expensive scopes and logic analyzers.

Anyway. From where you are now, I'd start with some cheap BNC connectors and an adapter, like tician suggests.

[Snoopy]

I gave my Fluke 123 to my relative. I need to buy a new one. Any other good product suggestions?