Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Tektronix MDO3034
What were the biggest problems encountered?: Only a very minor note that the scope can slide a bit on slippery bench tops when pushing buttons.
I have the exciting privilege of road testing the Rohde and Schwarz RTB2004 digital oscilloscope. This instrument is much more than a powerful oscilloscope - it includes a very capable function generator, spectrum analysis, serial bus decoding and 16 channel logic analyzer capabilities. There are so many features, I expect this road test is going to take quite a few sessions to cover them all. As I go through my exploration of the various capabilities I will be learning how to take advantage of all the clever little features that add power and productivity to the system. Initially when focusing on a particular aspect I may not be exploiting all the related features that would make the task easier or better, but I hope to cover most of them at some point during the road test. I want to publish my exploration sessions as I do them, so they are fresh in my mind and you don't need to wait for all of them to be complete before seeing progress. Be sure to check the test plan below to see if the blog is complete or still growing.
Road Test Plan
The RTB2004 user manual has 16 chapters which will form a rough structure of topics for this road test, so there will be at least 14 exploration sessions for this aspect of the road test.
Additionally I want to blog about specific uses of this instrument in real projects where I will show it in action troubleshooting real circuits and real problems - I have lots of those. Some of them have been sitting around for a while because I just didn't have enough instrumentation to make it worthwhile trying to troubleshoot further, but with the RTB2004 that has now changed.
A few real circuirts that come to mind are:
Pulse Induction Metal Detector
BBC micro:bit I2C
I do lots of projects with piezo-electric sensors and actuators. Some of these projects push the technology in new directions and I need to look at transient response as well as frequency response and resonances. I want to use the RTB2004 to help analyze these signals, including making use of its FFT capabilities.
I will probably think of more as I dig through old project and definitely will come across excellent uses in the future while developing new designs.
Before delving into the test plan, I wanted to start with a an appetizer that showcases the cool capabilities of this scope to plot X-Y data.
If you have a scope like this, you can play the stereo audio sample I embedded to display the same image.
This instrument is over the top gorgeous. The more I use it, the more I like it and the luckier I feel that I was chosen to be a road tester. The display is simply spectacular, and I haven't even beamed it onto a big screen yet (but I will). For me this instrument represents a paradigm shift in how I troubleshoot, it combines so much powerful functionality in one instrument and streamlines the tasks so efficiently that it will get used far more than my previous instruments. Features like the deep storage memory, the high resolution A/D, the 4 channels plus logic probes, and the FFT capability allow troubleshooting problems I couldn't even tackle before.
So far I have been using the scope without reading the manual to see how intuitive the operation is for my level of competence. It probably shows in my rudimentary use of the features, but I am finding it easy to navigate and the amount of information on the screen is outstanding. It is not intuitive for me to make scope adjustments with a touch screen, but as soon as I try it, it starts to become second nature and I expect it will get harder to go back to the old knob twiddling instruments. This instrument is obviously so capable and so versatile that every electronics developer would benefit greatly from having one available.
Exploring the Function Generator
The function generator includes a wide variety of built-in waveforms with great versatility and programmability. It can take basic waveforms and add offsets, sweep functions, modulations and noise. And they can all be adjusted with digital precision.
Complex waveforms are easily programmed. The responsive touch screen and intuitive menu structure really help make this complex capability into a highly useful feature.
Saving Captured Data
Saving waveforms has been simplified down to a single button. A lot of effort has obviously been spent on making complex functionality as simple and intuitive as possible.
Remote Viewing and Control Operation
Remote viewing and control is seamlessly built-in to this instrument, adding very impressive dimensions to its applications. I have not yet explored the true power of connecting to a remote computer for automated test applications, but that is clearly something this instrument was intended to be able to handle.
I found the remote connection facilities to be surprisingly easy to set up, very responsive and spectacularly impressive. I'm now looking for an excuse to bring it to work and run it on the giant screens in our conference rooms.
Measuring Frequency, Period and Voltage of a Servo Signal
Comprehensive measurement capabilities are very easy to use, including a one-touch intelligent multi-measurement button, and the screen is so large, lots of information can be displayed without obscuring the signal.
Power Supply Noise Investigation
The next section is a bit of a detour - I noticed my videos have some hum in the audio signal, so I decided to use the scope to have a look at the problem:
Here is a picture showing the noise when the power supply is under load:
This image shows all 4 channels in use - all displaying at 20mV/div.
The other signals are mainly to show that the noise is not everywhere - it is mainly on the camera power supply. The noise is a few hundred millivolts, which can be handled by many devices that have their own regulators and many low-quality power supplies have noise in this range. In fact the camera works okay off this noisy supply, however it does cause audible noise in the microphone circuit, so I need to clean it up. It was kind of nice to get to use the scope to improve the audio in its own road test blog.
Incidentally, the image above shows that this scope can display a spectacular amount of detail - far more than most other scopes.
Fast Fourier Transform Capability
Another whole instrument capability built into this scope is the ability to perform spectrum analysis using fast Fourier transforms. It is often hard to justify buying an expensive spectrum analyzer, but this powerful capability can be extremely useful when measuring bandwidth or performance in the frequency domain.
Here is a quick look at how this scope displays the spectrum of some common waveforms:
Don suggested I show the effects of a filter on a noisy signal:
Having both a traditional oscilloscope and a spectrum analyzer in the same instrument is a natural and even more useful combination.
Serial Bus Decoding
The RTB2004 has an outstanding ability to decode serial data. It can handle I2C, SPI, UART, CAN and LIN busses and display the decoded data as binary, octal, decimal, haxadecimal or ASCII.
There are numerous methods to trigger on frames, bit patterns, byte count, etc. It and capture different word sizes, frames and packets, and it can decode both transmit and receive at the same time on different decode channels.
Its deep memory allows large amounts of data to be captured. This is a quick example of decoding SPI data sent from a BBC micro:bit to a Nokia 5110 LCD:
The ability to capture, decode and save these long GPS NMEA messages is a real time saver in collecting data for analysis. It avoids having to get hardware and software working just to get a look at the data. Trying to do this with a normal scope is very tedious and error prone, even assuming the scope has enough memory to capture a complete message. This scope makes it seamlessly easy - storing the decoded data in spreadsheet compatible files.
Acoustic Resonance Measurement
Another interesting application for this instrument is acoustic resonance measurement. I happen to need this capability in the IoT On Wheels Design Challenge. This oscilloscope is such a complete instrument, it allows exploration of my application without me having to build anything. This is a spectacular time saver and it is such a fortuitous circumstance that I have access to this amazing instrument precisely when I need it. You can see a quick video blog about it here:
I had to split the video to get it to upload...
Here I started using the FFT capability to look at resonances.
Here I explore using a surface speaker exciter to create resonant frequencies:
Pulse Induction Metal Detector Analysis
This scope is absolutely great for analyzing and tuning this pulse induction metal detector. This particular circuit has four timing circuits that need to be adjusted relative to each other and a measured signal.
I designed this circuit long before I had an RTB2004 and it was always extremely difficult to see what was going on with the timing and tune the circuit properly. With this scope everything is very clear and all relationships are easy to analyze.
Here is a video of the antenna and circuit detecting all sorts of coins from around the world:
Here is a link to the blog about the metal detector:
The more things I try to use this scope for, the more I love it.
I'm hoping to get a look at a BBC micro:bit next....
Nice intro to your road test Doug, I think you are going to have many many hours of fun with this instrument. I've looked at the specs and seen various other reviews and it does look amazing! I can't wait…
Well done John! Interesting the approach to test with many different use-case.
Hey dougw, you seem to be very impressed by this oscilloscope. So far the video clips you have posted support your enthusiasm and I look forward to seeing more of what this instrument can do in your capable…
I am so jealous lol
Doug - I'm really enjoying your experiments. I'm going to show the acoustic resonant measurement to my son tonight - he'll think it is super cool!
The RPi has plenty of horsepower and because it is a popular platform it will be very useful and rewarding to become familiar with it. I like Racheal's Bleaglebone Blue suggestion, but the RPi will be lots of fun to experiment with and there is a lot of community help available if you need it.
Thanks for your input Douglas.
I am not worried about cost (too much)...I have already committed quite a bit of money to the car kit and other kits, so that a wide variety of capabilities are available. I have a wide arrangment of sensors, RTC, extra camera, extra pi-zero on top of the pi -3, interface cables, keyboards, speakers etc. I am hoping the platform allows for easy experimenting with small circuits. The car kit, I believe is mostly assemble and then it is ready to go. I am hoping this ease will interest my son, into further learning.
As far as those industry standard buses go, that is a good point you make.That will be a bit more cost and footprint, but hopefully acceptable for a prototyping environment.
There seems to be quite a lot of interest/publicity around the R-Pi driving its success. Maybe more Pi based boards and adaptor boards, like the compute module will be built, helping with robotics specific type work.
You never mentioned processing power. Is the R-Pi powerful enough as compared to the other competitors (with matching form size and cost)? From what I have read (possibly advertising propaganda) it seems to be.
The RPi is a great little computer and people do use them for robotics, but they aren't really designed for robotics applications.
Hardware wise, the built-in interfaces like HDMI are important but they are aimed at general computing applications, not robotics.
The RPi is not inherently designed to plug and play with servo motors, PWM motors, control systems, quadrature encoders, analogue sensors, CANBUS, LINBUS, etc.
Expansion "hats" are available for some of this, but it gets expensive and the form factor gets unwieldy.
Power supplies for RPi in an expanded hardware scenario also add complexity.
On the software side, RPi does not typically run a real-time operating system.
Also writing drivers for robotics peripherals requires extensive knowledge or a significant learning curve.
It is possible to utilize other people's work and build up functionality that way, but the system ends up with a lot of complex third party code that is not well understood and it can be very difficult to troubleshoot such systems.
If there is a specific robotics requirement, the RPi would almost never be the ideal hardware or software platform.
It mostly makes sense to use RPi for robotics if you are already very familiar with it, and do not want to go through the learning curve on a different platform.
I would not discourage use of RPi for robotics, just be prepared for the implications - it will likely be more expensive and more time consuming than competing solutions.
As Doug says, it's a major challenge to build test equipment suitable for the leading edge technology, at that very high end it's a lot of exceedingly custom designs, you certainly couldn't build them with commercially available parts, they tend to be full of custom ASIC's and RF circuits. There was a great detailed look at a 100GHz oscilloscope on The Signal Path a few years ago. Well worth a watch to see what goes into making such a device.
You are correct, it is definitely a major challenge for test instrumentation to keep up with leading edge high speed electronics, but the engineers at Rohde and Schwarz seem to do a pretty good job of it. They make a spectrum analyzer that goes from 2 Hz to 85 GHz.
Good luck with the RPi - they can be a bit tough to work with for robotics.