RoadTest: Tektronix TBS1202B-EDU Oscilloscope
Author: gpolder
Creation date:
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?: Desktop scopes from Rigol, Siglent, Atten, Lecroy, ...... USB scopes (picoscope).
What were the biggest problems encountered?: none
Detailed Review:
I'd like to thank Tektronix and element14 for choosing me to take on this particular RoadTest. I hope this review will be useful for the community, and specially for the educational market, where this scope is designed for.
Until last year I often used my old analog 15 MHz TRIO oscilloscope. Last year I switched to a Siglent 70MHz digital scope, which was a big improvement, I could do measurements which I only could only dream of before, like evaluating the pulse train of a 433 MHz domotica receiver. Then in february I got the chance to review the Picoscope 2205A which is a PC based oscilloscope, with its particular advantages and disadvantages. You can read about my findings here: http://www.element14.com/community/roadTestReviews/1705. And now I'm very happy that I can review the Tektronix TBS1202B-EDU, for two reasons:
(*) did you know that there are a lot of collector of these old scopes? A retired colleague of mine does, and already has a nice collection of working scopes.
Regarding the scope tests, I follow the same pattern as my picoscope test, which was based on the excellent articles on reviewing oscilloscopes by Colin O'Flynn of circuit cellar.
But before that I like to show you the usual .......
A packing list of all items in the box.
A calibration certificate! This is the first scope I own which comes with a certificate.
Compliance and Safety instructions in several languages.
CD with software. Tektronix could have economize on this one, since the software on the CD was already outdated, and I downloaded the latest versions from their website. Also in de box was a note with instructions on updating the firmware of the scope. The scope was equipped with firmware version (FV 1.11) the note hase info on upgrading to 2.0. I followed the instructions and it was quite simple to do. While writing this review even a newer version (2.02) was put on the website, so this is the version I finally installed on my scope. The road test below is partly done with version 2.0 and partly with 2.02.
Two TPP0201 passive 200 MHz 10x probes.
Colored rings for probe identification and a probe adjustment screwdriver.
An us power cord, which does not fit quite well in my wall socket. Luckily I had some european cords laying around.
And there is the scope itself, with a not to miss sign to register the device, which I immediately did. I had to sign up on the tektronix website for that, and also for downloading the latest versions of the software, manuals and firmware. So for a little bit of my privacy I got a up-to-date scope, and the chance to win their best selling scope.
Lets start with the serious stuff:
Colin gives a nice consideration for choosing a pc-based or stand-alone instrument. Personal preference determines your choice.
In a previous road test I reviewed a PicoScope 2205A a PC-Based instrument. I have some experience with old analog low bandwidth scopes and
recently with an Siglent digital scope. The Siglent is equipped with an usb port and can also be operated from a PC.
I have to say that I never used this option, I prefer to use a scope standalone. The same counts for the TBS-1202B, there is software available to operate it from a PC, but I prefer to use it in stand-alone mode. A nice option what all modern digital scopes have is the ability to dump screens to an USB stick. This is very handy to document your measurements. Also for educational use this is a must where students can use those screen dumps in their report. The TBS-1202B-EDU has even more options to support teachers and/or students. I will come to that later.
The screen size of the TBS-1202B-EDU is 7 inch, which is the same as my Siglent scope, but the resolution is 3.5 times higher (800x480) compared to (480 x 234). This makes a big difference as can be seen below.
TBS 1202B screendump.
Siglent screendump.
The ground for the input channels of this scope is connected to system 'Earth', as is with almost all standalone scopes.
For measuring differential signals with isolated inputs you will need a dedicated probe.
Both the scope as the tpp0201 probes are rated at 300V rms.
For input you can choose between AC and DC (or ground) coupling.
The input range is from 20mV/div to 50V/div. At 20mV/div the bandwidth is limited to 20MHz in order to reduce display noise and other unwanted high frequency components. With the other input settings you can choose to limit the bandwidth or not.
You can set the probe attenuation in the menu in order to display the real measured values.
There is no 50Ohm input impedance available, but when you need that, you can buy “feed-through” terminators for about $15, which operate at up to 1-GHz bandwidth. You simply add those to the front of your oscilloscope to get 50-Ω terminated inputs.
The scope comes with two probes (part number TPP0201). The probes are rated at 200 MHz and have a fixed 10:1 attenuation. Impedance is 10Mohm < 12 pf.
The quality looks good, it doesn't have a spring-loaded tip, but the size of the tip is pretty small. The compensation trimmer is on the connector. A plastic adjustment screwdriver is provided, and also a marker band set for labeling the probes.
Since I didn't have a calibrated signal source up to 200 MHz available, I could not precisely check the analog bandwidth.
In stead I looked at HF signals at 150 and 450 MHz. It appeared that both could be displayed properly. This was not the case for my 70 MHz Siglent scope, on which I could see the 150 MHz signal, but not the 450 Mhz.
The sample rate of the TBS-1202B-EDU is 2 GS/s, which means 10 samples per period for a 200 MHz signal. Note that in contrary with other scopes this one is equipped with two ADC's, which means that the sample rate for the second channel again is 2 GS/s.
Certain oscilloscopes have an equivalent time sampling (ETS) mode, which advertises an insanely fast sample rate. The picoscope I reviewed earlier does have this mode, which has its advantages and disadvantages. The TBS-1202B-EDU doesn't have this option and I have to say I don't miss it.
The vertical resolution is 8 bit, which means that there are 2^8 = 256 levels to display the waveform. Visually this is enough. There is no resolution enhancement like with the picoscope previous reviewed. Although for the YT display (amplitude versus time) 8 bit is sufficient, for spectrum display in the FFT mode the signal is hampered by quantization noise. You can find an illustration of this in the article of Colin O'Flynn (OFlynn_Part2_Fig4.jpg).
The TBS 1202-EDU standard can store 2.5k samples, which is not much. If you need to troubleshoot a signal, the problem needs to be close to the trigger in order to be seen. Surprisingly, my cheap chines Siglent scope has a memory depth which is 8 times larger (2MS). There is a data logging possibility, which kan log a large amount of data to an usb flash drive, but this function is not available for the EDU model.
As most modern digital scopes the TBS 1202-EDU provides the option to display a spectrum of the measured signal by performing fast fourier transform (FFT).
Although this is a nice feature, you can't compare this to a real spectrum analyzer. Furthermore PC based scopes like the picoscope from my privies road test tend to perform better in this sense than desktop scopes. I this case the FFT buffer is 2048 points, which is to less to zoom in on higher frequency signals. For low frequency signals you can lower the sample rate, but as already said, PC scopes are more flexible in this sense. Moreover, the manual gives a clear explanation about using the FFT and how to interpret the signal and how to deal with aliasing etc. There are some options available for zooming and selecting different anti aliasing filters.
Information about differences between buffer sizes and the resulting FFT signal are nicely described on Evaluating Oscilloscopes (Part 3) | Circuit Cellar.
A feature consider almost a “must-have” by Colin O’Flynn | Circuit Cellar is a segmented buffer. In which you can configure the oscilloscope to trigger on a certain event, and it will record a number of waveforms of a certain length. Unfortunately I didn't find this option. As already said there is a data acquisition option, but not for this (EDU) model.
This topic is about control of the scope from a PC. This is possible for this scope, but I didn't test it because I don't see the added value a lot. You easily can store screen captures to a memory stick connected to the front USB port, which is a very valuable feature which all digital scopes nowadays have.
But there is more to say:
This educational (EDU) version of this scope has the option to let students perform their lab work directly on the oscilloscope and record their progress in a report file consisting of oscilloscope screen captures. A PC Courseware Editor helps you create lab descriptions and instructions on a PC and upload the material directly onto a TBS1000B-EDU oscilloscope. Students can access the content on their TBS1000B-EDU oscilloscope by pushing the oscilloscope’s dedicated, front-panel Course button. Using the oscilloscope’s soft keys and the multipurpose knob, they can access up to eight courses which can have up to 30 labs each. To accommodate situations where and instrument is used for several classes, up to 100 MB of course material can be stored on the oscilloscope. Once the students choose a lab, they can review the overview section, perform the lab using the step-by-step procedure, collect data, check and save the data results and generate reports that show the waveforms created for each step in the procedure. They perform all of this work directly on the oscilloscope.
The associated Tektronix Courseware Web Page (http://www.tek.com/courseware) lets you exchange course material or get inspired by reviewing ideas from your peers. You can share courseware materials between different labs, fellow professors at the your institution or between educators from around the world.
I think this is a very valuable option, not only for college students, but for everyone who likes to learn tips and tricks to perform certain measurements. On the courseware webpage there are currently a number of interesting lessons available. On the other hand it comes at a price, since the data-acquisition and limit testing mode are not available for the EDU version. Furthermore it is not a big deal to put a PC next to the scope for use with lab exercises. And typing some text for entering your lab ID using the multipurpose knob is a pain. Saved lessons are written in HTML on the memory stick, so for finishing your report it needs to be imported in your text processing software. I'm curious how students judge this option, please comment on this at the bottom of this review.
Serial protocol analysis is a great option, unfortunately this scope doesn't have this.
In section 3-4 I already explained about the EDU option. Regarding other options like math on two channels, comparing with a reference signal etc. the features are comparable to other low end desktop scopes.
The oscilloscope provides three types of triggers: Edge (falling and rising), Video, and Pulse Width. The source can be the AC power line (available only with Edge triggers), or any signal connected to a channel BNC or to the Ext Trig BNC.
Trigger modes are Auto (default), Normal and Single. The Auto mode forces the oscilloscope to trigger when it does not detect a trigger within a certain amount of time based on the horizontal scale setting. You can use this mode in many situations, such as to monitor the level of a power supply output. The Normal mode updates displayed waveforms only when the oscilloscope detects a valid trigger condition. The oscilloscope displays older waveforms until the oscilloscope replaces them with new ones. To perform a Single Sequence acquisition, push the Single button.
As most oscilloscopes, the 1202B also has an “external trigger input” on the front panel of the scope. This external input doesn’t display on the screen but can be used for triggering.
Currently some scopes, and especially PC based scopes are equipped with some sort of function generator. The 1202B unfortunately doesn't. The only signal this scope outputs, is the 1kHz, 5V calibration signal, which can be used to adjust the probe compensation.
One final issue of interest: In certain applications, you may need to synchronize the sample rate to an external device. Oscilloscopes will often have two features for doing this. One will output a clock from the oscilloscope, the other will allow you to feed an external clock into the oscilloscope. Unfortunately none of these options is available for the 1202B.
Below is a picture of the TBS 1202B-EDU next to my Siglent SDS 1072CML.
It's amazing how similar these scopes are in sense of button and connector layout. The same counts for other brands like Rigol, Atten etc.
Screen on the left, then menu buttons, then channel one (always yellow), channel two (blue) trigger and probe compensation.
Buttons an knobs of the channels and triggers above the connectors and other function buttons above.
Except for the difference in screen resolution as already mentioned, there are two other remarkable differences:
So to finish up this review, in conclusion, the TBS 1202B-EDU scope is great. I really like the bandwidth of 200 MHz. Compared to Chinese scopes from Siglent, Rigol, Owon etc, the price is good, you get a real Tektronix for a price which is just the same or slightly higher than comparable 200 MHz models. I'm surprised by the small buffer size of 2.5 kS. Is there a particular reason for that?
The integrated courseware option of the EDU model is great, but it comes at the price that this model doesn't support limit tests, data logging, and trend plots.
Thanks for reading, and if there are any questions left, please post them below this article.
