Tektronix 3 Series vs. Keysight 3000T X-Series Oscilloscopes
2019-06-12 | 20 min read
With there being so many high-quality oscilloscopes available today, it’s hard to determine which one is truly the best for your testing. There are important capabilities to consider that can make a world of difference in debugging. When looking for an oscilloscope, keep these three questions at the front of your mind:
- Can I quickly and easily capture random or infrequent signal problems?
- Can I capture signal events with the highest accuracy possible?
- Are there enough analysis capabilities to fully characterize my device?
If the answer isn’t an immediate “yes” to each question, dive deeper to be sure the oscilloscope will meet your testing requirements. Ensure the instrument provides fast results to increase efficiency and accuracy in your debugging.
The new Tektronix 3 Series oscilloscopes and the popular Keysight InfiniiVision 3000T X-Series oscilloscopes have some key differences that will make or break the questions above.
The 3 Series and the 3000T X-Series range in bandwidths from 100 MHz to 1 GHz and feature an 8-bit ADC. Both offer either 2 or 4 analog channels with the option to add 16 digital channels to analyze digital data.
However, unlike the Tektronix 3 Series, the InfiniiVision 3000T X-Series oscilloscopes provide an industry-leading waveform update rate allowing you to capture elusive glitches and anomalies not possible on other oscilloscopes. Combined with an extensive set of software options, analysis capabilities and probes, the 3000T X-Series enables you to make measurements you can count on.
Let’s take a closer look at the specifications and features that make this true, and how you can be sure you answer a resounding “Yes!” to the three key questions.
1. Can I Quickly and Easily Capture Random or Infrequent Signal Problems?
Capturing errors and glitches is the name of the game when debugging. You expect to see all errors in your signal to verify there aren’t any bugs for your customer to find. There are two ways the 3000T X-Series oscilloscopes can do this that no other oscilloscope out there can: the fastest waveform update rate in the world and the most intuitive triggering system.
Waveform Update Rate
When I say the fastest waveform update rate in the world, I mean it. The industry-leading 1,000,000 waveforms per second (wfms/s) update rate of the 3000T X-Series out runs the update rate of the Tektronix 3 Series by a long shot. In FastAcq mode, the 3 Series can reach up to 280,000 wfms/s, but it is important to remember that FastAcq mode limits other critical capabilities of the oscilloscope. In the normal acquisition mode, the 3 Series can reach roughly 50,000 wfms/s. That is 20x slower than the InfiniiVision 3000T X-Series.
So why should we even care about this?
A faster waveform update rate improves an oscilloscope’s probability of capturing elusive events. To understand why this is true, you must first understand what is known as oscilloscope “dead time”.
Every oscilloscope has an inherent characteristic called “dead time” or “blind time”. This is defined as the time between each acquisition the oscilloscope collects. In other words, it is the time it takes for the oscilloscope to process the previously acquired waveform. During this dead time, any signal activity that may occur is completely missed by the oscilloscope, as shown in Figure 2. This means that you always want the dead time to be as short as possible.
The waveform update rate specification tells you the number of acquisitions by the oscilloscope per second. The larger the waveform update rate, the more acquisitions per second, and the shorter the dead time.
The less dead time there is, the more likely you are to capture elusive events. The fact that the Keysight 3000T X-Series oscilloscopes are 20x faster than the Tektronix oscilloscope means that you are 20x more likely to capture errors.
Figures 3 and 4 show the difference between a slow waveform update rate, such as 50,000 wfms/s, and the InfiniiVision 3000T X-Series’ fast 1,000,000 wfms/s update rate. The infrequent glitch that appears in Figure 4 cannot even be captured by the slower update rate seen in Figure 3. A slower update rate can be extremely misleading. It leads you to believe your signal is free of errors, when in reality it may not be.
In addition to capturing glitches, a higher waveform update rate means your oscilloscope is more responsive and shows you subtle waveform details you wouldn’t otherwise see. These details can illustrate the presence of noise and jitter that may require further analysis.
This only scratches the surface of what you should know about waveform update rate. Read more on what it means to your testing and how you can measure it yourself in the whitepaper Can Your Oscilloscope Capture Elusive Events? Be sure you can see the infrequent glitches that may be hiding in your signals.
Provided the waveform update rate is fast enough to capture rare events, the next step is to isolate them. Isolating an event this rare can often be cumbersome due to the multi-step process and required calculations or guess work. With the InfiniiVision 3000T X-Series, you can isolate signal events by simply dragging your finger over it to create a Zone. From there, the only choice you have to make is whether you want the signal to intersect with that zone. And just like that, your rare or complex event is triggered.
Note that you can also use the zone triggering capability to isolate portions of a serial bus. For example, if you see a slew of CAN bus errors, you can easily isolate one error by drawing a box over it.
Due to the slower waveform update rate of the Tek 3 Series, it is likely you won’t even see that there are glitches that need isolating. But if you are fortunate enough to see rare events, isolating those events on the Tek 3 Series is only possible using complex advanced triggers. Most advanced triggers require some knowledge of the signal you’re testing, its shape, parametric qualities, and how to set up the oscilloscope properly to capture it. This can be difficult or nearly impossible in most cases.
Keysight’s zone triggering capability was designed as a “point and shoot” system to quickly isolate difficult signals within your design. Tektronix 3 Series oscilloscopes do not offer zone triggering.
Learn more about zone triggering and other tricks for the InfiniiVision user interface in the Scopes University Episode 5 Tips That Will Save You Time in Your Setup.
2. Can I Capture Signal Events with the highest accuracy possible?
When capturing pulses or packetized information, such as serial buses, there are many cases where you will have to capture several hundred occurrences of those packets. On most oscilloscopes, including the Tektronix 3 Series, the only way to do this is to zoom out on your signal (increase your time base). However, the catch is that this coincidently lowers your sample rate. So much so, that the captures you get of each packet are distorted and useless when you try to analyze them.
The standard segmented memory capability on the 3000T X-Series oscilloscopes allows you to capture long time spans and use the highest sample rate possible. This ensures you seeing the truest representation of your signal and obtaining highly accurate measurements.
Learn more about sample rate in the 2-Minute Guru Video Oscilloscope Bandwidth and Sample Rate Tutorial.
Figure 8 shows the signal detail captured in each error packet thanks to the high sample rate. When using segmented memory for serial bus decoding, you are also provided with a lister display that consists of detailed decode information and time stamp of each individual packet. You can easily click through each line to analyze the packets and make measurements on them. Tektronix 3 Series oscilloscopes do not support segmented memory acquisitions.
Learn more about oscilloscope segmented memory and how to set it up in the video What is Oscilloscope Segmented Memory?
3. Are there enough analysis capabilities to fully characterize my device?
Characterizing your device should always go beyond the basic measurement capabilities. There are many analysis applications available on the Keysight 3000T X-Series that can not be found on the Tektronix 3 Series. These applications make it easy to test various parts of your device.
Mask testing is extremely helpful in validation testing, both in R&D and manufacturing. The mask testing capability very simply creates a mask around your signal. If there are errors in the signal, the mask will be violated, and an error is collected in red along with pass/fail statistics as you can see in Figure 9. This is the most efficient way to perform pass/fail testing and determine whether a signal experiences errors over a long period of time.
Additionally, the InfiniiVision mask-limit testing capability is hardware based and can test at 280,000 wfms/s, which makes it orders of magnitude faster than the software-based mask testing found on oscilloscopes from all other vendors. However, Tektronix 3 Series oscilloscopes do not support waveform mask testing of any kind.
You can either create a rise-time mask around your signal with the “automask” function, or you can upload custom masks of a more complex, known signal. Keysight offers free mask templates for many common serial buses, such as CAN and ARINC429.
Hardware-based Serial Decoding
Keysight’s InfiniiVision series instruments are the only oscilloscopes that use hardware-based serial decoding. All other oscilloscope vendors use software post-processing techniques to decode serial packets/ frames. With these software techniques, waveform and decode update rates are extremely slow. Sometimes as slow as a few updates per second. This only gets worse when you have to analyze multiple serial buses simultaneously.
Remember: a fast waveform update rate increases the probability of capturing infrequent serial communications.
Figure 10 shows an example of a Keysight InfiniiVision X-Series oscilloscope capturing a random and infrequent USB error frame. The upper half of the oscilloscope’s display shows the decoded data in a “Lister” format, along with a time-correlated decode trace shown below the waveform. The lister capability is supported with all serial decoding options.
In addition to the hardware-based decoding, the Keysight 3000T X-Series offers further analysis for automotive buses with:
- Symbolic decode files for some protocols to make it easier to understand each packet.
- Eye-diagram mask tests to characterize rare errors. For more information on this, download the CAN Eye-diagram Mask Testing application note.
Frequency Response Analysis
If you’re working with any sort of amplifier, filter, or power supply you must analyze how your device will respond to various input frequencies. There are many cases where you might find a certain input frequency causes your device to malfunction. The Keysight-exclusive frequency responses analysis capability (FRA) allows you to analyze how your device is functioning in the form of a bode plot. This enables you to view the gain and phase of the input signal vs. the output signal.
The FRA application uses the oscilloscopes built-in waveform generator to perform a frequency sweep at the input of your device. The sweep range and number of points per decade are user defined. When you probe the input and output of your device and run the sweep, the oscilloscope measures and calculates the gain and phase at each frequency test point and plots the results in the form of a Bode plot as seen in Figure 12.
With the frequency sweep range along the X-axis and the gain and phase data along the Y-axis, you can determine whether your device malfunctions at any of the input frequency values. If the bode plot looks out of whack at any point, you may need to perform further analysis at that specific input frequency to determine the cause. Note that the Tektronix 3 Series does not support frequency response analysis.
To learn more about the value of frequency response analysis and how to properly set it up, watch the video How to Perform Frequency Response Analysis on an Oscilloscope.
The optional software decoding and advanced analysis capabilities are much more affordable on the Keysight 3000T X-Series. For example, the Tektronix Embedded option includes I2C and SPI trigger and decode only. Keysight’s InfiniiVision embedded software package includes I2C, SPI, UART, I2S, and USB-PD trigger and decode, along with mask testing and the FRA application. The Tektronix and Keysight software options are available at roughly the same price, but the InfiniiVision software package enables more capabilities to truly give you full insight into your design.
Check out what protocol and analysis options are included in each 3000T X-Series software package.
Compare Keysight and Tektronix
You can see the many advantages the Keysight 3000T X-series has over the new Tektronix 3 Series, but why take my word for it? Make the comparison between the Tektronix 3 Series and Keysight 3000T X-Series yourself. Check out the key oscilloscope specifications included in the table below. This data was pulled from the most recent versions of the datasheets as of June 11th, 2019.
This data was pulled from the June 6, 2019 version of the Tektronix 3 Series MDO datasheet (48W61535-1) and the August 7, 2018 version of the Keysight 3000T X-Series datasheet (5992-0140EN).
Looking at the data, it is easy to see that the Keysight InfiniiVision 3000T X-Series oscilloscopes allow you to confidently say:
- Yes, I can quickly and easily capture random or infrequent signal problems with the world’s fastest waveform update rate and simple zone triggering.
- Yes, I can capture signal events with the highest accuracy with the segmented memory capability.
- Yes, there are enough analysis capabilities to help me fully characterize my device, like mask-limit testing, frequency response analysis, hardware-based serial decoding, and application packages.
When analyzing oscilloscopes, be sure you are considering the entire system and the capabilities that can help you accelerate your testing. The 3000T X-Series is the superior solution for general electronic debugging and manufacturing validation testing. Make measurements you can trust to create designs that will change the future.