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Oscilloscopes Blog

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Written by Min-Jie Chong

 

The Need for New SAS-4 Storage Standard

The increase of data traffic due to the advent of internet of things has driven the need for faster backbone and storage transmission to meet this need. The Serial Attached SCSI - 4 (SAS-4) is a new enterprise storage standard that is being created to meet this need. It supports data rate of 22.5 Gb/s which doubles the data throughput of previous generation SAS-3 standard.

 

What is SAS-4 standard?

The SAS-4 working committee decided to leverage the OIF-CEI 3.1 specification to speed up the development of SAS-4 specification. The consequence is the test methodology in SAS-4 will deviate from the previous SAS generations. In the previous generation, reference transmitter and receiver are defined, which describe how a “perfect” design would handle the outgoing and incoming signal. However, the OIF-CEI specification does not provide any reference designs, which changes how the SAS-4 designs are tested.

 

First thing first, accessing SAS-4 signals

SAS-4 specification has a new recommendation of the insertion loss profile of the test fixture being used for testing. The intents are to more accurately test the 22.5 Gb/s signal without the effect of test fixtures so the industry can get more consistent results and avoid marginal design from passing using better test fixtures, but not meet the actual performance in real world. Keysight has found the Wilder Technologies SAS-3 test fixtures to be suitable for SAS-4. They perform better than what the specification recommends. This is a good outcome because it is easier to supplement loss using the embedding methodology, using Keysight’s N5465A InfiniiSim software toolset.

 

Oscilloscope bandwidth requirement

The SAS-4 specification does recommend a minimum of 33 GHz oscilloscope bandwidth for transmitter test. Keysight’s Z and V Series oscilloscope models (i.e. DSAV334A, DSAZ334A and DSAZ504A) have bandwidth that meet this requirement.

 

Making SAS-4 transmitter measurements

Keysight’s new N5412E SAS-4 transmitter test application provides step-by-step instructions to guide an engineer through the process of configuring the test setup, selecting the tests and connecting the signals to the oscilloscope. After everything is setup correctly, the application will then make the necessary measurements and analysis, and then presenting a pass or fail status of the signal under test. A test report will also be automatically generated at the end of this process, documenting the test results and measurement screenshots. This can really remove the complexity of learning the specifications, which can save engineers a lot of time and effort.

 

 transmitter measurements

Figure 1: Keysight N5412E SAS-4 automated test application for the oscilloscope, which covers all the required transmitter test requirements.

 

The application includes all the transmitter requirements listed below.

  1. Spread spectrum clocking (SSC)
  2. Transmitter signal quality (TSG)
  3. Transmitter equalization (TXEQ) coefficient request and circuit response
  4. Out-of-band (OOB) signaling

 

SAS-4 is highly susceptible to crosstalk

SAS-4 interface packs a lot of high speed lanes densely in a connector, which makes it highly susceptible to crosstalk effect. It is important for oscilloscope jitter separation algorithm to be able to handle presence of crosstalk. The earlier, more common jitter separation with the “spectral” method is not capable of separating crosstalk from random jitter. Keysight oscilloscope uses a newer, more advanced “tail fit” method that can correctly separate the effect of crosstalk from the random jitter.  

 

After determining the presence of crosstalk, the Keysight N8833A crosstalk analysis tool can provide deep analysis and debug capabilities. The tool is able to identify which potential aggressor is aggressing at the victim, quantify the amount of crosstalk the aggressor is coupling into the victim and then removing the crosstalk from the victim signal. We can check if the design can pass the specification and how much margins can be recovered without the crosstalk. This can assist in making important design decisions such as whether improving the crosstalk can make our design passes the specification, and which part of the design needs to be fixed.

 

eye diagram

Figure 2: Keysight N8833A crosstalk analysis application showing the eye diagram before (top) and after (bottom) removing crosstalk from the signal. The eye height and width can be measured to see the improvements of the signal without crosstalk.

 

Vendor specific SAS-4 receiver equalization implementation

While SAS-3 mandates 5 tap of decision feedback equalizer (DFE) implementation to recover a closed eye at the receiver, the SAS-4 does not mandate any specific number of taps. It is left to the vendor specific implementation how many taps will be sufficient to open up the eye. Keysight’s N5461A equalization tool with DFE allows engineers to recover the eye with up to 40 taps. Engineers can specify the value for each tap and check the effect on the eye opening or use the tap optimization feature that will compute the values based on the constraints given by the engineers. This feature is very useful to reproduce the eye opening that the receiver sees after the DFE process.

 

equalization tool

Figure 3: Keysight’s N5461A equalization tool is used to open up the closed eyes at various SAS data rates, and what the SAS receiver would see after DFE is performed.

 

Summary

Keysight has been a key contributor to SAS-4 and previous standards, and understand the test requirements. New test and interoperability challenges exist at 22.5 Gb/s and Keysight has the solutions to overcome these challenges. The automated N5412E SAS-4 test application covers the complete transmitter test requirements. Other tools such as the N8833A crosstalk analysis and N5461A equalization application can provide deep analysis and debug capability. In addition, Keysight has other comprehensive test solutions from design simulation to physical layer testing that includes transmitter, receiver and channel for SAS-4 standard.

Understanding the effects of crosstalk in high speed communication circuitry and pin pointing the root causes have been extremely hard for designers, until now. Keysight’s industry leading N8833A and N8833B software not only identifies the crosstalk but also allows the user to determine the sources. In addition, it can remove the effects of the crosstalk and determine the recovered margin.

First let’s discuss the many types of crosstalk and their origins.  Crosstalk has become an important issue as data rates have increased, and more and more lanes are being packed into smaller and smaller spaces. The amplitude interference of crosstalk impacts the signal fidelity of a communication eye diagram, essentially causing the eye to become more closed. The majority of crosstalk is caused by capacitive or inductive coupling between multiple transmission lines and/or power delivery networks. Prominent sources are near end crosstalk, far end crosstalk, power supply induced jitter, voltage dependent amplitude noise and simultaneous switching noise. Transmission line crosstalk is the result of electromagnetic interference between electrical components and is mainly caused by capacitive or inductive coupling. Forward traveling or far end crosstalk travels the same direction as the aggressor signal and its energy grows and it travels down the transmission line resulting in amplitude bulge in one area of the eye pattern. Reverse traveling or near end crosstalk is constantly moving away from the aggressor edge and is spread somewhat evenly over the transmission line resulting in a smearing of the entire eye pattern. Power supply aggressor crosstalk is created by noise on the power rail supply and caused phase noise changes or jitter. Voltage dependent amplitude noise crosstalk adds noise to the voltage and ground bus and causes non-linear effects on each logic level. A power supply can also be a victim of crosstalk due to simultaneous switch noise on serial lines and this is caused parasitic inductances lying between board and system ground and is also known as ground bounce. The above crosstalk origins, effects and sources may seem overwhelming at first but Keysight’s N8833 application greatly simplifies both the user knowledge and effort needed to get to root cause.

 

Legacy methods of determining crosstalk digital communications systems has relied on the process of selectively disabling some channels while enabling others. This process usually took significant time and effort. Power supply noise adds yet another analysis hurdle creating a non-linear transfer on the serial data timing called the Time Interval Error and has been difficult to solve and correlate. Past troubleshooting methods also required special design and test modes to analyze the crosstalk. Another challenge is that many times crosstalk aggressor signals are created within a package or in a system that is not accessible to probing.

 

The new Keysight crosstalk analysis application meets all of the above challenges by:

1) identifying the sources of crosstalk affecting the victim,

2) quantifying how much each aggressor is disrupting the victim,

3) removing the effect of crosstalk from the victim signal for analysis and

4) checking how much design margin is recovered when crosstalk is removed from victim.

 

Other features of the Keysight software are:

1) analyzes up to four signals (aggressors or victims) at once,

2) requires no crosstalk simulation or model,

3) identifies and reports the amount of crosstalk present on victims from each aggressors,

4) plots waveforms without crosstalk,

5) compares them with the original waveforms using scope tools such as eye diagram and jitter separation to see how much margins can be recovered.

 

The key types of crosstalk that can be analyzed are:

1) transmission line aggressors: Near-End Crosstalk (NEXT) and Far-End Crosstalk (FEXT),

2) power supply aggressors: Power Supply Induced Jitter (PSIJ) and voltage-dependent amplitude noise,

3) power supply victim: Simultaneous Switching Network (SSN).

 

Finally the software can report the results in different ways:

1) Inter-Symbol Interference (ISI) magnitude of the victim on itself,

2) crosstalk magnitude of the transmission line aggressors on the serial data victim,

3) crosstalk magnitude and jitter of the power supply aggressors on the serial data victim,

4) crosstalk magnitude of the transmission line aggressors on the power supply victim.

 

The Keysight crosstalk application N8833A/B is the most comprehensive solution in the market enabling a closed loop design cycle, saving designers both time and money. This application effectively solves the challenges mentioned above by enabling designers and engineers to: 1) identify which signals are coupling into your victim signal, 2) quantifying how much error each aggressor signal adds to your victim signal, 3) see what the victim signal would look like without the crosstalk and how much eye margin can be recovered without the crosstalk, 4) determine if the existing crosstalk justifies a design change and where to improve the circuit or system design.

Written by Sheri Detomasi

 

There are many similarities and differences between oscilloscopes and wideband digitizers.  How do you know which is the right tool for your measurement need? 

 

Oscilloscopes use wideband data converters and typically provide a broad range of functionality.  They provide probing and visualization of time variant waveforms.  When debugging or troubleshooting a project, it’s important to see as much signal detail as possible.  Oscilloscopes typically provide waveform reconstruction filters for improved signal visualization. If the ADC waveform data is displayed with no waveform reconstruction, you would see a confusing cluster of points as shown in (a) below.  Whereas (b) shows with the waveform reconstructions.  Same with fast rise-times in (c) and (d)

 Waveform reconstructions

 

For visualization purposes, an oscilloscope also has continuous waveform acquisitions in display memory.  An oscilloscope can produce an extremely high waveform update rate > 1,000,000 waveforms per second.   Shown below, with an oscilloscope’s high speed waveform update rate and its ability to pick up glitches or unexpected events.   

 

Different measurement capabilities

 

 

 

Many oscilloscopes have a wide range of automatic measurement capabilities like rise/fall time, delay, peak to peak, zone triggering, etc. In addition, with the wideband acquisition, oscilloscopes are also ideal for high speed digital test, emerging serial protocols, and advanced communications.  With the wide bandwidth, vast measurement capabilities and robust user friendly interface, weather in bench or modular form factor, an oscilloscope is a general purpose tool that can be used for many applications. Keysight’s modular oscilloscopes, the M924xA series, range from 200 MHz to 1 GHz and feature the same functionality you would find on a benchtop oscilloscope.

 Digitizers

 

Digitizers are more purpose built.  Their main goal is to capture many channels of data with high resolution to achieve the best measurement fidelity.  While oscilloscopes typically have 8- to 10-bit ADCs, a digitizer is usually 10- to 16-bits.  This doesn’t tell the whole story though.  There are other noise factors to consider such as ADC differential and integral nonlinearities, thermal and shot noise, input signal distortion, as well as sample aperture jitter and ADC sample clock noise.  Therefore, a better measure of the resolution is the ENOB, or Effective Number of Bits.  One technique digitizers use to get even more ENOBs is digital down conversion (DDC).  DDC is extremely valuable when analyzing a small slice of spectrum within a wideband acquisition, allowing the user to reduce the bandwidth and ‘tune and zoom’ into a specific part of the signal.  Here is the digitizer DDC block diagram.

 ACD memory

 

 

It’s common for oscilloscopes to provide extremely wide bandwidth while digitizers provide higher ENOBs over smaller bandwidths. 

 

In normal use a digitizer will acquire many channels of data over longer time periods, producing lots and lots of data.  The data is either analyzed onboard or sent to a PC or storage device for post processing. For this reason, digitizers typically have deep memory buffers behind each ADC and very high data transfer rates.   For on-board processing, it’s useful to access the digitizers internal FPGA to do some real-time signal processing.  This allows the data processing and manipulation routines to reside in the hardware at GS/s processing rates and is useful for embedding algorithms to implement onboard custom filtering, correction routines, data reduction schemes as well as application specific routines.  This provides very specific application needs at very high speeds.  Here you can see a process for acquiring the data, processing, extraction, analysis and playback.

 

 

A digitizer is always connected to a PC and is controlled through a computer soft front panel or an automated program.  With this, there is less of a need for high-speed waveform update rate to the computer display.  The purpose-built nature of a digitizer makes it more of a dedicated tool for specific applications.

 

Characteristic

Oscilloscope

Digitizer

Ideal use

Interactive test and analysis with high performance user interface

Data capture with deep dive software analysis

Resolution and dynamic range

Good

Better

Measurement and analysis

Better automatic measures

Better data collection for post processing

Bandwidth

Better

Good

Acquisition memory (record time)

Limited

Good, extendable to external storage

Number of channels

Limited

Good, expandable

Waveform update rate

Better visual (display) update rate

Limited

Data streaming

Limited

Better, high data throughput

Triggering

Better

Good

FPGA access

Not typically

Possible

Probing

Better

Limited

 

 

 

A word of caution: some test equipment vendors will promote a digitizer as an oscilloscope or an oscilloscope as  a digitizer.  This may cause some confusion and the wrong choice can cause headaches down the road. Ensure you understand your needs and select the right instrument for your test application.  To find out more, check out these resources as well as a video of Keysight experts talking about the blog:

 

 

App Note: Understanding the Differences Between Oscilloscopes and Digitizers for Wideband Signal Acquisitions  

Webcast: "Oscilloscope or Digitizer for Wideband analysis - Why care?" .

Keysight just announced our new Infiniium S-Series oscilloscope promotion, it’s called “Your Scope. Your Way.” 

The S-Series oscilloscope (500 MHz to 8 GHz) has unmatched measurement accuracy with the best signal integrity and the most comprehensive measurement software for signal analysis, compliance, and protocol analysis.   And now the Keysight S-Series oscilloscope just got better with a great offer allows you to tailor the product for your own needs for FREE.

 

Choose ONE of the following three offers for free with the purchase of each new S-Series oscilloscope:

 

Offer #1:  Get the new N8888A Infiniium Protocol Decode Bundle for free (supports 33 protocols)

protocol decodes


or

Offer #2:  Get two N2796A 2 GHz single-ended active probes for free

            probe

or

Offer #3:  Get 400 Mpts/channel memory for free (DSOS000-400)

 

Take advantage of this offer:

Written by Ailee Grumbine and Brad Doerr

 

The design-to-manufacturing (D2M) process typically involves sequential stages from design to manufacturing. Each stage requires data collection that is specified in an initial design of experiments (DOE) and aimed at providing confidence that the design can meet critical requirements. Effective data analytics tools can help engineers evaluate the insights per the DOE in each stage of the design-to-manufacturing process. Time-to-market (TTM) can be greatly accelerated by utilizing modern data analytics tools while also increasing confidence in key technical decisions.

To hear more from the authors watch the video above

 

The first stages of the D2M process are design and simulation. The designer performs simulation to ensure that the design will meet the design specification. Simulation provides key statistics and produces waveforms that can be fed into compliance test applications. Simulation validation is a critical task prior to committing to expensive ASIC and PCB fabrication. The next stage is to perform design validation by using test equipment such as oscilloscopes and other measurement devices. The validation engineers will make measurements on multiple samples per the DOE created during the design stage. The DOE requires validation in a wide range of operating conditions, such as temperature and software configurations. The engineering team will then analyze the data with tools such as databases, PIVOT tables, JMP, R and/or other home-grown tools with data from instruments with data in CSV, XML or other formats. The challenge is that most engineering teams manage this data and the tools. This distracts from making measurements and promptly analyzing the findings. Next, the engineering team will perform compliance testing. Automated compliance test software saves a lot of time as it automates the measurements and produces the test report with statistical analysis to allow the engineers to determine the margins. This data is also very useful to determine if a second design cut is needed. Once the design is validated, the design can be released to manufacturing. The team will identify the production processes and measurements to ensure the design will meet the manufacturing goals derived from the original DOE. The manufacturing team will also seek efficiency improvements and/or yield improvements to improve. The data provides the basis for effective manufacturing management and optimization.

 

A capable data analytics platform integrates the DOE at the start of the process the engineering team will be able to achieve efficiency and confident decisions. The DOE is created in the early stages of design aimed at providing the data that can answer key questions about the design. This DOE defines the tests that need to be run in simulation and on the physical DUTs.  The DOE also identifies the test conditions and the number of tests that need to be run to achieve statistical confidence in the results. It is critical to choose a data analytics platform that can adapt alongside the DOE evolution. Nobody likes to delay a program while the team “re-architects the database schema”.            

 

There are many visualization tools in the market today that are used to help engineers analyze their test data. However, they are usually designed for a single user who has the time to acquire deep application expertise. These tools don’t fit well in the test and measurement D2M world especially as engineering teams are global and distributed. The visualization tool for D2M teams must provide data access to the entire team, with well-known visualization capabilities such as histogram, sweep, box-and-whisker and scatter plots.

 

Sweep or vector plots allow users to view 2-dimensional “sweep-data”. D2M and T&M applications rely heavily on sweep-data such as time-domain waveforms, frequency-domain magnitude plots and eye diagrams. The right analytics tool will enable the team to overlay for example, multiple eye diagrams with different test conditions. The overlay feature allows the user to determine test conditions that cause the eye to close or have less margin and allow the designer to optimize the design for best performance. Another example of a sweep/vector plot is a constellation diagram. Figure 1 shows an example of a 5G QAM4 constellation diagram. There are 3 sets of constellation data overlain which represent 3 different input voltages: 1V, 0.9V and 0.8V. The plot reveals that the constellation diagram with input voltage of 1V has the cleanest transmitted symbol. The constellation diagram with input voltage of 0.8V seems to be the one with the lowest received signal quality with potential phase noise issues.

Input voltages

Figure 1. Overlay of 3 different input voltages (1V, 0.9V and 0.8V) 5G QAM4 constellation data

Another visualization method in the test and measurement world is a box-and-whisker plot. Figure 2 shows an example of a box-and-whisker plot of a jitter measurement with multi-level split capability. The user can split on more than one property for analysis purposes. The plot on left is split by the three usernames: Sakata, Fernandez and Chang. The plot on right is split by username and input voltage. The plot indicated that most of Chang’s measurement values are higher than the upper limit especially for the input voltage of 0.8V.

Box-and-whisker plot

Figure 2. Box-and-Whisker plot of a jitter measurement with multi-level split capability.

In summary, successful D2M programs require a clear DOE and necessarily generate a great amount of data. With upfront planning and by choosing the right analytics platform, engineering teams can optimize effectiveness and time to market. This same data can also be leveraged into manufacturing ramp and manufacturing optimization.

 

Visit Keysight’s new Data Analytics Software here!

Keysight oscilloscopes are loaded with various applications. So many, that there may be some you don’t know how to use or don’t even know they exist. In the new Scopes University video series, Erin East and Melissa Spencer dive into when and how to use some of the different capabilities of the InfiniiVision and Infiniium oscilloscopes. Gain familiarity with features that will help save you time in your measurements, further your analysis, and deepen your insight.

 

Scopes University with Erin and Melissa

 

In the first couple episodes, Melissa and Erin start out with some of the basics, including some handy touchscreen tricks that will speed up your setup. Then, you’ll learn about some of the more advanced applications, like eye diagrams, jitter analysis, and frequency response analysis. Throughout the series, they will be covering the entire range of the oscilloscope family, from the low cost 1000 X-Series, to the deeper analysis Infiniium oscilloscopes.

 

Stay up to date on when new episodes come out by subscribing to our YouTube channel

Several years ago, the Keysight Oscilloscopes R&D team was working on a project to completely redesign the GUI for our Infiniium oscilloscopes. In the early stages of this project, we performed a ton of customer research to see what people expected out of a modern oscilloscope GUI. Most of these items were then included in the GUI you currently see on Infiniium oscilloscopes today – things like multitouch gestures, annotated markers, easy-to-use wizards, grids, flexibility of windows to choose what’s displayed on screen, etc. The other interesting thing we found was that many users wanted to have the ability to analyze, share, and document results at the comfort of their PC or laptop. From this discovery came the N8900A Infiniium Offline Oscilloscope Analysis Software. Many oscilloscope vendors offer offline software, but it is usually a pared-down version of the GUI found on an oscilloscope. With the Infiniium Offline Oscilloscope Analysis Software, the exact same GUI is used that is found on an oscilloscope – meaning you do not have to learn a new user interface and you can perform all of the analysis as if you were sitting in front of an oscilloscope.

 

Analyzing Data

 

During the customer research, we found that many people share an oscilloscope in their lab or work space. Doing so causes issues with scheduling and having enough time on the oscilloscope to capture and analyze the data properly. One large benefit to using Infiniium Offline is that you can capture your data on an oscilloscope, move the data to your PC via a thumb drive (or stream it directly to your PC), and then perform all of your analysis and documentation within the offline software – freeing up the oscilloscope to be used by another team member. This enables the team to much more efficiently use the oscilloscope and offers the added benefit of being able to analyze and document results from the comfort of your desk or even at home if you have a laptop.

 

 

Documenting and Sharing Results

 

Another finding in the customer research was how much time people spend documenting their results on an oscilloscope. The traditional method used by many was to take numerous screen shots and then import them into a document along with text describing the results. This was found to be very laborious so we sought out ways to help make this easier.

 

The first thing R&D did was include many items in the GUI to make documentation easier. All of these are then naturally found in the Infiniium Offline software since it matches what is found on the oscilloscope. Examples include annotated markers (so you can easily see the delta values directly on a screen shot), annotated axes, bookmarks (to make comments on certain measurements or portions of the waveform), measurement call-outs (to see measurements results directly on the screen), and so on. All of these enhancements enabled people to easily show valuable information in a screen shot in a much easier way.

 

Secondly being able to use offline software helped with documentation in two ways. People found it much easier to make screen captures and paste into a document on their PC/laptop than from the oscilloscope. They were able to finish their documentation quickly and more efficiently, freeing them up to do other tasks. Secondly, many of the people we interacted with needed to share their documentation with others. Using the offline software made this incredibly easy because not only could they send the report document, but they could also send the setup file/waveform via Infiniium Offline with the waveform/results completely annotated. The other team member could then open the file on their copy of Infiniium Offline and see all of this information. Collaboration made easy!

 

Controlling More than One Instrument

 

Several applications require more than four oscilloscope channels and while some vendors have oscilloscopes with this capability, Keysight found that people wanted the choice of when to use a setup for more than four channels and when to have two multiple oscilloscopes to use separately. From this, Keysight designed the N8834A MultiScope Application. This software enables people to synch up to 10 oscilloscopes and uses the Infiniium Offline software as the master control for all of these oscilloscopes. In this way, you can have up to 40 channels, all controlled from a single GUI on your laptop or PC. Then, when you do not need all of these channels for your application, you can disconnect the oscilloscopes and use them separately throughout your lab. This gives you incredible flexibility.

 

Test it Out - Download a Trial Version Today

 

If you are interested in seeing the N8900A Infiniium Offline Analysis software, you can download a trial version here. It enables you to test out the Infiniium GUI without having an oscilloscope as well – testing whether the capabilities match your needs.

Want to show off your cool project? E-mail moreinfo@keysight.com and your project could be featured here!

 

Quinton Martins, the leader of the Mountain Lion Project at the Audubon Canyon Ranch (ACR) in Northern California, had a problem.  Mountain lions needed to be trapped and GPS-tagged for research, but traditional trapping methods were just not effective enough.

 

 

Trapping method of the past

 

The traditional technique for trapping mountain lions involves the use of a one-door “single- ended” cage, with bait to lure the cat inside.  A mechanical pressure plate on the cage floor triggers the door-closing mechanism.  There are two significant issues with this approach.

 

  1. Bait isn’t tempting enough. Where food is abundant, mountain lions may not be hungry enough to venture into a cage. It can also be very difficult to source mountain lion munchies, like roadkill deer.
  2. The wrong animals are caught! Often smaller animals like foxes and bobcats end up in the traps instead of mountain lions.

 

 

Catching more mountain lions

 

Mountain lions commonly re-use the same walking paths, so Quinton is able to use bushes and sticks to ‘funnel’ the animal into a walk-through cage that is open at both ends. This works well because it is far easier to convince a mountain lion to walk into a cage if it can see a clear path through the other side. It also eliminates the need for bait by taking advantage of the mountain lion’s natural walking path.

 

The challenge was to develop a reliable electronic system that would simultaneously close both doors of the walk-through cage while the mountain lion was inside.

 

In this new design, the doors operate very simply. They are held vertically in “U” channel guides and drop when actuator rods are pulled (Fig. 1). 

 

 Cage Operation

Fig 1: Mountain Lion Cage Operation

 

 

A single, high-power solenoid pulls a wheel, which is connected to both actuator rods. The electrical system is controlled by an Arduino Uno microcontroller and a high current relay to activate the solenoid (Fig 2).

 

Prototype Actuator Mechanism

Fig 2: The prototype actuator mechanism

 

 

System design

 

The system needed to detect the motion of a mountain lion without trapping smaller animals. I investigated several options for sensing mechanisms including a horizontal light beam sensor and ultrasonic range sensors.  The light beam sensor worked, but it was difficult to set up and align and involved hanging wires over the side of the cage. I ultimately decided to use less intrusive ultrasonic range sensors installed at the top of the cage.

 

The system needed to detect the motion of a mountain lion without trapping smaller animals.

 

By measuring the distance from the top of the cage to the animal, we could set it to trigger on large animals only (mountain lions are typically at least 20 inches tall at their shoulders). The system was designed with two range sensors spaced 14 inches apart that would trigger only when both sensors detected an object at least 20 inches tall.  This double-sensor set-up minimizes the chance of triggering on a smaller animal, such as a fox, that might sniff the top of the cage with its nose.  If that happens, the small animal would only trigger one of the sensors, so the doors would not close.

 

The system was designed with two range sensors spaced 14 inches apart that would trigger only when both sensors detected an object at least 20 inches tall.

Debugging & deployment

 

With the basic design established, the next challenge was to write and debug the code controlling the actuator mechanism, which proved to be challenging. Incorrect timing caused the ultrasonic sensors to interfere with each other.  We needed a way to debug the trap while in the field - the Keysight 1000 X-Series low cost oscilloscope proved to be just the right tool. The 2-channel oscilloscope allows the signals from both sensors to be viewed simultaneously, enabling us to adjust the timing and ensure reliable operation.

We needed a way to debug in the field – the Keysight 1000 X-Series Oscilloscope proved to be just the right tool.

actuator circuitFigure 3:  Keysight EDUX1002A Oscilloscope being used to debug the actuator circuit.

 

 

 Setting up a trap in the field

Figure 4:  Quinton Martins, (Ecologist - in the cage!) and Neil Martin setting up the trap in the field (Picture by Jim Codington)

 

Mountain lions have very large territories, so patience is required when trapping these elusive animals.  After about two weeks, the waiting paid off, and we trapped our first mountain lion with this system, a female, and then caught a male 2 days later!

 

Trapped female mountain lion

Figure 5:  Trapped Female Mountain Lion

 

By Neil Martin 

 

More information about the ACR Mountain Lion project can be found here:

https://www.egret.org/acr-mountain-lion-project

 

 

Neil Martin is Keysight’s Corporate Marketing Director.  He used to be an R&D engineer and he can still remember a little engineering - which he makes use of in his spare time for volunteer projects.

mike1305

How Signal Modulation Works

Posted by mike1305 Employee Jun 20, 2017

Have you ever wondered how radio stations work? What about WiFi, or cell phones? These technologies (and countless others) all use modulation to send data at the same time, without interfering with each other! If electromagnetics wasn’t part of your college coursework, or you haven’t spent hours browsing Wikipedia, modulation of waveforms can be difficult to understand. To understand how wireless data transfer happens, we need knowledge of a handful of topics, which I plan to cover briefly in this blog post. For details, check out the full article.

 

Sending a signal that is a pure sine wave is called a "tone". It carries no real information, and doesn't sound that great either.

 

Single Tone

Single tone (time domain)

 

How about a signal composed of many tones of varying frequencies? We can see the signal is too complex to understand in the time domain.

 

Multi-tone Signal

Multi-tone signal (time domain)

 

For complex signals, engineers use a different way of graphing a signal in the frequency domain by using something called a Fourier transform. Let's see what our three signals above look like in this representation (skipping to the solution). Instead of plotting a signal’s voltage in time, we are plotting the power of the signal by frequency.

 

Multi-tone Signal of 10 tones

Multi-tone signal (frequency domain) of 10 tones, of varying amplitude

 

Notice the clear spikes? That is the mathematical representation of a sine wave at that particular frequency (x-axis). The multi-tone signal that was unreadable in the time domain has been clearly chopped into small spikes, representing all the frequencies that were summed to create the signal. A final example would be to show an audio signal.

 

Audio Signal

Audio Signal

 

This is how the spectrum of most signals appear, especially analog ones. The human voice and instruments do not play as discreet frequencies, and thus there is frequency content over an entire range. In theory, we can represent this analog signal as the sum of an infinite number of tones added together. That’s a fun one to wrap your head around.

 

Modulation is what takes a signal from low frequencies (we call this the message) and pulls it up to a higher frequency (the carrier). The idea is simple: Multiply your message by a high frequency carrier, such as 680kHz. Let's look at a few mathematical relationships. In this case, theta is the message and phi is the carrier.

The nifty relationships above show us that two signals multiplied can be represented as two signals added together! What does an audio spectrum look like when it's been modulated? We basically shift the signal up and around the carrier frequency.

 

Modulation of a Sound Clip

Modulation of a sound clip to 700 kHz

 

Just as expected, we see two signals. One is carrier + message, one is carrier - message (even notice how it is reversed). We can change the carrier frequency (radio station) to transmit a second, different signal at the same time. This is basically how a transmitter works in a radio tower. Now let's talk about receivers. Fortunately, it’s easy to bring our audio signal back to "baseband" (near 0 Hz instead of the carrier). We simply multiply everything by the carrier again. More math!

 

equation for modulation

 

That's a bunch of cosines, parenthesis, and f's all over the place. But it's correct, and we see that there are four signals that result from it. fC is the carrier frequency, and fM is the message.

 

  • ¼ power signal, (2*carrier + message)
  • ¼ power signal, (message)
  • ¼ power signal, (2*carrier – message)
  • ¼ power signal, (-message)

 

Let’s immediately disregard the last term with a negative frequency. It is a mathematical artifact which occurs quite often when talking about modulation and the math involved, but isn’t really, well… real. The two signals at double the carrier (assuming the carrier is much larger than the message, they are almost the same) can be filtered out with a low pass filter, leaving us with the original message at 25% power. Here's a picture of it, but backwards. Using this process, we can now hear the audio message that was transmitted at the 700 kHz carrier!

 

 

In summary, the purpose of this post was to give a 30,000 foot view of how radio transmission and signal modulation works. By taking multiple audio (or baseband) signals and mathematically multiplying them by different higher frequencies (the carrier), we can successfully transmit multiple signals over the same channel (our atmosphere) without interference. Multiplying it by the carrier again brings the modulated signal back to baseband, and a low pass filter and amplifier clean up and magnify the signal for our listening pleasure! I highly recommend reading the full length article for more details, fun facts about the FCC, as well as more in depth examples of signals being modulated for better understanding.

 

Have you ever set up your oscilloscope without a proper trigger? If so, you probably experienced something a little bit like this:

*disclosure – don’t watch this on repeat if you’re prone to epileptic fits*

 

In this case, I had an edge trigger and the level was set above my waveform.  The oscilloscope could not find any waveform data at that threshold and therefore, didn’t know what waveform data to display on screen.

When you have a trigger set up, the oscilloscope is looking at the acquisition data to see when your trigger conditions are met. If they are met, the oscilloscope will display the waveform data centered around the trigger event, thus stabilizing your display.  

Triggering

The easiest way to set up a quick trigger and stabilize your display is to hit Auto Scale.  That will take care of your vertical and horizontal scaling, and sets up the most common trigger type (Edge) at an appropriate level. This gets you to straight to basic troubleshooting.

 

Below is a trigger diagram showing the conditions for Edge trigger:

Trigger Diagram

Figure 1- edge trigger diagram

 

But triggering isn’t just used to obtain a stable display. It can also help you find events in your waveform. And there are many different triggers to help you find many kinds of events – even the tricky, hard to find events like glitches, runts, patterns, and sequences.  Keysight’s Infiniium oscilloscopes provide both hardware and software triggers.  Hardware triggers are quick and address the most common use cases. They are looking for events happening in real-time acquisition data.  Software triggers are used when the event you want to trigger on is just too complex for hardware alone.  To perform a software trigger, first the oscilloscope triggers in hardware to acquire the waveform data.  Then analysis and event searching happens in software before the waveform is displayed for that trigger. Perhaps a more accurate name for software triggering is event identification software. 

 

Below, you’ll find a quick reference guide for all the hardware and software triggers available on Keysight’s Infiniium oscilloscopes.  This will help you understand what triggers are available and determine what triggers you want to use when.

Hardware Triggers:

Trigger Type

What it Does / When to Use

Edge

looks for slope and voltage level of the selected source - mostly used for general purpose viewing and trouble shooting

Glitch

looks for a pulse that is narrower than other pulses in your source - used to capture infrequent glitches

Pulse Width

looks for a pulse that is either wider or narrower than other pulses in your source based on the pulse width and polarity you set - used to capture pulses that are too short or too long in time

Pattern/State

looks for a user specified pattern - used when you want to find a specific pattern across analog and/or digital channels

Runt

looks for a pulse that is smaller in amplitude than other pulses with low and high thresholds - to find pulses that are too low in voltage

Setup and Hold

looks for violations of setup time, hold time, or both setup and hold time based on a reference clock waveform

Edge Transition

looks for edges that do not rise or fall across two voltage thresholds in the amount of time you specify - used to find violations in rise/fall time

Edge Then Edge

looks for the two events you specify delayed by the number of events or time you set

Timeout

looks for a pulse that is lasting too long either at a high or low level - to find potential timeout errors

Window

looks for an event of the waveform exiting, entering, or remaining outside a voltage range as specified to use when you want to view a waveform either within or without certain thresholds

Protocol

looks for certain packets or patterns in protocol-based data. (Hardware protocol is only available on some Keysight oscilloscopes, the S-Series being one of them, with others performing protocol trigger in software).

Sequence

any two of the above performed in sequence used when you want to capture the signal based on two trigger events

 

Software Triggers (Available with InfiniiScan N5414B):

Trigger Type

What it Does / When to Use

Measurement

After hardware triggering and the waveform data is acquired, the specified measurement is performed, and then if the measurement condition is met, the InfiniiScan trigger condition is set to true and the waveform is displayed on screen

Zone Qualifying

create up to 8 zones and combine them with logic expressions to set triggering conditions

Generic Serial

capture packets of customized protocols or generic patterns

Non-monotonic Edge

capture small glitches or edges that may be hidden by hysteresis

Runt

capture runts that they may be hidden by hysteresis

 

I’m hoping as you advance past Auto Scale and try out a couple of these triggers, you’ll be a wiz and won’t even need this lookup table!

 

So how do you set up these different triggers? Easy.  Here are the two simple steps:

  1. Choose the Trigger Menu, then select Setup
  2. Choose the trigger you want from the list on the left and set your desired conditions

Now you’re rockin’ and rollin’! You’re ready to find all sorts of different anomalies that could exist in your waveforms and find the root causes of your malfunctioning DUT faster.  

 

If you have any interesting test conditions in which you used one of these triggers, we’d love to hear about it in the comments. Happy Triggering!

Oscilloscope users are constantly reviewing the signals of their design in the “normal” time vs voltage display of the scope.  It is easy to overlook the FFT (Fast Fourier Analysis) view of the same signal. It is a completely different way of reviewing the signal characteristics that often reveals clues to some very difficult to solve problems. FFT can be an invaluable tool for identifying noise, crosstalk, and other common problem in many designs that can stall prototype development. In digital designs, it is often used to highlight and pinpoint the source by the frequency content on power rails.

FFT measurement with an input sine wave

By applying the FFT algorithms to the sampled data, you convert the time domain operation of the oscilloscope into a frequency view of the signal. This results in two primary benefits. One, you can easily identify each of the frequency components. Two, it reveals the magnitude of each contributing signal.

Identifying the frequency

By identifying the frequency components, it reveals if there are any signals on that are not expected. For example, a digital signal should only have frequencies that are harmonics of the base signal. If you have a 10 MHz data, there should be only frequencies at 10 MHz (the primary harmonic), 30 MHz (the third harmonic), 50 MHz (the fifth harmonic), and the continuing odd harmonics up to the bandwidth of the source.

Any other frequency is a result of noise, or crosstalk, or some type of coupling on to the signal.

Frequency components of 10MHz clock

Figure 1: In this capture of a 10 MHz clock, we can easily identify the frequency components related to the fundamental frequency, but we can also see a 20 MHz signal that is -55 dB from the fundamental.

 

It’s important to understand how the oscilloscope sampling characteristics play into the quality of this FFT measurement. The oscilloscope analog bandwidth, sample rate, memory depth, and related time capture period all can have a profound effect on the measurement result. The math that is utilized for the calculation is using the data that was sampled at 5 GSa/sec, and it makes it possible to calculate a 10 GHz FFT. However, the front end of this scope is 1 GHz, so the FFT is only valid up to the bandwidth of the oscilloscope.

Identifying the Magnitude

The other key component of the signal is the power of each signal component. When looking at a signal in the time domain, it is only possible to see the very large signal power components. In the spectrum view (or FFT display) the horizontal axis is changed from a linear voltage scale to a logarithmic voltage scale (or dB for decibel).

The display on the right side of the display is listing the power level in dBV (decibel volts, or power relative to 1volt) of each frequency in order with the respective power level.  The first, or fundamental frequency of our signal is at just less than 10 MHz, and a power level of -13.9775 dBV, which is about 200mV rms. Looking at the time display of the signal (in green), you can see that it looks about right. We can also see that the next highest power signal is at 30 MHz and a power level of -30dBV, or about 3 mVrms-- something that cannot be seen in the time display that we are used to looking at.

FFT is just a button away

On Keysight oscilloscopes, the FFT operation is often enabled by simply pressing a button on the front panel. The new 1000X low cost oscilloscopes include this feature standard. The FFT view is a great way to examine a signal to find the frequency and power that you could not normally see any other way. Make sure to take advantage of this powerful tool that next time you are trying to find elusive signals in your design.

Learn other time-saving tips to get more out of your oscilloscope with this new eBook!

 Oscilloscopes are used to measure and evaluate a variety of signals and sources. They also play a major role in both design and manufacturing, providing a visual display of voltage over time. Many times oscilloscope users need more than a visual representation and want to validate the quality and stability of electronic components and systems. The Keysight Technologies mask test option, DSOX6MASK, for InfiniiVision Series oscilloscopes can save you time and provide pass/fail statistics in seconds. The mask test option offers a fast and easy way to test your signals to specified standards, as well as the ability to uncover unexpected signal anomalies and glitches. Mask testing on many industry oscilloscopes is based on software-intensive processing technology, which tends to be slow. Keysight’s mask test option is based on hardware-accelerated technology performing up to 270,000 real-time waveform pass/fail tests per second. This makes your testing throughout orders of magnitude faster. This Keysight InfiniiVision ground breaking Mask Technology is supported by their industry leading highest sampling rate at 1,000,000 waveforms per second allowing for improved display quality to catch subtle waveform details such as noise and jitter.

 

Mask Testing

Figure 1 shows a pulse-shaped mask using an input signal standard. You can easily specify horizontal and vertical tolerance bands in either divisions or absolute volts and seconds. You can set up the mask test to run continuously in order to accumulate valid pass/fail statistics. In this example, an infrequent glitch was quickly detected. In just six seconds, the mask test statistics show that the scope performed the pass/fail mask test on more than 1,000,000 waveforms and detected just two errors for a computed error rate of 0.0002%. In addition, you can see that this particular signal has a sigma quality relative to the mask tolerance of approximately 6.1 σ.

Mask Testing

Figure 1 - Mask testing uncovers an infrequent signal anomaly

 

Importing an industry-standard mask -

Figure 2 shows testing results of an industry standard imported eye-diagram mask. This particular polygon-shape mask is based on a published standard and was created using a simple text editor.

 Mask Testing

Figure 2 - Testing an eye-diagram with an imported industry standard mask.

 

You can also set up masks around areas of the signal that should be off-limits. That way you do not need a perfect signal; just an understanding of how a signal looks when it functions correctly. Mask testing provides more reliability than testing individual attributes because the entire signal can be evaluated against a correct signal to find glitches and/or errors. As a result, mask testing saves time and money in design and manufacturing and ensures customers receive higher-quality products sooner.

 

Keysight Mask Test Functions include -

  • Automatic mask creation using input standard
  • Easily download multi-region masks and setups based on industry standards
  • Detailed pass/fail statistics
  • Test to high-quality standards based on sigma
  • Multiple user-selectable test criteria

 

When setting up your specific mask test criteria, you can choose from multiple options including:

  • Run forever (with accumulated pass/fail statistics)
  • Run until a specified number of tests
  • Run until a specified time duration
  • Run until a maximum ideal sigma standard
  • Stop-on-failure
  • Save-on-failure
  • Print-on-failure
  • Trigger out-on-failure

 

Low Noise –

Lower inherent vertical noise is key when making quality and precise mask tests. Vertical noise can cause random increases (spikes) in all areas of the signal, including trigger timing issues. Figure 4 below shows test results in just 6 seconds, capturing 3 elusive failures out of one million waveforms sampled. A consistent trigger point is vital to prevent jitter and drift of the waveforms. If a signal drifts outside the mask limits due to noise and/or trigger jitter, mask testing will analyze the oscilloscope-induced error components as a failure, thereby corrupting the test results. A low noise floor is essential to attain the precision and reliability of Six Sigma testing.

 Mask Testing

Figure 3 - Mask testing to 6.2 sigma resolution takes only seconds using an InfiniiVision scope with a mask test rate of 270,000 waveforms/s

 

Conclusion –

Not only does Keysight provide the fastest, low-noise mask testing performance in the market, but the mask test application on InfiniiVision scopes also has a variety of features for customizing your measurements. The Keysight mask testing software allows you to setup the mask test to run for a specified time, until a certain sigma threshold is reached, continue running upon a failure, stop on a failure, or save the data on a failure. This allows you to run a complete six sigma test in around one second. If a failure occurs the waveform can be set to automatically stop or saved for viewing and later analysis work. The capability to assure the quality of products to Six Sigma in 1.1 seconds saves time and effort in R&D and manufacturing. In R&D environments, engineers can test signals they are developing through many waveform repetitions spending less time but still ensuring signal stability. The more waveforms they can test, the more confidence they have that the design functions correctly. In manufacturing environments engineers must test signals to ensure customers receive reliable products. Your company can save manpower hours and can invest the capital in profitable initiatives, such as new product design. At the same time, customer satisfaction will increase as you produce high-quality products and move them quickly into the market.

Here in Keysight Oscilloscopeland we talk a lot about our ASICs (application specific integrated circuits). But why? Who cares about the architecture of a cheap oscilloscope? All that matters is how well it works, right? We agree. That’s why we design and use oscilloscope-specific chips for all our scopes.

 

How, though? Custom ASICs don’t just materialize out of thin air, it takes years of planning and R&D effort. Here’s a high level look at what it takes to make an ASIC.

 

The making of an ASIC

There are several different steps (and teams) involved in the creation of an ASIC. Before anything is started, there must be a long-term product plan – what do designers want to have 5-10 years down the road? Future products will have new specs or features that will sometimes warrant an ASIC. To make that decision, product planners meet with the ASIC planners.

 

An oscilloscope's ADC ASIC

A custom 8 GHz oscilloscope ADC, used in Keysight S-Series Infiniium oscilloscopes.

 

Planning

First up is the planning team. They ask “what chips do we need to have in a few years? – Let’s make that.” And, “what will be available off-the-shelf in a few years? - Let’s not make that.” The planners will also make cost vs. performance trade-off decisions (device speed, transistor size, power consumption, etc.).

 

Also, ASICs generally fall into one of two categories: digital or analog. Analog chips are essentially signal conditioning chips designed to massage signals into a more desirable form. Digital chips are essentially streamlined FPGAs, designed for processing data inputs and providing coherent data outputs. For example, our MegaZoom ASICs take data from an oscilloscope’s front end circuitry + ADC and output waveforms, measurements, and other analytics. 

 

processor chips on 1000 X-Series scope

Fig 1: The Keysight-custom ADC and processor chips on the InfiniiVision 1000 X-Series oscilloscopes

 

It's worth noting there's a third type of ASIC - a mixed signal ASIC like an ADC (Fig 1.)

 

Digital ASICs

 

Now, let's take a closer look at process of creating digital ASICs, like the MegaZoom processor in the InfiniiVision oscilloscopes.

 

Front-end/RTL design

Once the chip is well defined by the planning, the front-end team gets to work. They are responsible for the “register-transfer level” (RTL) design (and typically spend their days with Verilog or VHDL). Their goal is to create a functioning digital model of the chip, but not a physical model. The RTL team is ultimately responsible for taking the chip design specs and turning it into actual logic and computation models. To do this, they use digital design components/building blocks and techniques like adders, state machines, pipelining, etc.

The RTL team is ultimately responsible for taking the chip design specs and turning it into actual logic and computation models.

 

As the front-end team is working, there’s also test team that works to check the RTL for errors. The goal is to try to avoid situations like the infamous Pentium FDIV bug that cost Intel nearly $500 million in 1995.

 

Once the RTL is proven to be functional by the test team, it is synthesized into a netlist. This essentially means that the RTL is converted from logic blocks into individual logic gates. Today, software handles this, but historically it was done by hand and engineers used truth tables and Karnaugh maps. The netlist is then run through a formal verification tool to make sure it implements the functionality described in the RTL before being passed to the back end team. 

 

Back-end

Once the logic is verified, it’s time to physically implement the chip. This is typically known as “floorplanning.” Floorplanners use crazy-expensive software (hundreds of $k) to place the RTL onto the chip footprint. In reality, the back end team generally gets early versions of the netlists so they can get a head-start on floorplanning.

 

The back end work begins with an overall placement of design blocks on the chip. The general workflow for the back-end team is:

 

  1. Floorplanning
  2. Individual gate placement
  3. Clock tree building
  4. Routing
  5. Optimizing
  6. Static timing analysis

For the chip to function properly, gates involved in the same computational processes should be close together. Also, designers have to make sure that power can be distributed properly throughout the chip.

 

A clock tree is a clock distribution network designed to make sure the clock reaches each of the gates at the same time. If clock edges arrived up at different times to different parts of the chip, it could cause painful timing errors. Sometimes, designers also intentionally add some clock skew to keep an edge from arriving too soon.

 

The back end work begins with an overall placement of design blocks on the chip.

 

Once placement is complete, software then auto-routes the connections between gates. You’re probably familiar with the phrase “never trust the autorouter.” In this case though, that’s really the only option unless you want to manually route hundreds of thousands (or millions) of connections.

 

Oscilloscope acquisition board

Fig 2: Routing of an oscilloscope acquisition board

 

Finally, an ongoing concern throughout the whole process is whether or not the design is actually manufacturable. This is known as DRC (design rule checking). Basically, this is a set of rules designers provide to the software to tell it what architectures (aka physical shapes) are and aren’t physically possible. Then, there's a layout vs. schematic check (LVS) to verify that the physical geometries actually implement the desired circuitry.

 

Tape Out

Once the front end and back end teams are done, it’s party time. This stage, known as “tape out,” is when the final design is prepped for production. Massive files are sent to the fab, who creates photomasks for each layer of the ASIC. It’s not unusual for there to be 30-50 masks for a single chip.

In the final stage, known as “tape out,” the final design is prepped for production.

 

Manufacturing

Once the masks are created, a number of different techniques are used to manufacture the chip. Usually a combination of photolithography, acid baths, ion implantation, furnace annealing (baking), and metallic sputter deposition is used. Each silicon wafer holds dozens (or hundreds) of identical layouts that will later be cut up into discrete chips.

 

The completed wafer is then tested for manufacturing errors. Depending on the size of the wafer and complexity of the process, planners can usually predict the failure rate of each chip. Microscopic anomalies, like a speck of dust under mask, can cause a chip to fail. “Scan testing” is used to check each gate. Scan testing consists of applying a pre-determined pattern of signals that will test every single gate on the chip, and each chips’ output is compared to the expected output. Each die is tested, and the chips that pass are sent on to be packaged.

 

Packaging

Good dies are then placed into packages and tested again. The packaging team typically designs a custom package for the die, and needs to consider signal integrity, cost, thermal regulation, and reliability. Often, we at Keysight will re-design the package of an existing ASIC using updated technology to reduce hardware cost and improve reliability of our oscilloscopes.

The packaging team typically designs a custom package for the die, and needs to consider signal integrity, cost, thermal regulation, and reliability.

For example, the ADC on our inexpensive oscilloscopes is the same ASIC used in some legacy oscilloscopes, but by improving the packaging over time we’ve reduced the package cost by nearly 5x. Thanks to that cost reduction, what was once used for only for a top-of-the-line oscilloscope we can now use in our cheap oscilloscope.

 

Support Circuitry

Once a chip is manufactured, tested, and packaged, it still needs to be surrounded with support circuitry. For example, what good is an op amp if you never configure it with resistors? But, that’s a topic for another blog post.

 

How it’s made

So, while you wouldn’t want to use this description to go design your own ASIC, you should now have a better understanding of what it takes to produce an ASIC. It’s a lot of work, but the benefits they offer compared to FPGAs are often worth the investment. For any given Keysight oscilloscope, we use a few different ASICs. We use analog ASICs for the front end, a custom low-noise ADC, and often a custom processor as the brain of our oscilloscope. While this comes with a fairly large non-recoverable engineering expense (NRE), being able to use the same chip in our $45,000 oscilloscopes and our $450 oscilloscopes earns our oscilloscopes special place on the budget-conscious engineer’s bench.

Lab benches are many times cluttered with multiple pieces of test equipment. Keysight’s InfiniiVision Oscilloscopes are equipped with a built in digital voltmeter, frequency counter and totalizer giving the oscilloscope user additional measurement options that can reduce the amount of test equipment needed. In addition, when you only measure the frequency of a signal, you rarely get the whole story. A repetitive signal can have spurs, intermittent spikes and noise that you need to see during design and or debug. The oscilloscope counter will show you all these attributes in addition to the frequency in one screen shot giving you the “big” picture. Keysight InfiniiVision oscilloscopes include both a 3 digit voltmeter (DVM) and a 5-10 digit Integrated Counter depending upon the oscilloscope model number (Figure 1 below).

 

 

Figure 1 – Functionality, options and specifications across the Keysight InfiniiVision family of Oscilloscopes

 

Digital Volt Meter

The DVM and Integrated Counter operate through the same probes as the oscilloscope channels. However, these measurements are decoupled from the oscilloscope triggering system measuring 100 points per second. This flexibility allows engineers to make DVM and triggered oscilloscope measurements with the same connection. DVM results are presented with an always-on seven-segment display keeping these quick characterization measurements at the engineers' fingertips. You get the added flexibility of measuring five types of DVM measurements depending upon your application: Peak-Peak, AC rms, DC, and DC rms. As a user you should also note that the oscilloscope DVM is designed for quick rough measurements as needed in design or debug and not meant to replace exact measurements you would get from a calibrated external DVM.

 

Standard 5 digit counter resolution

The traditional oscilloscope counter measurements offer only five or six digits of resolution, which may not be enough for the most critical frequency measurements are being made. With a 10 digit counter you can see your measurements with the precision you would normally expect only from a standalone counter. The Keysight integrated counter’s ability to measure frequencies up to a wide bandwidth of 3.2 GHz, allows it to be used in many high-frequency applications. This integrated hardware counter allows users to make much more accurate frequency measurements on signals. 4 digits is 1 part in ten thousand, or ~0.01% of the displayed number. In addition, relative to an industry standard oscilloscope frequency measurement, the Keysight counter measurement is designed to be very easy to use. It uses the trigger level of the oscilloscope as the trigger level for the counter independent of the cycles shown on the screen.

 

Up to 8 to 10 digit resolution with external time base

If an external 10MHz reference is used, the counter is as accurate as the externally fed 10MHz signal and the measurement resolution is increased. The 10MHz REF BNC connector on the rear panel is provided so you can supply a more accurate clock signal to the oscilloscope. To drive oscilloscope’s time base from external clock reference, connect a 10MHz square or sine wave reference signal to the 10MHz REF BNC input on the rear panel and go to the Utility -> Options ->Rear Panel menu and select Ref signal mode to 10 MHz input. The working 10MHz input voltage is 180mV to 1V in amplitude, with a 0V to 2V offset. To get the highest resolution, the time/div setting should be at 200mS/div or slower. With this setting, the resolution is increased up to 8 digits, which is what would be displayed if an external 10MHz reference is used. When the internal reference is used, the oscilloscope displays counter measurement in 5 digits. The counter measurements can measure frequencies up to the bandwidth of the oscilloscope.

 

Accuracy

Basically, the counter is as accurate as the time base reference that is used.  The oscilloscope’s time base uses a built-in 10MHz reference that has an accuracy of 1.6 ppm to 50 ppm depending upon the oscilloscope model number. This means that the number displayed is within 0.00016% to 0.0050% respectively of the actual signal measured. For example, if you are making a counter measurement of 32,768 Hz signal using a model 6000X with 1.6 ppm accuracy, you are measuring the signal at ~0.05 Hz accuracy (see calculation below).

32,768 Hz x 1.6 ppm (0.00016%) = ±0.0524288 Hz

 

Totalizer

The totalizer feature of the DSOXDVMCTR counter option adds another valuable capability to the oscilloscope. It can count the number of events (totalize), and it also can monitor the number of trigger-condition-qualified events. The trigger-qualified events totalizer does not require an actual trigger to occur. It only requires a trigger-satisfying event to take place. In other words, the totalizer can monitor events faster than the trigger rate of an oscilloscope, in some cases as fast as 25 million events per second. Keep in mind that the number of events is a function of the oscilloscope’s hold off time.

 

Summary

The voltmeter and counter functions discussed in this article are just two of the “6 instruments in one oscilloscope” of the Keysight InfiniiVision family. The six instruments are the oscilloscope, 16 digital channels (mixed signal), serial protocol analyzer, Dual channel 20 MHz function/arbitrary waveform generator, 3-digit voltmeter and 5 to 10-digit counter with totalizer.

 

The voltmeter operates through the same probes as the oscilloscope channels. However, the DVM measurements are made independently from the oscilloscope acquisition and triggering system so you can make both the DVM and triggered oscilloscope waveform captures with the same connection.

 

Traditional oscilloscope counter measurements offer only five or six digits of resolution. While this level of precision is fine for quick measurements, it falls short of expectations when critical frequency measurements are needed. With the integrated counter within the five Keysight oscilloscope families summarized in Figure 1, you can select between 5 and 10 digit counter options and see your measurements with the precision you would normally expect only from a standalone counter. Because the integrated counter measures frequencies up to a wide bandwidth of 3.2 GHz, you can use it for many high-frequency applications as well

Keysight continues to invest in the very popular InfiniiVision X-Series oscilloscopes with new oscilloscope models, new options, and customer-requested enhancements. Every 6 to 8 months, Keysight releases new firmware that our customers can download into their InfiniiVision scopes at no cost. The latest release of firmware (version 7.10) for the InfiniiVision 3000T, 4000, and 6000 X-Series oscilloscopes includes three new licensed “pay for” options as well as several FREE upgrades/enhancements including the following:

 

  • User-definable Manchester/NRZ Trigger & Decode Option
  • Frequency Response Analyzer (FRA) Option
  • CXPI Trigger & Decode Option (new on 6000X, existing on 3000T & 4000)
  • DVM/Counter Option – Now standard!
  • Education Training Kit Option – Now standard!
  • On-screen grid scaling factors – Standard!
  • FFT RF power measurements -Standard!

 

 

User-definable Manchester/NRZ Trigger & Decode Option (DSOXT3NRZ, DSOX4NRZ, & DSOX6NRZ)

 

Keysight’s InfiniiVision X-Series oscilloscopes support triggering on and decoding a broad range of today’s most popular serial bus protocols including I2C, SPI, UART, CAN, USB, etc.  But what happens if you are working with one of the less popular — or perhaps proprietary — serial bus protocols that isn’t supported? Available now on InfiniiVision 3000T, 4000, and 6000 X-Series oscilloscopes is a “user-definable” Manchester- & NRZ-encoded serial bus option. This new trigger and decode option allows you to define the specifics parameters and structure of your particular serial bus including:

 

  • Encoding type (Manchester or NRZ)
  • Baud Rate
  • Start edge
  • # of Synchronization bits
  • Word size
  • Header field size
  • Data field size
  • Trailer field size
  • Decode Base (binary, hex, ASCII, or unsigned decimal)

 
Also available are three new application notes that provide step-by-step instructions on how to set up triggering and decoding for three specific Manchester-encoded serial bus measurement applications including the automotive PSI5 sensor bus, automotive RF-modulated key fob signals, and NFC-F signals. Figure 1 show an example of triggering on and decoding the automotive PSI5 sensor bus, which is often used in airbag systems.

 

Figure 1: Triggering on decoding the Manchester-encode PSI5 sensor bus using Keysight’s user-definable serial bus option.

 

In the above PSI5 measurement example, after detecting the 2-bit Start field, the scope triggered on and decoded a 10-bit payload field followed by a parity bit. The scope also automatically detected a Manchester timing error in the frame that immediately followed the trigger frame (155h). To learn more about triggering on and decoding the PSI5 serial bus, download the new application note on this topic.


 


Figure 2 above shows an example of decoding automotive key fob signals.

 

Decoding RF-modulated key fob signals requires hardware digital demodulation. The new application note on this topic shows you how to capture the RF signal with a “sniffer” probe, how to demodulate the captured signal in hardware, and then how to decode each “code-hopping” RF burst. To learn more about how to set up the scope to demodulate and then decode RF-modulated key fob signals, download the new application note on this topic.


  
Figure 3 above shows an example of decoding NFC-F signals.

 

With NFC-F signals, the scope automatically demodulates the captured RF-modulated waveform if based on a baud rate of either 212 kbps or 424 kbps. When the new Manchester trigger and decode option is used along with the recently-introduced NFC automated test software, the designer of NFC-enabled device now has a very powerful set of debug and test tools. To learn more about how to set up the scope to decode NFC-F signals, download the new http://literature.cdn.keysight.com/litweb/pdf/5992-2337EN.pdf on this topic.

 

 

Frequency Response Analyzer (FRA) Option (DSOXT3FRA, DSOX4FRA, & DSOX6FRA)

 

Using the InfiniiVision oscilloscope’s built-in function generator (WaveGen), these scopes can now perform automatic frequency response analysis (Bode gain & phase plots) as shown in Figure 4 below.

 

 

Figure 1: Triggering on decoding the Manchester-encode PSI5 sensor bus using Keysight’s user-definable serial bus option.

 

Frequency Response Analysis (FRA) is often a critical measurement used to characterize the frequency response (gain & phase versus frequency) of a variety of today’s electronic designs including passive filters, amplifier circuits, and negative feedback networks of switch mode power supplies (loop response). Engineers typically use network analyzers or standalone low-frequency FRAs to perform these types of measurements today. To learn more about the new FRA option, download the data sheet.

 

 

Free InfiniiVision Enhancements with Firmware Upgrade

 
In addition to the new “pay-for” options listed above, there are also free enhancements available for InfiniiVision X-Series oscilloscopes with an upgrade to the latest firmware (v7.10). The built-in DVM and hardware counter option shown in Figure 5 will no longer be an option. These measurement capabilities will now be standard features of all InfiniiVision oscilloscopes.

 

 

Figure 5: The DVM/HW Counter option is now a standard feature in all InfiniiVision X-Series oscilloscopes.

 

The measurement example shown above shows output ripple riding on top of a 5 V dc output from a switch mode power supply (SMPS) with a switch rate of approximately 2 MHz. The scope’s built-in DVM shows that the actual DC output measures 4.97 V and the actual switching rate is 2.0112 MHz as measured by the 5-digit hardware counter.

 

Another new free enhancement is on-screen vertical and horizontal grid scaling factors along the left vertical axis and lower horizontal axis, which is also shown in Figure 5. This has been a very popular feature in Keysight’s higher-performance Infiniium oscilloscopes. Labeling each grid with scale factors can help you quickly estimate voltage levels and timing of your signals. 


In addition to making the DVM/Counter option standard, the education training kit (EDK) option is now standard as well on all InfiniiVision 3000T, 4000, and 6000 X-Series oscilloscopes with the latest firmware upgrade. Using the built-in training signals shown in Figure 6 along with available online training guides, users unfamiliar with the operation of Keysight InfiniiVision oscilloscopes can get up-to-speed quickly. To learn more about the EDK training kit and to download the training guides, go to the InfiniiVision http://www.keysight.com/en/pd-1952427-pn-DSOXEDK/educators-training-kit-for-infiniivision-2000-and-3000-x-series-oscilloscopes?cc=US&lc=eng webpage.

 

 

 Figure 6: The education training kit (EDK) is now standard and includes multiple built-in training signals and online training guides.

 

Also available at no cost in this latest firmware release are new automatic RF power measurements that can be performed on FFT math functions. Figure 7 shows an example of an Adjacent Power Ratio measurement performed on an RF-modulation sideband measurement. Other new RF measurements include Channel Power, Occupied Bandwidth, and Total Harmonic Distortion (THD).

 

Figure 7: New FFT analysis measurements.