You need to test, we're here to help.

You need to test, we're here to help.

19 September 2017

Automotive Ethernet Compliance: Tests in Detail (Part II)

Figure 1: Testing transmitter timing master jitter
entails creating a track of TIE measurements
We've begun our deep dive into the subject of Automotive Ethernet compliance testing. In our last post, we covered the first two of seven tests: maximum transmitter output droop and transmitter clock frequency. Let's now look at transmitter timing jitter in master and slave modes.

13 September 2017

Automotive Ethernet Compliance: Tests in Detail (Part I)

Maximum transmitter output droop should not exceed the specified maximum of 45%
Figure 1: Maximum transmitter output droop should not
exceed the specified maximum of 45%
We've looked in past posts at the basics of Automotive Ethernet compliance test, the five test modes, and an overview of the test setup. Now it's time to begin examining the physical-layer electrical tests in detail. As we've mentioned, there are a total of seven of these tests (six for BroadR-Reach and 100Base-T1 and one for the latter only).

08 September 2017

Automotive Ethernet Compliance: Test Setup Overview

Typical test setup for Automotive Ethernet PMA compliance test
Figure 1: Typical test setup for Automotive Ethernet
PMA compliance test
Our last post, an overview of the five test modes for Automotive Ethernet electrical compliance testing, prepared us for a deeper look at the compliance tests themselves. But before diving into details on the differential electrical compliance tests for Automotive Ethernet, be it BroadR-Reach or 100Base-T1, it might be helpful to take a look at the setup for this endeavor.

30 August 2017

Automotive Ethernet Compliance: The Five Test Modes

Automotive Ethernet electrical compliance test is defined at the connector of the transmitter
Figure 1:Automotive Ethernet electrical compliance test
is defined at the connector of the transmitter
Following up on our introduction to Automotive Ethernet compliance testing, let's move on to an overview of the five test modes that comprise the compliance test suite for the 100Base-T1 protocol. The test modes allow for a common pattern to test stressful conditions across all devices. Testing in this fashion offers the best possible odds for achieving true interoperability.

24 August 2017

Introduction to Automotive Ethernet Compliance Testing

As with most any networking scheme, Automotive Ethernet is subject to standardization to ensure that the various components of a given system reliably pass signals among themselves. Where there is a standard for a protocol, there must also be testing for compliance with that standard. This will be the first in a series of posts detailing compliance test of the Physical Media Attachment (PMA) aspect of the Automotive Ethernet standard.

17 August 2017

Back to Basics: Metrology

Some sciences are more obscure than others; these may be of interest and importance to relatively few. The term “metrology” may leave even some science geeks scratching their heads, but for those in the test and measurement arena, metrology is an extremely critical area of scientific endeavor.

Metrology is the science of studying the errors in measurements. Test equipment, such as the oscilloscopes we manufacture here at Teledyne LeCroy, are only as good as long as their measurements are consistently precise and accurate. So for us, metrology is a science that is central to our mission.

At the root of our practice of metrology are international standards of measurement for quantities such as currents, voltages, frequency, time, resistance, impedance, and power. These standards are defined by bodies such as the National Institute of Standards and Technology (NIST) in the United States, or the International System of Quantities as represented by the ISO/IEC 80000-1 standard.

An oscilloscope, like any other electronic system, is the sum of its parts. We design the instruments so as to maximize measurement accuracy, and specify the components built into them to deliver that accuracy. These components have themselves been characterized by their respective manufacturers, and their characterization process has some amount of error associated with it. Thus, the overall accuracy of our instruments incorporates that error as well.

Bear in mind that an instrument can be very precise and not accurate at all – or very accurate but not very precise. “Precise” means the measurement has many significant digits. “Accurate” means the digits are the correct ones.

It’s important to note that the objective of metrology is not to ensure that a given instrument is tweaked for perfect accuracy, but rather at determining how accurate the instrument actually is as measured against NIST or ISO/IEC standards. The metrologist documents that comparison so that the instrument’s end user knows exactly what he or she is getting. Unless specified otherwise, measurements are reported quoting an error of two “sigma”, which indicates a >95% chance that estimated errors are not exceeded. Another rule of good metrology is that the instrument is measured, when possible, against a standard that is 4X more accurate than the unit under test.

The Deeper Dive of Metrology


Of course, all Teledyne LeCroy oscilloscopes are subjected to quality control inspections. But metrology takes a deeper dive into how the parts come together to form the whole. It tells the customer, and our own staff, how close each instrument is to ever-elusive perfection.

All of our oscilloscopes come with a calibration certificate, and that calibration must be traceable to the definitions of quantities emanating from one or more international standard. The errors found through metrology reduce the margin of effort you can afford in your system. When the certificate states that an instrument is precise in measuring a given quantity to within ±1%, it typically means that we must measure the quantity to a fraction of 1% error. Thus, the instrument’s specifications are demonstrably met.

Calibration certificates spell out what equipment was used in the calibration of the instrument, and what the results of the testing showed. For example, a datasheet might show that a particular oscilloscope model is specified for DC measurement accuracy to within 1% ± some number of millivolts. The calibration certificate might show that a specific instrument is accurate to within 0.75% ± some smaller number of millivolts. It tells you the maximum amount of uncertainty in the instrument’s measurements.

To the oscilloscope’s owner, the calibration certificate represents a certificate of trust. It tells them how close the instrument is to the center of the range called for in the specification. It’s a matter of confidence in the owner’s measurements over time.

Metrology gives you a firm handle on your measurement margin for error. But with the advent of high-speed communications standards such as PCIe, that margin of error has been squeezed such that it becomes very difficult to ensure that everything works as it should. As a result, all oscilloscope makers have been pushed for greater measurement accuracy across ever-growing instrument bandwidths.

When instruments arrive at Teledyne LeCroy’s service department for calibration, some owners want the oscilloscope returned exactly as it was. They want only to learn how aging has affected the instrument. Did its measurement accuracy change, and if so, by how much? Other customers want their instrument restored to like-new condition, complete with software updates.

With the advent of high-speed communications standards such as PCIe, the margin for measurement error is minimal, making it extremely difficult to make sure everything is working correctly. Thus, the oscilloscope industry strives for more precision across the instruments’ wide frequency range. It could almost be said that Teledyne LeCroy’s LabMaster 10 Zi-A oscilloscope is akin to a 100-GHz voltmeter. There is an overriding need for high precision at every frequency. Thus, metrology will remain an integral part of the engineering effort for all instrument manufacturers.

27 July 2017

The Periodic Table of Oscilloscope Tools: Document

Teledyne LeCroy's Document toolset for its oscilloscopes
Oscilloscope users can find themselves managing a lot of detail in the course of driving their instruments. They need to keep track of instrument setups. They have to know standards-based compliance test routines backward and forward. Often, the need arises to remotely control the oscilloscope, interface it with other applications, and export/import acquisition data. And, importantly, the oscilloscope has to aid, and not hinder, collaboration with other members of the engineering team(s).

26 July 2017

The Periodic Table of Oscilloscope Tools: Analyze (Part III)

We're nearing the end of our tour of the Periodic Table of Oscilloscope Tools, our way of presenting our broad palette of oscilloscope tools in a concise, clear fashion. In this installment, we'll finish up the Analyze grouping, by far the largest on the Periodic Table.

20 July 2017

The Periodic Table of Oscilloscope Tools: Analyze (Part II)

The Analysis tools in an oscilloscope lend it debug power
Figure 1: The Analysis
tools in an oscilloscope
lend it debug power
Oscilloscopes are central to many engineering tasks, but perhaps to none more so than debugging. Something is going on with your design but you don't know what it is. However, armed with an oscilloscope with the sort of sophisticated analysis tools found in Teledyne LeCroy's instruments, even Mr. Jones can get to the bottom of the problem. Let's continue our survey of the Periodic Table of Oscilloscope Tools with more on analysis tools.

18 July 2017

The Periodic Table of Oscilloscope Tools: Analyze (Part I)

Analysis tools deepen insight into waveform behavior and relationships
Figure 1: Analysis tools deepen
insight into waveform behavior
and relationships
The path from problem to solution via oscilloscope moves through a number of stages. Doing so involves capture of a signal, determining how it's to be viewed, taking measurements of various parameters, and possibly applying math functions to the waveform. All of these stages depend on the roster of tools that the oscilloscope brings to bear on the process. Teledyne LeCroy's Periodic Table of Oscilloscope Tools represents our view of the world of such tools.

14 July 2017

The Periodic Table of Oscilloscope Tools: Math

DSP-based Math functions can reveal deep insights hidden in waveforms
Figure 1: DSP-based
Math functions can
reveal deep insights
hidden in waveforms
The usefulness of oscilloscopes skyrocketed once digital signal processing began to be applied to acquired waveforms. By applying DSP, oscilloscopes could now perform complex processing in the time, frequency, statistical, and other domains, all while imposing no restrictions on acquisition length. Here at Teledyne LeCroy, we collectively refer to these DSP-based processes as Math functions. We've presented those functions, along with all of the other functions our instruments perform, in chart form in our Periodic Table of Oscilloscope Tools.

12 July 2017

The Periodic Table of Oscilloscope Tools: Measure

Measure tools are at the heart of an oscilloscope's utility
Figure 1: Measure
tools are at the heart
of an oscilloscope's
utility
An oscilloscope is only as good as the tools it provides to users for acquiring, viewing, measuring, analyzing, and documenting waveforms. We present an overview of our deep collection of oscilloscope tools in our Periodic Table of Oscilloscope Tools, and in prior Test Happens posts, we've surveyed the Capture and View categories. Today we'll break down the Measure section of the Table.

07 July 2017

The Periodic Table of Oscilloscope Tools: View

The View tools arrange acquisition data to suit given needs
Figure 1: The View tools
arrange acquisition data
to suit given needs
We began our survey of Teledyne LeCroy's Periodic Table of Oscilloscope Tools by reviewing our set of Capture tools, which help to isolate and capture signals of interest and shorten time to insight. Now we'll turn our attention to the next grouping of tools: the View tools.

05 July 2017

The Periodic Table of Oscilloscope Tools: Capture

The Periodic Table of Oscilloscope Tools is a handy reference to oscilloscopes' capabilities
Figure 1: The Periodic Table of Oscilloscope Tools
is a handy reference to oscilloscopes' capabilities
Early analog oscilloscopes were quite a breakthrough in their day. For the first time, engineers and hobbyists were afforded the ability to "see" electrical signals displayed on a CRT as a function of voltage vs. time. The advent of analog oscilloscopes meant a new way to think about, compare, and visualize signals.

29 June 2017

Distinguishing BroadR-Reach and 100Base-T1

BroadR-Reach provides full-duplex operation over a single twisted pair of wires
Figure 1: BroadR-Reach provides full-duplex operation
over a single twisted pair of wires
The world of Automotive Ethernet can be a little confusing in that there are two dominant specifications that serve the application space: BroadR-Reach and 100Base-T1. Both are explicitly intended for automotive use and there's quite a bit of overlap between them. In this installment, we'll look a little more closely at BroadR-Reach applications and also explain the differences between it and 100Base-T1.

27 June 2017

The Basics of Automotive Ethernet Testing

Automotive Ethernet PHY test requires 1-GHz bandwidth and 2-GS/s sample rate minimum
Figure 1: Automotive Ethernet
PHY test requires 1-GHz bandwidth
and 2-GS/s sample rate minimum
Now that we've discussed what Automotive Ethernet is all about, discussed its benefits, and dug deeper into BroadR-Reach, the next topic for discussion is an overview of testing for the protocol and the equipment requirements to test the physical layer.

20 June 2017

VIDEOS: Exploring MAUI with OneTouch

MAUI with OneTouch makes child's play of complex oscilloscope operations
Figure 1: MAUI with OneTouch makes
child's play of complex oscilloscope
operations
If a picture is worth a thousand words, how many words is a video worth, even if it's only 10 to 15 seconds long? If the videos in question illustrate how to use Teledyne LeCroy's MAUI with OneTouch next-generation user interface (Figure 1), their value is inestimable. Once you've seen how easy it is to use an oscilloscope with MAUI with OneTouch, you'll know it was time well spent.

19 June 2017

Why Automotive Ethernet?

The MOST infotainment protocol offers a higher aggregate bandwidth than Automotive Ethernet, but its 150-Mb/s bandwidth is shared across the network
Figure 1: The MOST infotainment protocol offers a higher
aggregate bandwidth than Automotive Ethernet, but its 150-Mb/s
bandwidth is shared across the network
In recent posts, we've been reviewing the subject of Automotive Ethernet in general and the BroadR-Reach protocol in particular. In today's installment, let's look at some of the benefits of using the protocol while comparing it to some other protocols that see usage in the automotive environment.

14 June 2017

Fundamentals of the BroadR-Reach Protocol

BroadR-Reach delivers bandwidth of 100 Mb/s
Figure 1: BroadR-Reach
delivers bandwidth of
100 Mb/s
The burgeoning complexity of vehicular networks, the resultant high bandwidth demands, and the harshness of the automotive environment have driven the development of what we know today as Automotive Ethernet. Our last post began an overview of Automotive Ethernet technology, focusing on the physical/mechanical constraints and industry trends that influenced the protocol's development. Next, let's look more closely at the BroadR-Reach protocol.

12 June 2017

Back to Basics: Automotive Ethernet

Figure 1: Automotive Ethernet handles
a wealth of functionality
Today's vehicles are as networked, if not more so, than our homes, offices, and factories. According to one estimate, the wiring harness for a multiplexed bus in a high-end luxury vehicle can weigh as much as 110 lbs. Hence the rise of standards for automotive networking such as Automotive Ethernet (Figure 1). Let's begin a survey of the basics of Automotive Ethernet: What is it, where did it come from, where is it going, and what are the testing requirements?

30 May 2017

An Inside Look at an Automotive Ethernet Seminar

Students gain first-hand experience in Automotive Ethernet protocol testing
Figure 1: Students gain first-hand experience in
Automotive Ethernet protocol testing
Teledyne LeCroy's Automotive Technology Center (ATC) in Farmington Hills, MI recently hosted a full-day seminar on Automotive Ethernet. Below, Bob Mart, product line manager, shares some of his thoughts on how the seminar went and provides a preview of Teledyne LeCroy's next live Automotive Ethernet day at the ATC on June 15, 2017 (detailed information on this and other automotive-related events can be found here).

19 May 2017

Testing the DDR Memory Interface's Physical Layer (Part IV)

Probes are a key element of the total signal acquisition system
Figure 1: Probes are a key element of the total signal
acquisition system
In this multipart survey of testing the DDR interface's physical layer, we've looked at the basics of the interface itself, a high-level overview of the testing, how to access DDR signals, and read/write burst separation. In this installment, we'll cover preparation for the actual testing.

24 April 2017

Testing the DDR Memory Interface's Physical Layer (Part III)

For analysis purposes. it's critical to separate read and write bursts of interest
Figure 1: For analysis purposes. it's critical to separate
read and write bursts of interest
Last time around, we began examining some of the challenges that come with testing the DDR interface's physical layer. In that post, we concentrated on getting to the devices' physical connections by various means including interposers, backside vias, and DIMM series resistors. Now, presuming we've managed to gain access to the DDR's ball-grid array, the next hurdle is separation of read and write bursts.

11 April 2017

Testing the DDR Memory Interface's Physical Layer (Part II)

A typical BGA package for DDR memory
Figure 1: Shown is a typical BGA
package for DDR memory
In the first of this series of posts, we undertook a high-level view of physical test of a DDR memory interface. Moving forward, let's look into some of the specific challenges one faces in a close examination of these interfaces.

05 April 2017

Testing the DDR Memory Interface's Physical Layer (Part I)

Clock, strobe, and data are three critical signals in DDR test
Figure 1: Clock, strobe, and data are
three critical signals in DDR test
In an earlier post, we took a brief tour through what constitutes a DDR memory interface: clock, command, address, and strobe+data lines linking a memory controller and an array of DRAM memory ICs. Next, we'll examine what DDR interface testing is all about, concentrating primarily on the physical layer.

29 March 2017

Fundamentals of the DDR Memory Interface

A representative test setup for physical-layer DDR testing
Figure 1: A representative test setup
for physical-layer DDR testing
Double data-rate (DDR) memory has ruled the roost as the main system memory in PCs for a long time. Of late, it's seeing more usage in embedded systems as well. Let's look at the fundamentals of a DDR interface and then move into physical-layer testing (Figure 1).

20 January 2017

Back to Basics: Three-Phase Sinusoidal Voltages

Three-phase AC voltages consist of three voltage vectors
Figure 1: Three-phase AC voltages
consist of three voltage vectors
In a previous post, we briefly covered the basics of single- and three-phase AC power systems. Single-phase systems, as we've noted, comprise a single voltage vector with a magnitude (in VAC) and a phase angle. Of course, a three-phase voltage consists of three voltage vectors and three phase angles. This installment will go on to describe three-phase AC voltages in similarly brief fashion.