science

Jitterlyzer

Jitterlyzer is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jitterlyzer rather than just read about it. In short: The FS5000 Jitterlyzer performs physical layer serial bus jitter evaluation. It can inject controlled jitter and measure the characteristics of incoming jitter.

Key takeaways

Jitterlyzer belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jitterlyzer to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jitterlyzer from memory before moving on to harder problems.

Reference excerpt

The FS5000 Jitterlyzer performs physical layer serial bus jitter evaluation. It can inject controlled jitter and measure the characteristics of incoming jitter. When teamed with a logic analyzer or protocol analyzer, it can correlate these measurements with protocol analysis. Physical-layer tests can be performed while the system under test is processing live bus traffic.

Jitter measurements The FS5000 measures jitter in two categories:

Timing There are four different timing measurements:

Bathtub Plot - The bathtub curve can provide tremendous insight into the BER performance of a link under test. A bathtub curve is obtained by drawing a horizontal line across the waveform under test. The probability distribution function for signal transitions (zero crossings) from a high voltage to a low voltage or a low voltage to a high voltage is then computed. The bathtub curve is useful because it can provide a lot of insight into the behavior of a system. Apart from estimating BER, it also provides an indication for the amount of margin that is in the system. When coupled with protocol testing with the Jitterlyzer, a high margin enables engineers to quickly rule out the physical layer as a potential cause of certain protocol errors. Statistics - The Jitterlyzer’s measurement routines uncover total jitter and BER directly (without requiring mathematical extrapolation). This routine for random jitter (RJ) and deterministic jitter (DJ) separation is included for completeness. Also a number is provided for RJ and DJ on real-life traffic. Bus View - Shows channel to channel skew of four channels simultaneously. Jitter Histogram - This routine is performed on real-life traffic. It selects the zero-crossing voltage in the incoming data. It then counts the number of transitions of the high-speed serial signal as a function of phase positions. A histogram of number of hits versus delay is then plotted.

Eye There are three different eye measurements

Eye diagram - This routine is performed on real-life traffic. It provides much more information than just a vertical eye opening or a horizontal eye opening. Instead, it provides a first indication of parameters such as dispersion in the signal path, rise-time issues, etc. Click on the link and you will see an example of an eye diagram that is obtained using the Jitterlyzer. As can be seen, an indication of noise throughout the whole eye is made, as opposed to, for example, only at the center. Oscilloscope - This measurement allows the user to see an oscilloscope trace in persistent mode, allowing direct inspection of the eye. Color represents the frequency with which the measured trace passes through each point, with red representing the most frequent, and black representing the least. Note that frequency is normalized to a maximum value of 1. Voltage Histogram - This measurement is similar to the jitter histogram except that it is done in the vertical domain. It shows the amount of voltage noise that exists on the high-speed serial signal and is similar in principle to the vertical eye height.

Jitter generation

Data pattern LIVE traffic Preprogrammed Compliance patterns

Jitter profile Frequency range 19.07 kHz - 19.99 MHz Amplitude range 40ps - 1200ps

Differential swing 400-1600mv

External links Jitter analysis tool from FuturePlus Systems.

References

Illustrations

Worked examples

Example 1 — a first encounter with Jitterlyzer

Start with the simplest possible case. Write down what Jitterlyzer claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jitterlyzer before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jitterlyzer ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jitterlyzer

In research: Jitterlyzer appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jitterlyzer in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jitterlyzer is common in secondary-school and first-year university syllabi. It links to neighbouring topics Digital electronics, Electronic test equipment, so understanding it makes those chapters shorter.
In everyday life: Look for Jitterlyzer outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Jitterlyzer in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jitterlyzer means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jitterlyzer out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jitterlyzer in simple terms?

The FS5000 Jitterlyzer performs physical layer serial bus jitter evaluation. It can inject controlled jitter and measure the characteristics of incoming jitter.

Why does Jitterlyzer matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jitterlyzer?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jitterlyzer.