The Evolving Oscilloscope User Interface

Figure 1: MAUI is Teledyne LeCroy's
intuitive touch-based user interface

The means of interaction with test equipment has steadily evolved and improved over the years. Concepts such as remote control, for instance, broadened the possibilities for users of oscilloscopes and other equipment. Advancing display technology brought helpful elements such as color coding of traces, while more powerful graphics processing and computing gave us multiple grids, and so on.

The Challenges of GFCI Measurements

Figure 1: An example
of a GFCI

The ubiquitous ground fault circuit interrupter (GFCI), a fast-acting circuit breaker, has saved countless individuals from serious injury or death when they've inadvertently entered the low-resistance ground path of an electrical device or outlet. It's important to measure precisely the amount of time that elapses from when the 60-Hz cycle is present to when the GFCI disables the ground path. Other tests include determining the start, stop, and duration of the GFCI's tripping time. Let's take a look at the challenges these measurements present.

Performance Considerations For Optical Modulation Analysis

Figure 1: Error-vector magnitude defined

In recent posts, we've covered the fundamentals of coherent signals and the basics of optical modulation analyzers. Let's now turn to the operational parameters of OMAs, in particular system bandwidth, and how that figure of merit in an OMA can determine how far your measurement system can take you in terms of meaningful analysis.

What Is An Optical Modulation Analyzer?

Figure 1: A representative block diagram of a coherent
transmitter and receiver

In an earlier post, we looked at some of the fundamentals of coherent signals: what comprises a coherent signal, how and why they're used, and a bit about how they're represented visually on an oscilloscope. The advent of coherent signals has brought about the rise of a new class of test instrumentation, known as an optical modulation analyzer (OMA). In this post, we'll examine what an OMA is and what it brings to the party above and beyond a stand-alone oscilloscope.

The Fundamentals of Coherent Signals

Figure 1: These two coherent light waves have
a constant phase offset

Optical communications have come a long way from the simple direct detection of amplitude-modulated transmissions. Today's long-haul optical networks make use of coherent detection, and for good reason. Using coherent detection, receivers can track the phase of the incoming signal and thereby extract any information conveyed using phase and/or frequency modulation. Thus, coherent detection facilitates much higher capacity without using more bandwidth.

USB Type-C Cable Detection

Figure 1: The four possible states of
connection for a USB Type-C cable

Having examined some of the basics regarding the USB Type-C connector and the Power Delivery 2.0 specification that complements the Type-C spec itself, we'll turn our attention to the topic of cable detection. The Type-C connector is reversible, which is to say there are four ways a cable can be connected between upstream- and downstream-facing ports (Figure 1). Not only that, but there are different types of Type-C cables. So how do the devices discern what's between them?

A Look at USB Type-C and Power Delivery

Figure 1: The USB Type-C
connector alongside its
Micro-B counterpart

With USB 3.1, the latest iteration of the serial-data protocol, comes a new smaller and universal connector: USB Type-C, the USB-IF's answer to Apple's Lightning connector (Figure 1). Even Apple itself has adopted USB Type-C for its latest MacBooks, a rare show of support from Cupertino for an open standard. Like Lightning, USB Type-C is reversible, but it offers other interesting features, such as the ability to handle other protocols using "alternate modes." It also incorporates the new USB Power Delivery specification for improved power-supply capabilities over USB.