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AWG plug-ins simplify waveform creation

Wed, 2017-06-14 14:05 | by Tektronix Experts

If a waveform can be defined or captured, chances are good that a Tektronix arbitrary waveform generator such as our new AWG5200 series can generate the signal. What’s more, by taking advantage of advances in digital-to-analog converter (DAC) technology, the AWG5200 offers a compelling combination of high fidelity, high sample rate, up to eight output channels per instrument and a low per-channel cost.

With instruments like the AWG5200 on hand, the challenge for many applications isn’t so much in finding hardware that can generate the signals of interest, but in creating the waveforms for the AWG to playback. Here’s where you need to simulate a complex threat environment as in the case of electronic warfare applications, or see just how far you can push an RF or serial receiver.    

For many users, the default approach for generating signals has been to use MathWorks’ MATLAB and the Signal Processing Toolbox, which provides a broad set of functions and apps to generate, measure, transform, filter and visualize signals. The Instrument Control Toolbox lets users then configure and control AWGs in MATLAB. Waveforms can also be defined in Excel spreadsheets or even in text editors and imported into your AWG.

For users who fall short of MATLAB guru status, however, creating the signals needed for complex applications can be a high bar, particularly if there are many subtleties and changes that need to be made quickly for what-if analysis. And for applications like receiver compliance testing for complex standards like MIPI D-PHY or PCIe Express, using MATLAB or other tools for waveform creation will involve painstakingly walking through the standards’ test documentation to add appropriate stresses and impairments needed to simulate real-world conditions.

To improve efficiency and productivity for our customers, Tektronix has adopted a modular software-based plug-in architecture that allows for point and click waveform design. The plugins can be installed on the AWG5200 or AWG70000 instruments directly or you can use a Windows PC running our new SourceXpress platform. This platform, by the way, lets you load waveforms, create sequences, and enable playback without ever having to touch an AWG or set foot in the lab.

Assuming a plug-in is available for your needs, the plug-in will be the best way to get started and will save you time and deliver the best results. What’s more, plug-ins can be complemented with waveforms created externally or imported from a test instrument such as an oscilloscope. To better understand AWG plugins, here’s a quick overview of some of the more common ones and their capabilities:

Generic precompensation

Users today need the cleanest signals and the lowest EVMs possible. The precompensation plug-in simplifies the process of generating correction factors and applying them on signals to get the best signals and cleanest performance from an AWG5200 or AWG70000 signal generator.

When creating waveforms for testing wideband receivers, for instance, it is important that the AWG generates signals with flat frequency and linear phase response. Users can compensate for the first and second Nyquist zones of the AWG. If users can define the LO frequency and choose to get correction coefficients for either Lower Side Band or Upper Side Band as well as define the carrier frequency. Users can also define the bandwidth of compensation either by specifying start and end frequencies (RF & IF) or bandwidth (in IQ/IQ with modulator).

One of our AWG experts, Christopher Skach, offers up a detailed walk through of the precompensation plug-in in the video below:

High-speed serial

High-speed serial data signals continue to increase in complexity. The plug-in for high-speed serial simplifies signal creation and jitter simulations to reduce overall development and test time. It can be used to create the waveforms required for thorough and repeatable design validation, margin/characterization and conformance testing.

Specific capabilities include generation of jitter (Random, Periodic (Sinusoidal), Inter Symbol Interference (ISI), and Duty Cycle Distortion (DCD) as well as Spread Spectrum Clocking (SSC), pre-emphasis, and noise addition. This allows a combination of various impairments to be created simultaneously to stress the receiver. The input data pattern can be scrambled by defining a polynomial. The pattern duty cycle can also be defined using Pulse Width Modulation (PWM), which allows for alternatively encoding the bit stream at up to 16-PAM.

Multi-tone and chirp

This plug-in is useful for military, aerospace, and RF applications where creating and generating tones are part of a successful mission. Tones can be created for various applications, including noise power ratio (NPR), with a set of desired start and end frequencies, spacing or the number of tones. Frequencies can be notched out by setting the start and end frequency of choice. When generating chirps, the user can decide between "high to low" or "low to high" frequency sweeps and define chirp characteristics by sweep time or by sweep rate.

While creating waveforms for testing wideband receivers, it is important that the test equipment generate signals with flat frequency and linear phase response. Correction files can be directly applied to tones or chirp waveforms while they are being compiled.

Optical

High-speed telecommunications networks are moving toward faster and more complex modulated signals. The optical plug-in simplifies waveform creation to reduce design iteration intervals. Single or dual polarization modulation schemes can be defined with a variety of preloaded modulation formats including BPSK, QPSK, OQPSK, OOK, NRZ, up to 8 PAM and QAM8. Baseband data can be selected from predefined patterns, user defined patterns or from a PRBS 31 generator and each N-bit word can be defined with symbols from N unique data streams.

Signal generation simplified with the AWG5200

The AWG5200 is all about making your life easier. It’s an off-the-shelf solution offering performance, flexibility and reduced cost per channel.  It’s backward compatible with other Tektronix signal generators and lets you automate tests using MATLAB scripts. Plug-ins take that a step further to simplify the process of creating and generating complex signal environments. For the full story, please visit http://www.tek.com/arbitrary-waveform-generator/awg5200 where you’ll find a full data sheet, details about available plug-ins and in-depth technical documents such as the white paper, Overcoming RF Signal Generation Challenges with New DAC Technologies, and much more.

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