There are many cases where certain signals can cause your device to malfunction. This may be a problem your customer ends up finding if you don’t properly test during product development. Designers and test engineers frequently use an Arbitrary Waveform Generator (AWG) to simulate worst-case conditions during design verification. An AWG is the ideal tool for creating degraded or stressed signals to verify product performance limits. System or product noise susceptibility, timing problems, signal-level abnormalities, bandwidth loss, harmonic distortion, or a host of related maladies can be determined.
The AWG is a very powerful tool and can create waveforms or waveform bursts needed for your specific application. An AWG combines the capabilities of a function generator with that of a pulse generator, modulation source, noise generator, sweep generator, and trigger generator. It is a good tool for everyday use in the design lab or test environment. You can create custom solutions for a wide range of applications spanning many industries. AWG applications range from high dynamic range to high bandwidth output requirements.
Figure 1. Arbitrary Waveform Generator (AWG) applications.
Below is a list of common applications covered in this blog:
- Radio Frequency (RF) signals
- Radar signals
- Environment signals
- Coherent optical
- Generic Orthogonal Frequency-Division Multiplexing (OFDM)
- High-speed serial
- Simulating real-world aberrations in 100Base-T physical layer
- Dual Tone Multi-Frequency (DTMF)
- Automobile suspension testing
- Power line testing
Radio Frequency (RF) Signals
Creating the signals required for RF conformance and margin testing is increasingly difficult. Digital RF technologies require wide-bandwidths and fast-changing signals that other generators cannot produce. These types of signals are seen in RF communications and ultra-wide band radio applications.
Radar signals demand AWG-level performance in terms of sample rate, dynamic range, and memory. AWGs can oversample the signal in instances where phase and amplitude quadrature signal generation is desired. This improves signal quality, creating a spurious free dynamic output. AWG’s also provide Linear Frequency Modulation (LFM), Barker and Polyphase codes, step FM, and nonlinear FM modulation signals. They also generate pulse trains to resolve:
- Range and doppler shift ambiguity
- Frequency hopping for electronic counter-counter measures
- Pulse-to-pulse amplitude variation
Radar signals must coexist with commercial signals and not affect each other. Use your AWG to thoroughly test all the corner case issues at the design or debug stage. An AWG can be programmed to output many industry-standard signals:
- CW radar
You can also define the carrier frequency, power, start time, and duration of these signals. This allows control of the level of signal interaction or interference.
Today's web driven world is pushing the demand for high-speed short and long haul coherent optical solutions. Phase modulation, high baud rate, high sample rate, high bandwidth, and high resolution are all critical to optical applications. Multiple synchronized AWGs can be used to generate many desired coherent optical signals.
Generic Orthogonal Frequency-Division Multiplexing (OFDM)
OFDM has become the modulation method of choice for transmitting large amounts of digital data over short and medium distances. Wide bandwidths and multiple carriers are needed to test RF receivers in today’s wireless world. AWG OFDM packets can specifying the spacing between the symbols or frames or stressed by adding gated noise.
Serial signals are made of binary data (simple ones and zeros). These signals have begun to look more like analog waveforms with analog events embedded in the digital data. The textbook zero-rise time and flat top of the theoretical square wave no longer represent reality. Today’s serial communication environments are negatively impacted by noise, jitter, crosstalk, distributed reactances, and power supply variations. Your arbitrary waveform generator can create all these signals!
Using direct synthesis techniques, AWGs can simulate the effects of propagation through a transmission line.
Rise times, pulse shapes, delays, and aberrations can all be controlled by your AWG. You can also create a variety of digital data impairments such as jitter (random, periodic, sinusoidal), noise, pre/de-emphasis, duty cycle distortion, inter-symbol interference, duty cycle distortion, and spread spectrum clocking.
Simulating Real-World Aberrations in 100Base-T Physical Layer
To simulate physical layer test signals for 100Base-T transceivers, your AWG will create several analog parameters:
- Undershoot and overshoot
- Rise and fall time
- Amplitude variations
- Specific timing variations such as jitter
AWGs provide an efficient method for generating signal impairments like these for testing product margins.
Dual Tone Multi-Frequency (DTMF)
Touch-tone signals on push button telephones are created by combining a low frequency and a high-frequency signal. Simulating the superimposed frequencies creates a special challenge if the frequencies are not harmonically related. An arbitrary waveform generator can generate these signals along with controlled levels of noise and harmonic content.
A simple square wave or sine-wave pulse was used to test pacemakers in the past. Today’s AWGs can create a simulated heartbeat waveform that pacemakers are designed to detect.
The arbitrary waveform generator can customize pacemaker testing for particular heart rate types.
Automobile Suspension Testing
An AWG can simulate automobile sensor outputs just as a car would when it hits a bump. The suspension’s response and reliability can be tested under virtually any simulated road condition because the size of the “bumps” can be precisely controlled.
Power Line Testing
Multichannel AWGs can simulate three-phase power. Transients or glitches can be created to simulated problematic waveforms. For example, you could simulate a transient on one phase and signal dropout on another.
In addition to all the applications above, there are many more across several different industries, and the arbitrary waveform generator will support them all:
- Sequencing and deep memory
- Creating long scenario simulations
- Leading edge physics, chemistry, and electronics research
- Validation and compliance testing of high-speed silicon and communications devices
- Stressing testing receivers with a wide array of signal impairments
- Generating high Baud rate baseband signals with higher order, complex modulation
- Radar, satellite, electronic warfare, and multilevel signals
- Jitter margin testing for analog-to-digital converters
We have now covered the importance of an arbitrary waveform generator to ensure your device is working properly for your specific application. As you can see, AWGs excel in creating mixed-signal waveforms that can mimic real world conditions. To learn more about arbitrary waveform generators, check out: A High-Performance AWG Primer.