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Military Microwaves Supplement
Creating single-emitter pulse patterns for testing radar receivers is a complex, time-consuming process because of the extensive mathematics required, whether creating the initial waveform, modifying any of its characteristics such as pulse shaping and compression, or creating custom pulse patterns. A comprehensive software application called Signal Studio for Pulse Building has been created that dramatically simplifies these tasks. It performs all of the calculations and automates the process, allowing designers to concentrate on creating a library of complex pulse patterns rather than on the underlying math.
Signal Studio for Pulse Building is part of Agilent's Signal Studio suite of PC-based software tools designed to complement its PSG and ESG series vector signal generators and PSA and ESA series spectrum analyzers. In addition to Signal Studio for Pulse Building, the family includes software dedicated to 802.11 WLAN, 1xEV-DO, TS-SCDMA, multitone and Bluetooth applications.
Signal Studio for Pulse Building is specifically for use with the company's newest E8267C vector signal generator that was introduced last November. The E8267C generates vector-modulated carriers up to 20 GHz, and meets the requirements of designers of components used in aerospace and defense systems, digital microwave radios and wireless communications systems. The E8267C generator is currently the only single-instrument solution that can generate vector modulation above 6 GHz. The dual-mode baseband generator in the E8267C combines the functions of an 80 MHz arbitrary waveform generator with a real-time baseband generator, and, together with deep playback memory and waveform sequencing, creates an environment well suited to custom radar pulse pattern generation. Signal Studio for Pulse Building employs these capabilities and the instrument's fast sample rate to achieve flexible pulse shaping with resolution up to 10 ns between waveform sample points.
The software allows custom pulse shaping, intra-pulse modulation and user-defined pulse patterns to be created either through its user interface or another test executive using its COM-based application programming interface. Figure 1 shows how pulse shapes can be used to create a custom pulse pattern.
Complex pulse compression can be applied to a pulse without the need to manually perform complex calculations. The user simply selects a pulse from the pulse library, selects a modulation format (AM step, FM step, Barker, BPSK, custom BPSK, FM chirp, or QPSK) from a pull-down menu and sets the modulation parameters.
One of the most useful functions of Signal Studio for Pulse Building is its ability to create and manipulate a library of pulses that were created with the software itself, imported from other signal creation environments, or recorded from actual radar signals. With these waveforms available for instant recall, the designer can quickly configure pattern structures ranging from simple repeated pulses to complex single-emitter pulse patterns. The number of pulse repetitions can be varied, along with the repetition interval, amplitude scale, frequency offset and phase offset on a pulse-by-pulse basis.
Once a pattern has been created, it can be nested in another pattern for playback. For example, a sensitivity test pattern can be created and integrated into another pattern to create a frequency-agile sensitivity test pattern. Parameters such as pattern repetition interval, number of repetitions and phase offset can be quickly applied to the sensitivity test pattern.
When the designer wishes to create a pattern of pulses, a variety of parameters can be specified, including the number of repetitions of pulses and patterns, the repetition interval of pulses and patterns, Gaussian or uniform repetition interval jitter (with user-defined deviation), amplitude scaling, frequency and phase offset, and additional off time between pulses and patterns. With this level of flexibility, designers can configure even the most complex pulse patterns, including antenna scan patterns, frequency-agile pulse patterns with 80 MHz RF modulation bandwidth, and receiver sensitivity and selectivity test patterns.
When the Signal Studio for Pulse Building software is used with Agilent's ESA or PSA spectrum analyzers, predistortion can be applied to the calculated waveform to improve image rejection and optimize RF flatness over the entire modulation bandwidth of the signal generator.
The software is available as an option for the E8267C vector signal generator, which must be equipped with the internal baseband generator. More information about Signal Studio for Pulse Building software is available at www.agilent.com/find/ signalstudio.
Agilent Technologies, Santa Rosa, CA (800) 452-4844. Circle No. 303
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