Microwave Engineering Europe - October 2007 - (Page 44)

44 DIRECT SYNTHESIS Figure 10: Tone nulling. determine TFC (hopping sequences), and mask tests Power Spectral Density and channel power in these bands. Summary This direct synthesis implementation described in the paper provides a simple set up to generate clean good quality UWB WiMedia frequency hopping Band Group 1 waveforms with the ﬂexibility to add controlled interference and distortions. Thus it provides the best attributes of both methodologies described earlier. The article outlines the steps, using an advanced RF/IF/IQ waveform creation and editing tool, to easily generate UWB signals. With RF signals increasing in complexity, it is becoming more essential to utilize tools that help RF designers correctly synthesize these signals. Such tools enable design engineers to easily create signals up to 5 GHz with a single arbitrary waveform generator. With the increase of new applications that utilize wireless transmission and digital RF systems, engineers need faster and easier ways to create intricate RF signal behaviors and interactions. There are now new choices for generating frequency hopping UWB signals. About the authors Iqbal Bawa is an Engineer in Electronics and Communications, currently a Technical Lead in Tektronix’s Signal Sources Product Line. He has more than eight years of experience in the ﬁeld of Digital Signal Processing, Embedded systems and Communication. K A Muralidharan is an Electronics and Communication Engineer with a Post Graduate Diploma in Marketing. He is currently working as a Marketing Manager for SW applications in Tektronix’s Signal Sources Product Line. He has around 12 years of experience in sales and marketing and has been in the test and measurement industry for more than 5 years. Joan Mercadé is a telecommunication engineer trained by the Polytechnic University of Catalonia (UPC), Barcelona, Spain. He has worked in different areas of the test and measurement industry for more than 20 years in companies including Philips and Tektronix. Currently, he runs his own R&D and consulting company, Arbitrary Resources. Figure 11: Symbolic representation of gated noise. Figure 12: Generation and analysis solutions working together. RFXpress not only allows the nulling of tones, but also allows the ability to have intermediate values from +20 dB to -100 dB as shown in Figure 10. This enables the simulation of a real world scenario with the sub-carrier amplitudes at various levels for testing receivers. Gated noise It is not uncommon that only parts of the packet get corrupted during transmission. RFXpress has the functionality to add noise with desired intensity to a particular portion of the PPDU structure. For example, noise can be added only to the PLCP header and Payload as shown in Figure11. Noise also could be applied only to a speciﬁc number of symbols in a packet. Analysis of the results The WiMedia system is capable of transmitting information at data rates 53.3, 80, 106.7, 160, 200, 320, 400 and 480 Mb/s. Digitally synthesized signals using RFXpress can be veriﬁed using Tektronix WiMedia software. The Tektronix AWG7102 arbitrary waveform generator with option 6 high bandwidth output 20 GS/s interleaved can be used to generate UWB-WiMedia BG1 and BG2 RF signals. The WiMedia Analysis portion of the software includes real time spectrograms and spectrum plots for bandwidth and downconverted Spectrograms, as well as spectrum plots to user adjustable frequency bands. The WiMedia analysis software section also down-converts to WiMedia band groups to Company Information Tektronix www.tek.com Microwave Engineering Europe ● October 2007 ● www.mwee.com 034-036-038-040-042-044_MWEE.ind44 44 20/09/07 17:51:01 http://www.tek.com http://www.mwee.com

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Microwave Engineering Europe - October 2007 Contents Comment News CMOS RF: Si-On-Sapphire Goes Mainstream Cover Feature: New Data Protection Concept for UHF RFID Tags CMOS RF: RF Design Team Touts CMOS Spin for 3G PAs Wireless HID – Are You Following the Standard to Another “Average” Product Development? Phase Optimisation of the RF Front-End Direct Synthesis of UWB-WiMedia Signal Generation 4G Chips to Target 700 MHz Applications Femtocells Mobilize to Fight Wi-Fi in the Home Products Product Feature: AXIEM Pioneers the Future of EM Technology Calendar

Microwave Engineering Europe - October 2007

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