Signal Generation & Analysis
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SPECIAL ADVERTISING SECTION ® TECHNOLOGY LEADER SERIES Signal Generation & Analysis for W-i-d-e-b-a-n-d Aerospace/Defense Systems Choosing the right broadband measurement solution for your application The ever evolving need for improved radar resolution, high data rate of the unique test instrumentation communications, and robust interference immune reception is the driv- that is available to address the spe- ing force behind the increase in wide bandwidth signals used in modern cial needs of advanced aerospace/ Electronic Warfare (EW), MILitary COMmunications (MILCOMS), ELec- defense applications. tronic INTelligence (ELINT), and Direction Finding (DF) systems. New Architectures to Meet Finding instrumentation to and with the current state-of-the-art, the Challenge test these ever evolving wideband the wideband signal being generated Historically, these wideband test aerospace/defense systems can be a or analyzed may be in a digital form signal demands have required complex, challenge. Many of these advanced rather than an analog form. As signal custom-built test instrumentation. wideband systems are coherent multi- bandwidth exceeds 200 MHz, finding Agilent now offers test equipment channel designs, employing phased effective test equipment solutions for architectures with the features and array antennas that require multi-port today’s advanced RF system becomes interconnection ports needed to enable test capability. Both wideband signal increasingly difficult. advanced wideband multi-port micro- generation and analysis are needed, In this article, we look at some wave signal generation and analysis. Phased array Arbitrary Base-band I-Q modulation Performance waveform RF Out #N signal generator generator Arbitrary Base-band I-Q modulation 10MHz waveform Performance RF Out #2 ref. generator signal generator (N8241A) (E8267D) Distribution amplifier (Z5623AK08) Sync. Clock trigger Arbitrary Performance RF Out #1 waveform Base-band I-Q modulation signal generator MXI-4 generator (E8267D) (N8241A) LAN Phase coherent RF Out #1 Personal computer RF Out #2 Phase ajustable Figure 1: The Z2090B system can produce multiple modulated signal outputs that are phase coherent with precisely synchronized modulation patterns. This allows simulation of the spatial relationships of an arriving wave-front arriving at multiple antennas. TECHNOLOGY LEADER SERIES TECHNOLOGY LEADER SERIES To illustrate, let’s explore some of the specific test and analysis solutions Base-band I-Q beginning with signal generation. Arbitrary modulation 10MHz Performance waveform RF Out #2 ref. signal Wideband Signal Source Solutions generator generator N8241A Agilent’s Z2090B wideband signal ( ) (E8267D) source solution utilizes the low phase noise E8267D Performance Signal Generator (PSG) and the high-resolu- Sync. Clock tion N8241A arbitrary waveform trigger Performance generator. The unique N8241A leads Arbitrary Base-band I-Q signal RF Out #1 the industry with an amazing 15 bits waveform modulation MXI-4 generator of amplitude resolution at sample generator (E8267D) rates of 1.25 GS/s. (N8241A) Working together, the 44 GHz PSG LAN and high dynamic range N8241A arbitrary waveform generator deliver superb performance for a number of Personal difficult wideband applications. computer Phased Array & DF Testing Agile phased array antennas Figure 2: To generate entire spectral environments multiple N8241A arbitrary dominate new designs, many of which waveform generators can be up-converted to different frequency bands with the operate over wide bandwidths. Test- E8276D performance signal generators. ing the agile array’s ability to track a target hundreds of miles away often challenges of Phased Arrays and DF ing of modulated waveforms. requires a challenging test stimulus equipment. Architectural intercon- Phase offsets between multiple that is precisely phased across mul- nections have been provided to allow phase coherent signals from the 44 tiple channels to simulate an arriving multiple PSGs to be modulated with GHz E8267Ds are implemented using wave-front. multiple N8241A arbitrary waveform digitally synthesized modulation. This Similarly, some intelligence receiv- generators. The modulated outputs allows synthesis of complex signals ers use multiple phase coherent receiv- of the PSGs can then be connected to arriving at antenna ports with the ers to determine the bearing angle to a phase coherent array. This arrange- proper delays to simulate an arriving the signal emitter. ment can synthesize signal band- wave front. Testing these systems is difficult. widths up to 1 GHz from flexible Their wideband designs require pre- digital files defined in Agilent’s Signal Broadband EW Spectral Environments Bandwidth requirements for mili- As signal bandwidth exceeds 200 tary communications have also grown MHz, finding effective test equipment solutions over the years as systems move from for today’s advanced RF system becomes in- voice to bandwidth hungry high-reso- lution video. creasingly difficult. Aerospace/defense systems typi- cally function in complex RF spectral cisely phased signal inputs at multiple Studio modulation synthesis tool. environments, with jammers and input ports to simulate the spatial The Agilent Z5623A distribu- interferers that utilize many octaves of relationships of various emitters. tion amplifier, along with a common bandwidth. Compounding the growth Field-testing multi-port electronic 10 MHz reference locks the signal in data rate, many communications systems is often cost prohibitive as generators together to create a totally systems have gone to spread spectrum well, requiring expensive configura- phase coherent set of signal outputs. signals that frequency hop over huge tions of multiple airborne or surface The system further enables full bandwidths to reduce the probability assets spaced hundreds of miles apart. control over time, phase, ampli- of intercept and improve performance Responding to this demand, the tude and frequency. Synchronizing in messy signal environments. Agilent Z2090B system architecture the arbitrary waveform generator Generating gigahertz of spectral is uniquely capable of addressing the clocks together, allows precise tim- environment to test the robustness of TECHNOLOGY LEADER SERIES these data links can require extreme ity, coherency and the like, all present made. These unique capabilities are bandwidth capability. measurement challenges. ideal for comparing the phase differ- When confronted with the need For this reason, Agilent offers a ences between two different wideband to generate such a test environ- variety of signal analysis options for receiver channels. ment, multiple PSGs modulated with broadband system analysis and test. The VSA 90000A's unique wide- N8241A arbitrary waveform gen- band two-port measurement capabil- erators can be offset in frequency to Coherent Receiver Array ity makes it an effective measurement provide continuous signal bandwidths Measurements solution for advanced wideband greater than the 1 GHz available with Whether comparing the phase of multi-channel systems. a single PSG and N8241A system. arrival of two complex modulations For example, five PSGs and to resolve a bearing angle or charac- Software Defined Radios N8241As can generate up to 5 GHz terizing the spectral shape of an Ultra When considering broadband of spectrum to test a broad range of Wide Band (UWB) signal, the Infini- signal measurement capability, spectral situations. ium Oscilloscope offers a tremendous logic analyzers may not immedi- Furthermore, the N8241A's su- variety of wideband measurements. ately come to mind; however, with perior sequencing ability allows it to Agilent’s Infiniium 90000A series the ubiquitous trend to implement create complex signals using sequenc- oscilloscopes sample at rates up to 40 greater portions of complex systems ing of short repetitive signal snippets GS/s, providing analysis bandwidths in software defined hardware with without massive amounts of signal up to 13 GHz wide. Furthermore, ultra fast FPGA digital processing, memory. This important feature en- ables long or continuous play of wide bandwidth spectral environments, Field-testing multi-port electronic sys- without Tera bytes of high-speed tems is often cost prohibitive as well, requiring waveform storage memory. expensive configurations of multiple airborne or In addition, the N8241A incor- porates a built-in Direct Digital surface assets spaced hundreds of miles apart. Synthesis (DDS) feature that expands simulation capabilities without using the 90000A has the industry’s lowest increasingly the wideband signal is additional memory. noise floor, best phase noise per- digital rather than analog. The Z2090B can also be config- formance and the flattest frequency The Agilent analysis product line is ured to playback wideband signal response. unique in that the 89600A VSA soft- recordings taken from the field. These superior performance traits ware is available on a variety of hard- MILCOM engineers can employ the allow the multi-channel Infiniium ware platforms. Spectrum analyzers, Z2090B to analyze system responses oscilloscope to capture ultra narrow oscilloscopes and logic analyzers can to multi-path, interference and more, time domain events and conduct RF all host this powerful analysis tool. using either recorded or synthesized modulation analysis. The Agilent 16800 series logic ana- signals. The ‘VSA 90000A Ultra Wideband lyzers, for example, support measure- Advanced tools, like Signal Studio Signal Analyzer,’ bundles