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Test / Data Acq.
Frequency Synthesizers Fit Many Modular Formats |
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Thursday, 29 March 2007 |
Frequency synthesizers are used throughout RF/microwave applications in measurement labs; in commercial communications systems; in military avionics, electronic-warfare (EW), satellites, and other systems; and throughout industrial, automotive, and medical systems at every level from integrated circuits (ICs) to rack-mount subsystems in machined housings. Because the field of RF/microwave frequency synthesizers is so broad, this report will focus on modular, system-level frequency synthesizers....more  (0) Comments |
Take The WLAN Test Challenge |
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Tuesday, 27 March 2007 |
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A WLAN system’s RF environment challenges designers, installers and administrators with planning re-use patterns, interference detection and system coverage in both installation and maintenance. These challenges are also found in seemingly more complicated cellular phone systems. Frequency re-use patterns, coverage mapping, interference from neighbors, locating unauthorized users and locating stolen equipment must be considered in addition to the standard PER and throughput metrics. Installing and maintaining a large WLAN system can rival the complexity of a cellular phone system. The author presents a comparison of equipment that is available to designers, installers and administrators to measure and overcome these challenges. Spectrum analyzers, standard WLAN cards and RF equipment specifically designed to measure 802.11 on the air are examined. Examples are drawn from the author’s experience in designing WLAN test equipment; parallels are also drawn to methods and equipment that are found in the relatively mature cellular phone industry. The installation of an 802.11b Wireless LAN system to cover a large office setting can be very challenging and techniques found in cellular system engineering are often required. WLAN systems have the added complexity of operating in an unlicensed band where interference may not be under control of the WLAN manager, and the WLAN often operates in a harsher indoor RF environment....more (0) Comments |
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Normalized Q-Scale Analysis: Theory And Background |
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Tuesday, 27 March 2007 |
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A robust, repeatable, and accurate technique estimates and measures random and bounded, uncorrelated jitter components. Jitter is an important aspect of signal integrity for both optical and electrical serial data streams (and clocks). As data rates become faster and timing budgets smaller, it has become crucial for engineers to more accurately measure jitter and its components: random jitter (Rj), deterministic jitter (Dj), data-dependent jitter (DDj), duty-cycle distortion (DCD), and periodic jitter (Pj). A newly introduced method called “Normalized” Q-scale Analysis offers a more robust, repeatable, and accurate technique to estimate and measure the random and bounded, uncorrelated jitter components....more (0) Comments |
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Power This: Testing Audio ICs |
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Tuesday, 27 March 2007 |
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SOCs for set-top boxes, television monitors, disk players, and mobile media players have or soon will have HD capability. But another aspect of this evolution—one that could prove even more challenging to SOC designers and test engineers—is that, along with HD video comes a significant increase in the quality of the accompanying audio. It is a well-publicized trend that HDTV (high-definition TV) is sweeping through the next generation of SOC (system-on-chip) platforms. SOCs for set-top boxes, television monitors, disk players, and—in the near future—mobile media players will have HD capability. But another aspect of this evolution, audio quality, is slipping beneath the radar. The problem with high-resolution audio isn’t just in the circuit design. In fact, analog-IC designers are producing DACs and amplifiers that are arguably better than anything available during the golden age of discrete-component gear. The problem is in characterization and testing. The quality of high-end audio, as many analog designers will tell you and as audiophiles may insist to the point of religious discourse, is excruciatingly hard to quantify even on the characterization bench and almost impossible to verify in a manufacturing-test environment. SOC designers are now sizing up this new challenge, joining experienced audio-IC designers who have lived with it....more (0) Comments |
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Offensive Channels: Overcoming Obstacles In PCB Traces, Vias, IC Pins, And Connectors |
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Friday, 23 March 2007 |
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Signal-integrity measurements are essential to the development of high-speed communications systems. The higher a signal’s frequency, the more susceptible it is to degradation. Digital signals, especially those over 1 Gbps, lose amplitude and accumulate jitter as they travel through connectors, printed-circuit board (PCB) traces, vias, IC pins, and cables. Thus, the transmission channels “offend” a signal’s integrity. Digital circuit designers often rely on signal-integrity (SI) labs and engineers to characterize their transmission systems and create HSPICE models that the designers can use to simulate the performance of an individual circuit or an entire system. With these models, designers can predict how a component will behave in both the time domain and the frequency domain....more (0) Comments |
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National Instruments Rolls Out Data Acquisition Modules, Data-Logging Software |
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Friday, 16 March 2007 |
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The move toward software-based test and measurement instrumentation gains momentum today, as National Instruments rolls out 19 new I/O modules and a new brand of data-logging software. National Instruments, which has made its name in virtual instrumentation, said last week that the rollout is consistent with a movement it has dubbed “Instrumentation 2.0,” in which test and measurement equipment offers real-time data logging, custom interfaces, modularity, PC connectivity and user-definability. “We see the industry moving to a software-based approach,” notes John Graff, vice president, marketing and investor relations. “When you start looking at multi-core (processors) and FPGAs, there are incredible possibilities for the software-based approach.”...more (0) Comments |
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