Systems & Subsystems
 82 results found for Systems & Subsystems, displaying items 21 - 40

August 10, 2007
FreeWave Adds Tiny Spread-Spectrum Radio
 — Jack Browne

July 27, 2007
July 26, 2007 Newsletter
 — Jack Browne

July 26, 2007
MITEQ Offers LNB For 24 To 40 GHz
 — Jack Browne

July 2007
Spread-Spectrum Module Fits 3.4-GHz Military Radios
Secure communications is critical in battleplace as well as in public-safety and other government-agency applications. Frequency-hopping spread-spectrum techniques can ensure voice and data security over long-range communications links, and such technology is now with-in range of most radio system manufacturers with the introduction of the model 3400 SMR board-level spread-spectrum radios from FreeWave Technologies (Boulder, CO). Designed for use from 3.3 to 3.5 GHz, ...  — Jack Browne

July 12, 2007
July 12, 2007 Newsletter
 — Jack Browne

July 11, 2007
Surge Protection Reaches 6 GHz
 — Jack Browne

June 28, 2007
June 28, 2007 Newsletter
 — Jack Browne

June 26, 2007
Surge Protection Reaches 6 GHz
 — Jack Browne

June 2007
Optimized Transceiver Aids Broadband Wireless Access
Broadband-wireless-access (BWA) technology promises high-speed Internet connections by means of reliable wireless devices. But, in order to achieve cost-effective products in a competitive marketplace, the RF hardware in broadband-wireless-access products must be compact and reproducible. Fortunately, the authors have developed an RF/microwave module for broadband wireless access applications that provides excellent performance in a compact size. The module consists of an antenna...  — Wei Hong , et al.

June 2007
Small Synthesizers Arm Practical EW Trainers
Fast-switching frequency synthesizers are critical to many radar and electronic-warfare (EW) systems as well as in automatic-test-equipment (ATE) measurement systems where high throughput is important. But fast-switching microwave synthesizers are also widely used in radar simulators and EW training systems to emulate complex, multiple-signal threat environments. The requirements for these latter applications can be demanding, but the latest generation of compact, low-power,...  — Dennis Gable

June 2007
Checking Capacity For MIMO Configurations
Antenna elements arranged in a multiple-input-multiple-output configuration can impact the capacity of a wireless-communications system and combat multipath effects. But one of the keys to improved performance is finding the optimum MIMO layout for a given system scenario, and when it makes sense to stop adding antenna elements and simply optimizing the existing antennas. Last month, this two-part article introduced basic MIMO concepts; this conclusion explains how to calculate...  — Kaj B. Jakobsen , et al.

June 2007
PLL Synthesizer Tunes DCS1800 Band
Frequency synthesizers are critical components in modern mobile-communications systems, powering both transmitters and receivers. Typically, they are designed with a phase-locked-loop (PLL) approach.1 To demonstrate the effectiveness of this synthesizer architecture for one of the more challenging mobile wireless-communications formats, DCS1800, the authors designed and simulated a PLL frequency synthesizer for use in a DCS1800 base station. The base station operates in...  — Samir Kameche

May 2007
Multiple Antennas Arm Effective MIMO Systems
Capacity is critical for the profitability of larger wireless networks, and multiple-input-multiple-output (MIMO) systems provide potentially high capacity.1 These systems use multiple antenna elements in both the transmitter and receiver to improve the capacity over single antenna topologies when operated in multipath environment. The properties of these antennas play key roles in determining the overall system performance. And, in spite of the number of...  — Kaj B. Jakobsen , et al.

May 2007
Mobile WiMAX Promises Portable Broadband Wireless
WiMAX may represent the "future" of wireless broadband connectivty, but it will not succeed without the support of many in the WiMAX Forum working with vendor companies. The WiMAX Forum is dedicated to making the WiMAX wireless communications standard a commercial reality and ensuring that WiMAX products will seamlessly work with each other. The promise of broadband wireless access has existed for almost as long as cellular networks. Previous efforts at providing...  — Mark W. Andrews , et al.

May 2007
Spread-Spectrum Radios Hop Across 900-MHz Band
Spread-spectrum technology has long provided the military with secure communications. For almost as long, it has also fueled the growth of FreeWave Technologies (Boulder, CO), a leading supplier of long-distance, high-data-rate radios to military applications as well as customers in the oil and gas industries, the electric power industry, automated manufacturing, and even golf courses. The firm's latest series of frequency-hopped spread-spectrum radios operate in the...  — Jack Browne

March 2007
Frequency Synthesizers Fit Many Modular Formats
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...  — Jack Browne

February 2007
Speedy Synthesizers Shoot For Low Noise
Frequency synthesizers come in many forms, depending upon the needs of an application.For the price of banks of filters and large bulk, direct analog frequency synthesizers offer unmatched frequency switching speed, although usually with trade-offs in spurious and phase noise. By sacrificing switching speed, few sources can match the low-noise performance of a phase-locked-loop (PLL) synthesizer with narrow loop filters and a high-quality crystal reference oscillator.1-7...  — Jack Browne

February 2007
Microwave Modules Increasing Integration
Integration packs multiple microwave functions into a single housing. Military requirements, and to a less degree commercial systems, are driving increased integration of microwave functions into smaller and smaller footprints, often to accommodate a growing amount of digital hardware in these systems. In general, most companies that manufacture microwave components also offer some level of integration at a standard or custom level. A variety of approaches are being tried to...  — Jack Browne

January 2007
Sigma-Delta Synthesizer Steps Across Multiple Standards
Frequency synthesizers are fundamental building blocks in wireless systems. Market pressures drive higher levels of integration in support of multiple wireless standards. But each wireless standard requires a specific crystal reference frequency and specific channel spacing. Integer-N frequency synthesizers can achieve the small step sizes required in support of multiple standards, but with high phase noise. Fortunately, a sigma-delta fractional-N frequency synthesizer can combine...  — Seste Dell'Aera , et al.

January 2007
Electronically Steerable Antenna Cuts Low Profile
Two-way mobile communications require tunable antennas for best performance. But mechanically tuned antennas lack the tuning speed and reliability demanded of security, public safety, and first-responder teams. Fortunately, high-frequency innovator AK Electromagnetique, Inc. (Les Coteaux, Quebec, Canada) has developed a low-profile antenna system that can scan electronically in both azimuth and elevation angles. The innovative antenna system [...  — Dr. A. Kumar





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