Ron Brewer EMC/ESD Consultant Shielding has been with us a long long time. Early AM radios had shielded RF and IF transformers, shielded electron tubes, and compartmentalized shielded chassis. These shields were necessary to prevent RF pickup, feedback, and oscillation by the electron tubes, radiation from the local oscillator, RF contamination of the IF strip, and crosstalk … [Read more...]
Utilizing Overlooked Characteristics of Ferrites for Improved Printed Circuit Board EMI Suppression
ABSTRACT While nickel-zinc composition soft ferrites are routinely used for PCB EMI suppression, the consequences of DC and low frequency AC bias on a device's high frequency impedance has not been widely discussed in the EMC and magnetic component literature. Virtually all EMI suppression applications in DC and AC power filter circuits place two-terminal ferrites under … [Read more...]
Spectrum Aeromed Module Passes EMI Testing and Wins Military Air Worthiness Award
North Dakota-based Spectrum Aeromed has announced that its ambulance module was subjected to exhaustive testing requested by the U.S. Air Force. The Spectrum Aeromed ambulance module was subjected to EMI, electrical safety, severe vibration periods, altitude changes, rapid decompression, and environment testing. Following this testing, Spectrum Aeromed equipment was awarded … [Read more...]
Air Force Looking for Customized Van for EMC Lab
The U.S. Air Force Air Education and Training Command at Keesler AFB in Mississippi is looking for a Dodge Sprinter Van converted for use as a mobile EMC lab. The solicitation calls for a work area, 42 ft mast, equipment racks for test equipment and an AC power generator. Incorporated into the solicitation is a Statement of Need that provides information on specifications of … [Read more...]
British Agency to Study the Health Effects of EM Energy from MRIs
The Chairman of Great Britain’s Health Protection Agency, Sir William Stewart has announced that the Agency’s Board has approved in principle the need for an epidemiological study of possible adverse health effects from high static Magnetic Resonance Imaging (MRI) machines. He noted, “The exposures to patients and to medical staff from the magnetic fields can be high, and there … [Read more...]
Radio Free Europe Accuses Kazakhstan of Deliberate Interference
Radio Free Europe has issued a statement on a “very disturbing” case that smacks of “deliberate interference” by the Kazakh government , Internet users have been prevented for more than five weeks from accessing the Kazakh-language website of Radio Free Europe/Radio Liberty. Access to the Kazakh site was interrupted on April 11 and has continued despite RFE/RL’s repeated … [Read more...]
Active Filter Protects DC-DC Converters in Harsh Electrical Environments.
The DSF500 from XP Power is a 500-W active filter unit for use in harsh electrical environments. It has been crafted to protect DC-DC converters from the surges, spikes, and ripples that are typically found within the electrical system of any military platform—such as aircraft or vehicles. This filter complies with MIL-STD 1275A-D without the incorporation of any additional … [Read more...]
National Security Agency Declassifies Report on TEMPEST
On April 29, 2008, the National Security Agency declassified a report titled, "TEMPEST: A Signal Problem--The story of the discovery of various compromising radiations from communications and Comseq equipment." The story begins during World War II when a researcher noticed that every time a Bell Telephone encrypting machine encrypted a letter, a spike appeared on an … [Read more...]
A Second Look at the FCC Dynamic Frequency Selection Certification Issues
Both manufacturers and test labs must decide on the proper test procedures for DFS products. Since July 20, 2006, systems operating under FCC Part 15.407, specifically in the 5250- to 5350-MHz and the 5470- to 5725-MHz bands, are required to support Dynamic Frequency Selection (DFS) before the products can be certified. As part of the approval process, the FCC must carry out a … [Read more...]
In-Flight Cell Phone Ban Approved by Congressional Committee
H.R. 5788 received approval via voice vote by the House Transportation and Infrastructure Committee and can now move on to consideration by the U.S. House of Representatives. This bill would make permanent the long-standing ban on onboard use of cell phones by the Federal Aviation Commission and the Federal Communications Commission. Cell phone calls have long been prohibited … [Read more...]
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