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Tag: Military; Defense Aerospace

On October 30, 2019, Army, Navy, and Air Force representatives gathered at the Association of Old Crows Conference to discuss the electromagnetic spectrum (EMS) and its potential as a separate domain of warfare. While some consider it unnecessary to label the EMS as a separate domain, officials agree that the United States is lagging behind China and Russia in this aspect of war.   

Published in MultiPoint Blog

 

We provide MIL-STD-461 testing / sales@hfytxx.com

Reviewed in this article are RE01 and RE102, with updates found in MIL-STD-461-G, the current version.  These tests quantify undesired signals being radiated into the air from a device and the associated cables. If unchecked, these signals couple onto other equipment cables or may enter into the other equipment chassis and onto internal conductors.  The received field has the potential to induce current in other equipment conductors and may cause harmful interference from either field.

Published in MultiPoint Blog

Switching-Mode Power Supply Switching-Mode Power Supplies (SMPS) are used extensively in many electronic applications. Many manufacturers offer MIL-STD-461 compliant solutions, as well as Commercial Off-The-Shelf (COTS) solutions for military applications. SMPS offer many advantages when compared to Linear Power Supplies. The primary advantage of an SMPS is that it offers power conversion and regulation at 100% efficiency – albeit, given ideal components. All power loss is due to less than ideal components and the power loss in the control circuitry. Other advantages of the SMPS are smaller size and therefore less weight. SMPS have switching frequencies that range from 50 kHz to 1 MHz.

Published in MIL STD

Power regulation on Navy platforms can be severely affected if the quality of power is not regulated. Harmonic currents levels are controlled through MIL-STD-461E and MIL-STD-461F, CE101 conducted emissions limits and test thereof.

The quality of power, technically referred to as power quality, can be quantified as a set of parameter values to include variation in voltage amplitude, transient voltages and currents, service continuity, and harmonic current levels in power distribution system waveforms. Power quality is affected when electronic power supplies, and other non-linear loads in particular, cause distortion in the power distribution system of Navy platforms.

In a typical electrical power AC system source, loads are either linear or non-linear。 When the load is linear, the current drawn by the load is sinusoidal, which does not distort the waveform。 Conversely, non-linear loads produce non-sinusoidal current waveforms, which create a distortion of the voltage waveform。 Non-linear loads produce harmonics, which can cause interference to radios, telephones and other communication devices and navigation instrumentation on the Navy platform。 The harmonics can also cause a breakdown in the insulation materials of the platform’s electrical wiring。

Published in MultiPoint Blog
  1. The RE102 test method in MIL-STD-461E required using a 41” rod antenna below 30 MHz with the counterpoise grounded to the ground plane, which called into question the accuracy of the measurement results above the 10 MHz frequency range. To address this, MIL-STD-461F requires that the counterpoise be isolated from the groundplane.

A client recently inquired as to whether it would be possible to see a reduction in radiated spurious emission levels on Spread Spectrum Clock (SSC) fundamental frequency and harmonics using Peak Detectors during MIL-STD-461F testing of a COTS product, when previous FCC Part 15 testing of the COTS product proved compliance using Quasi-Peak Detectors. We are pleased to share our response: If COTS with SSC products with Part 15 compliant fundamental frequencies and harmonics are tested to MIL-STD-461F using required Peak Detectors, the spectral peaks of their fundamental frequencies and harmonics should comply with MIL-STD-461F, provided the SSC timing parameters are properly configured. A properly configured SSC would produce lower spectral peaks of the fundamental frequency and harmonics in the SSC mode than the spectral peaks of the fundamental frequency and harmonics in the non-SSC mode by levels that are dependent on the manufacturer of the SSC, modulating waveform profile, modulation rate used to modulate the fundamental frequency clock frequency in the SSC mode, spreading rate style used (down, center or up) as depicted using (Δ) in Figure 1 below:

 
Published in MultiPoint Blog
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