Test & Measurement World: US Military EMC Standard gets a revision

By Martin Rowe, Senior Technical Editor, Test & Measurement World -- EDN Europe, 01 Sep 2009

MIL-STD-461, “Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment,” has long defined military EMC (electromagnetic-compliance) tests. With version F, the standard incorporates numerous changes—both significant and minor—and reinstates an old test method. Released in December 2007, MIL-STD-461F is now being implemented on products and systems developed for Department of Defense applications.

The current version of the standard incorporates a dozen or so significant changes. Some of those changes are easy to understand, but others may lead to confusion. A paper by Steve Ferguson, vice president of operations at Washington Laboratories (www.wll.com), spells out these changes in detail.

In his paper, Ferguson assumes that you’re already familiar with previous versions of MIL-STD-461.

Ferguson points to a new frequencyscanning technique as a possible point of confusion. He notes that the standard lets you run faster scans, but that these faster scans don’t mean you’ll reduce testing time. You still must comply with a minimum measurement time defined in the standard, even though new equipment can scan faster than older units.

A requirement for power-line voltage testing, dropped from the standard with revision D in 1993, has been reinstated for some applications. MIL-STD- 461F requires a single 400V, 5-µsec pulse calibrated with a non-inductive 5Ω resistor.

If you perform automated tests, then MIL-STD-461F requires that you verify operation of your software, whether you use commercial software or develop your own. You must describe the control and methodology of your software. If you write your own test procedure for use at a commercial EMC lab, you’ll need detailed knowledge of how the software works.

Digital EMI receiver enables CISPR 16 measurements

The PMM 9010 digital EMI receiver from Teseq lets you perform emissions testing from 30 MHz to 6 GHz. The receiver makes measurements in the time domain, digitizes them, and converts them to the frequency domain. You can use the receiver to make measurements that comply with CISPR 16-1-1, including the new RMS-AVG (root-mean-squareaverage) detector and APD (amplitudeprobability distribution) for testing above 1 GHz.

The PMM 9010 includes a fully compliant CISPR 14-1 click-meter option, which automatically evaluates the click rate and applies the use of exceptions when appropriate, using the upper-quartile measurement method. Because of its digital-signal-processing capability, the PMM 9010 lets you swap out components such as the ADC and RF signal generator. You can replace system firmware to add measurement features such as detectors, resolution bandwidth filters, and other measurement methods as they become available.

- Teseq, www.teseq.com

Anritsu introduces 4G handheld base-station analyzer

Anritsu has introduced the BTS Master MT8221B, a handheld base-station analyzer that supports emerging 4G standards as well as installed 2G/3G networks. The MT8221B’s platform provides a 20-MHz demodulation capability to measure technologies such as LTE and WiMAX, and it offers a 30-MHz zero-span IF output for external demodulation of virtually any other wideband signal. In addition, the company offers a vector- signal-generator option that can generate two modulated signals plus noise for receiver testing.

The instrument detects key performance indicators, such as dropped calls, call denial, or call-blocking rates caused by a malfunction at the cell site or by interference. Additionally, it can measure the RF and modulation quality of a wireless signal to verify the performance of virtually every subsystem in a base station’s transmitter. The BTS Master comes with the MST (Master Software Tools) package, which allows data acquired by the analyzer to be easily transferred to a computer. The software also provides a remote-access tool for monitoring and controlling the BTS Master over the Internet. Pricing is from $19,950.