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CommShield® Technology Improves RF Resistance

Microflex® microphones from Shure are used in a wide variety of applications for sound reinforcement, recording, and distance conferencing. They are found in boardrooms, conference rooms, courtrooms, interview rooms, on podiums, and even hanging from ceilings for choir vocal pick-up. Microflex product lines are very popular with sound contractors, consultants, and end users. They provide unmatched quality for many applications.

Over the last couple of years, users have enthusiastically embraced new communications products using GSM cell phone technology. The acceptance and growth of messaging capability has led to new user habits. With the introduction of multipurpose devices featuring Personal Digital Assistant, web access, instant messaging as well as voice capabilities, it is common for users to place their device on a conference table or podium for easy viewing and access. In fact, it is not uncommon to place or prop the devices close to or on a microphone located on a conference table or podium.

The GSM radio transmission protocol is a digital format, where the voice and media data is transmitted on a series of radio frequency pulses. In the GSM technology, the base pulse rate is 217 Hz. These pulses are very short, but also very intense. The intense radio frequency energy can couple a significant amount of interference into nearby audio electronics devices, such as microphones. Active electronic devices, such as transistors and integrated circuits, can detect this signal. The base repetitive pulse rate, along with harmonics, falls in the audio frequency range. The resulting “buzz” is very unique and recognizable, not to mention undesirable.

Shure engaged their development teams to redesign Microflex microphones to be highly resistant to radio frequency interference such as might be experienced with GSM cell phone technology. Because of the intensity of the interfering signal, advanced electromagnetic interference (EMI) techniques are employed in the new designs to provide robust shielding and RF filtering for the audio circuits. Design techniques include multilayer circuit boards for microphone preamplifiers, improved grounding techniques, tighter enclosures for improved shielding, as well as improved microphone cable and audio connectors. The combination of improved techniques, known as CommShield® Technology, is utilized to deliver Microflex microphones that are highly resistant to intense nearby radio signals. The new designs have been extensively tested in Shure’s RF laboratory.

The newly designed Microflex microphones are poised for the future. New product designs are now released and available. Product package labeling identifies the new designs with the phrases “RF Filtering” or “CommShield Technology for RF Filtering”.  Shure Easyflex microphones, now discontinued, also feature Commshield technology.

Please contact the Shure Product Support Group (1-800-516-2525) with any questions or for additional assistance, or check out our FAQ database.

Registered trademark update: November 23, 2009

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