Clarifying a sale
In the June issue, the News Report, “Disparate Solutions Work To Fill Communications Gap,” on p. 44, the following paragraph was misleading regarding M/A-COM being acquired by Cobham plc. :

The SLERS system is the result of a unique public-private partnership between M/A-COM (www.macom.com), which was just acquired by Cobham plc (www.cobham.com), and the state of Florida. It accommodates more than 6500 users with 14,000 radios in patrol cars, boats, motorcycles, and aircraft wherever they are in the state. The all-digital radio network covers 60,000 square miles.

Cobham did acquire a part of Tyco Electronics M/A-COM, but it was the commercial product segment and the aerospace and defense segment, not the public safety radio business. Our apologies for any confusion this may have caused our readers.
The Editors

Sorting through hype
The editorial in the May issue of Microwaves and RF (“Novel Approaches Vow To Upset The Status Quo,” was disappointing, containing industry hype about products without being backed by research as to the correctness or validity of the hype.

Specifically, p. 56 reports on a MEMS-based oscillator, about how it delivers impressive stability. But compared to standard quartz-based CMOS oscillators, it is exceptionally noisy and has severe short-term stability issues.

Refer to the presentation that Dave Kenny and Robert Henry of Pletronics Inc. presented at this year’s IEEE Frequency Control Symposium where the MEMs and other frequency control technologies were compared.

MEMs technology exhibits shortterm stabilities in the order of +/-3 ppm over several seconds while quartz crystal resonators provide +/-0.02 ppm or better in the same tests. The jitter is so severe from existing MEMs resonators that they cannot be used in most systems. Quartz resonator-based products are also lower in cost.

I would hope you would provide added information in future editorials so designers will not be lead to a technology that will not meet their needs.

Bob Gubser, Vice President
PRA Inc.
www.prainctest.com

Editor’s Note: Our thanks to Mr. Gubser. His comments may spark a closer look at MEMS technology and its uses for frequency control.