Evolving roles for walkie-talkies

Focusing on 10-meter to 1-km communications, the GMRS380 two-way we analyzed was part of a two-pack purchased for $59.95 at Best Buy. Work settings, family gatherings and ski trips present typical use modes, when a small group needs to keep tabs on one another over a modest range.

The radio has 15 channels: seven for Family Radio Service (FRS) and eight for the higher-powered General Mobile Radio Service (GMRS), all in the 462- or 467-MHz region of the spectrum. A scan feature seeks out and locks onto an active channel. While the FRS channels are available to all, an FCC license is technically required to transmit over the GMRS frequencies. No meaningful controls to suppress unlicensed GMRS use exist, however, so effective FCC enforcement may be unrealistic with the large numbers of unrestricted units being marketed and sold.

The electronics start with a chip-on-board Zilog microcontroller (Z86L99), responsible for user interface and system tasking. The FM IF system (SL5018) comes from AUK Semiconductor, while frequency synthesis and phase lock is performed in Toshiba BiCMOS (TB31202). Elsewhere, the audio amplifier is a Japan Radio Corp. component (NJM2113) and miscellaneous functions are picked up by two AUK Semi quad op amp chips (S324).

Beyond these ICs, discrete components make up much of the RF circuitry, where relatively simple radio design is possible with the narrowband FM architecture of the FRS/GMRS standard. Weight of the product is divided among batteries, enclosures and electronics.

While touted to have a range of 5 miles, casual urban testing revealed one closer to only half to three-quarters of a mile, no matter whether FRS or GMRS channels were used. Nothing's perfect, but for the money this class of product presents a decent balance in price and performance.

Commodity manufacturing rules, with a sub-$15 estimated cost of goods sold for the GMR380. But in the future the entry-level cellphone market may closely resemble today's FRS/GMRS radio in cost and complexity, so the product is worth studying for its broader implications. Additionally, while FRS/GMRS may threaten cellphone use in highly local situations it might also make for an interesting addition to otherwise standard cellular handsets.

David Carey is president of Portelligent (www.teardown.com). The Austin, Texas, company produces teardown reports and related industry research on wireless, mobile and personal electronics.

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