Trunking on VHF frequencies bodes well for SMR
SMRs are looking for opportunities to build out trunking systems, and a wealth of frequencies are available in the part of the band where they said it could be done-until someone did it.
Service industries continue to be one of the fastest-growing sectors of the U.S. economy. With their business expanding, the need for dispatch services is also growing within these companies. While this represents tremendous opportunity for specialized mobile radio (SMR) service providers, the biggest limiting factor following refarming has been the lack of available spectrum.
The worst congestion is in the 800MHz band, where nationwide digital networks such as Nextel Communications and Southern LINC are aggressively competing with the small SMRs. Following the entry of these two giants, one-third of all 800MHz channels are now reported as being crowded, a significant number, since this band accounts for 60% of all licensed SMR channels.
Expand or die The rule of evolution is that those who don’t adapt to changing conditions become extinct. Recognizing this, many enterprising SMRs are taking advantage of the FCC’s new channel offerings in the 900MHz, 450MHz, and 220MHz bands. Now, an enterprising California company is pioneering a brand-new SMR business operating in the allocated 150MHz-174MHz VHF band allocated in 1999.
California Metro Mobile Communications (MMC) is located in Menlo Park, in the heart of the Silicon Valley, about halfway between San Francisco and San Jose. The nine-person company, founded in 1984, is a successful sales and service dealership, and the exclusive representative for Kenwood Systems in the San Francisco Bay Area. MMC is also a factory-authorized sales and service dealership for Motorola Radius, E.F. Johnson and Bendix/King land mobile products.
However, co-owners John Singer (sales) and Bill Graves (service/technical) knew that to realize the company’s full potential, they would have to expand their business’ scope.
“We’d never owned our own trunking infrastructure before,” Singer said. “We sold systems to end-users and loaded them onto other customers’ infrastructure, so we were never able to participate in the long-term revenue stream of billing for airtime. “We knew that, for our long-term success, Metro Mobile needed to be able to do that.”
Finding the perfect band But, in choosing to start an SMR business in the Bay Area, MMC faced a number of daunting challenges. First, while the area’s large population promise d plenty of subscribers, it also meant that frequency congestion and availability would be issues. Second, the mountainous topography of the Bay Area would necessitate the deployment of multiple mountaintop repeater sites to provide adequate coverage. Third, Singer and Graves decided early on that the exclusivity afforded by YG (private trunked) frequencies would be a requirement. Fourth, MMC needed a system that would allow it to be a good neighbor by not interfering with older, existing systems and would also be compatible with the narrowband frequencies required by the FCC by 2002.
Knowing the type of SMR they wanted to offer, Singer and Graves began researching frequencies.
“We knew that the 800MHz and 900MHz frequencies were basically all gone,” Singer said, “But we had not had good success in the T-band lottery. Furthermore, we wanted to make a true YG trunking system, not an IG [non-trunked conventional] system where users have to monitor the frequency before transmitting. Unfortunately, I’m not sure you can find any eligible YG frequency pairs in the 450MHz band. It’s our feeling that the UHF frequencies are already totally messed up, with a lot of overlap between the various repeaters already on the air.”
In the course of their research, Singer and Graves discovered that the FCC had recently changed the rules and was now allowing trunking in the VHF band (150MHz-174MHz). The immediate advantage was obvious-almost no one else was operating on these new frequencies. However, a major drawback was the fact that no manufacturers were currently producing subscriber equipment in the VHF band. Believing that such equipment would eventually become available, MMC took a calculated risk. The company applied for and was subsequently licensed for a number of YG frequency pairs in the VHF band. Although the FCC has since changed the rules to define licenses by contours, at that time the frequencies were totally exclusive for a 70-mile radius.
Pulling the pieces together With their YG licenses in hand, MMC had to meet construction deadlines to hold onto them. The next part of the search focused on finding and developing the necessary subscriber equipment.
Graves, as MMC’s service manager and technical expert, knew the technical requirements would not be easy.
“Because of the close spacing of the frequencies with the refarming at 7.5kHz, we faced the technical challenge of finding equipment that would work within those parameters. Nobody was making such equipment at that time because everybody’s idea of narrowband was 12.5kHz, not 7.5kHz,” Graves said.
Because MMC was aiming to introduce a previously unexplored trunking frequency in one of the highest RFI markets in the United States, it needed equipment with excellent adjacent-channel, signal-rejection audio quality. It also needed a supplier that would work with it to develop a VHF trunking system and then stand behind that product with first-rate technical support. In the end, MMC selected equipment from three major wireless manufacturers: DX Radio, Zetron and Kenwood.
DX Radio Systems of Los Angeles supplies repeaters and trunking systems from 900MHz down to VHF frequencies. For MMC’s planned system, DX Radio developed a special VHF version of its DXRS Millennium series trunking system. This “up-scale” system features a built-in Zetron model 42 trunking controller specially modified by Zetron for the VHF application.
“With our repeaters and the Zetron model 42 trunking controller, we produce one of the highest-quality audio reproduction radio systems on the market today,” said Fred Goodwin of DX Radio. “Metro Mobile selected the DX trunking system for its adjacent-channel signal rejection and because it reproduced the audio and signaling better than anyone else’s controller. In this emerging deployment of VHF trunking, Metro Mobile wants to be a good RF neighbor whose system won’t interfere with other users.”
System deployment With its mountains and valleys, the topography of the Bay Area prevents any single repeater from providing 100% coverage. MMC performed beta testing at two mountaintop sites with the goal of having a total of four sites up and running before the end of 1999. Based on satisfactory coverage results from the beta testing, the company is now marketing its system as the Metronet VHF Trunked Radio Network.
Singer characterized the performance of the DX Radio and Zetron equipment as “phenomenal” at one fairly low site selected as a beta-test location, Calaveras Ridge. “It tends to cover a greater distance than any other radio system I’ve used, and the signal is very clear. VHF gets into some areas that neither 800/900MHz, nor UHF will,” he said. “On the downside, our experiments with portables inside buildings have not been that good, since VHF signals don’t penetrate man-made structures that well.”
Serving basic dispatch needs Singer added that the latter point is actually not that much of a drawback because MMC designed its trunking system as a “plain-vanilla radio- dispatch system, with no frills or bells and whistles-just top-of-the-line equipment, featuring low operating cost, good access and good clarity.”
MMC’s target clients are the traditional users of wide-area dispatch: waste-disposal companies, couriers, delivery companies, bus and taxi companies, and anyone else who needs wide-area, over-the-road dispatching. The system, however, does have potential for more advanced services.
“There are technologies that will work on our system, such as GPS and data, which we may decide to add later,” Singer said. “Kenwood is developing a new radio feature called Fleetsync, which allows for low-tier mobile status messaging built right into the Kenwood radio, and our system will accommodate that.”
The future of SMR trunking MMC sees the expansion into these new frequencies as a trend that will only get stronger as the squeeze on available radio spectrum increases. “I think there are a whole bunch of SMRs who are in the same boat we are, in that they are looking for opportunities to build-out their own trunking system,” Singer said. “There are a multitude of VHF frequencies available throughout the U.S., and I think it’s the next frontier for companies like ours.” N
