News
ComSpace readies DCMA for 2000 ComSpace, founded by former Uniden America executives David George and Steve Fulford, has spent several years in developing a spectrum-efficient technology with initial applications in business and industrial private two-way radio. The Irving, TX-based company demonstrated its progress toward delivery of icrochips, software, mobiles and base stations at IWCE in April.
As microchips and software become available, any radio manufacturer will be able to use them to make mobile two-way radio units with “digital channel multicarrier architecture” (DCMA) capability. DCMA places the equivalent of eight voice channels within the space of one 25kHz FM channel at 450MHz and 800MHz, four channels within 12.5kHz at 900MHz and two channels within 5kHz at 220MHz.
“We have received full samples of the application-specific integrated circuit (ASIC) from VLSI,” said George, the company’s executive vice president. “It’s the whole back end of a digital radio, including the analog and digital converters, vocoder, keyboard decod-er, LCD driver and IRD port and SIMM card reader, plus the DCMA system. That makes a very nice implementation for a man-ufacturer. They have only to put this chip in a digital radio, and they have a fully compliant DCMA product. That means brand ‘X’ can talk to brand ‘Y’ without standards documents, auditing or testing.”
Last summer, ComSpace altered its technology direction, discarding a previous analog air interface in favor of a digital interface.
“With digital, we were able to improve bandwidth efficiency, and we now have eight times capacity improvement,” George said.
George described the digital DCMA design as “a lot more work and a good decision” despite its higher complexity compared to analog DCMA. In an analog system, any problem with a synthesizer comes out as an audio signal, which can result in odd squeaks and buzzes, he said.
“In a digital radio, it’s just ones and zeros. Noise might come out as a fraction. Mechanisms do error correction and detection. You can have a lot more of those issues than in analog without degrading the sound quality, and as a fringe benefit, a digital radio is good for carrying data,” he said.
DCMA supports trunking protocols through its “service option negotiation” or SON.
“SON is like the modem on your PC,” George explained. “It takes data, whether Microsoft Word or PowerPoint or JPEG, and converts it into a signal that can pass over telephone wires and reconverts at other end. That’s roughly what SON does. If the people who use DCMA want to use Johnson LTR trunking, SON converts the trunking data stream to high-speed digital mixed with voice. At the other end, it filters the LTR out and reconverts it to 300-baud FSK.”
One part of ComSpace’s strategy that hasn’t changed is its plan to build base stations.
“We’ve always intended to make the base stations ourselves,” George said. “Then we also decided to build our own mobile radio because most of the manufacturers are slow, and we need some kind of a product to develop the marketplace and to prove the technology. We’re developing our own radio for that. We will eventually sell the design to someone. We don’t intend to be a radio manufacturer. We want to seed the market.
“We want to build base stations, though, because they need to be built robustly. A base station needs to be reliable to support hundreds of customers,” he said. Another motivation is the profit margin on base stations, which is higher than that for mobiles.
“We’ve already spent $13 million to develop DCMA. We took all the risk and spent the money, and we need to recover the investment,” George explained. “The base stations sell for a higher price, so they produce more revenue.”
ComSpace’s goal is to maintain the dynamics that the FM market enjoyed, meaning a lot of suppliers who are motivated to make innovative products at good prices. “The FM market is not as healthy as it used to be because users are out of capacity,” he said. “With DCMA, we’d like the manufacturers to ‘duke it out’ for the best units, all with our chips in them. DCMA works at multiple bandwidths, and it isn’t frequency-sensitive. We can even double the capacity of a 220MHz channel.”
DCMA doubles 220MHz channel capacity with time-domain duplexing. The method allows two voice paths within the same bandwidth, and it allows a single duplex voice path of the type used for telephone-type interconnect. In other words, each party to a conversation can be heard by the other without using a push-to-talk switch common to “half-duplex” mobile radio telephone interconnect. The use of time-domain duplexing avoids the need for a mobile cavity-type duplexer, which at 220MHz would be large.
ComSpace had licensed several manufacturers for its previous analog DCMA, and it has licensed a few for the new digital DCMA. Among the licensees are Datamarine International with its SEA Division, Transcrypt International and its EFJohnson Division, the Kenwood Systems subsidiary of Kenwood Communications, Zetron, Trident Micro Systems, SmartLink Development and Lenbrook. Lenbrook is one of ComSpace’s initial investors.
Additional information is available on two Web sites: www.comspacecorp.com and www.dcmaradios.com. DB
ACT changes name to Enrev, licenses software Advanced Charger Technology (ACT), Atlanta, has changed its corporate name to Enrev Corporation. The company will use the name ACT, but only for the unit that will continue its business in battery chargers. The company’s main growth engine will be the licensing of the battery operating system. The company, still privately held, has been raising money from venture capitalists and has raised $5.5 million. Enrev employs 65 people.
The software, Enrev OS, allows batteries to charge five times faster, deliver consistent, dependable power between charge and sustain four times longer than currently available technologies.
“Research has shown that battery limitations are a significant hindrance to mobile device performance and long-term reliability,” said Karen Robinson, president of Enrev. “If battery performance can be substantially improved, so can the usefulness and productivity of the devices they power. That’s what Enrev Corporation is all about.”
Throughout the charging process, the Enrev operating system adapts responsively to the battery’s electrochemical state via a unique algorithm that provides real-time feedback, maintaining the battery at the optimum charge level. Scalable and effective with all major battery chemistries in use today, Enrev technology can be designed into the electronics of devices such as cellphones, personal digital assistants and laptop computers as well as forklifts and electric vehicles. The system blends the disciplines of electrochemistry and electrical engineering to form a stimulus response model that interactively and dynamically charges the battery. Enrev technology works with all major battery chemistries including Li-ion, NiMH, NiCd, lead acid and Li-polymer. MRT
FCC Notes LMDS auction raises $45 million In May, the FCC completed a Local Multipoint Distribution Services (LMDS) auction that raised a total net revenue of $45,064,450. The auctioned licenses can be used by companies to provide a variety of wireless services for consumers including: one- and two-way broadband services, such as video programming distribution; video teleconferencing; wireless local loop telephony and high-speed Internet access.
The auction began on April 27, 1999, and closed after 43 rounds. A total of 161 licenses, 100% of the licenses available in the auction, were sold to 40 bidders. The licenses will be awarded in various geographic areas throughout the continental United States and Puerto Rico.
FCC dismisses petition against Nextel License Holdings 4 On June 22, 1998, Dennis Brown and Robert Schwaninger Jr. filed a Petition to Dismiss or Deny against Nextel License Holdings 4 on behalf of clients who operate 800MHz SMR systems in the Maricopa County, AZ, area. In the petition, dismissed by the FCC on April 30, 1999, Brown contended that certain 800MHz SMR applications filed by Nextel were defective and did not comply with the FCC’s rules. He also alleged that the applications contained misrepresentations of material facts that require the FCC to ascertain whether Nextel had the character qualifications to be an FCC licensee. He contended that the applications did not comply with Section 90.693 because Nextel had no incumbent stations whose 22dBu field strength contour could encompass Nextel’s proposed sites. The FCC requested that Nextel provide additional information regarding the application, and Nextel acknowledged that it had incorrectly calculated its existing composite 22dBu contour with respect to certain sites specified on the applications. Base d on this, Nextel surrendered the licenses for all 800MHz stations that were previously granted in Maricopa County and also withdrew its one remaining pending application in Maricopa County. The FCC also rejected the claim of whether Nextel had made intentional misrepresentations.
