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8 Problems with this alternative are that there may still be an uplink problem on the NPSPAC channel, because it will need to continue operating at the 4,800 BPS raw data rate. In addition, it is considered unlikely that the Metropolitan Radio Board will allow temporary use of a NPSPAC channel based on previous decisions by the Board. In addition this will be expensive, as a new Motorola RNC controller will cost at least $100,000, and that controller would need to be disposed of in a few years, well before the end of its useful life, when one of the new high -speed data communication links is selected by Anoka County. 2.2.2 Use of Tetra Tetra is a European standard for digital modulation of radio signals. The data rate is 28.8 kBPS with forward error correction. As of May 10, 2000, there is apparently no manufacturer that has submitted a type acceptance application for a Tetra radio to the Federal Communications Commission. There may be problems with the emissions envelope of Tetra radio when compared to the Federal Communications Commission standards. It also appears that any Tetra radios type certified in the United States in the relatively near future will operate at frequencies below 512 MHz. Simulcast is not possible with Tetra technology. At this time, it is unclear if there will be an acceptable trunking protocol with Tetra radios, and Tetra radios operate at low power so that frequencies can be reused at short distances. All of these issues indicate that Tetra is not available as an alternative now and may not be for several years. By the time Tetra becomes available, if it ever becomes available, one of the other very high data rate alternatives is likely to be available for use in Anoka County. In addition any major move to Tetra will involve buying very expensive equipment that will cost more than the CDPD alternative discussed later in this report, and the equipment would have to be disposed of well before the end of its useful life when the new high data rate alternatives borne available. 2.2.3 CDPD CDPD is a service offering from one of the cellular telephone carriers operating in the Minneapolis -St. Paul metropolitan area. CDPD operates using the TCP /IP communications protocol. CDPD requires a minimum capital investment in equipment at this time; however, there is a relatively high recurring cost. CDPD will provide multiple 19.2k BPS communication links with fair coverage and high reliability. The system will make it possible to use laptop computers, which would be fully usable in a high data rate communication link later. The investments in hardware and software that