Motorola V186 User Manual - Page 177

Appendix B - FCC Information Spectrum and Regulatory Update were channels licensed for data (or voice) use on a "secondary" basis; that is usage could not interfere with operations licenses on the primary channels. Through the adoption of the refarming decision, the low-power, secondary offset channels have been converted to primary channels with a maximum bandwidth of 12.5 kHz. Many of the old offset channels have been (or soon will be) converted to high power operations. However, a fairly large number of these channels have been designated for continued low power use and can be a good source of spectrum for some MOSCAD systems. More about this in the Spectrum section. VHF Splinter Channels The FCC had defined certain frequencies in the 154 MHz and 173 MHz bands for data operation. The frequencies are few in number, are heavily used and have severe deviation restrictions. These splinter frequencies, whose availability and use were not affected by refarming, require the use of a radio certified with a less common F2 emission designator (digital FM emission with a modulated subcarrier). A few radios may be used with MOSCAD for these frequencies, but refer to the FCC rules for limitations on power output, antenna height and antenna gain. Emission Designators MOSCAD units interface to the radio through several different modems, typically DFM, FSK or DPSK. The nature of these modems will determine the type of emission characteristics of the radio. FCC rules define and classify the basic characteristics of the radio waves according to the type of modulation of the main carrier as well as the nature of the signals that modulate the main carrier and the general type of information that is transmitted (see FCC rule sections 2.201 and 90.207)1. Traditional MOSCAD radios such as a MTS2000 use FM modulation (indicated by the FCC emission designator - F), operate in the analog mode (indicated by the FCC emission designator -3) and are used for voice (telephony) (indicated by FCC emission designator - E), or Data, (telemetry, or telecommand) (indicated by emission designator - D). Hence, a radio used for DPSK or FSK could use a F3E or F3D designation whereas a DFM application would require a F1D to reference a digital FM signal containing digital information. See section below on data efficiency. Data Efficiency Standards As part of its initial refarming decisions, the FCC adopted a new minimum data efficiency standard of 4800 bits per second per 6.25 kHz of channel bandwidth. Initially, the FCC definition of data was not clear and caused confusion as to how the standard was 1 FCC Rules can be found in Title 47 of the Code of Federal Regulations. Part 90 of that title provides rules applicable to the private land mobile radio services. Among other things, Part 2 of that title provides rules governing the equipment authorization process. Current FCC rules can be found at this web site: http://wireless.fcc.gov/rules.html 173