Frequency Tolerances and Spurious Emission Limitations

Appendices 7 and 8 of the WARC-79 Final Acts contain, respectively, the Table of Transmitter Frequency Tolerances and the Table of Maximum Permitted Spurious Emission Power Levels. Decisions taken at that Conference on these two new Tables will eventually touch transmitter manufacturers and users everywhere. Frequency tolerances in most bands are tightened for new equipment effective January 2, 1985. TV broadcast for system M (NTSC) from 29.7 to 2450 MHz and broadcasting in the 535 to 1606.5-kHz bands remain the same. Earth and space services were introduced in the Table for the first time with impact from 4 MHz on up to 40 GHz after 1985. Relatively tight frequency tolerances are those for HF broadcasting, single sideband (SSB), and pulse modulation above 10 GHz. Peak envelope power rather than mean power is shown generally for SSB transmitters limits. The frequency tolerance limits, again, did not reach beyond 40 GHz. New spurious emission limits come into effect on that same date for new transmitters operating between 235 MHz and 17.7 GHz, although radiodetermination and emergencytype transmitters are excluded. There is also a special exception for spurious emissions of transmitters operating above 235 MHz where transmitters feed a common antenna or where an antenna farm exists [see Note 10 of Appendix 8]. Spurious emissions have been significantly redefined. It is suggested those concerned with such limits be familiar with the new definition contained in RR 139 of Article 1 of the Final Acts.