For compatibility with NWS, the power density in the 1670-1675 MHz range from all sources and from all azimuths at each NWS ground-based receiver site must not exceed the following limits:
Power density in a 1.3 MHz bandwidth shall not exceed [-150 dBW/(meter)^2] more than 0.24% of the time, nor [-135 dBW/(meter)^2] more than 0.03% of the time. These power densities correspond to field strengths of 0.67 microvolts/meter and 3.5 microvolts/meter respectively. These levels are applicable during the hours of 2300-0200 Universal Time (UT) and 1100-1400 UT every day. During periods of abnormal weather and special research programs, protection must be provided at additional times. These special events can last 3 or more hours and may cover one or more launch sites. During current or anticipated regional level severe weather conditions when the accuracy of weather forecasts, warnings or alerts could affect safety-of-life and property for communities, means must be provided by the non-Federal user(s) to shut down their transmitters within 10 minutes of being notified and prior to radiosonde release. The non-Federal transmitters shall remain off until the end of the radiosonde flight(s). NOAA agencies such as the National Severe Storms Laboratory and the Hurricane Research Division require these specialized radiosonde flights for severe weather and hurricane forecasting.
In the new generation of GOES satellites, called GOES I through M, the received signal will occupy the band centered on 1676 MHz with a 5.0 MHz bandwidth. The noise level is not currently known. The first of these satellites, the former GOES-I, now called GOES-8, is currently in its operational demonstration phase. Should tests be completed successfully, it will replace Meteosat-3 around February, 1995. GOES-7 will eventually be replaced by GOES-9 around early 1996. In an emergency (e.g., failure of an operational satellite), GOES-7 may be recalled to operational status at any time up to the end of its useful life, estimated to be about two years.
The criterion for adequate protection of the CDA stations at Wallops Island and Fairbanks is as follows:
Appendix 28 of the ITU Radio Regulations is customarily used to develop coordination contours for satellite stations. However, this Appendix contains no coordination criteria for METSAT ground stations -- they are currently under development -- and makes certain assumptions regarding the number and characteristics of the terrestrial stations with which the satellite ground stations must share the band. In the present case, there is no way to predict the use of the band by non-Federal users. It will therefore be necessary to coordinate all proposed ground systems, regardless of type or location. Moreover, the use of airborne or satellite transmitters in this band must be avoided.