Earth Exploration-Satellite Service - Active Spaceborne Remote Sensing and Operations. Bryan HUNEYCUTT (NASA/JPL) WMO, Geneva, Switzerland 7 October 2002. Active Sensor Types.
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Bryan HUNEYCUTT (NASA/JPL)
WMO, Geneva, Switzerland
7 October 2002
Active Sensor: a measuring instrument in the Earth exploration-satellite service or in the space research service by means of which information is obtained by transmission and reception of radio waves (RR)
Earth Exploration-Satellite Service: a radiocommunication service between earth stations and one or more space stations, which may include links between space stations, in which:
- information relating to the characteristics of the Earth and its natural phenomena including data relating to the state of the environment is obtained from active sensors or passive sensors on earth satellite;
- similar information is collected from airborne or earth-based platforms;
- such information may be distributed to earth stations within the system concerned
Space Research Service: a radiocommunications service in which spacecraft or other objects in space are used for scientific or technological research purposes
SAR-Radar Image Honolulu,HI
Precipitation Radar-Rain Rates
Cloud Radar-Cloud Reflectivity Profile
SAR Illumination Swath
Illustration of Altimeter Return
Variation of Backscatter with Aspect Angle
SEAWINDS scanning pencil beam illuminates scans at two different look angles from nadir, and scans 360 degrees about nadir in azimuth
NSCAT illuminates the Earth’s surface at several different fixed aspect angles
The WRC-2003 resolution 727 resolves to consider provision of up to 6 MHz of frequency spectrum to the EESS (active) in the band 420-470 MHz.
Several studies from the spaceborne active sensor community has analyzed the interference from spaceborne SARs in the band 420-470 MHz into Earth stations, the radio amateur service, fixed service, and ISM equipment, concluding that although there may be occasional interference to the various other services, that the interference will be short in time and will have a very long interval of six months or longer and thus the affected service will not be rendered incapable of operating effectively; current studies include sharing analyses with terrestrial radars, military radiolocation systems, and amateur systems.
Another study by the the spaceborne active sensor community analyzes the interference levels of a lower power, lower sidelobe spaceborne SARs into the amateur and amateur satellite services and airborne radiolocation radars, offering that the SAR parameters can be chosen to reduce the interference level to acceptable levels. Mitigation techniques include lowering the antenna sidelobes in both azimuth and range, and lowering the average power with reduced backscatter sensitivity. Limiting operations to geographical regions, delineated by boxes of latitude, longitude may also be an option.
The WRC-2003 resolution 736 resolves to consider additional primary allocation for the EESS (active) and SRS (active) in the band 5460-5570 MHz.
For the 5460-5570 MHz band, the previous studies in the 5250-5460 MHz band showing compatibility between spaceborne active sensors and the radiolocation/ radionavigation services, have been extended to the band 5460-5570 MHz.
For interference mitigation techniques as provided in the Rec. ITU-R SA.1280, the selection of active spaceborne sensor emission characteristics can help to mitigate the interference potential to terrestrial radars. One consideration for this 5460-5570 MHz band is to use it for the wideband SARs with high time- bandwidth products, which tend to give high on-tune rejection factors and thereby lower the interference levels into terrestrial radars.
In addition, several studies from the spaceborne active sensor community have analyzed the compatibility between spaceborne SARs in the band 5470-5570 MHz and wireless access systems including RLANs in the mobile service. The wider SAR bandwidths also give higher kTB system noise temperatures, allowing greater acceptable interference levels from other services, and further improves the sharing situation.