At the 1995 World Radio Conference, the US registered a constellation of previously unacknowledged satellites as operating in the 17.8-21.2 GHz downlink and 30-31 GHz uplink bands. These systems have been operating at these locations since the 1970s, and their spectrum/orbit allocations were grandfathered to protect them from potential interferrence from new KA-band applicants, such as Teledesic.
|US CSID-A1||E 000|
|US CSID-A2||E 044|
|US CSID-A3||E 075|
|US CSID-A4||E 082|
|US CSID-A5||E 092|
|US CSID-A6||E 110|
|US CSID-E1||W 010|
|US CSID-E2||W 013||UI spacecraft observerd|
|US CSID-E3||W 024|
|US CSID-E4||W 030||Vortex?|
|US CSID-W1||W 141|
|US CSID-W2||W 144|
The US also registered
US CSID-P non-GSO [63 degrees, 39400-1000 km, 8 satellites]
It is to be expected that geostationary SIGINT [VORTEX, MAGNUM, etc] birds will be found occupying some [but perhaps not all] of the registered orbital locations, and that the HEO registrations cover JUMPSEAT/TRUMPET spacecraft. It is almost certainly the case that at least some of these locations are currently un-occupied, based on the precedent of MILSTAR, where they registered about twice as many slots as they had satellites. At least some of these satellites should be pretty readily visible, compared to other GEO objects. Apart from the two MILSTARs, some of these puppies are the largest objects in GEO -- about 5 metric tons or so, and the rest of them are not small, massing about half this. Rainer Kracht has observed uncatalogued geosynchronous satellites at 13 and 28 degrees west. Those locations correspond to US CSID-E2 and possibly -E3 or -E4 in the above list. He thinks, based on older filings, that the one at 28 west is a Chalet/Vortex SIGINT satellite.
These systems are associated with two ground stations, one in the Washington area, and the other at Castle Rock near Denver. These ground stations have a 200 dbi gain.
Additional public documents released in early 1997 shed further light on the ground segment of this system. FCC has issued licenses in the 17.8-20.2 GHz band to networks in the Digital Electronic Messaging Service (DEMS) that include both the Denver and Washington areas. Since co-frequency, co-coverage use of the 17.8-20.2 GHz band by earth stations of the Government fixed-satellite service and the non-Government DEMS would not be possible within 40 km of the national security earth stations, DoD, through NTIA, requested and obtained special exclusion zones around these areas.