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SDS Satellites in HEO


Tyneside, UK
2018 Apr 21
Saturday, Day 111

Maintained by:






SDS Tracking and Analysis:





Operational Frequencies

This is a list of all frequencies reported to be associated with known SDS satellites. Not all have been verified and some satellite names are tentative, based on circumstatial evidence when associating objects from Mike McCants's "classified.tle" file with known satellite names.

In addition, earlier SDS satellites in HEO also transmitted the AFSATCOM signal near 243.7 MHz. In recent years, only the transmissions from USA 125 and USA 137 have been logged.


Freq (MHz) Satellite Mission Signal Type Notes
2242.515 USA 21
(SDS-1 F-6)

1987-015A
17506
Satellite Data System government/military communications satellite. CW carrier, oscillates in frequency due to satellite spinning at 4.6s per rev Identification very tentative - highly eccentric orbit, non-operational, the signal oscillation is probably due to the originally de-spun aerial platform having matched rotation with the satellite body, probably an SDS-1 satellite (either F4 or F6) - listed in classfd.tle as 90004
2242.500 USA 40
(SDS-2 F-1)

1989-061B
20167
Second generation Satellite Data System government/military communications satellite. CW carrier, oscillates in frequency due to satellite spinning at 5.2s per rev Tentative identification of satellite with received signals - non-operational but still transmitting, the signal oscillation is probably due to the originally de-spun aerial platform having matched rotation with the satellite body - identified as 90020 in classfd.tle
2242.496 USA 67
(SDS-2 F-2)

1990-097B
20963
Second generation Satellite Data System government/military communications satellite. PSK with sub-carrier, 1024 kHz Originally GEO but the orbit has evolved to an inclination of 15° and is slightly elliptical so reception varies according to the sub-satellite latitude - a study by Ivan Artner 2006 March showed that the transmitter responds to eclipse periods by becoming intermittent while out of direct sunlight, indicating that the batteries are not charging properly from the solar cells
2242.500 USA 89
(SDS-2 F-3)

1992-086B
22518
Second generation Satellite Data System government/military communications satellite. CW carrier plus side-bands During 2006, Ivan Artner tracked a spinning satellite in HEO, the times did not fit known satellites in that type of orbit - it has been tentatively identified as 90026 (last observed in 2004) but transmissions ceased during the first quarter of 2007 before an orbit could be determined, the identification of it as USA-89 is also tentative
251.325 USA 155
(SDS-3 F-1)

2000-080A
26635
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a triplet of similar of transmissions from a secondary payload on a US classified satellite in GEO, signal appears to be continuous and is similar to ones from USA-179 - Also transmits at 252.675 MHz, 258.775 MHz, 268.6755 MHz and 2242.486 MHz. No longer operational.
268.675 USA 155
(SDS-3 F-1)

2000-080A
26635
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a triplet of similar of transmissions from a secondary payload on a US classified satellite in GEO, signal appears to be continuous and is similar to ones from USA-179 - Also transmits at 251.325 MHz, 252.675 MHz, 258.775 MHz and 2242.486 MHz. No longer operational.
2242.486 USA 155
(SDS-3 F-1)

2000-080A
26635
Third generation Satellite Data System government/military communications satellite. PSK with sub-carrier, 1024 kHz Geosynchronous orbit, frequency variable according to onboard power available - increases significantly at times of eclipse. Also transmitted at 251.325 MHz, 252.675, 258.775 and 268.775 MHz. No longer operational.
252.675 USA 155
(SDS-3 F-1)

2000-080A
26635
Third generation Satellite Data System government/military communications satellite. AM - high speed (19.2 kb/s?) data transmission Transmissions from a secondary payload on a US classified satellite in GEO, signal appears to be continuous - Also transmits at 251.325 MHz, 258.775 MHz, 268.675 MHz and 2242.486 MHz. No longer operational.
258.775 USA 155
(SDS-3 F-1)

2000-080A
26635
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a triplet of similar of transmissions from a secondary payload on a US classified satellite in GEO, signal appears to be continuous and is similar to ones from USA-179 - Also transmits at 251.325 MHz, 252.675 MHz, 268.675 MHz and 2242.486 MHz. No longer operational.
250.075 USA 162
(SDS-3 F-2)

2001-046A
26948
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a triplet of reported frequencies carrying similar signals from satellite in geosynchronous orbit, exact frequency not known - also reported to transmit at 256.475, 263.225, 267.550 MHz and 2242.5 MHz
263.225 USA 162
(SDS-3 F-2)

2001-046A
26948
Third generation Satellite Data System government/military communications satellite. AM - high speed (19.2 kb/s?) data transmission Reported frequency for a satellite in geosynchronous orbit, exact frequency not known - also reported to transmit at 250.075 MHz,256.475, 267.550 MHz and 2242.5 MHz
267.550 USA 162
(SDS-3 F-2)

2001-046A
26948
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a triplet of reported frequencies carrying similar signals from satellite in geosynchronous orbit, exact frequency not known - also reported to transmit at 250.075 MHz, 256.475 MHz, 263.225MHz and 2242.5 MHz
2242.500 USA 162
(SDS-3 F-2)

2001-046A
26948
Third generation Satellite Data System government/military communications satellite. CW carrier (plus side-bands?) Reported frequency for satellite in geosynchronous orbit - also reported to transmit at 250.075 MHz, 256.475, 263.225 and 267.550 MHz
256.475 USA 162
(SDS-3 F-2)

2001-046A
26948
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a triplet of reported frequencies carrying similar signals from satellite in geosynchronous orbit, exact frequency not known - also reported to transmit at 250.075, 263.225, 267.550 MHz and 2242.5 MHz
251.700 USA 179
(SDS-3 F-3)

2004-034A
28384
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a pair of transmissions from a secondary payload on US classified satellite in HEO - Switched on and off to co-ordinate coverage with USA-198 - Prior to 2008 Mar 14, USA-179 was operating alone and was providing near 8 hours' coverage per pass at this frequency - Also transmits at 256.375 MHz and 2242.50 MHz
2242.503 USA 179
(SDS-3 F-3)

2004-034A
28384
Third generation Satellite Data System government/military communications satellite. CW carrier plus side-bands - strong Part of a constellation of three satellites in highly eccentric orbit (HEO), switches to low power when over the southern hemisphere - Also transmits at 251.700 MHz and 256.375 MHz
256.375 USA 179
(SDS-3 F-3)

2004-034A
28384
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a pair of transmissions from a secondary payload on US classified satellite in HEO - Switched on and off to co-ordinate coverage with USA-198 - Prior to 2008 Mar 14, USA-179 was operating alone and was providing near 8 hours' coverage per pass at this frequency - Also transmits at 251.700 MHz and 2242.50 MHz
251.275 USA 198
(SDS-3 F-4)

2007-060A
32378
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone plus various test modes One of a pair of transmissions from a secondary payload on US classified satellite in HEO used during the test phase of the satellite up until 2008 March 13 - on March 14, USA-198 switched to its operational frequencies at 251.700 MHz and 256.375 MHz, test transmission also at 258.800 MHz, plus transmitter at 2242.50 MHz
2242.504 USA 198
(SDS-3 F-4)

2007-060A
32378
Third generation Satellite Data System government/military communications satellite. CW carrier plus side-bands - strong Part of a constellation of three satellites in highly eccentric orbit (HEO), lanched 2007 Dec 10 as a replacement for USA-125, also transmits at 251.700 MHz and 256.375 MHz, and used 251.275 and 258.800 MHz during the orbital test phase up to 2008 Mar 13

Frequency discovered independently by Bob Christy and Sven Grahn about 20 minutes after launch.
251.700 USA 198
(SDS-3 F-4)

2007-060A
32378
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a pair of transmissions from a secondary payload on US classified satellite in HEO - Switched on and off to co-ordinate coverage with USA-179 - Also transmits at 256.375 MHz and 2242.50 MHz
256.375 USA 198
(SDS-3 F-4)

2007-060A
32378
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone One of a pair of transmissions from a secondary payload on US classified satellite in HEO - Switched on and off to co-ordinate coverage with USA-179 - Also transmits at 251.700 MHz and 2242.50 MHz
258.800 USA 198
(SDS-3 F-4)

2007-060A
32378
Third generation Satellite Data System government/military communications satellite. AM - 4.8 kHz data tone plus various test modes One of a pair of transmissions from a secondary payload on US classified satellite in HEO used during the test phase of the satellite up until 2008 March 13 - on March 14, USA-198 switched to its operational frequencies at 251.700 MHz and 256.375 MHz, sharing duties with USA-179 - Test transmission also at 251.275 MHz, plus transmitter also at 2242.50 MHz
2232.498 USA 198
(SDS-3 F-4)

2007-060A
32378
Third generation Satellite Data System government/military communications satellite. CW carrier plus side-bands Navy Ocean Surveillance System
2242.504 USA 227
(SDS-3 F-5)

2011-011A
37377
Third generation Satellite Data System government/military communications satellite. Checked out at 30° west longitude before moving to the operational location at 10° west. Replaced USA 155/SDS-3 F1 (2000-080A/26635). Orbital elements not released by Spacetrack so parameters are based on amateur observation. Carrier + sidebands Continous transmission
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