UHF SATCOM Satellite Downlinks Receivable in North America

Matt Blaze

1 October 2012, updated 20 February 2017

I've found a number of excellent web resources (such as uhf-satcom.com and satelliteenwel.de) that list UHF military satellite downlinks, but most of them, for whatever reason, are focused on signals that can be received in Europe.

So I've set about cataloging the downlink signals between 243 and 270 MHz that can be easily and regularly received in North America. This page lists the UHF satellite signals that I can receive and measure with my own (limited) equipment at several (sub-optimal) receiving sites on the East and West coasts of the US. The focus is on geostationary downlinks (which can be received over a large footprint and without the need to calculate their position based on time), but non-geostationary LEO, MEO, and HEO transponders will be included if I happen to catch them. Some samples of the spectrum produced by various transponders can be found here.

UHF military satellites are used chiefly to support the low bandwidth voice and data TACSAT system. This system is used by ground troops, typically employing portable "manpack" transceivers and lightweight tripod-mounted antennas, as well as by aircraft and ships when they travel outside of HF and VHF line-of-sight range. Most military traffic is digitally encrypted, but there are occasional analog clear transmissions as well, usually in FM mode (the transponders will pass almost any modulation that fits within their passband).

But military messages are not the only transmissions that pass through the TACSAT transponders. There are a number of unauthorized and unintentional signals as well, which vary by region. In South America -- principally Brazil -- a large community of "pirate" users have discovered ways to modify VHF amateur radio gear to access the SATCOM system, and their signals comprise the vast majority of the clear traffic going through the transponders that cover the Americas. The satellites over Asia, on the other hand, do not appear to carry much pirate traffic but suffer from a large number of legitimate terrestrial signals on the uplink frequencies that make it into the satellites and that are relayed on the downlink. In particular, many Pacific transponders frequently pick up signals from Russian mobile telephone base stations. These unauthorized and unintentional signals are discussed in more detail in the sections that follow.

This guide catalogs the downlink signals I can intercept in each of two representative geographic areas: in the central New Jersey / Philadelphia area on the East coast and in the San Francisco Bay area on the West coast. This should provide reasonably complete coverage of just about every geostationary transponder downlink in the 243-270 MHz band that can be received in the continental US and most of the rest of the Americas. Because UHF TACSAT footprints are quite wide, any downlink that reaches at least some of the continental US should be receivable on at least one US coast. Any transponder downlink signal received at both of my East and West coastal receiving sites should be receivable almost anywhere in the Americas, while those received at only one will be receivable over only part of the US (precisely how much of the US is covered depends on how far East or West the satellite is positioned over the Equator.)

Any modern, reasonable quality narrowband FM receiver that covers 240-270 MHz should be sufficient for receiving unencrypted UHF TACSAT signals. A spectrum display is helpful for finding the transponders, but not essential once the active transponder channels are known (see this page for details on the different kinds of downlink signals). The downlink signal levels are are relatively weak (they're traveling almost 25,000 miles, after all), making an outdoor antenna with a radiation pattern favoring the satellite is virtually mandatory. A specially-designed circularly polarized directional antenna (such as are used by the military) is ideal but not essential. I have not found receiver preamplifiers, however, to be especially helpful, at least within the satellite footprints.

This is a small personal effort, and while I've tried to be as accurate as possible, it is by no means comprehensive. I'd greatly appreciate any corrections or updates; contact me at mab@mattblaze.org .

UHF Satellites

Although military communications satellites carry classified traffic, surprisingly little about the actual satellite systems themselves is considered sensitive or kept secret. Detailed information about virtually all man-made satellites (there are currently a bit more than a thousand in operation) can be found in public databases. This data is relied upon -- and thus also frequently checked and double checked -- by the amateur astronomy community, with the effect that launches of, and changes to, even "black" military satellites are typically published on the Web quite quickly. I rely here especially on the UCS Satellite Database and the Zarya Database.

Many of the satellites used for tactical military communication operate on UHF frequencies in the 240-318 MHz band. At UHF, the potential "footprint" (coverage area) of a geostationary satellite can be quite large -- about ± 65 longitudinal degrees (this decreases a bit as one moves away from the Equator). The continental US spans from about 67° West (Maine) to about 124° West (Washington state). Most of the known geostationary UHF military satellites with footprints covering all or part of this region are operated by the US military, with a few British and NATO birds mixed in as well. (Actually "UHF" is a bit of a misnomer here, since the downlinks are technically at what is usually considered the upper end of the VHF spectrum, which runs to 300MHz.)

The US divides the world into four regions for UHF satellite purposes: CONUS, covering the Americas; LANT, covering the Atlantic, Western Europe and Africa; IO, covering the Indian ocean, Eastern Europe and Asia; and PAC, covering the Pacific and Australia. Constellations of geostationary "UFO" and "FLTSATCOM" satellites are positioned roughly over the center of each region, yielding effectively worldwide coverage for the US TACSAT system (excluding the arctic and subarctic polar regions, which are covered by HEO and MEO satellites). All of the continental US is within the CONUS constellation's footprint, with the East and West US coasts also touching the edges of the LANT and PAC footprints, respectively. No part of the continental US is within the footprint of the IO region satellites.

Those near either coast thus have access to more TACSAT transponders than those in the center of the country. The regions overlap considerably; Brazil, for example, home to a large number of unauthorized "pirate" TACSAT users, is covered by both the CONUS and LANT footprints.

In all, there are 22 currently known candidate geostationary military communications satellites that are positioned to cover all or parts of the North America and that are either known to or believed potentially to carry UHF transponders. Military satellites are generally known by a variety of names and designators, which makes cataloging them a bit of an exercise in arcane jargon. Also, many "geostationary" satellites actually move around quite a bit with respect to the Earth; their positions listed in different databases can disagree by several degrees over time. Many of these satellites are already well beyond their expected service lifetimes, and could fail or be replaced at any time.

The relevant currently operating satellites I'm aware of are, from East to West:

Name Longitude
(estimated) Notes

SDS III-2 F5 NRO L10 (USA-155) 10.03° W UHF downlinks

WGS3 (USA-221) 12.0° W No known UHF transponders

DSCS III-F6/B12 (USA-82) 12.09° W No known UHF transponders

DSCS III-F12/B11 (USA-153) 12.15° W No known UHF transponders

FLTSATCOM8 (USA-46) 14.7° W LANT; bandplans Bravo and Charlie

Skynet 5C (UK) 17.83° W British; several UHF transponders

UFO7 (USA-127) 21.9° W LANT; bandplan Papa

SDS III-6 NRO L-27 (USA-227) 30.4 W Possible UHF downlinks

Skynet 4F (UK) 34.0° W British; several UHF transponders

NATO 4B (USA-98) 35.05° W No known UHF transponders

Milstar DFS1 / Milstar 1-F1 (USA-98) 38.9° W Possible SS UHF transponders

DSCS III-F9/B7 (USA-113) 52.4° W No known UHF transponders

DSCS III-B6 (USA-170) 52.5° W No known UHF transponders

Milstar DFS-4 / Milstar 2-F2 (USA-157) 67.9° W Possible SS UHF transponders

Milstar DFS 6 (USA-169) 90.0° W Possible SS UHF transponders

UFO5 (USA-111) 99.4° W CONUS; bandplan November; not in UCS db

UFO6 (USA-114) 105.5° W CONUS; bandplan Quebec

DSCS III-F10/B13 (USA-135) 130.05° W No known UHF transponders

DSCS III-F11/B6 (USA-148) 135.11° W No known UHF transponders

SDS III-3 / NRO L12 (USA-162) 143.88° W UHF downlinks

UFO4 (USA-108) 177.12° W PAC; bandplan Oscar?

UFO8 (USA-138) 172.28° E PAC; bandplan Papa?

All these satellites are in geostationary/geosynchronous orbit (that is, 35,786 km directly above the Equator at their longitudinal position).

Note that even very directional UHF antennas (of any reasonable size) have much wider beamwidths than the typical small satellite dishes used, e.g., for direct broadcast television (which operate at much higher frequencies and with lower received signal levels). The good news is that this means that antenna aiming is much less critical here than it is for setting up a satellite TV dish -- it is generally sufficient to just point in the general direction of the satellite, above the horizon and toward the Equator. The bad news is that it is effectively not possible to authoritatively determine from which satellite a signal emanated using the receiving antenna's heading alone. In practice, we can usually only distinguish signals between satellites spaced at least 20° or 30° apart this way.

Figuring out from which satellite a given UHF signal originated thus requires some guesswork and information beyond just the antenna heading and known satellite positions. Fortunately, some UHF frequency data has been published by the military that can help reduce uncertainty here. An official list of US TACSAT channels can be found in the US TACSAT FM 6-02.90 manual [pdf], but does not specify which channels are carried on which satellites. Frequency bandplans for some satellites (e.g., "Bandplan Novemeber") can be found on satellitenwelt.de. Even then, it is sometimes impossible to be completely certain exactly which satellite hosts a given transponder signal, at least based on unclassified public data.

Most US UHF voice transponder channels use an uplink that is 41.000 MHz above its downlink frequency (although there are a number of exceptions to this rule). The voice transponders are completely analog; unlike repeaters used in land mobile radio systems, they do not demodulate the signals that pass through them. Whatever signal is received by the transponder on the uplink frequency (within the passband bandwidth) is translated directly into a transmitted signal on the downlink. This means that satellite retransmission is independent of the modulation type used, as long as the signal fits within the passband (generally 25 KHz for voice channels). Most current military voice satellite traffic is encrypted and digitally modulated, but, as Brazilian pirates have discovered, conventional analog FM signals are retransmitted just as well. The uplink frequency range is also used for non-satellite military communications (mostly aviation, which uses analog AM, and, in Asia, mobile phone traffic, which uses narrowband FM). Unintended signals from such users will occasionally make their way up to a satellite and be retransmitted on the corresponding downlink channel.

Notes on Methodology

All signals were captured with a Trivec or D&M portable TACSAT antenna just above ground level and manually rotated for maximum signal level. Given a reasonably clear view to the satellite, these antennas generally yield peak received signal levels between about -6 and +6 dBµV for military geostationary transponders, which is more than sufficient for measurement and demodulation on modern receivers without resort to higher-gain (and narrow beamwidth) director elements or preamplifiers. To eliminate any local terrestrial-based sources all signals were captured from at least two different locations in the local area. I used a Rohde and Schwarz PR100 portable receiver to find the signals and measure their characteristics.

Frequency: Frequency (in MHz) is measured from the center of the received downlink signal, generally rounded to the nearest known channel.

Heading: Between the wide beamwidth of the small antennas used and my lack of a completely clear view of the horizon, my receiving arrangement doesn't provide high resolution directional bearings. So I'm just recording a coarse heading where the (manually rotated) antenna maximizes the received signal strength. As noted above, this does not permit distinguishing different satellites whose geostationary slots are near one another. (Reporting bearings with any greater precision than a rough direction would be false advertising here.)

Bandwidth: Most satellite transponders transmit a (relatively weak) signal even when they are idle. This consists of broadband noise spread throughout the entire output bandwidth, generally with a steep cutoff at the edges. The distinctive shape of these signals makes transponder downlinks easy to identify, and their exact bandwidth can serve as a simple "signature" for different satellite families. I'm measuring the bandwidth here as the approximate size of the "flat" part of the downlink output, which is not always the same as the published bandwidth of the transponder. For example, US UFO TACSAT transponders "advertise" 25 KHz or 5 KHz of bandwidth per voice or data channel, respectively, but I measure the transponder downlink bandwidths from UFO5, UFO6 and UFO7 as 30 KHz and 6 KHz. The older FLTSATCOM8 voice transponders, on the other hand, have downlinks closer to the same size as their intended channel bandwidths: 25 KHz and 4.5 KHz for voice and data, respectively. See example spectrum capture plots here.

Satellite: The "Probable Satellite and GEO Position" are my best guesses based on the most likely transponders in the direction of maximum signal strength among those listed in unclassified published sources. For the US TACSAT channel numbers, I relied on the US DoD's (somewhat out of date) MULTI-SERVICE TACTICS, TECHNIQUES, AND PROCEDURES FOR ULTRA HIGH FREQUENCY TACTICAL SATELLITE AND DEMAND ASSIGNED MULTIPLE ACCESS OPERATIONS [pdf] (FM 6-02.90) manual. For frequency band-plan information on individual satellites, I rely heavily on the excellent web page at http://www.satellitenwelt.de/uhfmilsat.htm, which is essential reading for anyone interested in UHF satellites. The latter is in German (but is amenable to comprehensible translation via Google Translate).

Notes: The "notes" reflect traffic that I happened to notice during measurements. The ubiquitous Brazilian pirates continue to be well represented on the US CONUS and LANT TACSAT birds as well as on the British Skynet 5C system. ("Portuguese" here refers to the language spoken, not the owner of the satellite.)

East Coast: Central New Jersey / Philadelphia

The East coast of the US is in the primary footprint of satellites that cover the CONUS region (e.g, UFO5 and UFO6) and on the edge of many that cover the LANT region. I believe there are two US LANT region TACSAT satellites currently operating (UFO7 at 23W and FLTSATCOM8 at 14.7 W). We are technically outside the primary coverage area of the LANT constellation, but I have no trouble receiving UFO7 and FLTSATCOM8 transponders here.

Most channels receivable on the East coast have signals from only one satellite. A few, however, have signals from one transponder in the CONUS constellation and another in the LANT constellation. These require more careful antenna aiming to disambiguate the signal source. Note in particular that 255.550 has a 30 KHz transponder on UFO6 (at 105W) and a 25 KHz transponder on FLTSATCOM8 (at 15W). This frequency is very popular with Brazilian pirates, who are within the footprints of both of these satellites; I have occasionally heard both 255.550 transponders in use by pirates simultaneously.

UFO6 (bandpland Quebec) appeared to go off the air some time around 2012-11-02, but most (thought not all) of its transponders were back on the air by 2012-11-09, and the remaining transponders were back by 2012-12-14.

This section last updated 2012-12-14.

Frequency Heading Bandwidth Probable Satellite and GEO Position Notes

243.8195 SSE 58 KHz Milstar DFS-4 67.9W? spread spectrum from 243.7905-243.8485

243.915 SW 6 KHz Ch 199 - CONUS: UFO5 99.4W

243.925 SW 6 KHz Ch 200 - CONUS: UFO5 99.4W

243.935 SW 6 KHz Ch 201 - CONUS: UFO5 99.4W

243.945 SW 6 KHz Ch 202 - CONUS: UFO5 99.4W

243.955 SW 6 KHz Ch 203 - CONUS: UFO5 99.4W

243.965 SW 6 KHz Ch 204 - CONUS: UFO5 99.4W

243.975 SW 6 KHz Ch 205 - CONUS: UFO5 99.4W

243.985 SW 6 KHz Ch 206 - CONUS: UFO5 99.4W

244.075 ESE 6 KHz Ch 218 - LANT: UFO7 21.9W

244.085 ESE 6 KHz Ch 219 - LANT: UFO7 21.9W

244.095 ESE 6 KHz Ch 221 - LANT: UFO7 21.9W

244.105 ESE 6 KHz Ch 223 - LANT: UFO7 21.9W

244.115 ESE 6 KHz Ch 225 - LANT: UFO7 21.9W

244.125 ESE 6 KHz Ch 226 - LANT: UFO7 21.9W

244.135 ESE 6 KHz Ch 227 - LANT: UFO7 21.9W

244.145 ESE 6 KHz Ch 228 - LANT: UFO7 21.9W

244.155 SW 6 KHz Ch 229 - CONUS: UFO6 105.5W

244.165 SW 6 KHz Ch 230 - CONUS: UFO6 105.5W

244.175 SW 6 KHz Ch 231 - CONUS: UFO6 105.5W

244.185 SW 6 KHz Ch 232 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8

244.185 ESE 4.5 KHz Ch 232 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

244.190 ESE 4.5 KHz Ch 233 - LANT: FLTSATCOM8 14.7W

244.195 SW 6 KHz Ch 234 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8

244.195 ESE 4.5 KHz Ch 234 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

244.200 ESE 4.5 KHz Ch 235 - LANT: FLTSATCOM8 14.7W

244.205 SW 6 KHz Ch 236 - CONUS: UFO6 105.5W

244.210 ESE 4.5 KHz Ch 237 - LANT: FLTSATCOM8 14.7W

244.215 SW 6 KHz Ch 238 - CONUS: UFO6 105.5W

244.225 SW 6 KHz Ch 239 - CONUS: UFO6 105.5W

245.800 ESE 34 KHz Skynet 5C: 17.8W Portuguese

248.825 SW 30 Khz Not in bandplan first noticed 20140314

248.845 SW 6 KHz Ch 129 - CONUS: UFO5 99.4W

248.855 SW 6 KHz Ch 131 - CONUS: UFO5 99.4W

248.865 SW 6 KHz Ch 132 - CONUS: UFO5 99.4W

248.875 SW 6 KHz Ch 133 - CONUS: UFO5 99.4W

248.885 SW 6 KHz Ch 134 - CONUS: UFO5 99.4W

248.895 SW 6 KHz Ch 135 - CONUS: UFO5 99.4W

248.905 SW 6 KHz Ch 137 - CONUS: UFO5 99.4W

248.915 SW 6 KHz Ch 138 - CONUS: UFO5 99.4W

248.925 SW 6 KHz Ch 139 - CONUS: UFO5 99.4W

248.935 SW 6 KHz Ch 140 - CONUS: UFO5 99.4W

248.945 SW 6 KHz Ch 141 - CONUS: UFO5 99.4W

248.955 SW 6 KHz Ch 143 - CONUS: UFO5 99.4W

248.965 SW 6 KHz Ch 144 - CONUS: UFO5 99.4W

249.105 ESE 6 KHz Ch 161 - LANT: UFO7 21.9W

249.115 ESE 6 KHz Ch 162 - LANT: UFO7 21.9W

249.125 ESE 6 KHz Ch 163 - LANT: UFO7 21.9W

249.135 ESE 6 KHz Ch 164 - LANT: UFO7 21.9W

249.145 ESE 6 KHz Ch 165 - LANT: UFO7 21.9W

249.155 ESE 6 KHz Ch 167 - LANT: UFO7 21.9W

249.165 ESE 6 KHz Ch 168 - LANT: UFO7 21.9W

249.175 ESE 6 KHz Ch 169 - LANT: UFO7 21.9W

249.185 ESE 6 KHz Ch 170 - LANT: UFO7 21.9W

249.195 ESE 6 KHz Ch 171 - LANT: UFO7 21.9W

249.205 ESE 6 KHz Ch 173 - LANT: UFO7 21.9W

249.215 ESE 6 KHz Ch 174 - LANT: UFO7 21.9W

249.225 ESE 6 KHz Ch 175 - LANT: UFO7 21.9W

249.235 SW 6 KHz Ch 176 - CONUS: UFO6 105.5W

249.245 SW 6 KHz Ch 177 - CONUS: UFO6 105.5W

249.255 SW 6 KHz Ch 179 - CONUS: UFO6 105.5W

249.265 SW 6 KHz Ch 180 - CONUS: UFO6 105.5W

249.275 SW 6 KHz Ch 181 - CONUS: UFO6 105.5W

249.285 SW 6 KHz Ch 182 - CONUS: UFO6 105.5W

249.295 SW 6 KHz Ch 183 - CONUS: UFO6 105.5W

249.305 SW 6 KHz Ch 185 - CONUS: UFO6 105.5W

249.315 SW 6 KHz Ch 186 - CONUS: UFO6 105.5W

249.325 SW 6 KHz Ch 187 - CONUS: UFO6 105.5W

249.335 SW 6 KHz Ch 188 - CONUS: UFO6 105.5W

249.345 SW 6 KHz Ch 189 - CONUS: UFO6 105.5W

249.355 SW 6 KHz Ch 191 - CONUS: UFO6 105.5W

249.375 SW 30 KHz Not in bandplan first noticed 20140314

249.450 ESE 6 KHz Skynet 5C: 17.8W

249.500 ESE 34 KHz Skynet 5C: 17.8W

249.550 ESE 34 KHz Skynet 5C: 17.8W

249.918 ESE 34 KHz Skynet 5C: 17.8W Portuguese

250.075 WSW 25 KHz SDS III-3 (USA 162) 143.88W

250.130 ESE 6 KHz Skynet 5C: 17.8W

250.350 SW ? CONUS: UFO5 99.4W? narrow carrier

250.450 SW 30 KHz? normally distributed peaks over 30 KHz

250.550 ESE 25 KHz Ch 5- LANT: FLTSATCOM8: 14.7W or UFO7 21.9W wide data; probably FLTSATCOM8

250.650 SW 30 KHz Ch 7 - CONUS: UFO6 105.5W

251.275 SW 30 KHz not in bandplan - CONUS ? first noticed 20140314

251.325 SW 30 KHz not in bandplan - CONUS ? first noticed 20140314

251.325 ESE 37 KHz SDS3-F2 (USA155): 10.3W data; check status

251.700 ESE 34 KHz ? Possible LEO/HEO

251.850 SW 30 KHz Ch 9 - CONUS: UFO5 99.4W off air 20140314

252.050 ESE 30 KHz Ch 11 - LANT: UFO7 21.9W

252.150 SW 30 KHz Ch 12 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8; off air 20140314

252.150 ESE 25 KHz Ch 12 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

253.500 ESE 36 KHz Milstar DFS4 67.9W/Milstar DFS1 39.7W? Portugese at 1600Z-20120930

253.550 SW 30 KHz Ch 13 - CONUS: UFO5 99.4W

253.750 ESE 30 KHz Ch 15 - LANT: UFO7 21.9W Portuguese 1600Z-20120930

253.850 SW 30 KHz Ch 16 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8;

253.850 ESE 25 KHz Ch 16 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

253.900 ESE 34 KHz Skynet 5C: 17.8W Portugese at 1600Z-20120930

254.100 SW 30 KHz Ch 241 - CONUS ? first noticed 20140314

254.150 SW 30 KHz Ch 192 - CONUS ? first noticed 20140314

255.250 SW 30 KHz Ch 17 - CONUS: UFO5 99.4W

255.450 ESE 30 KHz Ch 19 - LANT: UFO7 21.9W Portuguese + "twin peak" data 20120930

255.550 SW 30 KHz Ch 20 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8; Portuguese 20120930

255.550 ESE 25 KHz Ch 20 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6; Portuguese 20121003

256.375 E 25 KHz? data - maybe HEO sat

256.600 ESE 34 KHz Skynet 5C: 17.8W Portuguese

256.850 SW 30 KHz Ch 21 - CONUS: UFO5 99.4W Ch shared w/ FLTSATCOM8; data bursts 20120930

256.850 ESE 25 KHz Ch 21 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO5

257.050 ESE 30 KHz Ch 23 - LANT: UFO7 21.9W "buzzy" data

257.150 SW 30 KHz Ch 24 - CONUS: UFO6 105.5W Portuguese

257.425 ESE 36 KHz Skynet 4F 34.0W Portuguese? music

257.550 SW 30 KHz UK Channel first noticed 20140314

258.350 SW 30 KHz Ch 25 - CONUS: UFO5 99.4W "buzzy" data

258.550 ESE 30 KHz Ch 27 - LANT: UFO7 21.9W data bursts

258.650 SW 30 KHz Ch 28 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8

258.650 ESE 25 KHz Ch 28 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

258.775 ESE 25 KHz? SDS 3-F2 (US155) 10.3W data

260.375 SW 30 KHz Ch 46 - CONUS: UFO5 99.4W

260.425 ESE 30 KHz Ch 48 - LANT: UFO7 21.9W data bursts

260.475 SW 30 KHz Ch 50 - CONUS: UFO5 99.4W

260.525 ESE 30 KHz Ch 52 - LANT: UFO7 21.9W

260.625 SW 30 KHz Ch 56 - CONUS: UFO6 105.5W Portuguese child? 20120930

260.725 SW 30 KHz Ch 60 - CONUS: UFO6 105.5W

261.400 ESE ? ? periodic/intermittent carrier

261.450 SE 30 KHz FLTSATCOM8 14.7 KHz? Portuguese 20121014; no idle transponder signal

261.575 SW 30 KHz Ch 71 - CONUS: UFO5 99.4W

261.675 SW 30 KHz Ch 75 - CONUS: UFO5 99.4W

261.775 SW 30 KHz Ch 79 - CONUS: UFO5 99.4W

261.875 SW 30 KHz Ch 83 - CONUS: UFO5 99.4W

262.125 SW 30 KHz Ch 90 - CONUS: UFO6 105.5W

262.200 ESE 34 KHz Skynet 5C 17.8W signal partly overlaps w/ 262.225

262.225 SW 30 KHz Ch 94 - CONUS: UFO6 105.5W Portuguese; partly overlaps w/ 262.200

262.325 SW 30 KHz Ch 98 - CONUS: UFO6 105.5W

262.425 SW 30 KHz Ch 102 - CONUS: UFO6 105.5W Portuguese

262.675 SE ? SDS III-6 F5 30.4W? data

263.225 WSW ? SDS III-3 F3 143.8W data

263.575 SW 30 KHz Ch 109 - CONUS: UFO5 99.4W

263.625 ESE 30 KHz Ch 111 - LANT: UFO7 21.9W data bursts

263.675 SW 30 KHz Ch 113 - CONUS: UFO5 99.4W

263.725 ESE 30 KHz Ch 115 - LANT: UFO7 21.9W data bursts

263.825 SW 30 KHz Ch 119 - CONUS: UFO6 105.5W

263.925 SW 30 KHz Ch 123 - CONUS: UFO6 105.5W B/c audio @ .020

265.250 SW 30 KHz Ch 29 - CONUS: UFO5 99.4W data

265.450 ESE 30 KHz Ch 31 - LANT: UFO7 21.9W Portuguese

265.550 SW 30 KHz Ch 32 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8

265.550 ESE 25 KHz Ch 32 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

266.750 SW 30 KHz Ch 33 - CONUS: UFO5 99.4W

266.950 ESE 30 KHz Ch 35 - LANT: UFO7 21.9W

267.050 SW 30 KHz Ch 36 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8

267.050 ESE 25 KHz Ch 36 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

267.550 WSW 30 KHz SDS III-3 (US162) 143.8W data

267.825 SW 30 KHz not in bandplan - CONUS ? first noticed 20140314

267.925 SW 30 KHz not in bandplan - CONUS ? first noticed 20140314

268.150 SW 30 KHz Ch 37 - CONUS: UFO5 99.4W

268.350 ESE 30 KHz Ch 39 - LANT: UFO7 21.9W

268.450 SW 30 KHz Ch 40 - CONUS: UFO6 105.5W Spanish lang broadcast; Ch shared w/ FLTSATCOM8

268.450 ESE 25 KHz Ch 40 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

268.675 ESE 30 KHz SDS III-2-F5 (US155) 10.03W data

269.650 SW 30 KHz Ch 41 - CONUS: UFO5 99.4W

269.850 ESE 30 KHz Ch 43 - LANT: UFO7 21.9W data bursts

269.950 SW 30 KHz Ch 44 - CONUS: UFO6 105.5W Ch shared w/ FLTSATCOM8

269.950 ESE 25 KHz Ch 44 - LANT: FLTSATCOM8 14.7W Ch shared w/ UFO6

West Coast: San Francisco Bay Area

The West coast of the US is in the primary footprint of satellites that cover the CONUS region (e.g. UFO5 and UFO6) and on the edge of many that cover the PAC region (e.g., UFO4 and UFO8). Most of the PAC satellites are a bit weaker here than the CONUS birds are, at least from my SF Bay Area vantage point. Overall, the PAC region satellites carry several more transponders than their LANT region counterparts, and so those on the West coast are in range of a few more downlinks across the band than are those in the East.

The Pacific constellation is a bit less well documented than the Atlantic region, and I've had to make a few educated guesses and fill in a few missing details from the existing open literature based on my measurements. satellitenwelt.de lists the two main PAC region TACSATS, UFO4 (at 177.1°W) and UFO8 (at 173.3°E), as following bandplans Oscar and Papa, but does not specify which satellite follows which bandplan. I measure the Oscar downlink channels at a bearing that is rather distinctly, if only slightly, to the SW of the Papa channels. So I'm concluding (tentatively) that UFO4 (the Easternmost of the two) follows Oscar and UFO8 follows Papa.

There have also been a number of "mystery downlinks" over the Pacific whose origin is not obvious from the published sources to which I have access. In particular, during October 2012 there were strong downlink signals from the SW on many (but not all) of the frequencies used by CONUS UFO6 (bandplan "Quebec"), but no satellite on this bandplan was listed in any database for the PAC region. (Because these channels have two downlink signals coming simultaneously from different directions on them, it's difficult for me to take a more accurate bearing than just "generally SW", and so I can't really tell where these were coming from is with respect to the known positions of other satellites.) These transponders went off the air some time in early November 2012; time will tell whether they will reappear. There are also several signals (e.g., 267.925) on frequencies that do not appear in any US or NATO bandplan.

As on the East coast, Portuguese-speaking (presumably Brazilian) pirates are the main source of clear (FM) traffic through the voice transponders, although less of this traffic can be heard on the West coast than on the East coast. This is because Brazilians can choose either CONUS or LANT satellites (being within both footprints), but the Western US is well outside of the LANT footprint. So only the portion of Brazilian traffic that goes through CONUS constellation satellites can be received in the Western US.

While the PAC constellation may lack Brazilian pirates, it has its own source of unintended signals not found on CONUS or LANT satellites: Russian mobile telephones. Some areas of Russia (and the former Soviet Union generally) are still served by a non-cellular trunked analog mobile telephone system, called Altai, that operates in the 300-344 MHz range. Certain TACSET uplink frequencies are shared with those of Altai base station outputs, whose signals often make their way up to (and are retransmitted by) PAC region transponders whose uplinks are on those frequencies. The Altai system dates from the Soviet era and long predates the UHF TACSAT system, so this unintended traffic has presumably been an issue from the very beginning of TACSAT deployment.

UFO6 (bandpland Quebec) appeared to go off the air some time around 2012-11-02, but most (thought not all) of its transponders were back on the air by 2012-11-09, with the remaining transponders back on the air by 2012-12-14.

2014 saw a number of small but notable changes. In the CONUS constellation, several new 30 KHz voice transponders appeared on 248.825, 249.375, 251.275, 251.325, 267.825, and 267.925; note that the first two of these are in the data portion of the band, and several do not appear in any standard bandplan of which I'm aware. In the PAC constellation, we have a new 30 KHz voice transponder on 258.450 and three new 6 KHz data transponders on what the bandplan says should be voice channels: 262.100, 262.150 and 262.200.

This section last update 2014-03-16

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