SATCOM: Operation Deep Freeze flights

[VK3RX]

Nothing heard of these flights this season on SATCOM till a couple of days ago, but now hearing data transmissions and the occasional voice on 261.925MHz and 263.725MHz. Mode is FM and bandwidth 30kHz.

I suspect the data transmissions are most likely weather reports directed from DEEP FREEZE OPS in Christchurch to the aircraft for their destination in Antarctica, and Christchurch on return. In past seasons these were given out by voice.

Audio clips attached.

Perhaps instead of SATCOM the aircraft and MAC CENTER are making use of HF or CPDLC to talk to each other until within VHF range.

Info below re Operation Deep Freeze & SATCOM for those interested.
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Operation Deep Freeze occurs during the Antarctic Summer and involves resupply flights between Christchurch N.Z. and U.S. bases in Antarctica, using LC-130 and C-17 aircraft.

https://en.wikipedia.org/wiki/Operation_Deep_Freeze

Primary comms are on HF between the N.Z. air traffic authority and MAC CENTER air traffic control at McMurdo while the aircraft are in their respective airspace areas of responsibility, transferring to VHF when within range. However comms also take place between the aircraft and DEEP FREEZE OPS at Christchurch and MAC CENTER on UHF SATCOM frequencies. The satellite used is positioned in geosynchronous orbit over the Pacific, and comms can be heard in the clear FM mode (not scrambled or encrypted).

A discone isn't likely to cut it, instead you will need some form of antenna designed for the 240-270MHz range. See MT article links for an easy to construct antenna that turns in good results. Commercially made SATCOM antennas made by Trivec and Harris come up on ebay from time to time, but these days they command fairly high - sometimes ridiculously high - prices. Google "sitcom antenna" to see the various designs.

You could test your current antenna by checking 265.450MHz for a data transmission that occurs on the hour for a minute or so, as well as 269.750 & 269.850MHz, where right now there are continuous data bursts.

[domestos]

...listening now, lately I have been hearing what sounds like TV audio from Chinese TV on 253.750, lucky to hear anything as I use a discone, years ago I did hear much FLTSATCOM traffic on 261.950, mostly M.I.A. teams in P.N.G.

[VK3RX]

Hearing that on 253.750 too.

Also distorted audio on 269.750, said to be a Philippines FM station, and from time to time Russian phone calls on 266.950.

I used to listen to the JTF-FA (Joint Task Force - Full Accounting) teams in Vietnam, Laos and Cambodia using callsigns like TIGER, WOLF, LION etc. looking for the remains of servicemen. They usually used 261.65MHz, 261.85MHz and 261.95MHz. Their comms suddenly stopped, and I assumed they went to satphones.

[domestos]

I can remember hearing the base ( 261.950 ) in a carrier, hearing choppers in the background, talking to a search crew in the jungle of PNG, dealing with a request for a pig, to be used by the village chief, to appease the gods before the MIA crew could search. - funnily enough, years later I hooked up with my partner who's father and fellow crew members were found in PG by the MIA hunter team ( led by Brian Moon ) and we all met years later in the US for their funeral at Arlington.

[VK3RX]

Wow, great story - thanks for sharing it with us.

Back in 2002 I picked up a CD called "Shortwave With A Difference" (the name of a column in the local mag "Radio Communications) which contains audio of many different comms heard by the author "Caradoc" and others including me. I just checked and it only has a single recording of JTF-FA stuff. I should have kept my recordings from back then.

Today I heard WARLOCK calling PARRAMATTA on 263.875 followed by data transmissions so that's maybe another frequency to put in.