Receiving and listening techniques for monitoring military satellites.

Published in the WANSAC (Western & Northern Suburbs Amateur Radio Club) monthly club magazine.

Issue August 2026

http://www.wansarc.org.au/

UFO-11 a Military Workhorse in a Noisy Sky

By Peter Miles – VK6YSF  

For many radio amateurs and SDR radio listeners, the first encounter with military UHF satellite communications is a high point – pardon the pun. Tune across the 240–270 MHz range with the right setup, and you may hear brief voice exchanges, digital bursts or often something far less official.

At the centre of much of this activity sits UFO-11, one of the U.S. Navy’s long-serving UHF Follow-On (UFO) satellites. UFO – someone in the Pentagon has a great sense of humour. To the monitoring community, it has gained a reputation not only as a reliable signal source, but also as a place where structured military communications and unauthorised transmissions appear to share the same spectrum.

So what’s really going on up there - and how does it all work?

UFO-11 is a geostationary satellite, or more accurately, a geosynchronous satellite with orbital inclination. Over time, its orbit has been allowed to tilt slightly relative to the equator, producing the familiar figure-8 ground track when plotted over a 24-hour period.

For the satellite operator, this is a deliberate trade-off. Maintaining a perfectly fixed position requires continuous north–south station-keeping burns, consuming valuable fuel. By relaxing this requirement, the satellite’s operational life can be extended significantly and often by decades.

From a monitoring perspective, this has a subtle but noticeable effects in that daily variation in elevation angle and may have small changes in signal strength and a slight pointing tolerance for directional antennas, however UHF in this situation is sufficiently forgiving with the few degrees change of inclination rarely cause problems for end users or listeners. For listeners in Melbourne, Australia, this places UFO-11 either just above or just below the horizon, depending on the time of day. When it is just above the horizon, reception should likely be possible, provided there are no buildings obstructing the line of sight.

Fig 1. UFO-11 geostationary orbit positioned over the Indian Ocean with a figure of 8 ground track.

Technically, UFO-11 is straightforward. It is a bent-pipe repeater. Signals are received on one frequency, translated to another frequency, amplified and retransmitted with no on-board decoding or routing. The satellite simply relays whatever it hears.

Its primary operating ranges are well known:

• Uplink range: 292 - 318 MHz

• Downlink range: 243 - 270 MHz  

Channel spacing is typically narrow (5 kHz or 25 kHz), supporting, narrowband FM voice, low-rate digital modes, other higher bandwidth and control channels.

Fig 2. SDR receiver spectrum showing four channels. The centre with voice traffic and the three to the right showing channel noise floor.

For the listening public, this makes UFO satellites particularly interesting. Unlike many modern systems, the signals are narrowband, often within reach of modest equipment and detectable with an SDR receiver and suitable antenna such as a small Yagi.

Spend a little time monitoring these frequencies and you’ll likely encounter something unexpected: transmissions that don’t sound military at all.

These may include, casual voice chats, music and broadcasting - mostly foreign-language traffic.

This has led to the widespread belief that UFO satellites are easily disrupted. While there is some truth to that, it’s important not to misinterpret what you’re hearing.

In reality, the critical traffic is usually happening elsewhere in the band, out of the spotlight.

A natural question is: why isn’t this shut down? - The answer lies in the nature of radio itself.  

Regulators like the Australian Communications and Media Authority or the United States - Federal Communications Commission can enforce rules within their own borders. But satellite uplinks can originate from anywhere within the footprint that can spans continents and oceans.

Fig 3. UFO-11 coverage footprint.

International coordination exists via the International Telecommunication Union, however enforcement relies on cooperation. There’s no global enforcement body that can simply “switch off” an offending transmitter.

Add to that the mobile transmitters, wide-area coverage, difficulty geolocation and you have a classic RF cat-and-mouse problem.

In some cases, transmissions attributed to countries such as Russia may not be “pirate” at all, but deliberate state-level activity - jamming, spoofing, or opportunistic use. That moves the issue from regulation into geopolitics.

From a technical and operational standpoint, the key question is whether this activity degrades the system and in most cases, the answer is: not significantly.

With most operational traffic being encrypted. Even if you can hear it, you can’t interpret it.

There is also the flexibility to change channels, adjust power or even switch satellites. Importantly these are military assets that are required to operate under adverse conditions including deliberate attempts at disruption.

Monitoring activity has taken on new relevance in the context of the war in Ukraine.

There have been credible however unconfirmed reports that forces associated with Russia may have used legacy UHF satcom systems, including UFO satellites, during the conflict.

The monitoring community has reported a lot of Russian-language voice traffic often unencrypted communications that appear operational military or just covering deficiencies in Russian military communication infrastructure - all of this is unconfirmed.

However hearing a signal does not confirm the satellite used and nor does it confirm the identity of the operator.

Many transmissions are simply radio pirates that in the case of UFO-11 are mostly Russian from my listening.

What is clear is that satellite communications are now a contested domain, and legacy systems may be used opportunistically when needed.

All this raises an interesting question: does this kind of activity actually benefit intelligence agencies such as the National Security Agency or the Central Intelligence Agency?

In theory, it can - at least occasionally. Unsecured transmissions may reveal radio procedures, operational habits and in some cases troop morel.

Even encrypted signals provide metadata who is transmitting, when, and how often.

The catch is that it also create opportunities for deception and low quality information, or in other words a signal to noise situation.

Not everything heard is what it seems.

It’s also worth noting that UFO-11 is no longer the primary system it once was. Much of its role, but not all has been taken over by the U.S. Space Force and U.S. Navy’s MUOS (Mobile User Objective System) constellation.

MUOS is digital with tight access controls, greater capacity and security; and for the monitoring folks, it’s also far far less accessible.

For radio amateurs, UFO-11 offers something increasingly rare, a real-world, active satellite system, signals that can still be observed with modest gear and glimpse into how a space based communications systems behave under imperfect conditions.

This is also fantastic opportunity to test and refine radio techniques quickly in a way that separates reality from theory.

With an SDR receiver, the experience shifts from simply hearing signals to seeing the entire band in motion.

The SDR waterfall display reveals channel occupancy patterns, burst transmissions and control channels

Upper VHF and UHF frequencies are ideal for practical antenna design and construction work. Designs are compact, materials are inexpensive, and results are immediately measurable.

An exciting new area to explore is the application of AI (Artificial Intelligence) in conjunction with Speech Note software (Linux) for speech-to-text transcription and translation tasks. Speech Note can utilise speech recognition engines such as Whisper (including local implementations of OpenAI’s Whisper models, e.g. whisper.cpp or faster-whisper) to convert audio into text, and optionally pass that text through translation engines for language conversion.

Speech Note is an audio-to-text application capable of near real-time processing depending on configuration and system performance. A practical use case is routing audio from an SDR (Software Defined Radio) receiver into Speech Note, allowing received voice signals to be transcribed. This is typically achieved using virtual audio routing via PulseAudio or PipeWire (Linux) or VB-Cable (Windows) between software applications.

Performance depends heavily on the selected speech recognition model. Smaller Whisper models (e.g. tiny or base) offer faster processing with lower accuracy, making them suitable for near real-time transcription of cleaner signals. Larger models (e.g. medium or large) provide higher accuracy and improved noise robustness but require significantly more processing time and are generally not real-time on modest computer.

This makes the system suitable for transcribing radio voice communications (AM, SSB, FM) as an alternative to simple audio recording, with the added capability of processing in near real-time transcription. When combined with translation models, it can also provide language identification and conversion (e.g. Russian to English), although translation introduces additional latency beyond the speech recognition stage.

Even when transmissions can’t be decoded, they can still be studied.

Photo 1. A 5 element Yagi antenna aimed at the UFO-11 satellite.

It’s a rare glimpse into a working communications network operating under real constraints and chaos.

As newer systems like the MUOS take over, much of this activity is moving toward more controlled, less observable platforms.

This makes the UFO-era satellites something of a last accessible frontier for this kind of hands-on learning.

For the amateur experimenter, this isn’t just casual listening. It’s a chance to refine equipment under realistic conditions, develop practical SDR and analysis skills, build and evaluate antennas with immediate feedback and gain insight into complex RF systems

Tracking UFO-11: https://www.n2yo.com/?s=28117&live=1

Conclusion

UFO-11 is not a pristine, tightly controlled communications platform. It is something more interesting: a practical system operating in the real RF world.

Yes, there is unauthorised activity. Yes, it can be heard. But rather than undermining the system, it highlights its strengths, including its resilience, flexibility and tolerance to interference

For the listener, it offers the opportunity to observe a living system, but also a reminder that what we hear is only part of a much larger and more complex picture.

In an increasingly digital and closed communications landscape, that alone makes UFO-11 worth tuning in to.

Photo 2. Station listening to the UFO-11 satellite while transcribing and translating Russian radio pirate voice traffic – tell me this doesn’t look like fun.

Cautionary Legal Note:

If a transmission is not clearly intended for public reception, treat it as receive-only. Avoid recording, publishing, disclosing, retransmitting, or otherwise distributing the content.

Receiving unauthorised or “pirate” transmissions is generally treated differently from transmitting them; however may raise legal issues depending on jurisdiction and the nature of the signals involved.

Extra caution applies to any communications associated with military or government systems, regardless of whether they appear unsecured or originate from unauthorised users.

References:

5 Element Yagi-Uda antenna for 250MHz to 260MHz.

https://vk6ysf.com/yagi_250mhz_5el_20220925.html

Speech Note (Linux) speech-to-text tool that transcribe audio and even translate between languages.

https://flathub.org/en/apps/net.mkiol.SpeechNote

StarWhisper v1.3.130 is a Windows alternative to the Linux Speech Note.

https://apps.microsoft.com/detail/9nxrf1n01vsn?hl=en-GB&gl=AU

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Page initiated 04 August, 2026 

Page last revised 10 August, 2026