Receiving SSTV from the International Space Station
Several times a year the ISS spends a few days transmitting pictures on 145.800 MHz, and anyone under the pass can receive them. You need no licence, no HF radio, no antenna farm and no permission — a handheld, a laptop and ten minutes of a clear sky will put a picture from a spacecraft on your screen. It is the best first result in amateur radio.
What ARISS actually is
Amateur Radio on the International Space Station is a long-running programme that puts amateur equipment aboard the station. Most of the time it is used for scheduled contacts with schools. Periodically it runs SSTV events — a few days of continuously transmitted pictures, usually commemorating an anniversary, with certificates for those who submit received images.
Events are announced ahead of time on the ARISS sites and across the amateur press. They are not frequent, which is why the search interest spikes and then vanishes: if you find this page between events, note the frequency and come back.
The essentials
| Frequency | 145.800 MHz, FM |
| Mode | Varies by event — Robot 36 historically, PD120 recently |
| Pass length | About 10 minutes at best, often less |
| Doppler | Roughly ±3.5 kHz across the pass |
| Licence | None required to receive |
You do not need to know the mode. The transmission carries a VIS header identifying it, and any competent decoder — Open Signal included — reads that and configures itself. This is exactly the situation automatic mode detection exists for.
Finding a pass
The ISS is only in range when it is above your horizon, which happens for a few minutes at a time, a handful of times a day. Pass prediction sites and applications will tell you when and where to look — you want the maximum elevation figure, because it matters more than anything else.
- A pass peaking above 40° is worth getting up for.
- Below about 20° you are listening through a lot of atmosphere and most of your neighbourhood.
Doppler, and why you can mostly ignore it
The station is moving at around 7.7 km/s, which shifts the received frequency up as it approaches and down as it recedes — about 3.5 kHz either side at 145.8 MHz.
On a narrow mode that would be fatal. On FM it is survivable, because FM receivers have a wide enough passband to cope. Many people simply park on 145.800 and accept slightly degraded audio at the start and end of the pass.
If you want the extra few percent: start around 145.805 as the station rises, pass through 145.800 at closest approach, and end near 145.795. Adjust in small steps and only between pictures, because a tuning change mid-picture puts a visible band across it.
Setting up in ten minutes
- Tune to 145.800 MHz, FM, squelch open.
- Squelch open matters: a closed squelch chops the quiet start of each transmission and you lose the VIS header, which is the one part you cannot afford to miss.
- Get the audio into the computer — a cable if you have one, the laptop microphone if you do not.
- Start the decoder before the pass, not when you hear something.
- Leave it alone and let it work.
What you will actually get
Be realistic and you will not be disappointed. A single pass rarely yields a complete picture: the station rises mid-transmission, and you catch the second half of one image and the first half of the next.
Over several passes across an event, the fragments accumulate into complete pictures. That is the normal experience, and the partial ones are still genuinely satisfying — you pulled them out of the sky.
Why it is such a good starting point
- The signal is strong. Far stronger than most HF work, and there is no propagation lottery — it either is overhead or it is not.
- The schedule is known. You are not waiting for someone to happen to transmit.
- The equipment is trivial. No HF rig, no antenna tuner, no licence.
- You can submit what you receive to ARISS during events and get a certificate back.
ISS SSTV — FAQ
What frequency does the ISS transmit SSTV on?
145.800 MHz FM. That is the standing ARISS downlink frequency and it does not change between events. Doppler shift moves it by roughly ±3.5 kHz across a pass, which FM handles well enough that many people simply leave the radio on 145.800 throughout.
Do I need a licence to receive ISS pictures?
No. Listening requires no licence in the UK, and receiving the ISS is one of the best possible introductions to the hobby — the signal is strong, the schedule is published in advance, and a picture from a spacecraft is a genuinely good first result.
What mode does the ISS use?
It varies by event. The MAI-75 experiments used Robot 36; more recent ARISS commemorative events have generally used PD120. You do not need to know in advance — the transmission carries a VIS header and the decoder configures itself from it.
What antenna do I need?
Less than you would think. A handheld's rubber duck will produce recognisable fragments at high elevation. A quarter-wave ground plane on a windowsill does noticeably better, and a small hand-held Yagi you point at the pass does better still. The limiting factor is usually buildings, not gain.
More about Open Signal
Point it at the sky and let it decode
Open Signal reads the VIS header and paints the picture line by line as it arrives — so a pass that starts mid-transmission still gives you everything that follows. Receiving is free, permanently.