Receiving SSTV Signals from the ISS with a Handheld Transceiver

In the world of amateur radio, there is a romance that goes beyond terrestrial communication: receiving radio waves from the space station with a handheld transceiver that weighs just a few hundred grams. This activity does not require any special license or expensive equipment. If you hold a Japanese amateur radio operator license (Class 4 or higher) and have a radio that supports the 144 MHz or 430 MHz bands, you can receive SSTV (Slow Scan Television) signals from the International Space Station (ISS) and decode the images sent from space.

The mechanism of SSTV is simple. A still image is converted into an audio signal, which is then transmitted via radio waves. On the receiving side, the recorded audio is analyzed by software and restored to the original image. Because each image takes about two minutes to transmit, rather than being a continuous video, it is called “slow” scan, but this allows the image to arrive stably even over narrow bandwidths. The concept of SSTV itself was proposed by American amateur radio operators in the 1950s–1960s, and at that time it was a black-and-white image with about 120 lines and about 120 pixels per line. Today, formats such as PD120, which include color information, are mainstream, and the ISS mainly sends images in this format.

The ISS orbits Earth at an altitude of about 400 km and a speed of about 28,000 km/h. As a result, its visibility from the ground constantly changes. A receivable time window (pass) lasts up to about 10 minutes. Within this short time, you need to capture the signal and record it without interruption. The fact that this activity, which to the uninitiated looks like “leaving it to luck,” is actually supported by careful calculation and preparation is one of the interesting aspects of SSTV.

The Role of SSTV and ARISS

What many people call “NASA’s ISS SSTV activity” is strictly organized and coordinated by an international cooperation project called ARISS (Amateur Radio on the International Space Station). ARISS is an educational program participated in and supported by space agencies such as NASA, ESA, JAXA, CSA, and Roscosmos, as well as amateur radio organizations and AMSAT groups around the world. It is not just a “pastime” for radio enthusiasts; it is positioned as part of STEM education targeting students and the general public. NASA also officially recognizes ARISS as an opportunity to learn about astronauts’ lives and space science.

Among its activities, SSTV is a particularly accessible entry point. While “ARISS School Contacts,” which involve actual communication with astronauts, require school-based applications and extensive preparation, anyone can receive SSTV signals. Behind this is ARISS’s mission to “widely share the space experience.”

How to Choose the Necessary Equipment

The equipment needed for reception can be broadly divided into three categories. First is the radio. Any radio that can receive the UV bands (144 MHz and 430 MHz bands) will work, whether a handheld transceiver or a mobile unit. For mobility, a handheld radio is suitable. Since you may need to move to an open location during the satellite pass, a lightweight, easy-to-set-up model is practical. If you have the budget, a multiband radio like the ICOM IC-705 is an option, but beginners should first try with whatever radio they already own. There is no need to aim for a perfect image from the start. First, listen for the signal. Once you have successfully recorded clear audio, you can gradually improve the decoding quality.

Next is the antenna. The simplest method is to use the whip antenna that comes with the radio. However, because the ISS appears near the horizon, you need to pay attention to the antenna’s position and polarization. For more stable reception, a glass fiber pole antenna such as the Diamond NR701 or NR770 designed for mobile use, or a Yagi antenna, can be effective. A Yagi antenna amplifies signals from a specific direction, making it suitable for tracking the ISS orbit while receiving. If installing it fixed, choose a feeder cable with low loss and check the connector types (SMA, M-type, N-type, etc.) between the antenna and the radio in advance. Keeping several types of conversion connectors on hand can prevent trouble on site.

The feeder cable also affects the result. When running a long cable, choose a low-loss cable with good shielding. Even with a handheld radio, many people use extension cables to place the antenna outside a window. A common mistake is scrambling at the last minute during the pass because the connector conversion didn’t work out.

Practical Steps for Reception

The actual reception procedure is as follows. First, obtain ISS orbital predictions. Use the European Space Agency (ESA) or ARISS official websites, or smartphone tracking apps (such as ISS Detector) to find out when the ISS will be visible from your location (pass times). During SSTV activities, signals are transmitted at 145.800 MHz (some activities also use 145.990 MHz) when the ISS passes overhead. Preset this frequency on your transceiver.

The moment the signal arrives, the noise does not suddenly clear. The signal strength gradually increases, and you will start to hear the distinctive “beep, beep, beep” SSTV audio. Record this audio using a voice recorder on your smartphone or recording software on your computer. During reception, the frequency shifts due to the Doppler effect as the ISS moves, so manual or automatic fine-tuning is necessary. The Doppler shift causes the frequency to be higher in the first half of the pass and lower in the second half, so the basic approach is to adjust to the center frequency when the ISS is at its highest elevation angle.

After recording, use dedicated software such as MMSSTV (for Windows) or Robot36 (for Android) to decode. These programs analyze the recorded SSTV audio and restore the image. Even if only part of the image, including the callsign in half-width Roman letters, is received, it can be considered successful. Especially at first, an incomplete image with noise is fine. Radio communication improves through “accumulated refinements.”

If reception is successful, report the image, reception date and time, and equipment used through the application form that ARISS publishes after the activity period. If conditions are met, a commemorative electronic certificate (PDF format) will be sent via email. This certificate is proof that “you received a signal from space at home,” and among SSTV participants, it has become a collectible.

How the Antenna Changes Reception Results

The biggest factor affecting SSTV reception quality is the choice of antenna and feeder system. Even with a whip antenna, you can capture the signal when the ISS is directly overhead, but it is difficult to maintain stable quality throughout the entire pass.

Using a Yagi antenna dramatically improves sensitivity and directivity. The Yagi antenna was developed by two Japanese researchers, Yagi Hidetsugu and Uda Shintaro. Despite being a technology invented in Japan, it is famous that during World War II, Allied forces discovered the structure in Japanese radar equipment and evaluated it with surprise. After the war, this design became widely used for television reception and radio communication, and today it is established as a standard high-gain antenna in amateur radio.

A fixed Yagi antenna needs to be manually pointed toward the ISS orbit, but for SSTV, you can aim for the signal even just at the time of maximum elevation within the approximately 10-minute pass. Commercial satellite tracking rotators enable automatic tracking, but it is practical for beginners to try manually first and then step up.

Editorial View

In the short term, SSTV reception can be evaluated as going beyond the hobby of amateur radio enthusiasts. ARISS activities are officially supported by public space agencies such as NASA and JAXA, and are attracting attention as teaching materials for STEM education. In Japan, as of 2026, the ISS continues to operate, and SSTV activities are conducted several times a year. The fact that orbit predictions can now be easily obtained with smartphone apps also lowers the barrier for beginners. Within the next six months, there is a possibility that beginner-oriented kits packaging SSTV reception will be sold at domestic amateur radio shops.

From a long-term perspective, this activity is part of a larger trend of democratizing “access to space.” Space communication that decades ago was only possible by specialized institutions can now be achieved with a palm-sized radio. This is not merely technological progress; it means expanding the foundation of space education and citizen science. In particular, the culture of sharing SSTV images on social media has the effect of sustaining public interest in space. Over a span of one to three years, as commercial space stations emerge and the lunar orbital outpost “Gateway” is developed, our editorial team speculates that the scope of SSTV activities may expand beyond the ISS to other space facilities.

We would like to pose one question from the editorial team: Should SSTV reception be positioned as a “hobby” or as “education”? ARISS explicitly states it is an educational program, but many actual participants enjoy it as an extension of amateur radio. This duality arguably enhances the activity’s sustainability. However, there is also criticism that with the boundary between educational and hobby purposes blurred, space agency resources might be diverted to hobby uses. How do our readers perceive this activity?

References

• 少数派 - 接住来自空間站的信号：如何用手台接收 SSTV？ — Published June 7, 2026
• ARISS Official Website (https://www.ariss.org)