ACURA SSTV Picture Decoder & Sender featuring the International Space Station, Atlantic City, New Jersey, and slow-scan television images transmitted using amateur radio.

SSTV Picture Decoder & Sender

Our free SSTV decoder turns your phone or laptop into a slow-scan TV receiver. Hold it near your radio, and pictures sent over the air paint onto the screen line by line, including the ones the International Space Station sends from orbit. It also works in reverse, so you can turn your own photo into SSTV audio and send it to other hams.

📥 Receive a Picture

Press Start Listening, then hold your device near the radio.
Audio level
— Hz
Auto-detect waits for the start tone that begins every SSTV picture. If you tuned in late, pick the format and press Start now.

🖼️ Pictures received this visit

None yet.

📤 Send a Picture

📻 To put it on the air, hold your radio’s microphone near the speaker (or use an audio cable), key up and press Play. A ham license is required to transmit. Try it on a simplex channel such as 145.550 FM, and announce it first.

🧪 Try It Without a Radio

Sending and receiving work through sound alone. One device plays the SSTV tones out loud, and the other hears them through its microphone and rebuilds the picture, just like a real radio contact.

Setup A: computer sends, phone receives (recommended)

A computer speaker is louder and clearer than a phone speaker, so this direction works best.

On the phone (the receiver):

  1. Open acurahamradio.org/sstv-decoder/ in Safari or Chrome.
  2. In the Receive a Picture box, leave Picture format on Auto-detect.
  3. Tap 🎤 Start Listening. When the phone asks to use the microphone, tap Allow.
  4. The status reads “Listening for a picture…” and the audio level bar moves a little with room noise.

On the computer (the sender):

  1. Open this same page.
  2. In the Send a Picture box, set Format to Robot 36, the quickest at 36 seconds.
  3. Use the ACURA test card, or click Choose File to pick a photo. Change the big and small text if you like.
  4. Click 🎵 Make SSTV Audio. It says “Ready: 0 min 37 sec.”
  5. Set the computer volume to about two-thirds.

Send it:

  1. Hold the phone 6 to 12 inches from the computer speaker, with the phone’s microphone (bottom edge) facing it.
  2. Click 🔊 Play. You hear a long tone, a short burst of beeps (the start code that tells the phone which format is coming), then the picture tones.
  3. Within a second or two the phone shows “Receiving Robot 36 · line 2 of 240” and the picture paints from top to bottom.
  4. After about 36 seconds it says “Picture received!” Tap 💾 Save Picture to keep it.

Setup B: phone sends, computer receives

Same steps with the roles swapped: make the audio on the phone, tap 🔊 Play, and hold the phone near the computer’s microphone.

  • iPhone: make sure the side silent switch is off. Web pages play no sound when the phone is on silent.
  • Phone speakers are quiet, so turn the volume all the way up and hold it close to the computer’s microphone (on a laptop, usually near the camera).

Setup C: one device, no microphone

Click 🔁 Send to the decoder on this page. The picture decodes right away on the same screen. It’s handy for a quick explanation or a noisy room.

Tips for a clean picture

  • Press Start Listening before you press Play. The receiver needs to hear the start code. If you missed it, pick the format on the receiver and tap ▶️ Start now in this format.
  • Keep the room quiet. Talking, fans and music show up as colored speckles or streaks.
  • Not too loud. If the speaker rattles or distorts, the picture gets noisy. About two-thirds volume is usually right.
  • Hold still while the picture comes in.
  • Disconnect Bluetooth headphones or speakers on both devices.
  • A few faint lines or a little speckle is normal through the air. It’s the same thing you’d see from a real radio signal.

Doing it at a school with radios

Once the phone-to-computer demo works, add two handheld radios on 145.550 MHz FM simplex at low power:

  1. The computer plays the audio into Radio 1, held near the speaker with the push-to-talk button pressed.
  2. Radio 2, across the room, receives it, and the phone listens to Radio 2’s speaker.
  3. Give your callsign by voice before and after, since you are transmitting.
🎒 Students hear the picture “sound” travel by radio and watch their own photo appear on the phone. Then point them to the next ISS SSTV event below.

📻 Where to Find SSTV on the Air

BandFrequencyModeWhat you’ll findTo transmit (US)
2 m145.800 MHzFMISS pictures during ARISS SSTV eventsReceive only
80 m3.845 MHzLSBMain SSTV calling frequency, best in the eveningGeneral and up
80 m3.857 MHzLSBAlternate when 3.845 is busyGeneral and up
40 m7.171 MHzLSBMain SSTV calling frequencyExtra (and Advanced) only
40 m7.173 MHzLSBDigital SSTVExtra (and Advanced) only
20 m14.230 MHzUSBThe busiest SSTV frequency in the world. Start here.General and up
20 m14.233 MHzUSBDigital SSTV and overflow from 14.230General and up
15 m21.340 MHzUSBSSTV calling frequency, good during the dayGeneral and up
10 m28.680 MHzUSBSSTV calling frequency when 10 m is openGeneral and up
👂 Anyone can listen, with no license needed. Below 10 MHz, set your radio to lower sideband (LSB). On 20 meters and up, use upper sideband (USB). Tune to the exact frequency shown, and the decoder will lock on by itself. No HF radio? Listen on our WebSDR or SDR Receiver page, play the audio through your speakers, and let this page decode it.
Technicians: the HF frequencies above are outside the Technician phone privileges, so they are for listening only until you upgrade. In Europe, look a few kHz away on 3.730–3.740, 14.225–14.235 and 21.335–21.345 MHz. Frequencies from the ARRL Considerate Operator’s Frequency Guide.

🛰️ Catching Pictures From the ISS

  1. Watch for an ARISS SSTV event. The space station sends pictures for a few days at a time, usually in the PD120 format.
  2. Tune an FM radio to 145.800 MHz. Open the squelch so weak signals still come through, and set the volume to about half.
  3. Check our Satellites page for when the ISS passes over South Jersey. A pass lasts about 10 minutes.
  4. Press Start Listening before the ISS rises and keep the device close to the speaker in a quiet room. A simple audio cable from the radio’s headphone jack gives the cleanest picture.
  5. When the picture finishes, press Save Picture. You can request an official ARISS award certificate for the pictures you receive.

How an SSTV Decoder Works

Slow-scan television sends a picture as sound. Each tone stands for the brightness of one dot, from about 1,500 Hz for black to 2,300 Hz for white. A short 1,200 Hz pulse starts every line, and a code at the very beginning tells the SSTV decoder which format is coming. As a result, the page can listen through your microphone and rebuild the picture as it arrives.

Formats You Can Send and Receive

The page handles Robot 36, Martin M1, Scottie S1, PD120 and PD180. The space station usually uses PD120, while Martin and Scottie are the most popular formats among hams. Robot 36 is the quickest, so it is a good choice for demonstrations.

A Great Demonstration for Schools and Scouts

First, take a photo of the group and turn it into SSTV audio. Next, send it on a low-power simplex channel with one handheld radio. Then let a second laptop across the room decode it. Students hear the tones and watch their own picture appear. Finally, point them to the next ARISS SSTV event so they can catch a picture from space.