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How to Set Up and Send SSTV (Slow Scan Television)

Slow Scan Television (SSTV) allows amateur radio operators to send still images over the airwaves. Unlike voice communication, SSTV transmits images pixel by pixel, making it a fascinating mode to try. Here’s how you can get started with SSTV transmission.

Equipment You’ll Need

  1. Transceiver (Radio) – You’ll need a transceiver capable of operating in HF (High Frequency) or VHF (Very High Frequency) bands, typically on 20m (14 MHz), 40m (7 MHz), or 2m (144 MHz) bands.
  2. Computer with SSTV Software – Software like MMTTY, EasyPal, or QSSTV is used to generate the images and interface with your radio.
  3. Sound Card Interface – This can be a simple sound card interface that connects your computer’s audio output to the microphone input of your radio. Some rigs have digital mode interfaces built in.
  4. Antenna – Ensure you have an antenna tuned to the frequency you’ll be operating on.
  5. Microphone or Interface Cable – To connect your radio to your sound card or PC.

Setting Up Your SSTV Station

1. Install SSTV Software

You’ll need to download and install SSTV software to send and receive images. Here are some popular options:

  • MMTTY – A simple SSTV software for Windows.
  • QSSTV – A Linux-based option with a user-friendly interface.
  • EasyPal – Allows for both SSTV and digital modes, great for sending pictures.

Install the software, and make sure it’s configured to match your operating system and hardware (sound card, transceiver).

2. Connect Your Computer to Your Radio

To interface with your radio, connect your sound card (usually via a USB cable) to the radio’s microphone or data input port. Alternatively, use a rig interface like the Signalink USB if you want more control and sound isolation.

Here’s a simple connection diagram:

  • Radio → Mic Input (or Data Input if your radio supports digital modes)
  • PC Sound Card Output → Audio In (Mic Jack on Radio)
  • PC Sound Card Input → Audio Out (Speaker Jack on Radio)

3. Set the Mode on Your Radio

  • Set your transceiver to the SSB (Single Sideband) mode, Upper Sideband (USB) is commonly used for SSTV.
  • Choose a frequency that is popular for SSTV operations. Common SSTV frequencies are:
    • 14.230 MHz (20 meters)
    • 7.173 MHz (40 meters)
    • 144.500 MHz (2 meters)
  • Ensure that your radio is in the appropriate mode for the frequency you are transmitting on (SSB).

Preparing Your Image

1. Create or Choose Your Image

Before you send an image via SSTV, make sure it’s in the right format:

  • SSTV typically sends images in grayscale or low-color resolution.
  • The image is sent line by line and pixel by pixel, so the resolution is lower than what you might use for regular photos. Aim for a simple, clear image with good contrast.
  • Recommended formats: JPG, BMP, PNG. Avoid large files, as SSTV software may not handle them well.

2. Convert the Image into SSTV Format

Once you’ve selected your image, the SSTV software will convert it into an audio signal:

  • SSTV modes (e.g., Martin, Scottie, and others) are different modulation schemes that encode the image into audio signals.
  • Most SSTV programs will automatically handle the conversion to the correct format.

Sending Your SSTV Image

1. Configure Your Software

  • Open your SSTV software.
  • Select the transmit mode based on the SSTV format you want to use (e.g., Martin, Scottie, or PD modes).
  • Adjust the sound card settings in the software, ensuring that it is using the correct input/output channels (e.g., the microphone/speaker or audio-in/out ports).

2. Adjust Power Settings

Set your transceiver power output to a reasonable level for SSTV transmission. SSTV transmissions tend to be longer than voice transmissions, so adjust your power to avoid excessive heating of the radio.

3. Start Transmission

Once everything is set up:

  1. Choose the image you want to transmit in the SSTV software.
  2. Press “Transmit” in the software. This will convert your image to an audio signal that the radio will broadcast.

Your radio will then transmit the image in audio tones across the airwaves. If you’re listening to it on a receiver, you’ll hear a series of beeps and tones that correspond to the pixels and lines of the image.

Receiving SSTV Images

To receive SSTV images, you’ll need to:

  1. Tune to a popular SSTV frequency (e.g., 14.230 MHz or 7.173 MHz).
  2. Set your radio to USB mode.
  3. Use your SSTV software to decode the incoming audio signal and display the received image.

Many SSTV programs like MMTTY and QSSTV have a “receive mode” that automatically decodes SSTV transmissions and shows the images on your screen.

SSTV Tips for Better Results

  • Clear Skies, Clear Signals – SSTV works best during good propagation conditions, such as during the day or during solar peaks.
  • Band Conditions – Check for clear frequencies. Sometimes, SSTV activity can get crowded, especially during contests or events.
  • Use a High-Quality Antenna – A good antenna will make a huge difference in your ability to send and receive clear images.
  • Use Filters – Some SSTV software programs allow you to use audio filters to reduce noise, which is especially helpful on HF bands.

Where to Use SSTV

SSTV is popular during contests and events, but you can also use it in everyday ham radio operations. Here are some places to look for SSTV transmissions:

  • SSTV Nets – These are scheduled events where hams gather to exchange images.
  • Satellites – Many amateur radio satellites use SSTV to send pictures back to Earth.
  • Special Events – Watch for SSTV usage during events like Field Day, special contests, or anniversaries of historic events.

Conclusion

Sending SSTV images is a fun and rewarding aspect of amateur radio that allows you to share pictures with fellow operators. By following these steps, you’ll be transmitting stunning images across the airwaves in no time. Be sure to experiment with different SSTV modes and images to fully experience this fascinating mode.

Happy transmitting!