Slow Scan Television (SSTV) is a method of transmitting and receiving still images over radio frequencies. It is commonly used in amateur radio and can be a fun way to share images, especially during special events or from locations like the International Space Station (ISS). Here’s a guide on how to work SSTV:
1. Understanding SSTV:
- Transmission Method: SSTV transmits images by sending a series of audio tones that represent the pixels of the image. The receiving station decodes these tones back into a visual image.
- Modes: There are several SSTV modes, such as Martin, Scottie, and PD, each with different resolutions and transmission speeds. The most common modes for amateur radio are Scottie 1 and Scottie 2.
2. Equipment Needed:
- Radio Transceiver: A VHF or HF transceiver capable of operating on the desired frequencies (e.g., 20m, 40m, or 2m bands).
- Computer or Laptop: A computer is typically used to run SSTV software for encoding and decoding images.
- Sound Card Interface: This connects your radio to your computer, allowing audio signals to be transmitted and received. Some operators use a dedicated sound card interface, while others use a simple audio cable.
- SSTV Software: There are several software options available for SSTV, including:
- MMSSTV: A popular Windows-based SSTV software.
- QSSTV: A Linux-based SSTV software.
- SSTV for Android: Mobile apps are available for SSTV operation on smartphones.
3. Setting Up:
- Install Software: Download and install your chosen SSTV software on your computer.
- Configure Audio Settings: Set up the audio input and output settings in the software to ensure it works with your sound card interface.
- Connect Equipment: Connect your radio to your computer using the sound card interface. Ensure that the audio levels are set correctly to avoid distortion.
4. Operating Procedure:
- Select Frequency: Choose a frequency where SSTV activity is common. Popular SSTV frequencies include:
- 14.230 MHz (20m band)
- 7.578 MHz (40m band)
- 144.500 MHz (2m band)
- Monitor for Activity: Before transmitting, listen to the frequency to see if other stations are active. SSTV images are often sent in a series of transmissions, so you may hear ongoing activity.
- Sending an Image:
- Prepare the image you want to send. Most SSTV software allows you to load images in common formats (e.g., JPEG, BMP).
- Select the desired SSTV mode and adjust the settings as needed.
- Start the transmission in the software, and it will send the image as audio tones over the air.
- Receiving an Image:
- When you hear SSTV signals, start the receiving function in your software.
- The software will decode the audio tones and display the received image.
5. Best Practices:
- Keep Transmissions Short: SSTV images can take time to transmit, so be mindful of other operators on the frequency. Avoid monopolizing the channel.
- Use Clear Calls: When calling CQ SSTV, clearly state your call sign and the mode you are using.
- Log Contacts: Keep a log of your SSTV contacts, noting the time, frequency, and call signs.
6. Community Engagement:
- Participate in Events: Many amateur radio events and contests include SSTV activities. Engaging in these events can enhance your experience and connect you with other SSTV enthusiasts.
- Share Images: After a successful SSTV transmission, consider sharing your received images on social media or amateur radio forums to showcase your work.
7. Special Applications:
- ISS SSTV: The ISS occasionally transmits SSTV images as part of special events. Monitoring the ISS frequency (145.800 MHz) during these events can provide opportunities to receive unique images.
Working with SSTV can be a rewarding and enjoyable aspect of amateur radio, allowing operators to combine their love of radio with visual communication. With the right setup and a bit of practice, you can successfully send and receive images over the air!