Slow Scan Television - SSTV (.hrz)

The HRZ file extension is linked to Slow Scan Television (SSTV), a specialized method employed by amateur radio operators for the transmission and reception of static images through radio frequencies. This approach facilitates image sharing over vast distances, even in suboptimal transmission environments, establishing it as an essential communication medium when conventional methods are inadequate. An HRZ file encapsulates an image measuring 256 x 240 pixels, stored as an RGB bitmap. Its design is optimized for situations with restricted bandwidth, enabling the effective transfer of image data, whether in grayscale or color, across narrowband frequencies.

SSTV functions by translating image pixels into variable audio tones, distinguished by their frequency and length. These tones are then broadcasted using high-frequency bands and single-sideband modulation (SSB). At the receiving end, SSTV software decodes the audio, reconstructing it into a visual file for display or archival purposes. The HRZ file represents the culmination of this process, embodying the visual data transmitted via radio. Notably, while the HRZ format may not be as widespread as other image file types, it fulfills a distinct role within the amateur radio sphere, offering a means to visualize data communicated through radio signals.