Still-pictures Radio Transmission Using Dither Method

Abstract

A still-picture radio transmission equipment, which is portable and used for remote observation, has been developed. Dither coding of half - tone pictures and progressive transmission of from coarse to fine resolution pictures has been effectively adopted to reduce the equipment memory size and to improve subjective transmission speed through the 2400 bps radio link. In the equipment, bi-level and multi-level dither codings are selectable with 512×512 and 256×256 resolutions, respectively. The 400 MHz radiofrequency band is used and a high-gain receiving antenna permits a lower radio radiation power than the range controlled by regulations.