Fresh off from successfully shrinking its Super Hi-Vision camera, Japan's NHK is sticking another feather in its cap -- the first over-the-air broadcast of its super-duper high-resolution technology. The broadcaster says it recently managed to send a compressed Super Hi-Vision signal from the roof of its Science and Technology Research Laboratories in Tokyo to a distance about 4.2 kilometers away with no issues. NHK used two UHF channels during the experiment. To optimize and boost transmission capacity, NHK leveraged technologies such as orthogonal frequency-division multiplexing (OFDM) and multiple-input multiple-output (MIMO). Low-density parity check coding was also used for error correction. NHK has been constantly experimenting with its Super Hi-Vision high-resolution (7,680 x 4,320) video format, including a UK-to-Japan broadcast via a 24Gb/s internet connection in 2010. Folks who happen to be in Japan from May 24th to 27th can check the tech at the NHK labs' open house in Tokyo's Setagaya ward.