1-GBPS VLBI, the first detection of fringes

We report on the detection of VLBI fringes from quasars by a new VLBI syste m operating at 1 Gbps (1024 Mbits-per-second). Newly developed 1024 Msps (m ega sample-per-second) AD samplers and 1024 Mbps recorders were used for th e observations. A correlator with external buffers was used for the 1024 Mb ps correlation processing of the tapes data. Our new VLBI system enabled 10 24 Mbps VLBI, and this allowed the sampling of a 512 MHz bandwidth from a r adio telescope receiver. This is the highest sampling speed ever used for V LBI, and the widest bandwidth used for VLBI observation. Initial sensitivit y as evaluated by SNR comparison with earlier VLBI systems produced results to matched the expanded bandwidth. In our first observations, simultaneous optical fibre linked real-time VLBI observations were made to check the va lidity of data and precisely detemine the clock offsets among the radio tel escopes.