... Astrophysics Group . ... COAST . Fringes and Power Spectra from COAST . ... After acquiring a star, measurements must be made of the (complex) fringe visibility on each baseline. ... Fortunately, even in the presence of very strong atmospheric turbulence there is a good observable: the phase of the triple product of the visibilities on three baselines, commonly known as the closure phase. ... We then form the power spectrum of the resultant data, and hence estimate the visibility. ...

... The design employs a differential structure. ... The input is adapted to 100 differential, and the outputs use standard Low Voltage Differential Signaling (LVDS). ... T/H SINGLE T/H Single Input T/H Single Output 1.35 0.15 0.2 T/H DIFFERENTIAL Input T/H Output T/H 0.1 1.3 0.05 volts volts Figure 5: Digital part and digital gate 0 1.25 -0.05 -0.1 1.2 Integrated Test System A test system is integrated on chip to evaluate the transmission to the data acquisition card (fig: 7). ...