Pseudo-random-bit-sequence phase modulation for reduced errors in a fiber optic gyroscope.
Low noise and drift in a laser-driven fiber optic gyroscope (FOG) are demonstrated by interrogating the sensor with a low-coherence laser. The laser coherence was reduced by broadening its optical spectrum using an external electro-optic phase modulator driven by either a sinusoidal or a pseudo-random bit sequence (PRBS) waveform. The noise reduction measured in a FOG driven by a modulated laser agrees with the calculations based on the broadened laser spectrum. Using PRBS modulation, the linewidth of a laser was broadened from 10 MHz to more than 10 GHz, leading to a measured FOG noise of only 0.00073  deg/√h and a drift of 0.023  deg/h. To the best of our knowledge, these are the lowest noise and drift reported in a laser-driven FOG, and this noise is below the requirement for the inertial navigation of aircraft.
A low Power 28 Gb/s 27-1 PRBS Generator and Check with Correlate Dual Outputs in 40 nm Technology
A 28 Gb/s PRBS generator and checker with correlation Dual outputs is presented in this paper, with the proposed dual outputs interleaved structure, the PRBS has only the half data rate, which is able to expand the communication data rate. A hybrid counter is proposed to undertake both high frequency and low frequency signal, the proposed PRBS generator and checker has been designed in TSMC 40 nm CMOS 1P9M technology, post-simulation results confirm that can output 28 Gb/s data, the check and counter can work, the power dissipation is 1.5 μW.
Prediction of net pressure on pressure equalized cavities
Abstract A numerical model has been developed for prediction of net pressure on pressure equalized cavities. The results based on this model show good agreement with those obtained from mock-up tests. Parametric studies verify that reductions in cladding load are possible, with proper design of curtain walls.