6:15 PM - 7:30 PM
[PEM27-P01] Water vapor estimation using digital terrestrial broadcasting wave
Keywords:water vapor, radio wave, propagation delay, digital terrestrial broadcasting
We are developing a real-time delay (phase of delay profiles) measurement system with software-defined radio technique. We have improved this system and maximum number of channels which can be processed in real-time has expanded to 5. Measurement accuracy of this system is evaluated, and the time resolution of measured delay time is found to about 50 ps. We plan to use CATV to synchronize the local oscillators at different sites. Signals pass-through in the CATV network are the same RF signals as that transmitted from the radio tower, and they can be also processed with the system mentioned above. Phase fluctuations of local oscillators at both sites are canceled out using the signals pass-through in CATV as references. Each signal pass-through in CATV has its own delay due to the difference of network path. We have developed the method to correct it. The precision of synchronization is less than 100 ps, and in-house test is going on to improve it. We are planning demonstration experiments to estimate water vapor using two receiving stations in next summer. We will use optical fiber synchronization method, which is already established by NICT, to evaluate CATV synchronization. We investigate miniaturization of measurement system using DSP board for the multi-point measurement in the future.