Homestake meeting 06/12/2014
Attending: Noah, Vuk, Gwynne, Tanner, Victor
Homestake wiki: https://zzz.physics.umn.edu/groups/homestake/home
1) Homestake update (Vuk)
Started preparatory work for some of the stations. Trip planned for the end of July to finalize location choices and GPS/network details. Gary should be at Homestake at the end of June to find surface locations and check the performance of the radio equipment from PASSCAL.
2) UMN test setup (Tanner)
Received a new demo from Liteway, each box can now receive and transmit both signals (1PPS and NMEA data) in a single fiber. Reduces power requirements. Should run it on a battery to estimate the power consumption. Checked the timing, with one master and one slave digitizer, with the seismometer attached to the slave digitizer - looks like everything works well, the GPS clock is running on the slave digitizer with high SNR.
Vuk: Will finalize the GPS distribution system, and then make the order.
3) Analysis of existing data
Noah posted slides describing a sequence of tests made for Pwave simulations and recovery (with Shivaraj's code). Slide are here. Observe aliasing (checkerboard pattern in recovery) if the spacing between detectors is too large compared to the wavelength of the simulated wave. Recovery improves when spacing is reduced or when frequency of the wave is reduced. Detector arrangement alters the checkerboard pattern, but does not make it disappear. Similar conclusions are achieved when a broadband source is simulated (bit recovered at a single frequency bin). Adding detectors helps to the extent that it reduces detector spacing, but if the recovery is good to start with, the size of the recovered blob does not seem to change with increasing the number of detectors.
Victor/Vuk: recovering over multiple frequencies should help with the aliasing problem.
Victor: Surprising that increasing detector number does not improve recovery.
Eric: The recovered map is a power map, not necessarily giving the probability distribution for the source location. Blob size likely limited by the leakage from one spatial bin to the next.
Next meeting: June 26.