Possible RFI causing rise in backscattered amplitude on beam 2 during periods between sunset and sunrise, Probable cause is noisy mercury vapor lamp(s) on bridge.
Suggestions for exploration/resolution:
Contact Caltrans to see if we can have them turn the lights on for a couple of hours during the day to verify that the lamps are the issue. This could be used to convince Caltrans that the lamps are the culprit.
Flip the CM 180 degrees to see if the trouble switches to beam 1. This could verify that it is an in-water issue (or not).
investigate the RFI using detectors to see if we can localize the problem lamp. We have one detector for low frequency, and another is on order and should be available by Friday 7/13/2018
Possible RFI causing rise in backscattered amplitude on beam 2 during periods between sunset and sunrise, Probable cause is noisy mercury vapor lamp(s) on bridge. Suggestions for exploration/resolution: