Without a remote reference noise removal scheme, it is difficult to obtain an adequate ratio of signal to noise below 0.1 Hz for frequency-domain processing and below 0.3 Hz base frequency for time-domain processing for a typical source-receiver configuration. A digital high-pass filter substantially facilitates rejection of natural field noise above these frequencies; however, at lower frequencies where much longer stacking times are required, it becomes ineffective. Use of a remote reference to subtract natural field noise extends these low-frequency limits by one decade, but the remote reference technique is limited by the resolution and dynamic range of the instrumentation.--Modified journal abstract.
This content is PDF only. Please click on the PDF icon to access.