| 摘要 |
<p>A method of deriving a calibration filter for electromagnetic data is provided. The method comprises providing a source (21, 22) of electromagnetic radiation and subsequently measuring components of the source electromagnetic field (23, 24, 25) at a receiver when the source is sufficiently close to the receiver that the down-going signal dominates over the up-going signal reflected from features below the receiver. Such a measurement can be used in frequency domain analysis (26, 28, 29) to extract the down-going signal component and derive a calibration filter for the receiver. The method is repeated (27, 30) for each receiver used in an electromagnetic sounding survey.</p> |
