Crosspower file format for Audio-magnetotelluric Data
Crosspower file format
The X_file is an ASCII file containing the
results of auto-power and
crosspower spectral density calculations. These so-called crosspower
results are calculated from time-series data stored in file Y_file
with the same root name and extension. The crosspower file is 19 columns wide and each column is 11 characters long. For example:
6.250e+000 2.930e+000 2.100e+001 5.204e+007-1.727e+009 3.523e+006
7. 500+000 2.930e+000 0.000e+000 0.000e+000 0.000e+000 0.0000e+000
The data on each line
correspond to a single frequency, and the
units for the crosspower values
are geophysical: H in Gamma; E in mV/km. The data values are listed by
column number in table below.
|
Columns 1- 3 |
Columns 4 -
7 |
Columns 8 -
11 |
Columns 12 -
15 |
Columns 16 -
19 |
|
Freq (Hz) |
CH1*CH1 |
re(CH2*CH1) |
re(CH3*CH1) |
re(CH4*CH1) |
|
Bandwidth (Hz) |
im(CH1*CH2) |
CH2*CH2 |
re(CH3 *CH2) |
re(CH4*CH2) |
|
# of averages |
im(CH1*CH3) |
im(CH2*CH3) |
CH3*CH3 |
re(CH4*CH3) |
|
|
im(CH1*CH4) |
im(CH2*CH4) |
im(CH3*CH4) |
CH4*CH4 |
For frequencies where no crosspowers are available, ‘# of averages’ value is 0. The notation CHi *CHj indicates the >spectral density of channel i and channel j which is:
Where
and chj,k is the spectra for the kth time-series from channel ‘i’. (*) indicates complex conjugation,
is the bandwidth, and w is the angular frequency.
[Microsoft Word document making equations accessible]
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