-- ELFNOTES.TXT --


Experimental notes and descriptions of geomagnetic digital recordings.
Files made by Will Payne, N4YWK using ULF loop, preamp, and RS-168A dvm.

( * The only file included in the present package is elf014b.wav )


elf01  -  02/18/96 ???? UTC  -  stillborn

elf02  -  02/18/96 ???? UTC  -  stillborn

elf03  -  02/18/96 ???? UTC  -  stillborn

elf04  -  02/18/96 ???? UTC  -  1686 samples
Monster loop, Ae = 22400 m2, 12 turns, high gain integrator preamp.
First stage:    Integrating amp, LM1458, 100k and 10meg || 100nf
Second stage :  Integrating amp, LM1458, 100k and 10meg || 100nf
Instrumentation test, file size too small for Gram 2.3.

elf05  -  02/18/96 ???? UTC  -  stillborn

elf06  -  02/18/96 ???? UTC  -  80327 samples
Monster loop, Ae = 22400 m2, 12 turns, high gain integrator preamp.
First stage:    Integrating amp, LM1458, 100k and 10meg || 100nf
Second stage :  Integrating amp, LM1458, 100k and 10meg || 100nf
Too much near-DC for microsoft speaker driver to handle

elf07  -  02/19/96 ???? UTC  -  22286 samples
Monster loop, Ae = 22400 m2, 12 turns, high gain integrator preamp.
First stage:    Integrating amp, LM1458, 100k and 10meg || 100nf
Second stage :  Integrating amp, LM1458, 100k and 10meg || 100nf
The "3-impulse" record.  GRAM shows 3 noise spikes near end, about 300 sec apart.
This file was processed several ways, including linear detrending, to remove DC drift, and differentiation to compensate out the preamp's heavy integration.  As-amplified file sounds heavy and dull, like a weight dragged on cement.  The differentiated version sounds more like conventional static.  All versions show the 3-spike in GRAM but it is hard to distinguish otherwise.

elf08  -  02/20/96 0136 UTC  -  15293 samples
Digitized signal level output from RYCOM 6040 tuned to WWVB.
The WWVB PCM time code plays back as a pronounced 'whine'.

elf09  -  02/20/96 1212 UTC  -  77590 samples

elf10  -  02/24/96 1451 UTC  -  49600 samples

elf11  -  02/24/96 1519 UTC  -  nnnnn samples

elf12  -  03/05/96 0027 UTC  -  nnnnn samples
Monster loop, Ae = 22400 m2, 12 turns, NEW MKII preamp/filter circuit.
First stage:    40db amp, LM1458, 100k and 10meg || 1nf
Second stage:   MAX281 filter, Bessel, k=1.158, Fc=10Hz, R=100k C=.18uF
Third stage :   43db amp, LM1458, 47k and 10meg || 50nF
While recording, large, slow transients near sunset overranged the DVM, restarted.
Original data lost due to bug in METEX software from Radio Sh***, does not close file!
Seems to be lots of periodicity around 1/3 Hz.

elf13  -  03/05/96 0208 UTC  -  nnnnn samples
Monster loop, Ae = 22400 m2, 12 turns, MKII preamp/filter circuit.
First stage:    40db amp, LM1458, 100k and 10meg || 1nf
Second stage:   MAX281 filter, Bessel, k=1.158, Fc=10Hz, R=100k C=.18uF
Third stage :   43db amp, LM1458, 47k and 10meg || 50nF
Seems to be lots of periodicity around 1/3 Hz.

elf14  -  03/05/96 1436 UTC  -  70564 samples
Monster loop, Ae = 22400 m2, 12 turns, new preamp/filter circuit, reduced gain 3db.
First stage:    40db amp, LM1458, 100k and 10meg || 1nf
Second stage:   MAX281 filter, Bessel, k=1.158, Fc=10Hz, R=100k C=.18uF
Third stage :   40db amp, LM1458, 100k and 10meg || 50nF
Some periodicity around 1/3 Hz, GRAM 2.3 shows weak narrowband line.
Differentiated wave: BB near .45Hz and .1Hz, distinct NB almost coherent at .33Hz.

elf15  -  03/05/96 1800 UTC  -  43646 samples
Monster loop, Ae = 22400 m2, MKII preamp/filter circuit as in elf014.
Some periodicity around 1/3 Hz, GRAM 2.3 shows thin, weak narrowband line.
Differentiated wave: BB near .4Hz and .07Hz, distinct NB almost coherent at .33Hz.