Memo to: File
From: Kurt Metzger
Date: 14 October 1991
Notes for digitization of NOAA data sets at Patrick AFB during the week of
September 30, 1991.
The Bermuda source parameters are law 2033 (1023 digits) using 3
cycles/digit sending 8 periods. Turn on times are 0030, 0830, 1630. The
nominal source position is 32 degrees 31.160 minutes N, 64 degrees 52.860
minutes W. Depth is 974 meters. The nominal receiver location at
Ascension Island is 7 degrees 57 minutes S, 14 degrees 32 minutes W. The
spherical earth distance between source and receiver is 3763.0 nm. The
predicted propagation time using a spherical earth is 77 minutes 30
seconds.
The predicted propagation time to Antigua was 1647.30 seconds. The Antigua
data is corrupted by an extremely strong 60 Hz and harmonics waveform.
The sample clock was obtained by filtering the IRIG-B track and converting
the result to TTL which was used to trigger a/d converter scans. The
nominal sample rate per channel was 1 KHz for all data sets. Channel
one was a one second square wave generated by the portable BCSG box.
Channels 2 and 3 were data. On the Heard Island snippets, channel 4
was IRIG-E.
The one second time track was included to facilitate the detection of
any problems in extracting a reliable sample clock from the IRIG-B track
on the analog recordings.
There was a nearby FAA radar installation which generated pulses every
12 seconds that seems to have managed to impact the a/d converter. It
appears that these pusles can be seen in the timing track. The effect
of these pulses on the timing and data values needs to be looked at.
All data sets were started manually watching a time of day clock which
was driven from the IRIG-B channel on tape. It should be possible to
establish a precise timing relationship between the Heard Island data
sets because of the inclusion of the IRIG-E on data channel 4.
Dave Palmer supplied the following hydrophone locations:
The (unclassified) Antigua hydrophone locations are:
#91: 18 deg, 15 min, 19.0 sec 59 deg, 39 min, 24.3 sec
#92: " , 3 min, 4.3 sec " , 34 min, 55.4 sec
#94: " , 27 min, 20.5 sec " , 36 min, 27.4 sec
#96: " , 7 min, 52.0 sec " , 48 min, 52.6 sec
The (unclassified) Ascension BOA hydrophone locations are:
19 07 deg 49 min 29.9 sec S 14 deg 36 min 08.1 sec W
20 07 49 32.0 14 36 05.9
21 07 59 13.8 14 29 42.6
22 08 00 41.3 14 29 40.7
23 08 04 11.5 14 25 09.4
24 08 03 24.8 14 26 51.8
25 08 56 48.1 14 39 43.2
26 08 56 40.4 14 37 05.1
27 07 51 11.2 14 21 58.2
28 07 53 31.4 14 19 14.9
29 07 56 56.8 14 16 00.2
30 07 59 23.8 14 15 52.2
Data Sets
These data sets are from Antigua.
ant01.sam ch1: 1 sec ch2: ph 96 ch3: ph 91 start 247:1642
ant02.sam ch1: 1 sec ch2: ph 96 ch3: ph 91 start 248:1642
ant03.sam ch1: 1 sec ch2: ph 96 ch3: ph 91 start 249:1642
ant04.sam ch1: 1 sec ch2: ph 96 ch3: ph 91 start 247:0042
ant05.sam ch1: 1 sec ch2: ph 96 ch3: ph 91 start 246:1642
ant06.sam ch1: 1 sec ch2: ph 96 ch3: ph 91 start 245:1642
The next block of data sets required placing 20 dB gain transformers
in the circuit to raise the signal levels at the a/d inputs. These
data sets are from Ascension Island.
asc01.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 165:0142
asc02.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 165:0942
asc03.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 165:1742
asc04.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 169:0142
asc05.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 169:0942
asc06.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 169:1742
asc07.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 173:0142
asc08.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 173:0942
asc09.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 173:1742
asc10.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 177:0142
asc11.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 177:0942
asc12.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 177:1742
asc13.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 181:0142
asc14.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 181:0942
asc15.sam ch1: 1 sec ch2: ph 19 ch3: ph 22 start 181:1742
seq01.sam test data set to check tape speed and dropout performance
The next block of data sets is from Antigua.
ant01b.sam ch1: 1 sec ch2: ph 92 ch3: ph 94 start 245:1642
On the next data set we could hear SSB transmitter at the recording
site on the data channels.
ant02b.sam ch1: 1 sec ch2: ph 92 ch3: ph 94 start 246:1642
ant03b.sam ch1: 1 sec ch2: ph 92 ch3: ph 94 start 247:0042
ant04b.sam ch1: 1 sec ch2: ph 92 ch3: ph 94 start 247:1642
ant05b.sam ch1: 1 sec ch2: ph 92 ch3: ph 94 start 248:1642
We noted low signal levels and so inserted the 20 dB gain transformers
for the next data set. The gain level of the signals recorded on tape
increased at about time 1643:28.
ant06b.sam ch1: 1 sec ch2: ph 92 ch3: ph 94 start 249:1642
The 20 dB signal boosting transformers were again used for the following
Ascension Island data sets.
asc01b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 165:0142
asc02b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 165:0942
asc03b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 165:1742
asc04b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 169:0142
asc05b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 169:0942
asc06b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 169:1742
asc07b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 173:0142
asc08b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 173:0942
asc09b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 173:1742
asc10b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 177:0142
asc11b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 177:0942
asc12b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 177:1742
asc13b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 181:0142
asc14b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 181:0942
asc15b.sam ch1: 1 sec ch2: ph 20 ch3: ph 28 start 181:1742
Data for making a lowpass noise study was taken next. The tape
output was fed through the 20 dB transformers thru lowpass
filters which had a 48 dB/octave fall off. The filters were set
to cutoff at 300 Hz.
The data source was Ascension Island.
lp01.sam ch1: 1 sec ch2: ph 19 ch3: ph 20 start 177:0942
lp02.sam ch1: 1 sec ch2: ph 22 ch3: ph 24 start 177:0942
lp03.sam ch1: 1 sec ch2: ph 25 ch3: ph 28 start 177:0942
Changed a/d gain from 1 to 4 to get more bits in the a/d active.
This caused the 1 sec time track values to saturate but should
not cause problems elsewhere. Also changed the a/d scan interval
from 30 microseconds to 50 microseconds.
lp04.sam ch1: 1 sec ch2: ph 19 ch3: ph 20 start 173:0142
lp05.sam ch1: 1 sec ch2: ph 22 ch3: ph 24 start 173:0142
lp06.sam ch1: 1 sec ch2: ph 25 ch3: ph 28 start 173:0142
The next data sets were 10 minute snips of HIFT data. The a/d gain
was set at 2, the tape outputs were lowpass filtered at 100 Hz. The
IRIG-E time track was placed on a/d channel 4.
hrd01.sam ch1: 1 sec ch2: ph 23 ch3: ph 25 ch4: irig-e start: 029:1943
hrd02.sam ch1: 1 sec ch2: ph 24 ch3: ph 29 ch4: irig-e start: 029:1943
hrd03.sam ch1: 1 sec ch2: ph 29 ch3: ph 30 ch4: irig-e start: 029:1943
There is noticable seismic data in the next data set starting at about 1648.
hrd04.sam ch1: 1 sec ch2: ph 23 ch3: ph 25 ch4: irig-e start: 030:1643
A dc offset of about 0.146 volts on the ch2 lowpass filter output and of
about 0.046 volts on the ch 3 lowpass filter output was detected and was
nulled. This offset probably was associated with the changing of the
filter cutoff frequency range.
hrd05.sam ch1: 1 sec ch2: ph 24 ch3: ph 29 ch4: irig-e start: 030:1643
hrd06.sam ch1: 1 sec ch2: ph 29 ch3: ph 30 ch4: irig-e start: 030:1643
hrd07.sam ch1: 1 sec ch2: ph 19 ch3: ph 21 ch4: irig-e start: 030:1643
hrd08.sam ch1: 1 sec ch2: ph 28 ch3: ph 22 ch4: irig-e start: 030:1643
hrd09.sam ch1: 1 sec ch2: ph 22 ch3: ph 26 ch4: irig-e start: 030:1643
Other misc data sets were taken at the start of our digitizing session and
are considered "training" data sets. These were:
runas1.sam Ascension Island date/time not recorded
runas2.sam Ascension Island 165:01:47:30
runant.sam Antigua. date/time not recorded
heard1.sam HIFT data. about 15 minutes of HIFT data..Pentaline