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