3 Jan 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "time: 1100 Zulu." [MLNS notes: low level thumps throughout, with several louder trains - at 0:14, 1:59, 3:18, 6:38, 7:58, 13:01, 15:22, 17:43, 23:42 [incomplete], 26:44, 32:00 [incomplete].] Notes from analysis log: "Cassette number side up, rewind. Ambient level low. Distant ship traffic. Ambient level drops off to low by 500. At 615 [~23:50] short break, restart. At 690 area a gear turbine tone heard. Humpback: Neg.; Minke: Pos.; No. Heard: 2; No. Trains: 11+; Need for further analysis: Yes (differentiate between 2 different sources may be done). Notes: At 082 a thump train, again at 125 only weaker, again at 153, weak one (have 2 different ones). At 227 is a good level, long train (more hi freq's in this one than past). Around 280 a distant thumper. At 389 a moderate level thumper. At 422 the loud source comes in again. At495 the weaker one shows. Again at 613, the loud source, at 668 the weak one heard, at 760 one more."
[Notes from analysis log for all tapes in the GRANDTURKS series: "Six half-hour background recording samples on selected days for a period of 53 days... to detect the arrival and departure of the Humpback whales (via sounds) for the season in the Caribbean Sea, Mouchier, Navidad and Silver Banks...There are indications that recordings used a 420Hz Low Pass Filter. Recording equipment used was a Realistic model CTR-19. Cassette recorder operating on 110VAC, Freq 60-10,000Ha.. The Realistic recorder is poor recording frequencies below 60Hz as evidenced by spec sheet and sonograms. There is 120 & 180Hz electrical interference 'splatter' on some tapes. In certain cases when the ambient is low, the gain of the systems are raised hence we have heavy interference masking wanted signals. This could be caused by a fluorescent light fixture near the recording system? I doubt that it is in the hydrophone pre-amp network." See analysis log for more details.] SEAOCEAN