3 Jan 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "time: 1930 Zulu." [MLNS notes: low level thumps throughout, with several louder trains - at 3:40, 12:46, 13:45, 15:53, 18:51, 20:50, 25:22, 27:21, 29:35.] Notes from analysis log: Cassette number side up - rewind. Ambient level hight - ship traffic in area, begins to lower about 600 then starts up again 630. Humpback: Neg.; Minke: Pos.; No. Heard: 3; No. Trains: 9+; Need for further analysis: Yes: strong levels. Notes: At 135+ 140 (2?) sources, strong level on 140. At 406, good stong thump train. At 457 thumps maybe ship noise at 556 thump train, again 646. At 679 there are strong beats, from Minke? 80 [88?] beats per min.; at 719 a weak thump train."
[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