14 Jan 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "Time: 1040 Zulu." [MLNS notes: low level thumps throughout, with several louder trains interspersed.] Notes from analysis log: "Good Horn sound (511,573,736); Cassette number side up, rewind. Ambient level low - Fog Horn sound every 3 min. Ship traffic picks up some (180). At 514 the Fog Horn gets louder. At 625 a new electrical signal is heard, cuts in and stays till 686. Humpback: Neg.; Minke: Pos.; No Heard: 2?; No. Trains: 8+; Need for further analysis: Yes; Notes: 020 Thump train (weaker one) at 079 the strong thump train; at 155 strong low thumps in background, at 291 thump train. At 320 strong thumper; 364 the strong low thumper is heard briefly. At 491 the strong thump train is heard, at 645 strong 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