17 Jan 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes on tape: "Time1212 Zulu." [MLNS notes: low level thumps throughout, with several louder trains interspersed.] Notes from analysis log: "Cassette number side up - rewind. Ambient sea noise low - Hear distant fog hor sound. Ship traffic noise increases at 146. At 411-415 noise, blackout. Humpbacks: Pos.; Need for further analysis: No. Notes: Maybe distant humpback sounds at start of reel and for sure at 469. Minke: Pos.; No. Heard: 2? No. Trains: 7. Need for further analysis: No. Notes: At 023 hear distant thumper, at 201 distant thump train. At 312 a stonger one, 416 thump train. At 584 mod level train, again 626, at 734, a stronger one."
[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