17 Mar 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes on tape: "Time 0315 Zulu 18Mar1974" [MLNS notes: This should be 2215 the previous date. Low level thumps throughout, with several louder trains interspersed. Much masked by ambient noise. First ~13:30 removed from cut due to high noise levels. Cut begins with several humpback sounds. -16Dec2003CB] Notes from analysis log: "Cassette number side up - rewind. Ship propeller beats heard at start of reel (113RPM). Ambient noise otherwise lowered around 400 but picks up again around 600 with more ship traffic noise. Humpback: Pos.; No. Calling: 1? No. Full Calls: N.A.; Need for further analysis: No. Notes: At 145 have distant humpback ship noise masking, ship clears area, humpback signal gets better, still not good for grams. Minke: Pos.; No. Heard: 2?; No. Trains: 5+. Need for further analysis: No. Notes: 022 thump train, 415, 516, 596, 737. At 767 1/2 a click is heard."
[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