15 Apr 1974
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "Unscheduled; Time 1944 Zulu 15Mar1974." Notes from analysis log: "Good signals. Cassette "Special" side up - rewind. Ambient level low, no ship traffic noise. Only 3 analyzable Hump tapes, page 49, 85 & 86 [MLNS notes: refers to tapes 1-GRANDTURKS-90, 1-GRANDTURKS SPECIAL #1, and 1-GRANDTURKS SPECIAL #2.]. Humpback: Pos.; No. Calling: 1; No. Full Calls: 2?; Need for further analysis: Yes. Notes: Starts with mupps, recorder stops and restarts - good signal to noise ration, missed portion of call after restart - has echo effects. Two surface indications 0 may be two full calls, check with analyzer. Wished for wider band recording in this example. Minke: Pos.; No. Heard: 1; No. Trains: 7; Need for further analysis: No. Notes: At 035 thump train, again at 202. At 281 a weak thump train, again 343 weak, at 455 mod. level, again at 693 (weak) again 742 only louder."
[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