7 Dec 1973
- waterbody:North Atlantic OceanGrand Turk Island; U.S. Naval Facility
NOTES: Notes from tape: "Time 1155 Zulu." Notes from analysis log: Cassette number side up, rewind. Starts off with ship traffic, heavy overloading, fading gradually. Overall background gain is high to moderate, still overloaded. Humpback: Neg.; Minke: Pos.; No. Heard: 1? No. Trains: 6; Need for further analysis: No. Notes: At counter time 160, 332, 423, 559, 644 and 707 hear strong portions of thump train. Occasional single crack clicks heard (not as many as in reel #1). The ship traffic sounds are heavy but the thumpt trains are heard above it. #s 644 & 707 are reasonably clear thump trains as the background has since lowered, making this train more outstanding."
[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