Marine mammal acoustic survey data from sonobuoy deployments on the BROKE-WEST Survey

• Other Authors: Australian Antarctic Division (isOwnedBy)
• Format: Dataset
• Language: unknown
• Published: data.gov.au
• Subjects: ACOUSTIC SURVEY; AMD; AMD/AU; CEOS; CONTINENT > ANTARCTICA; DISTRIBUTION; EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > ANIMAL; AQUATIC ECOSYSTEMS; EARTH SCIENCE; BIOSPHERE; ECOLOGICAL DYNAMICS; OCEANS > OCEAN ACOUSTICS > AMBIENT; GEOGRAPHIC REGION > POLAR; MARINE MAMMAL; OCEAN > SOUTHERN OCEAN; R/V AA > R/V Aurora Australis; SEAL; SHIPS; SONOBUOY; SONOBUOYS; WHALE; Southern Ocean; Antarc*; Antarctica; aurora australis
• Online Access: https://researchdata.edu.au/marine-mammal-acoustic-west-survey/1931412; http://data.gov.au/dataset/61bef84b-08cf-4d81-980e-93f069b30972

Data Acquisition:\n\nDIFAR (DIrectional Fixing And Ranging) 53D sonobuoys were deployed every 30 minutes of longitude during each of the north-south sampling transects as part of the acoustic survey for marine mammals. Sonobuoys were also deployed opportunistically when large numbers of whales (in particular minke whales) were sighted. Additionally, on the initial E-W transect (#12) sonobouys were deployed prior to the majority of CTD stations.\n\nThe VHF receiving system for the sonobuoys aboard the ship began with a 6 element YAGI antenna mounted atop the ship's mast. The sonobuoy's VHF signal output from the YAGI was amplified through an Advanced Receiver Research VHF amplifier and received on ICOM PCR-1000 VHF receivers modified to improve low frequency audio output. The audio signal passed through a low pass anti-alias filter (National Instruments analogue bessel SCXI module) and was recorded onto a laptop through a National Instruments E-series (model 6062E) sound card at a sampling rate of 48kHz. Difar sonobuoys have an effective audio response up to 2.5kHz before the low-pass filter roll-off starts. DIFAR bearing information is carried on 7.5 and 15kHz carrier frequencies. \n\nOnce sonobuoys were deployed, recordings were made for at least 70 minutes unless the sonobuoy failed or the signal was lost. During recordings at CTD stations, recordings were typically made for the length of time it took to complete the CTD (4 or more hours). \n\nData Processing:\n\nSignals were monitored in real-time during acquisition using Ishmael software (Dave Mellinger, http://www.pmel.noaa.gov/vents/acoustics/whales/ishmael/index.html ). A scrolling spectrogram (FFT size: 16384 samples, overlap: 50%, frequency range displayed: 0-1000 Hz, time scaling: 5 sec/cm) was monitored in real-time. Sounds of interest were clipped and the time and description were logged in the sonobuoy deployment data logs. Bearings to sounds were attained with a modified version of DiFarV (Mark McDonald, http://www.whaleacoustics.com ). Note that ...