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Channels

The channels contained in this library come from various experiments. The experiments differ by geographical location, transmission distance, water depth, transmitter/receiver mobility, acoustic bandwidth and the size of the recording array. The channels are color-labeled, and a detailed description of relevant parameters is given below for each. To download the channels, click here.

Each channel is estimated from the experimental data and stored in a matrix ${\bf C}$ of complex-baseband impulse responses evolving over time. If a recording array is available, there is one such matrix for each array element. Each row of this matrix represents an instantaneous channel response as a function of delay. Different rows correspond to different, equi-spaced instants in time. Any motion-induced delay drifting is suppressed in the channel matrix to enable compression for efficient storage. A separate vector $\theta$ is provided which contains the uncompressed time-varying channel phase that is directly related to the delay. To fully reconstruct the channel, the matrix ${\bf C}$ needs to be uncompressed, and the phase/delay needs to be imparted to re-introduce phase shifting and delay drifting. Details of this process, along with the ready-to-use code, are given in the User’s Guide.

LocationDate$d_{T}$/$d_{R}$/$d_{w}$ [m]Mobility$d$ [km]$f_c$ [kHz]$R$ [kHz]Array$M$$\ell$ [m]
BlueNorth AtlanticJun. 201030-60/50/100Up to 1.5m/s3-713$10^7/2048$Vertical1212
RedSingaporeNov. 20246/3/8Drifting0.1259.6Vertical30.8
YellowHawaiiJun. 201150/50/100Moored3136.25Vertical245
720
PurpleNorth AtlanticOct. 200811/10/15Moored0.0612.56.5Cross323.75
0.2Vertical245
1Vertical1212
GreenNorwayNov. 202420/43/60Moored0.2764.5N/A
11.525.625
289
SkyblueEarthJan. 1990175/?/xMobile55135711.4N/A
9192Vertical4?
NamikazeKochi Prefecture, JapanJul. 2022176/146/xMoored1464Vertical24x
AbyssalMariana TrenchOct. 20246/8718/8720Moored8.721812.5Circular8x

1 - Blue

  • Experiment:
    • Location: 40.2N, 70.5W
    • Date recorded: June 2010
    • Center frequency: 13 kHz
    • Bandwidth: 5 kHz
    • Symbol rate: R = 10^7/2048 Hz (approximately 4.9 kHz)
    • Distance: 3 km - 7 km
    • Tx/Rx/water depth: 30-60 m/50 m/100 m
    • Mobility: varying, up to 1.5 m/s
    • Receiving array: vertical, 12 elements, 12 cm spacing (numbered top to bottom)
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 25 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 1 minute

2 - Red

  • Experiment:
    • Location: Singapore
    • Date recorded: November 2024
    • Center frequency: 25 kHz
    • Bandwidth: 9.6 kHz
    • Symbol rate: R = 9.6 kHz
    • Distance: 100 m
    • Tx/Rx/water depth: 6 m/3 m/20 m
    • Mobility: drift
    • Receiving array: vertical, 3 elements, 0.8 m spacing (numbered top to bottom)
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 15 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 50 seconds

3 - Yellow

  • Experiment:
    • Location: 22.1N, 159.8W
    • Date recorded: June 2011
    • Center frequency: 13 kHz
    • Bandwidth: 6.25 kHz
    • Symbol rate: R = 6.25 kHz
    • Distance: 3 km and 7 km
    • Tx/Rx/water depth: 50 m/50 m/100 m
    • Mobility: static
    • Receiving array: vertical, 24 elements, 5 cm and 20 cm spacing (numbered bottom to top)
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 35 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 1 minute

4 - Purple

  • Experiment:
    • Location: 41.2N, 70.3W
    • Date recorded: October 2008
    • Center frequency: 12.5 kHz
    • Bandwidth: 6.5 kHz
    • Symbol rate: R = 6.5 kHz
    • Distance: 60 m (array 1), 200 m (array 2), and 1 km (array 3)
    • Tx/Rx/water depth: 11 m/10 m/15 m
    • Mobility: static
    • Receiving array 1: cross, 16 elements each leg, 5 cm spacing (numbered top to bottom, then left to right)
    • Receiving array 2: vertical, 24 elements, 5 cm spacing (numbered top to bottom)
    • Receiving array 3: vertical, 12 elements, 12 cm spacing (numbered top to bottom)
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 30 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 1 minute

5 - Green

  • Experiment:
    • Location: 60N, 5.3E
    • Date recorded: November 2024
    • Center frequency: 6 kHz, 11.52 kHz, and 28 kHz
    • Bandwidth: 4.5 kHz, 5.625 kHz, and 9 kHz
    • Symbol rate: R = 4.5 kHz, 5.625 kHz, and 9 kHz
    • Distance: 270 m
    • Tx/Rx/water depth: 20 m/43 m/60 m
    • Mobility: static
    • Receiving array: none
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 80 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 1 minute

6 - Skyblue

  • Experiment:
    • Location: from Heard Island and McDonald Islands to the world
    • Date recorded: January 1991
    • Center frequency: 57 Hz
    • Bandwidth: 11.4 Hz
    • Symbol rate: R = 11.4 Hz
    • Distance: varies, 5513 and 9192 km (Chrismas Island and Ascension Island)
    • Tx/Rx/water depth: 175/?/?
    • Mobility: mobile
    • Receiving array: yes
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 25 seconds
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 1 hour

HIFTmapMawsonAnt

7 - Namikaze

  • Experiment:
    • Location: Off the coast of Kochi Prefecture
    • Date recorded: July 2022
    • Center frequency: 6 kHz
    • Bandwidth: 4 kHz
    • Symbol rate: R = 4 kHz
    • Distance: 14 km
    • Tx/Rx/water depth: 176 m/146 m/x. The data contain down-slop, up-slope and flat. The water depth in the flat scenario is 200 m.
    • Mobility: moored
    • Receiving array: vertical, up to 24 elements. There are six hydrophone groups. Within each group, the inter-element spacing is 0.9 m. The distance between groups is 1.8 m.
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 117.5 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 1 minute

8 - Abyssal

  • Experiment:
    • Location: Mariana Trench
    • Date recorded: Oct. 2024
    • Center frequency: 18 kHz
    • Bandwidth: 12.5 kHz
    • Symbol rate: R = 12.5 kHz
    • Distance: 8.7 km (vertical)
    • Tx/Rx/water depth: 6 m/8718 m/8720 m.
    • Mobility: moored
    • Receiving array: circular.
  • Parameters:
    • Sampling rate in delay: 2R
    • Total delay coverage: up to 5 ms
    • Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
    • Total time coverage: 40 seconds.