# Black

> A vertical, 18 kHz channel recorded over the Mariana Trench in October 2024, linking a near-surface planar array to a transmitter 8718 m below.

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LLMS index: [llms.txt](/llms.txt)

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* Experiment:
  * Location: Mariana Trench
  * Date recorded: October 2024
  * Center frequency: f<sub>c</sub> = 18 kHz
  * Bandwidth: B = 12.5 kHz
  * Symbol rate: R = 12.5 ksym/s
  * Distance: d = 8.7 km (vertical)
  * Tx/Rx/water depth: d<sub>T</sub>/d<sub>R</sub>/d<sub>w</sub> = 8718 m/6 m/8720 m
  * Mobility: moored
  * Receiving array: planar, M = 8 elements arranged at the vertices of two concentric squares (outer square side 264 mm, inner square side 88 mm, so that &#8467; &ge; 88 mm)
* Parameters:
  * Sampling rate in delay: f<sub>s</sub> = 2R
  * Total delay coverage: up to 7 ms
  * Sampling rate in time: R/100 for the channel response, 2R for the phase/delay
  * Total time coverage: 36 seconds

> [!PRIMARY] Acknowledgement
>
> The Underwater Acoustic Channels Group gratefully acknowledges the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for their efforts in providing the data.