{
  "id": 238852,
  "title": "Question on numerical values in spectrograms",
  "url": "/competitions/seti-breakthrough-listen/discussion/238852",
  "author_name": "Markus Frank",
  "post_date": "2021-05-13T16:17:53.737000",
  "votes": 2,
  "comment_count": 2,
  "views": 0,
  "content": "<p>I'm wondering what the numerical values in the spectrogram snippets actually mean. The float16 values are positive as well as negative. Spectrograms -to my knowledge- show the power spectral density, i.e. amplitude² and should be strictly positive. Could anyone help me out here or point to a paper which explains the data format? Thanks!</p>",
  "messages": [
    {
      "id": 1306160,
      "postDate": "2021-05-13T16:33:35.800Z",
      "content": "<p>Indeed, the input spectrograms are power spectral density (they are small regions in frequency cut out from <a href=\"https://arxiv.org/pdf/1906.07391.pdf\" target=\"_blank\">filterbank files from GBT</a>), but after we did the signal injection for this competition, we rescaled the data values.</p>",
      "rawMarkdown": "Indeed, the input spectrograms are power spectral density (they are small regions in frequency cut out from [filterbank files from GBT](https://arxiv.org/pdf/1906.07391.pdf)), but after we did the signal injection for this competition, we rescaled the data values.",
      "votes": 7,
      "replies": [
        {
          "id": 1306416,
          "postDate": "2021-05-13T18:45:16.617Z",
          "content": "<p>Thanks for your quick and clear reply, that helps a lot to understand the data better. I really appreciate that you as an organizer replied so quickly!</p>",
          "rawMarkdown": "Thanks for your quick and clear reply, that helps a lot to understand the data better. I really appreciate that you as an organizer replied so quickly!"
        }
      ]
    },
    {
      "id": 1306140,
      "postDate": "2021-05-13T16:17:53.737Z",
      "content": "<p>I'm wondering what the numerical values in the spectrogram snippets actually mean. The float16 values are positive as well as negative. Spectrograms -to my knowledge- show the power spectral density, i.e. amplitude² and should be strictly positive. Could anyone help me out here or point to a paper which explains the data format? Thanks!</p>",
      "rawMarkdown": "I'm wondering what the numerical values in the spectrogram snippets actually mean. The float16 values are positive as well as negative. Spectrograms -to my knowledge- show the power spectral density, i.e. amplitude² and should be strictly positive. Could anyone help me out here or point to a paper which explains the data format? Thanks!",
      "votes": 2
    }
  ],
  "comments": [
    {
      "id": 1306160,
      "author_name": "Steve Croft",
      "author_url": "",
      "post_date": "2021-05-13T16:33:35.800000",
      "content": "<p>Indeed, the input spectrograms are power spectral density (they are small regions in frequency cut out from <a href=\"https://arxiv.org/pdf/1906.07391.pdf\" target=\"_blank\">filterbank files from GBT</a>), but after we did the signal injection for this competition, we rescaled the data values.</p>",
      "votes": 7,
      "replies": [
        {
          "id": 1306416,
          "author_name": "Markus Frank",
          "author_url": "",
          "post_date": "2021-05-13T18:45:16.617000",
          "content": "<p>Thanks for your quick and clear reply, that helps a lot to understand the data better. I really appreciate that you as an organizer replied so quickly!</p>",
          "votes": 0,
          "replies": []
        }
      ]
    }
  ],
  "raw_markdown_by_id": {
    "1306160": "Indeed, the input spectrograms are power spectral density (they are small regions in frequency cut out from [filterbank files from GBT](https://arxiv.org/pdf/1906.07391.pdf)), but after we did the signal injection for this competition, we rescaled the data values.",
    "1306140": "I'm wondering what the numerical values in the spectrogram snippets actually mean. The float16 values are positive as well as negative. Spectrograms -to my knowledge- show the power spectral density, i.e. amplitude² and should be strictly positive. Could anyone help me out here or point to a paper which explains the data format? Thanks!"
  }
}