"echo time" meaning in English

{
  "forms": [
    {
      "form": "echo times",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "echo time (plural echo times)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Sound",
          "orig": "en:Sound",
          "parents": [
            "Energy",
            "Nature",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Time",
          "orig": "en:Time",
          "parents": [
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The time between a sound or pulse of radio waves being produced and the receipt of the corresponding echo"
      ],
      "id": "en-echo_time-en-noun-TbxjOEK3",
      "links": [
        [
          "time",
          "time"
        ],
        [
          "sound",
          "sound"
        ],
        [
          "pulse",
          "pulse"
        ],
        [
          "radio wave",
          "radio wave"
        ],
        [
          "echo",
          "echo"
        ]
      ]
    }
  ],
  "word": "echo time"
}

{
  "forms": [
    {
      "form": "echo times",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "echo time (plural echo times)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Sound",
        "en:Time"
      ],
      "glosses": [
        "The time between a sound or pulse of radio waves being produced and the receipt of the corresponding echo"
      ],
      "links": [
        [
          "time",
          "time"
        ],
        [
          "sound",
          "sound"
        ],
        [
          "pulse",
          "pulse"
        ],
        [
          "radio wave",
          "radio wave"
        ],
        [
          "echo",
          "echo"
        ]
      ]
    }
  ],
  "word": "echo time"
}