marker beacon

Japanese: marker beacon（英語表記）markerbeacon

...The height of the glide path at the end of the runway is at least 50 feet (1 foot is about 0.3 m), and the allowable error is usually ±10 feet, but if the landing decision height (final decision altitude, see below) is less than 200 feet in Category II and less than 100 feet in Category III, the allowable error is +10 feet and -0 feet, respectively, to ensure a clearance between the wheels of the airplane at the end of the runway. (3) Marker beacons (also simply called markers) are installed at a designated position directly below the approach course and emit a unique directional modulated radio wave (75 MHz) upward, and when passing overhead, the pilot is notified of the passing position by lighting up the lights on the instrument panel in the cockpit and by a modulated sound. In principle, the inner marker (modulation frequency 3000Hz) is installed 1000 feet from the end of the runway, the middle marker (1500Hz) is installed about 3500 feet, and the outer marker (400Hz) is installed about 5 to 6 miles (1 mile is about 1.6 km).

From [Air Safety Radio Facility]

…TVOR (Terminal VOR) is a low-output VOR designed for use around airports to prevent the effects of radio waves reflected from buildings, etc. Marker beacon A radio location indicator, sometimes simply called a marker. A facility for informing aircraft that they have passed over a specified point. …

*Some of the terminology explanations that mention "marker beacon" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…滑走路端におけるグライドパスの高さは最低50フィート(1フィートは約0.3m)を基準とし，その許容誤差は通常±10フィートだが，着陸のデシジョンハイト(最終決定高度，後出)が，200フィート未満のカテゴリーII，同じく100フィート未満のカテゴリーIIIの場合は許容誤差がそれぞれ＋10フィート，－0フィートとなり，滑走路端において飛行機の車輪との間隙（かんげき）が確保されるようになっている。(3)マーカービーコンmarker beacon(単にマーカーともいう)は進入コース直下の定められた位置に設けられ，上方に向け特有の指向性変調電波(75MHz)を発射し，上空通過時に操縦室内の計器板上のライトの点灯および変調音で，パイロットに通過位置を知らせる。原則として滑走路端から1000フィートの位置にインナーマーカー(変調周波数3000Hz)，約3500フィートにミドルマーカー(1500Hz)，約5～6マイル(1マイルは約1.6km)にアウターマーカー(400Hz)が設置される。…