pip-squeak
... that the RAF's pip-squeak system kept track of their fighters during the Battle of Britain using their voice radio sets?
... that the <a href="./Royal_Air_Force" id="mwBDs" rel="mw:WikiLink" title="Royal Air Force">RAF</a>'s <b id="mwBDw"><a href="./Pip-squeak" id="mwBD0" rel="mw:WikiLink" title="Pip-squeak">pip-squeak</a></b> system kept track of their <a href="./Fighter_aircraft" id="mwBD4" rel="mw:WikiLink" title="Fighter aircraft">fighters</a> during the <a href="./Battle_of_Britain" id="mwBD8" rel="mw:WikiLink" title="Battle of Britain">Battle of Britain</a> using their voice radio sets?