As early as 1977, HP started production of the HP856x spectrum analyzers to enhance its RF energy meters and sensors capable of measuring indicators in surplus of twenty GHz. HP also generated configurable chassis centered sweep generators capable of building alerts to 20 GHz. Other T&M products of the time https://borna.news/fa/news/2055964/%D8%B3%D8%B1%D9%88%D8%B1-hp-%DA%86%DB%8C%D8%B3%D8%AA-%D9%88-%DA%A9%D8%A7%D8%B1%D8%A8%D8%B1%D8%AF-%D9%87%D8%A7%DB%8C-%D8%A7%D9%86-%D8%AF%D8%B1-%D9%BE%D8%B2%D8%B4%DA%A9%DB%8C