As early as 1977, HP started production of the HP856x spectrum analyzers to enrich its RF power meters and sensors effective at measuring signals in extra of 20 GHz. HP also created configurable chassis centered sweep turbines able to creating alerts to twenty GHz. Other T&M merchandise of some 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