As early as 1977, HP began creation of the HP856x spectrum analyzers to enhance its RF energy meters and sensors able to measuring signals in surplus of 20 GHz. HP also manufactured configurable chassis based sweep generators capable of producing signals to 20 GHz. Other T&M solutions 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