Signal spectrum display apparatus

A signal spectrum display apparatus comprising:

• a plurality of band-pass filters respectively having filtering bands of different center frequencies and operating to filter an input signal thereby to band-divide the input signal fed through an input terminal;
• a plurality of rectification and charging circuits connected respectively to said band-pass filters, each of said rectification and charging circuits comprising a rectifying element, and a capacitor which is charged and discharged by being supplied with voltage rectified by said rectifying element;
• a display section having displaying means including the same number of display systems as band-pass filters each of said systems respectively corresponding to a band-pass filter;
• means for supplying the output signals of rectification and charging circuits to the displaying means and causing level displaying by the displaying means of those systems corresponding respectively to the output signal levels of said band-pass filters;
• and
• switching means connected between a point between said rectification and charging circuit and said display section, and the ground,
• said capacitor charging and discharging when said switching means is closed, whereby the input signal level is displayed in real-time in said display section, and said capacitor stopping charging and discharging when said switching means is opened, whereby the maximum input signal level is successively displayed in said display section in response to the output voltage held in response to successive higher input signal voltage.