Spectrum display apparatus

A 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;
• holding means normally passing the output signals of the band-pass filters and holding output signal voltages of the band-pass filters when a control signal is applied to said holding means;
• a display section having displaying means of systems of the same number as the band-pass filters respectively corresponding to the band-pass filters;
• means for supplying output signals of the holding means to the displaying means for displaying signals corresponding respectively to the output signal levels of said band-pass filters;
• means for producing the control signal and apply the same to the holding means during a specific time period after manipulation of the switch;
• a manually-operated control switch in said means for producing the control signal, said control signal being applied to said holding means after operation of said control switch;
• said means for producing the control signal being connected to the control manipulation switch and comprising a capacitor which is charged whiled the control switch is open and is instantaneously discharged by the closure of the control switch, and which is recharged by a subsequent opening of the control switch, a resistor determining the charging time constant of the capacitor, and a circuit for producing as output the control signal during the period from the time of discharge of the capacitor to the time when the charged voltage of the capacitor reaches a specific threshold value.

A 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;
• holding means normally passing the output signals of the band-pass filters and holding output signal voltages of the band-pass filters when a control signal is applied to said holding means;
• a display section having displaying means of systems of the same number as the band-pass filters respectively corresponding to the band-pass filters;
• means for supplying output signals of the holding means to the displaying means for displaying signals corresponding respectively to the output signal levels of said band-pass filters;
• means for producing the control signal and applying the same to the holding means during a specific time period after manipulation of the switch;
• a manually-operated control switch in said means for producing the control signal, said control signal being applied to said holding means after operation of said control switch;
• said holding means comprising analog switches which are normally in the "ON" or closed state and assume the "OFF" or opened state when the control signal is applied thereto and capacitors for voltage holding connected to the output sides of the analog switches;
• rectifying circuits for rectifying output signals of the band-pass filters and supplying the signals thus rectified to the analog switches, and in which the capacitors of the holding means operate to smooth the outputs of the rectifying circuits which have passed through the analog switches when the analog switches are in the "ON" or closed state and, when the analog switches are in the "OFF" or opened state, to hold the output voltages of the rectifying circuits immediately prior to the instants at which the analog switches assume the "OFF" state.