CENTER FREQUENCY MEASURING APPARATUS FOR SWEEP SIGNAL

PURPOSE:To measure the center frequency of a sweep signal quickly and accurately by counting sweep signals gated for a specified time separately at a specific time position from the center frequency to the upper frequency thereof and that from the center frequency to the lower frequency to determine the sum of the two counts. CONSTITUTION:A trigger pulse generation circuit 1 generates a pulse receiving such a pulse signal with a specified pulse width that the time position of rising and falling thereof applied at an input terminal 2 coincides with the time position at which the center frequency occurs in a sweep signal with a required band width for example, by sweeping with a sine wave. A trigger pulse generation circuit 3 generates a pulse delayed by a specified time from the circuit 1. A gate signal generation circuit 4 generates two gate signals with a pulse width of a specific time in one cycle. A sine wave as sweep signal applied at an input terminal 6 is provided to a pulse converter 5 and then, a sweep signal from the center frequency to the upper frequency and that from the center frequency to the lower frequency are gated 7 alternately for a specified time. A counting circuit 8 counts and adds signals gated in one cycle and the center frequency is indicated on a display 9.