| 摘要 |
PURPOSE:To ensure the high-accuracy reading of the carrier frequency by using the TV signal as the input and with installation of the FM modulation circuit, pulse generator circuit, gate circuit, frequency detector and display circuit respectively. CONSTITUTION:When TV signal A featuring the synchronous tip and the white peak is applied to terminal 21, the FM modulation is given through FM modulator circuit 1 to deliver the frequency of fLHz according to the synchronous part of the TV signal as well as signal B of frequency of fHHz according to the white peak part. Digital signal C of H-level is generated only at the synchronous part and the white peak part at pulse generator circuit 4 to be applied to gate 2 as well as to frequency detector circuit 3. The output of circuit 1 is applied to circuit 2, and signal D corresponding to the output of circuit 4 is supplied to circuit 3. The pulse number is counted at circuit 3 for the reference input signal of a fixed frequency and then displayed at display circuit 5 in the form of the digital signal. Thus, the quick and accurate measurement is possible for the frequency at the areas of the synchronous tip and the white peak. |
