| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an instrument for frequency shift measurement which roughly find a frequency in advance for a digital modulated signal and widen a measurement range of synchronous detection while holding the measurement precision of a frequency shift. SOLUTION: A frequency counter 2 having inputted a modulated signal measures its frequency F in advance and determines a synchronous detection frequency B according to the frequency F. An adder 7 obtains the difference G between the synchronous detection frequency B and a reference frequency C, a frequency shift detector 6 finds the frequency shift E by a phase tracking method from an I and a Q signal which are synchronously detected by using the synchronous detection frequency B, and an adder 8 obtains the difference G and frequency shift E together to find the frequency shift.
|
