| 摘要 |
PROBLEM TO BE SOLVED: To easily and securely measure the transmission frequency of a direct spread spectrum communication equipment which does not have a function generating a non-modulation wave without inversely spreading a direct spread spectrum wave from the direct spread spectrum communication e equipment. SOLUTION: The transmission signal of a direct spread spectrum communication equipment contains the slight level of the non-modulated component S2 of an RF local oscillation frequency f2 against the modulated direct spread spectrum wave St of a transmission center frequency ft. In a measurement device, the component S2 of the RF local oscillation frequency f2 contained in the transmission signal of the direct spread spectrum communication equipment is extracted by a branching filter circuit. A frequency counter measures the frequency of the extracted component S2, namely, the RF local oscillation frequency f2. A relation that the difference f2-ft of the frequencies becomes a prescribed frequency f1 as shown by f2-ft=f1 or ft-f2=f1 between the RF local oscillation frequency f2 and the transmission center frequency ft. Thus, the transmission center frequency ft can be measured without inversely spreading the direct spread spectrum wave St. |
