| 摘要 |
PURPOSE:To exactly perform tuning, by controlling the oscillation frequency of an FM local oscillation circuit so that the noise output of an FM detector can be suppressed at the minimum level. CONSTITUTION:An RF signal to be inputted to an FM front end IC2 to be tested is generated not as an FM modulation signal but a no modulation signal, and an IF signal outputted from the FM front end IC2 is inputted to the FM detector 3 whose frequency is set at a prescribed tuning frequency in advance. By constituting a method in such a way, the output of the FM detector 3 is outputted as only noise because the no modulation signal is inputted. And by controlling the oscillation frequency of the local oscillation circuit 5 connected to the FM front end IC2 so that the level of the noise can be suppressed at the minimum level, the frequency of the IF signal can be fitted to the tuning frequency of the FM detector 3. In such a way, it is possible to perform the tuning exactly even when the automization of the tuning is performed.
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