| 摘要 |
A scanning radio is provided having a plurality of the following elements: 1. a circuit to develop an output representative of the noise power contained in a demodulated signal at a present time; 2. a circuit to delay the output of (1) thereby generating an output representative of the noise power contained in the demodulated signal at a past time; 3. a comparison circuit to compare the output of (2) with the output of (1) to develop an output indicating decreasing noise power and therefore improving signal quality; 4. a comparison circuit to compare the output of (2) with the output of (1) to develop an output indicating increasing noise power and therefore degrading signal quality; 5. a comparison circuit to compare the output of (1) with a reference level to develop an output indicating noise power above/below a threshold and therefore signal strength below/above a corresponding threshold; 6. control processor responsive to outputs (3), (4), and (5) to control local oscillator generator; 7. control processor responsive to outputs (3) and (4) to control local oscillator generator.
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