| 摘要 |
A method is described for operating a radio receiver (4, 12) in such a manner as to accurately and rapidly identify unlistenable, very listenable and marginally listenable channels, and display the listenable and very listenable channels along with an indication of their signal strength, noise and quality on a screen (44). A reference value of automatic fine tuning voltage is found for the particular receiver. Capacitors (24, 26) that are charged in accordance with the levels of signal strength, noise and automatic fine tuning voltages are sampled before being fully charged at each channel change, and averages of the respective samples are computed as well as the offset between the average of the automatic fine tuning samples and the reference value of automatic fine tuning voltage. A channel having sample averages not meeting certain criteria is rejected as unlistenable, and, of the others, a channel having a very low average on its noise capacitor is identified as very listenable. Those of the remaining channels that are at least marginally listenable are identified by similar analysis of a second group of samples. The criteria for signal strengths and noise may be varied with ambient temperature, and the criteria for noise can be adjusted on the basis of the noisiest channel or the noise produced when the antenna (2) is grounded. Those channels having the greatest signal strength are associated with tuning buttons (42), and indications of these associations are made on the screen. |
