| 摘要 |
A radio receiver (10) having a tuned IF stage (20) which is followed by a detector stage (24) producing an output representative of the change in frequency of a signal applied at its input. A predetermined frequency alignment signal (80) and a white noise source signal are alternately switched through the IF amplifier stage (20) of the receiver being aligned. A series connected integrating capacitor (50) and a tuning meter (60) are coupled between the receiver's detector output (24b) and ground potential (70).
<??>In operation, during the interval of white noise being applied to the IF stage, the tuning meter (60) is shorted (40, 44, 46) and the capacitor (50) is charged to a net voltage Vn which is representative of the center frequency of the IF. When the alignment signal is applied to the IF stage, the tuning meter (60) short is removed and a signal Vs appears across the capacitor-meter circuit, whereby the meter reading is indicative of Vs-Vn which represents relative receiver alignment. |
