| 摘要 |
A frequency responsive device, such as a tuned amplifier, filter, etc., is tested for center frequency and bandwidth. A decreasing sweep frequency signal is applied to the device and the output detected. A waveform analyzer produces a first pulse when the detected signal reaches a predetermined amplitude and a second pulse when the detected signal falls below the predetermined amplitude. The first and second pulses trigger or operate a counter which counts the cycles of sweep frequency signal for a predetermined duration in response to each pulse. The sum in the counter is indicative of the center frequency. The count after the first pulse is multiplied by 2 and added to the complement of the sum in the counter after the second pulse to produce a remainder which is multiplied by 2 to indicate the bandwidth.
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