| 摘要 |
The invention relates to a noise-figure measuring circuit for the determination of the receiver noise in an operational radar receiver. A comparator is alternatively supplied with the receiver noise and the sum of the receiver noise and the noise signals, which are obtained from a noise source connected to the input of the radar receiver, each pulse repetition period. This comparator converts the noise signals exceeding a certain threshold into standardised noise pulses. The noise-figure measuring circuit comprises two counters which are supplied with the noise pulses derived from the receiver noise and also with the noise pulses derived from the sum of the receiver noise and the noise signals from the noise source. One of the two counters functions as reference counter. If this counter has reached a certain count position, the counters are both blocked, and the ratio of the count positions determines the ratio between the power of the receiver noise and the power of the noise signals from the noise source.
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