| 摘要 |
A principal object of the invention is to detect sparks or arcs (12) in electric circuits (13) or otherwise to detect a spectrum of a broad band of distinct instantaneous radio frequencies in radio frequency noise. The invention rejects extraneous narrow-band signals having frequencies within the broad band, such as by means of filters (21, 27, 29) or a balanced mixer arrangement (32-39). The mixer (37) may be fed from a radio frequency signal duplicator (32, 33, 34) having an input (25) coupled to a source of the spectrum, a first ouptut for one spectrum as duplicated by that duplicator connected to one mixer input (35), and a second output for the other spectrum as duplicated by that duplicator connected to the other mixer input (36). Alternatively, the radio frequency mixer (37) may receive the output of a wide band noise generator (68) at its other input (36, Fig. 5). A combination of a multitude of the distinct instantaneous radio frequencies indicative of the spectrum of the arc (12) is detected, such as with a frequency combination detector (42) having an input (40) coupled to the radio frequency mixer output (38). |
