| 摘要 |
PCT No. PCT/US90/06113 Sec. 371 Date Mar. 18, 1993 Sec. 102(e) Date Mar. 18, 1993 PCT Filed Oct. 24, 1990 PCT Pub. No. WO92/08143 PCT Pub. Date .A principal object of the invention is to detect sparks or arcs (12) in electric circuits (13) or otherwise to detect a signal having 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 unbalanced to balanced converter (32) having an input (25) coupled to a source of the signal having the spectrum and having balanced outputs connected to the mixer inputs (35, 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 or 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).
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