Patent ID: 6634240
Filing Date: 2003-10-21
Classification: H03K

Abstract:
A zero crossing detector comprising:an analyzer supplied with a current input electrical pulse packet exhibiting multiple zero level crossings, said analyzer detecting one and only one of said zero level crossings of said current input electrical pulse packet occurring anywhere in said electrical pulse packet and emitting a trigger signal indicative of said occurrence; a pre-trigger unit, also supplied with said current input pulse packet, which monitors variations in an amplitude of said current input pulse packet to detect crossing of a pre-trigger level, having a variable amplitude, by said current input pulse packet, said pre-trigger unit being connected to said analyzer to inhibit emission of said trigger signal by said analyzer until said detection of said crossing of said pre-trigger level; and a control unit, connected to said pre-trigger unit, and supplied with an amplitude signal derived from one of said current input electrical pulse packet and at least one previous input electrical pulse packet, for comparing the amplitude of the said pre-trigger level to said amplitude signal and for automatically controlling the amplitude of said pre-trigger level to maintain a working difference therebetween to insure that said analyzer detects said one and only one of said zero level crossings.