Zero crossing detectors

Claim 2

Apparatus for processing signals derived from a transducer reading a recording of digital signals on a magnetic storage carrier moving relative to the transducer, the transducer having an output circuit to provide electrical readout signals, comprising: first means connected to the output circuit and differentiating readout signals as provided by the output circuit in response to transducer readout operation, the first means having a pair of terminals between which the differential signals develop; second means connected to the pair of terminals for clipping the signals at each polarity as developed between the terminals of the pair; a delay line differentiating circuit connected to the pair of terminals to receive the clipping signals and having two-phase outputs; and means connected for separately comparing the output signals of the two-phase output with a pair of reference signals representative of the clipping levels as provided by the second means to provide a train of pulses having characteristics repeatedly occurring when the signal across the terminals of the pair has a particular value between the clipping levels.

Claim 3

Apparatus as set forth in claim 1, the delay line differentiating circuit including a low gain differential amplifier and a delay line connected across its output terminals.

Claim 4

Apparatus as set forth in claim 1, the second means being a pair of first diodes connected across the terminals of the pair of reference signals.

Claim 5

Apparatus as set forth in claim 1, the delay line differentiating circuit including a low gain differential amplifier and a delay line connected across its output terminals, the second means being a pair of first diodes connected across the terminals of the pair; the apparatus including a second pair of diodes individually matched to the diodes of the first pair for providing the pair of reference signals; and the comparing means including a pair of high-gain differential amplifiers respectively comparing the signals at one side of the delay line as connected to one output terminal of the low-gain amplifier with a reference signal of the pair as provided by one diode of the second pair of diodes.

Claim 6

A crossover detector, comprising: first means including a pair of terminals for providing an AC signal of possibly variable amplitude and/or frequency across the terminals of the pair; clipping means connected across the terminals to clip the AC signal at each polarity; a low-gain differential amplifier having its input connected to said terminals to receive said clipped signal and having a pair of output terminals; a delay line connected across the output terminals of the pair to establish a delay line differentiating circuit; second means for providing a voltage representative of at least one of the clipping levels at one polarity; and high-gain differential amplifying means having two input terminals one of which is connected to one of the pairs of output terminals, the other of the input terminals connected to receive the voltage provided by the first means.

Claim 7

A crossover detector, comprising: first means including a pair of terminals for providing an AC signal of possibly variable amplitude and/or frequency across the terminals of the pair; clipping means connected across the terminals to clip the AC signal at each polarity; a low-gain differential amplifier having its input connected to said terminals to receive said clipped signal and having a pair of output terminals; a delay line connected across the output terminals of the pair to establish a delay line differentiating circuit; second means for providing a voltage representative of at least one of the clipping levels at one polarity; and high-gain differential amplifying means having two input terminals one of which is connected to one of the pairs of output terminals, the other of the input terminals connected to receive the voltage provided by the first means.

Claim 8

A crossover detector as set forth in claim 5, the first means including a transducer for reading a recording on a storage carrier, the signals being provided in response to the readout process.

Claim 9

A detector as set forth in claim 6, the first means including a second delay line to establish a delay line differentiating circuit from the transducer readout signal, the signal being derived from across the second delay line.

Claim 10

A crossover detector, comprising: first means including a pair of terminals for providing an AC signal of possibly variable amplitude and/or frequency across the terminals of the pair; clipping means connected across the terminals to clip the AC signal at each polarity; means connected to receive the clipped signal and providing first and second signals in phase opposition representative thereof; reference means to provide first and second reference signals; and first and second comparing means connected to compare the first and second reference signals respectively with the first and second signals and respectively responsive to provide first and second signal pulse trains, the pulses of the first train provided when in response to a change of the clipped signal in one direction the first signal compares with the first reference signal, the pulses of the second train provided when in response to a change of the clipped signal between clipping levels in the opposite direction the second signal compares with the second reference signal.

Claim 11

A crossover detector, comprising: first means including a pair of terminals for providing an AC signal of possibly variable amplitude and/or frequency across the terminals of the pair; clipping means connected across the terminals to clip the AC signal at each polarity; means connected to receive the clipped signal and providing first and second signals in phase opposition representative thereof; reference means to provide first and second reference signals; and first and second comparing means connected to compare the first and second reference signals respectively with the first and second signals and respectively responsive to provide first and second signal pulse trains, the pulses of the first train provided when in response to a change of the clipped signal in one direction the first signal compares with the first reference signal, the pulses of the second train provided when in response to a change of the clipped signal between clipping levels in the opposite direction the second signal compares with the second reference signal.

Claim 12

A crossover detector as set forth in claim 8, the first means including a transducer for reading digital signals from a storage carrier, the spacing of sequential zero crossings of the AC signal having digital significance.

Claim 13

A crossover detector for the detection of zero crossing of signals of the type resulting from reproduction of digital recordings comprising: first means for receiving a signal of variable amplitude and variable polarity as derived from a transducer or the like; second means connected for clipping the amplitude of the signal as received at least in one polarity and at a particular level from zero crossing of the signal; third means for providing a reference signal in representation of the particular level; and fourth means including comparator means connected to receive the clipped signal to compare a representation thereof with the reference signal and including pulse producing means to provide an output pulse at steeper rise time than the slope of the clipped signal pulse subsequent to clipping and at duration shorter than the period between two sequential zero crossings of the signal at opposite polarity.

Claim 14

A crossover detector for the detection of zero crossing of signals of the type resulting from reproduction of digital recordings comprising: first means for receiving a signal of variable amplitude and variable polarity as derived from a transducer or the like; second means connected for clipping the amplitude of the signal as received at least in one polarity and at a particular level from zero crossing of the signal; third means for providing a reference signal in representation of the particular level; and fourth means including comparator means connected to receive the clipped signal to compare a representation thereof with the reference signal and including pulse producing means to provide an output pulse at steeper rise time than the slope of the clipped signal pulse subsequent to clipping and at duration shorter than the period between two sequential zero crossings of the signal at opposite polarity.

Claim 15

A circuit for providing representation of the zero crossing of an AC signal of variable frequency and/or amplitude as developed between a first pair of terminals comprising: first means connected to the first pair of terminals and having a second pair of terminals and providing a signal between the terminals of the second pair in representation of differentiation of the signal developed between the terminals of the first pair; second means connected across the terminals of the second pair for clipping the signals between the second pair of terminals so that the latter signal does not exceed a clipping level at least for one polarity; third means including nonsaturation amplifier means and connected to the terminals of the second pair to provide two separate signal trains mutually representative of each other; fourth means providing a pair of reference signals individually representative of the clipping levels; a pair of fifth means connected to the third means and to the fourth means to separately compare the signals of the train with the reference signals of the pair, and respectively providing output signals with sharp rise times in mutually clutching relation and if individually the signals of a train of the trains has particular relation to the respective reference signal with which it is compared; and sixth means for combining the outputs of the pair of fifth means.

Claim 16

A circuit for providing representation of the zero crossing of an AC signal of variable frequency and/or amplitude as developed between a first pair of terminals comprising: first means connected to the first pair of terminals and having a second pair of terminals and providing a signal between the terminals of the second pair in representation of differentiation of the signal developed between the terminals of the first pair; second means connected across the terminals of the second pair for clipping the signals between the second pair of terminals so that the latter signal does not exceed a clipping level at least for one polarity; third means including nonsaturation amplifier means and connected to the terminals of the second pair to provide two separate signal trains mutually representative of each other; fourth means providing a pair of reference signals individually representative of the clipping levels; a pair of fifth means connected to the third means and to the fourth means to separately compare the signals of the train with the reference signals of the pair, and respectively providing output signals with sharp rise times in mutually clutching relation and if individually the signals of a train of the trains has particular relation to the respective reference signal with which it is compared; and sixth means for combining the outputs of the pair of fifth means.

Claim 17

A circuit for providing representation of the zero crossing of an AC signal of variable frequency and/or amplitude as developed between a first pair of termiNals, comprising; first means connected to the first pair of terminals and having a second pair of terminals and providing a signal between the terminals of the second pair in representation of differentiation of the signal developed between the terminals of the first pair; second means connected across the terminals of the second pair for clipping the signals between the second pair of terminals so that the latter signal does not exceed a clipping level at least for one polarity; third means connected to the terminals of the second pair and providing a first signal equal to the sum of a second signal as derived from the signal between the second pair of terminals, and a third signal equal to a delayed inversion of the second signal; and fourth means providing a fourth signal in representation of the clipping level, comparing same with the first signal and producing a representation when the fourth signal equals the first signal.

Claim 18

A circuit for providing representation of the zero crossing of an AC signal of variable frequency and/or amplitude as developed between a first pair of termiNals, comprising; first means connected to the first pair of terminals and having a second pair of terminals and providing a signal between the terminals of the second pair in representation of differentiation of the signal developed between the terminals of the first pair; second means connected across the terminals of the second pair for clipping the signals between the second pair of terminals so that the latter signal does not exceed a clipping level at least for one polarity; third means connected to the terminals of the second pair and providing a first signal equal to the sum of a second signal as derived from the signal between the second pair of terminals, and a third signal equal to a delayed inversion of the second signal; and fourth means providing a fourth signal in representation of the clipping level, comparing same with the first signal and producing a representation when the fourth signal equals the first signal.