Correlators using shift registers

Claim 2

A correlator comprising: two sets of multivibrators, each of which are serially connected to form a shift register, each set having the same number of multivibrators; each multivibrator of the two sets having a set and a reset output lead, indicating its binary state; one of the multivibrators at one end of the series of each of the two sets being connectable to a source of signals, generally a stream of bilevel signals or pulses, having a predetermined time duration or a multiple thereof; each multivibrator of both sets being connectable to a clocking source for shifting the states of the multivibrators in synchronism with the streams of pulses; two pluralities of resistors, one plurality for each set of the multivibrators; one resistor for each multivibrator; each resistor being connected by its input end to a set or reset output lead of a multivibrator of its own set, and by the output end to the output end of a resistor which is connected to an output set or reset lead of a corresponding multivibrator of the other set; a set of single-pole double-throw switches, one switch for each pair of multivibrators from corresponding multivibrator sets; each of whose switch arms are connected to the point joining two resistors connected to corresponding multivibrators; corresponding contact points of each of the switches being coNnected together to form two sets of common contact points; an inverter whose input is connected to one of the sets of common contact points; a summing circuit, having two inputs, one input being connected to the other set of common contact points, the other input being connected to the output of the inverter, for summing the currents developed across all of the resistors; control means for controlling the polarity, or setting, of the individual switch arms, so that, with input signals at the input multivibrators, a maximum sum signal may be obtained at the output of the summer when the settings of the switch arms matches a particular combination of binary states of both sets of multivibrators.

Claim 3

A correlator according to claim 1, wherein the resistance of each of the resistors of one plurality of resistors connected to one of the sets of multivibrators has a weighted value with respect to the resistance of the other set of resistors.

Claim 4

A correlator according to claim 2, wherein the resistance of each of the resistors of one set is twice the resistance of the resistors of the other set.

Claim 5

A correlator according to claim 3, wherein the control means for controlling the position of the switch arms comprises: a control shift register, having the same number of multivibrators as there are switches, and adapted for receiving a bilevel input signal; each multivibrator having a set or reset output lead, at which a voltage at one of two voltage levels is available; a set of relays of the same number as the number of switches; the control winding of each relay being connected to a set or reset output lead of a multivibrator of the control shift register, one of the voltage levels at the set or reset output leads causing the switch arm to be at one of its two positions, the other voltage level causing the switch arm to be at its other position; the plunger of each relay, actuated by current through the control winding of each relay, controlling the motion of a switch arm; with the result that the position of the switch arm of each switch is determined by the binary state of the multivibrator to whose set or reset lead it is connected.

Claim 6

A correlator according to claim 4, wherein the control register ceases to shift after every multivibrator of the control register has been set, by a signal to its input, to one of the two binary states.

Claim 7

A correlator according to claim 5, wherein all of the input ends of the resistors of one of the pluralities of resistors are connected to only the set or to only the reset output leads of the multivibrator set to which they are connected; and all of the resistors of the other plurality of resistors are connected to only the set or to only the reset output leads of the multivibrator set to which they are connected.

Claim 8

A correlator comprising: a J number of rows of signal shift registers, each row containing an I number of serially connected multivibrators, all the shift registers being arranged in I columns; each multivibrator having a set and reset output lead, at one of which appears one bilevel voltage, and at the other of which appears the other bilevel voltage, the voltages indicating the binary state of the multivibrator; a reference shift register, substantially identical to one of the signal shift registers; one of the multivibrators at one end of the series of each shift register being connectable to a source of signals, generally a stream of bilevel signals, or pulses, each pulse having a predetermined time duration or multiple thereof; each multivibrator of every signal and reference shift register being connectable to a clocking source for shifting the states of the multivibrators in synchronism with the streams of pulses; a compound ladder arrangement of resistors comprising an I number of columns and a J number of rows of resistors; the columns of resistors being connected to common junction points at both ends of the column, one junction point being a common ground point; each of the I columns of resistors consisting of a series connection of J-I resistors having a value of R/2 ohms, and one resistor at the common ground point end having a value of R ohms; each of the J rows of resistors including I resistors, one for each column, each of the I X J row resistors having a value of R ohms, one end of one row resistor from all but one of the J rows being connected at a junction of two columnar resistors, one end of each of the other row resistors from the other row being connected to the other, ungrounded, junction point of the columnar resistors; an I X J number of modulo-two adders whose inputs are the set or reset output leads of the signal and reference shift registers as determined from the logical expression Sij - Ri Sij Ri + Sij Ri, 1 < or = i < or = I, 1 < or = j < or = J, where the unbarred terms relate to the voltage level of the bilevel signal at a set, or reset, output lead, the barred terms relate to the negative of the voltage level of the bilevel signal at a set, or reset, output lead, Sij relates to the specific multivibrator of the signal shift register in the ith column and jth row, and Ri relates to the ith multivibrator of the reference shift register.

Claim 9

A correlator comprising: a J number of rows of signal shift registers, each row containing an I number of serially connected multivibrators, all the shift registers being arranged in I columns; each multivibrator having a set and reset output lead, at one of which appears one bilevel voltage, and at the other of which appears the other bilevel voltage, the voltages indicating the binary state of the multivibrator; a reference shift register, substantially identical to one of the signal shift registers; one of the multivibrators at one end of the series of each shift register being connectable to a source of signals, generally a stream of bilevel signals, or pulses, each pulse having a predetermined time duration or multiple thereof; each multivibrator of every signal and reference shift register being connectable to a clocking source for shifting the states of the multivibrators in synchronism with the streams of pulses; a compound ladder arrangement of resistors comprising an I number of columns and a J number of rows of resistors; the columns of resistors being connected to common junction points at both ends of the column, one junction point being a common ground point; each of the I columns of resistors consisting of a series connection of J-I resistors having a value of R/2 ohms, and one resistor at the common ground point end having a value of R ohms; each of the J rows of resistors including I resistors, one for each column, each of the I X J row resistors having a value of R ohms, one end of one row resistor from all but one of the J rows being connected at a junction of two columnar resistors, one end of each of the other row resistors from the other row being connected to the other, ungrounded, junction point of the columnar resistors; an I X J number of modulo-two adders whose inputs are the set or reset output leads of the signal and reference shift registers as determined from the logical expression Sij - Ri Sij Ri + Sij Ri, 1 < or = i < or = I, 1 < or = j < or = J, where the unbarred terms relate to the voltage level of the bilevel signal at a set, or reset, output lead, the barred terms relate to the negative of the voltage level of the bilevel signal at a set, or reset, output lead, Sij relates to the specific multivibrator of the signal shift register in the ith column and jth row, and Ri relates to the ith multivibrator of the reference shift register.